22.8: India under British Imperialism
Indian Architecture under British Imperialism
The establishment of the British Empire greatly influenced the architecture and culture of India and led to a fusion of styles and techniques.
Summarize the changes that took place in Indian architecture during the establishment of the British Empire
Key Points
- The establishment of the British Empire in the 18th century and the subsequent westernization of India paved the way for a radical change of artistic taste, and a new style of art and architecture emerged.
- As a whole, the European advent was marked by a relative insensitivity to native art traditions; former Indian patrons of art became less wealthy and influential, and Western art became more ubiquitous .
- The fusion of Indian traditions with European style at this time became evident in architectural styles; as with the Mughals, architecture under European colonial rule became an emblem of power designed to endorse the occupying power.
- The Indo-Saracenic Revival was an architectural style and movement in the late 19th century, where public and government buildings were often rendered on an intentionally grand scale.
Key Terms
- Company style : A hybrid Indo-European style of paintings made in India by Indian artists, many of whom worked for European patrons in the British East India Company or other foreign Companies in the 18th and 19th centuries.
- aesthetic : Concerned with beauty, artistic impact, or appearance.
- advent : Coming; coming to; approach; arrival.
- ubiquitous : Being everywhere at once: omnipresent.
Impact of British Imperialism in India
The British arrived in India in 1615; over the centuries, they gradually overthrew the Maratha and Sikh empires and other small independent kingdoms. The establishment of the British Empire in the 18th century laid the foundation for modern India’s contact with the West. Westernization paved the way for a radical change of artistic taste, and a style emerged that represented the adjustment of traditional artists to new fashions and demands.
British colonial rule had a great impact on Indian art. As a whole, the European advent was marked by a relative insensitivity to native art traditions; former Indian patrons of art became less wealthy and influential, and Western art became more ubiquitous as the British Empire established schools of art in major cities, such as the Bombay Art Society in 1888. The Company style of paintings, for example, became common, created by Indian artists working for European patrons of the East India Company . By 1858, the British government took over the task of administration of India under the British Raj. The fusion of Indian traditions with European style at this time became evident in architectural styles. Toward the end of the 19th century, rising nationalism attempted a conscious revival of Indian art.
Architecture Under British Imperialism
As with the Mughals, architecture under European colonial rule became an emblem of power designed to endorse the occupying power. Numerous European countries invaded India and created architectural styles reflective of their ancestral and adopted homes. The European colonizers created architecture that symbolized their mission of conquest, dedicated to the state or religion. Among the key British architects of this time were Robert Fellowes Chisholm, Charles Mant, Henry Irwin, William Emerson, George Wittet, and Frederick Stevens.
The Indo-Saracenic Revival
The Indo-Saracenic Revival (also known as Indo- Gothic , Mughal-Gothic, Neo-Mughal, or Hindu-Gothic) was an architectural style and movement by British architects in the late 19th century. It drew elements from native Indo-Islamic and Indian architecture and combined them with Gothic revival and Neo-Classical styles favored in Britain. Public and government buildings, such as clock towers, courthouses, municipal buildings, colleges, and town halls, were often rendered on an intentionally grand scale, reflecting and promoting a notion of an invincible British Empire. Infrastructure was composed of iron, steel, and poured concrete and included domes , overhanging eaves, pointed arches , vaulted roofs, pinnacles , open pavilions, and pierced open arcading.
Examples of Colonial Architecture
The major cities colonized during this period were Madras, Calcutta, Bombay, Delhi, Agra, Bankipore, Karachi, Nagpur, Bhopal, and Hyderabad. St. Andrew’s Kirk in Madras (now Chennai) is known for its colonial architecture. The building is circular in form and is sided by two rectangular sections; the entrance is lined with 12 colonnades and two British lions, with the motto of East India Company engraved on them. The interior holds 16 columns , and the dome is painted blue and decorated with gold stars.
The Victoria Memorial in Calcutta is another symbol of the British Empire, built as a monument in tribute to Queen Victoria’s reign. The plan of the building consists of one large central part covered with a larger dome, with colonnades separating the two chambers. Each corner holds a smaller dome and is floored with marble plinth. The memorial stands on 26 acres of garden surrounded by reflective pools.
Indian Painting under British Imperialism
Under British Imperialism, painting in India took on many western characteristics throughout the 18th and 19th centuries.
Discuss the effects the arrival of the British Empire had on Indian painting
Key Points
- The establishment of the British Empire in the 18th century and the subsequent westernization of India paved the way for a radical change of artistic taste, and a new style of art and painting emerged.
- In the 18th century, the merchants of the East India Company provided a large market for native art, and a distinct genre of watercolor painting developed known as the Company style .
- The attitude in the mid-19th century was one of general British disregard for Indian art, followed by the establishment of British schools and the propagation of Western values in art education.
- Raja Ravi Varma was among the first Indian painters to use Western techniques to illustrate Indian themes and traditions.
- The Bengal School of Art arose in the early 20th century as an avant garde and nationalist movement reacting against the Western academic art styles; instead, it promoted a return to paintings such as the Mughal miniatures .
Key Terms
- Company style : A hybrid Indo-European style of paintings made in India by Indian artists, many of whom worked for European patrons in the British East India Company or other foreign Companies in the 18th and 19th centuries.
- East India Company : An English and later British joint-stock company, which was formed to pursue trade with the East Indies but ended up trading mainly with the Indian subcontinent and Qing China.
Overview: British Imperialism and Art
British colonial rule had a great impact on Indian art. Old patrons of art became less wealthy and influential, and Western art more ubiquitous as the British Empire established schools of art in major cities, such as the Bombay Art Society in 1888. The Company style of paintings became common, created by Indian artists working for European patrons of the East India Company. The style was mainly Romanticized, with watercolor the primary medium used to convey soft textures and tones . By 1858, the British government took over the task of administration of India under the British Raj, and the fusion of Indian traditions with European style at this time is evident in a great deal of the artwork from this period.
Painting Under British Imperialism
The Company Style
In the 18th century, oil and easel painting brought many European artists to India in search of fame and fortune, including Thomas and William Daniel, Joshua Reynolds, George Chinnery, and others. The merchants of the East India Company provided a large market for native art in the 18th century, and a distinct genre of watercolor painting developed that depicted scenes of everyday life, regalia of princely courts, and Indian festivities and rituals . Referred to as the Company style or Patna style, this style of painting flourished at first in Murshidabad and spread to other cities of British India.
The Establishment of Art Schools
While the 18th century saw moderate British manifestations of Indian art, monuments, literature, and culture , the attitude in the mid-19th century shifted to one of disregard for Indian art. To propagate Western values in art education along with the colonial agenda, the British established art schools in Calcutta and Madras in 1854 and in Bombay in 1857. After 1857, John Griffith and John Lockwood Kipling came out to India together and headed the Sir JJ School of Art. Griffith was considered one of the finest Victorian painters to come to India, and Kipling went on to head the Mayo School of Arts in 1878.
Raja Ravi Varma
Raja Ravi Varma (1848–1906) was a remarkable self-taught Indian painter from the princely state of Travancore. He is considered the first of the modernists, and he advocated for the use of Western techniques to develop a new aesthetic in the subjective interpretation of Indian culture. His work was considered to be among the best examples of the fusion of Indian traditions with the techniques of European academic art, and it came to play an important role in the development of the Indian national consciousness.
The Bengal School
As more artists began using Western ideas of composition , perspective , and realism to illustrate Indian themes, others rebelled against these styles. The Bengal School of Art, commonly referred to as the Bengal School, arose in the early 20th century as an avant garde and nationalist movement reacting against the Western academic art styles previously promoted in India. Also known as “Indian style of painting” in its early days, it was led by Abanindranath Tagore (1871–1951) and supported by British art teacher E. B. Havell. Following the influence of Indian spiritual ideas in the West, Havell attempted to reform the teaching methods at the Calcutta School of Art by encouraging students to imitate Mughal miniatures. This caused controversy among some who considered it to be a retrogressive move; however, Havell and Tagore believed the technique to be expressive of India’s distinct spiritual qualities, as opposed to the “materialism” of the West.
The best known painting by Tagore is Bharat Mata (“Mother India”), depicting a young woman with four arms in the manner of Hindu deities , holding objects symbolic of India’s national aspirations. Other painters and artists of the Bengal school included Gaganendranath Tagore, Asit Kumar Haldar, M.A.R Chughtai, Sunayani Devi, Kshitindranath Majumdar, Nandalal Bose, Kalipada Ghoshal, Sughra Rababi, and Sudhir Khastgir. The Bengal school eventually paved the way for future modernist movements, and its influence declined in the 1920s.
- Curation and Revision. Provided by : Boundless.com. License : CC BY-SA: Attribution-ShareAlike
- Municipal Corporation Building, Mumbai. Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/File:Municipal_Corporation_Building,_Mumbai.jpg. License : CC BY-SA: Attribution-ShareAlike
- 375px-St_Andrews_Church_-_The_Kirk.jpg. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/File:St_Andrews_Church_-_The_Kirk.jpg. License : CC BY-SA: Attribution-ShareAlike
- Indian art. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Indian_art. License : CC BY-SA: Attribution-ShareAlike
- Visual Arts Of The Indian Subcontinent. Provided by : Wikibooks. Located at : en.wikibooks.org/wiki/Visual_Arts_Of_The_Indian_Subcontinent. License : CC BY-SA: Attribution-ShareAlike
- Modern Indian painting. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Modern_Indian_painting. License : CC BY-SA: Attribution-ShareAlike
- Indo-Saracenic Revival architecture. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Indo-Saracenic_Revival_architecture. License : CC BY-SA: Attribution-ShareAlike
- Bengal school of art. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Bengal_school_of_art. License : CC BY-SA: Attribution-ShareAlike
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- Shakuntala (Raja Ravi Varma). Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Shakuntala_(Raja_Ravi_Varma). License : CC BY-SA: Attribution-ShareAlike
- Visual Arts of the Indian Subcontinent. Provided by : Wikipedia. Located at : en.wikibooks.org/wiki/Visual_Arts_Of_The_Indian_Subcontinent. License : CC BY-SA: Attribution-ShareAlike
- Modern Indian painting. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Modern_Indian_painting. License : CC BY-SA: Attribution-ShareAlike
- Indian Art. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Indian_art. License : CC BY-SA: Attribution-ShareAlike
- Bengal School of Art. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Bengal_school_of_art. License : CC BY-SA: Attribution-ShareAlike


What is your responsibility for learning in college?
What resources will you use to meet these expectations?
What are the common challenges in the first year?
College Has Its Own Language and Customs
Going to college—even if you are not far from home—is a cultural experience. It comes with its own language and customs, some of which can be confusing or confounding at first. Just like traveling to a foreign country, it is best if you prepare by learning what words mean and what you are expected to say and do in certain situations.
Let’s first start with the language you may encounter. In most cases, there will be words that you have heard before, but they may have different meanings in a college setting. Take, for instance, “office hours.” If you are not in college, you would think that it means the hours of a day that an office is open. If it is your dentist’s office, it may mean Monday through Friday from 8 a.m. to 5 p.m. In college, “office hours” can refer to the specific hours a professor is in her office to meet with students, and those hours may be only a few each day: for example, Mondays and Wednesdays from 1 p.m. until 3 p.m.
“Syllabus” is another word that you may not have encountered, but it is one you will soon know very well. A syllabus is often called the “contract of the course” because it contains information about what to expect—from the professor and the student. It is meant to be a roadmap for succeeding in the class. Understanding that office hours are for you to ask your professor questions and the syllabus is the guide for what you will be doing in the class can make a big difference in your transition to college. The table on Common College Terms, has a brief list of other words that you will want to know when you hear them on campus.
Table 1.1: Common College Terms, What They Mean, and Why You Need to Know
Term
What It Means
Why You Need to Know
Attendance policy
A policy that describes the attendance and absence expectations for a class
Professors will have different attendance expectations. Read your syllabus to determine which ones penalize you if you miss too many classes.
Final exam
A comprehensive assessment that is given at the end of a term
If your class has a final exam, you will want to prepare for it well in advance by reading assigned material, taking good notes, reviewing previous tests and assignments, and studying.
Learning
The process of acquiring knowledge
In college, most learning happens
outside
the classroom. Your professor will only cover the main ideas or the most challenging material in class. The rest of the learning will happen on your own.
Office hours
Specific hours professor is in the office to meet with students
Visiting your professor during office hours is a good way to get questions answered and to build rapport.
Plagiarism
Using someone’s words, images, or ideas as your own, without proper attribution
Plagiarism carries much more serious consequences in college, so it is best to speak to your professor about how to avoid it and review your student handbook’s policy.
Study
The process of using learning strategies to understand and recall information
Studying in college may look different than studying in high school in that it may take more effort and more time to learn more complex material.
Syllabus
The contract of a course that provides information about course expectations and policies
The syllabus will provide valuable information that your professor will assume you have read and understood. Refer to it first when you have a question about the course.
Activity
The language that colleges and universities use can feel familiar but mean something different, as you learned in the section above, and it can also seem alien, especially when institutions use acronyms or abbreviations for buildings, offices, and locations on campus. Terms such as “quad” or “union” can denote a location or space for students. Then there may be terms such as “TLC” (The Learning Center, in this example) that designate a specific building or office. Describe a few of the new terms you have encountered so far and what they mean. If you are not sure, ask your professor or a fellow student to define it for you.
In addition to its own language, higher education has its own way of doing things. For example, you may be familiar with what a teacher did when you were in high school, but do you know what a professor does? It certainly seems like they fulfill a very similar role as teachers in high school, but in college professors’ roles are often much more diverse. In addition to teaching, they may also conduct research, mentor graduate students, write and review research articles, serve on and lead campus committees, serve in regional and national organizations in their disciplines, apply for and administer grants, advise students in their major, and serve as sponsors for student organizations. You can be assured that their days are far from routine. See the Table on Differences between High School Teachers and College Professors for just a few differences between high school teachers and college professors.
Table 1.2: Differences between High School and College Faculty
High School Faculty
College Faculty
Often have degrees or certifications in teaching in addition to degrees in subject matter
Most likely have not even taken a course in teaching as part of their graduate program
Responsibilities include maximizing student learning and progress in a wide array of areas
Responsibilities include providing students with content and an assessment of their mastery of the content
Are available before or after school or during class if a student has a question
Are available during office hours or by appointment if a student needs additional instruction or advice
Communicate regularly and welcome questions from parents and families about a student’s progress
Cannot communicate with parents and families of students without permission because of the Federal Educational Rights and Privacy Act (FERPA)
The relationships you build with your professors will be some of the most important ones you create during your college career. You will rely on them to help you find internships, write letters of recommendation, nominate you for honors or awards, and serve as references for jobs. You can develop those relationships by participating in class, visiting during office hours, asking for assistance with coursework, requesting recommendations for courses and majors, and getting to know the professor’s own academic interests. One way to think about the change in how your professors will relate to you is to think about the nature of relationships you have had growing up. In Figure 1.8: You and Your Relationships Before College you will see a representation of what your relationships probably looked like. Your family may have been the greatest influencer on you and your development.
"The relationships you build with your professors will be some of the most important ones during your college career."
In college, your networks are going to expand in ways that will help you develop other aspects of yourself. As described above, the relationships you will have with your professors will be some of the most important. But they won’t be the only relationships you will be cultivating while in college. Consider the Figure on You and Your Relationships during College and think about how you will go about expanding your network while you are completing your degree.
Your relationships with authority figures, family, and friends may change while you are in college, and at the very least, your relationships will expand to peer networks—not friends, but near-age peers or situational peers (e.g., a first-year college student who is going back to school after being out for 20 years)—and to faculty and staff who may work alongside you, mentor you, or supervise your studies. These relationships are important because they will allow you to expand your network, especially as it relates to your career. As stated earlier, developing relationships with faculty can provide you with more than just the benefits of a mentor. Faculty often review applications for on-campus jobs or university scholarships and awards; they also have connections with graduate programs, companies, and organizations. They may recommend you to colleagues or former classmates for internships and even jobs.
Other differences between high school and college are included in the table about Differences between High School and College. Because it is not an exhaustive list of the differences, be mindful of other differences you may notice. Also, if your most recent experience has been the world of work or the military, you may find that there are more noticeable differences between those experiences and college.
Table 1.3: Differences between High School and College
High School
College
Why You Need to Know the Difference
Grades
Grades are made up of frequent tests and homework, and you may be able to bring up a low initial grade by completing smaller assignments and bonuses.
Grades are often made up of fewer assignments, and initial low grades may keep you from earning high course grades at the end of the semester.
You will need to be prepared to earn high grades on all assignments because you may not have the opportunity to make up for lost ground.
Learning
Learning is often done in class with the teacher guiding the process, offering multiple ways to learn material and frequent quizzes to ensure that learning is occurring.
Learning happens mostly outside of class and on your own. Faculty are responsible for assigning material and covering the most essential ideas; you are responsible for tracking and monitoring your learning progress.
You will need to practice effective learning strategies on your own to ensure that you are mastering material at the appropriate pace.
Getting Help
Your teachers, parents, and a counselor are responsible for identifying your need for help and for creating a plan for you to get help with coursework if you need it. Extra assistance is usually reserved for students who have an official diagnosis or need.
You will most likely need help to complete all your courses successfully even if you did not need extra help in high school. You will be responsible for identifying that you need it, accessing the resources, and using them.
Because the responsibility is on you, not parents or teachers, to get the help you need, you will want to be aware of when you may be struggling to learn material. You then will need to know
where
the support can be accessed on campus or where you can access support online.
Tests and Exams
Tests cover small amounts of material and study days or study guides are common to help you focus on what you need to study. If you paid attention in class, you should be able to answer all the questions.
Tests are fewer and cover more material than in high school. If you read all the assigned material, took good notes in class, and spent time practicing effective study techniques, you should be able to answer all the questions.
This change in how much material and the depth of which you need to know the material is a shock for some students. This may mean you need to change your strategies dramatically to get the same results.
Some of What You Will Learn Is “Hidden”
Many of the college expectations that have been outlined so far may not be considered common knowledge, which is one reason that so many colleges and universities have classes that help students learn what they need to know to succeed. The term, which was coined by sociologists,
7
describes unspoken, unwritten, or unacknowledged (hence,
hidden
) rules that students are expected to follow that can affect their learning. To illustrate the concept, consider the situation in the following activity.
Activity
Situation: Your history syllabus indicates that, on Tuesday, your professor is lecturing on the chapter that covers the stock market crash of 1929.
This information sounds pretty straightforward. Your professor lectures on a topic and you will be there to hear it. However, there are some unwritten rules, or hidden curriculum, that are not likely to be communicated. Can you guess what they may be? Take a moment to write at least one potential unwritten rule.
What is an unwritten rule about what you should be doing before attending class?
_______________________________________________________________
What is an unwritten rule about what you should be doing in class?
_______________________________________________________________
What is an unwritten rule about what you should be doing after class?
_______________________________________________________________
What is an unwritten rule if you are not able to attend that class?
_______________________________________________________________
Some of your answers could have included the following:
Before class:
Read the assigned chapter, take notes, record any questions you have about the reading.
During class:
Take detailed notes, ask critical thinking or clarifying questions, avoid distractions, bring your book and your reading notes.
After class:
Reorganize your notes in relation to your other notes, start the studying process by testing yourself on the material, make an appointment with your professor if you are not clear on a concept.
Absent:
Communicate with the professor, get notes from a classmate, make sure you did not miss anything important in your notes.
The expectations before, during, and after class, as well as what you should do if you miss class, are often unspoken because many professors assume you already know and do these things or because they feel you should figure them out on your own. Nonetheless, some students struggle at first because they don’t know about these habits, behaviors, and strategies. But once they learn them, they are able to meet them with ease.
Learning Is Your Responsibility
As you may now realize by reviewing the differences between high school and college, learning in college is your responsibility. Before you read about the how and why of being responsible for your own learning, complete the Activity below.
Activity
For each statement, circle the number that best represents you, with 1 indicating that the statement is least like you, and 5 indicating that the statement is most like you.
Table 1.4
Most of the time, I can motivate myself to complete tasks even if they are boring or challenging.
1
2
3
4
5
I regularly work hard when I need to complete a task no matter how small or big the task may be.
1
2
3
4
5
I use different strategies to manage my time effectively and minimize procrastination to complete tasks.
1
2
3
4
5
I regularly track my progress completing work and the quality of work I do produce.
1
2
3
4
5
I believe how much I learn and how well I learn is my responsibility.
1
2
3
4
5
Were you able to mark mostly 4s and 5s? If you were even able to mark at least one 4 or 5, then you are well on your way to taking responsibility for your own learning. Let’s break down each statement in the components of the ownership of learning:
Motivation.
Being able to stay motivated while studying and balancing all you have to do in your classes will be important for meeting the rest of the components.
Deliberate, focused effort.
Taking ownership of learning will hinge on the effort that you put into the work. Because most learning in college will take place outside of the classroom, you will need determination to get the work done. And there will be times that the work will be challenging and maybe even boring, but finding a way to get through it when it is not exciting will pay in the long run.
Time and task management.
You will learn more about strategies for managing your time and the tasks of college in a later chapter, but without the ability to control your calendar, it will be difficult to block out the time to study.
Progress tracking.
A commitment to learning must include monitoring your learning, knowing not only what you have completed (
this is where a good time management strategy can help you track your tasks
), but also the quality of the work you have done.
Taking responsibility for your learning will take some time if you are not used to being in the driver’s seat. However, if you have any difficulty making this adjustment, you can and should reach out for help along the way.
What to Expect During the First Year
While you may not experience every transition within your first year, there are rhythms to each semester of the first year and each year you are in college. Knowing what to expect each month or week can better prepare you to take advantage of the times that you have more confidence and weather through the times that seem challenging. Review the table on First-Year College Student Milestones. There will be milestones each semester you are in college, but these will serve as an introduction to what you should expect in terms of the rhythms of the semester.
Table 1.5 While each student’s first semester will differ, you will likely experience some of the following typical college milestones.
First-Year College Student Milestones for the First Semester
August
September
October
November
December
Expanding social circles
Completing first test and projects
Feeling more confident about abilities
Balancing college with other obligations
Focusing on finishing strong
Experiencing homesickness or imposter syndrome
Earning “lower-than-usual” grades or not meeting personal expectations
Dealing with relationship issues
Staying healthy and reducing stress
Handling additional stress of the end of the semester
Adjusting to the pace of college
Learning to access resources for support
Planning for next semester and beyond
Thinking about majors and degrees
Thinking about the break and how to manage changes
The first few weeks will be pretty exhilarating. You will meet new people, including classmates, college staff, and professors. You may also be living in a different environment, which may mean that a roommate is another new person to get to know. Overall, you will most likely feel both excited and nervous. You can be assured that even if the beginning of the semester goes smoothly, your classes will get more challenging each week. You will be making friends, learning who in your classes seem to know what is going on, and figuring your way around campus. You may even walk into the wrong building, go to the wrong class, or have trouble finding what you need during this time. But those first-week jitters will end soon. Students who are living away from home for the first time can feel homesick in the first few weeks, and others can feel what is called “imposter syndrome,” which is a fear some students have that they don’t belong in college because they don’t have the necessary skills for success. Those first few weeks sound pretty stressful, but the stress is temporary.
After the newness of college wears off, reality will set in. You may find that the courses and assignments do not seem much different than they did in high school (more on that later), but you may be in for a shock when you get your graded tests and papers. Many new college students find that their first grades are lower than they expected. For some students, this may mean they have earned a B when they are used to earning As, but for many students, it means they may experience their first
failing or almost-failing grades
in college because they have not used active, effective study strategies; instead, they studied how they did in high school, which is often insufficient. This can be a shock if you are not prepared, but it doesn’t have to devastate you if you are willing to use it as a wake-up call to do something different.
By the middle of the semester, you’ll likely feel much more confident and a little more relaxed. Your grades are improving because you started going to tutoring and using better study strategies. You are looking ahead, even beyond the first semester, to start planning your courses for the next term. If you are working while in college, you may also find that you have a rhythm down for balancing it all; additionally, your time management skills have likely improved.
By the last few weeks of the semester, you will be focused on the increasing importance of your assignments and upcoming finals and trying to figure out how to juggle that with the family obligations of the impending holidays. You may feel a little more pressure to prepare for finals, as this time is often viewed as the most stressful period of the semester. All of this additional workload and need to plan for the next semester can seem overwhelming, but if you plan ahead and use what you learn from this chapter and the rest of the course, you will be able to get through it more easily.
Don’t Do It Alone
Think about our earlier descriptions of two students, Reginald and Madison. What if they found that the first few weeks were a little harder than they had anticipated? Should they have given up and dropped out? Or should they have talked to someone about their struggles? Here is a secret about college success that not many people know: successful students seek help. They use resources. And they do that as often as necessary to get what they need. Your professors and advisors will expect the same from you, and your college will have all kinds of offices, staff, and programs that are designed to help. This bears calling out again:
you need to use those resources
. These are called “help-seeking behaviors,” and along with self-advocacy, which is speaking up for your needs, they are essential to your success. As you get more comfortable adjusting to life in college, you will find that asking for help is easier. In fact, you may become really good at it by the time you graduate, just in time for you to ask for help finding a job! Review the table on Issues, Campus Resources, and Potential Outcomes for a few examples of times you may need to ask for help. See if you can identify where on campus you can find the same or a similar resource.
Table 1.6
Issues, Campus Resources, and Potential Outcomes
Type
Issue
Campus Resource
Potential Outcome
Academic
You are struggling to master the homework in your math class.
The campus tutoring center
A peer or professional tutor can walk you through the steps until you can do them on your own.
Health
You have felt extremely tired over the past two days and now you have a cough.
The campus health center
A licensed professional can examine you and provide care.
Social
You haven’t found a group to belong to. Your classmates seem to be going in different directions and your roommate has different interests.
Student organizations and interest groups
Becoming a member of a group on campus can help you make new friends.
Financial
Your scholarship and student loan no longer cover your college expenses. You are not sure how to afford next semester.
Financial aid office
A financial aid counselor can provide you with information about your options for meeting your college expenses.
Application
Using a blank sheet of paper, write your name in the center of the page and circle it. Then, draw six lines from the center (see example in the figure below) and label each for the six areas of adjustment that were discussed earlier. Identify a campus resource or strategy for making a smooth adjustment for each area.
Common Challenges in the First Year
It seems fitting to follow up the expectations for the first year with a list of common challenges that college students encounter along the way to a degree. If you experience any—or even all—of these, the important point here is that you are not alone and that you can overcome them by using your resources. Many college students have felt like this before, and they have survived—even thrived—despite them because they were able to identify a strategy or resource that they could use to help themselves. At some point in your academic career, you may do one or more of the following:
Feel like an imposter.
There is actually a name for this condition: imposter syndrome. Students who feel like an imposter are worried that they don’t belong, that someone will “expose them for being a fake.” This feeling is pretty common for anyone who finds themselves in a new environment and is not sure if they have what it takes to succeed. Trust the professionals who work with first-year college students: you
do
have what it takes, and you
will
succeed. Just give yourself time to get adjusted to everything.
Worry about making a mistake.
This concern often goes with imposter syndrome. Students who worry about making a mistake don’t like to answer questions in class, volunteer for a challenging assignment, and even ask for help from others. Instead of avoiding situations where you may fail, embrace the process of learning, which includes—is even dependent on—making mistakes. The more you practice courage in these situations and focus on what you are going to learn from failing, the more confident you become about your abilities.
Try to manage everything yourself.
Even superheroes need help from sidekicks and mere mortals. Trying to handle everything on your own every time an issue arises is a recipe for getting stressed out. There will be times when you are overwhelmed by all you have to do. This is when you will need to ask for and allow others to help you.
Ignore your mental and physical health needs.
If you feel you are on an emotional rollercoaster and you cannot find time to take care of yourself, then you have most likely ignored some part of your mental and physical well-being. What you need to do to stay healthy should be non-negotiable. In other words, your sleep, eating habits, exercise, and stress-reducing activities should be your highest priorities.
Forget to enjoy the experience.
Whether you are 18 years old and living on campus or 48 years old starting back to college after taking a break to work and raise a family, be sure to take the time to remind yourself of the joy that learning can bring.
Get Connected
Which apps help you meet the expectations of college? Will you be able to meet the expectations of being responsible for your schedule and assignments?
My Study Life
understands how college works and provides you with a calendar, to-do list, and reminders that will help you keep track of the work you have to do.
How can you set goals and work toward them while in college?
The Strides
app provides you with the opportunity to create SMART (Specific, Measureable, Attainable, Relevant, and Time bound) goals and track daily habits. These daily habits will add up over time toward your goals.
What can you do to develop your learning skills?
Lumosity
is a brain-training app that can help you build the thinking and learning skills you will need to meet learning challenges in college. If you want to test your memory and attention—and build your skills—take the fit test and then play different games to improve your fitness.
How can you develop networks with people in college?
LinkedIn
is a professional networking app that allows you to create a profile and network with others. Creating a LinkedIn account as a first-year college student will help you create a professional profile that you can use to find others with similar interests.
Internships.com
provides information, connections, and support to help your career planning and activities. Even if you are not planning an internship right away, you may find some useful and surprising ideas and strategies to motivate your approach.
Footnotes
P.P. Bilbao, P. I. Lucido, T. C. Iringan and R. B. Javier. (2008).
Curriculum Development
.


12.2: Contraception
As we continue through our understanding of human sexuality, at this point it has become clear that sexual activity reaches far beyond the need to procreate. Humans throughout history have enjoyed the pleasure of sex without the purpose of procreation. Contraception is a technique that prevents a sperm cell and an ovum from uniting. Controlling fertility is something that is done to avoid pregnancy, and there are various options of birth control currently available. There are many birth control options: permanent, intrauterine devices (IUDs), hormonal, barrier, spermicidal and behavioral. It is important to note that when no birth control is used, 85 out of 100 sexually active women of childbearing age become pregnant in a year (Britton, et al, 2019). From very low maintenance options to ones that must be used every time a person has sex, the choices range and it is best to find the type of birth control that works for you and your lifestyle. Proper use of the choice of birth control is critical in preventing unwanted pregnancy. These methods vary in the ways in which they prevent pregnancy as well. Some, like condoms and cervical caps, can physically block sperm from reaching the eggs, while hormonal methods like the pill or birth control injections work with a woman's hormones to prevent ovulation. Other methods like fertility awareness, sometimes known as the rhythm method, require the person to know where their body is in its fertility cycle. There are also more permanent methods like vasectomy and tubal ligation which are surgical options. There are a variety of options to choose from and new options become available periodically, so be sure to double check with a healthcare provider to see what may be available. All people regardless of their ability to become pregnant are also at risk for Sexually Transmitted Infections (STIs aka STDs). Condoms are the only birth control method that also prevents infection transmission.
Planned Parenthood is one of the leading organizations in the United States that offers free or low cost birth control options. They offer support for various types of reproductive services. They have created an easily accessible site entitled: Birth Control Options and which is best for you which goes into greater detail about each method. The infographic below highlights some of the more popular forms of birth control currently available and how well they work to prevent unwanted pregnancy.
This short video describes a vasectomy. As described in this video, a vasectomy is a procedure in which a small section of the ductus (vas) deferens is removed from the scrotum. This interrupts the path taken by sperm through the ductus deferens. If sperm do not exit through the vas, either because the person has had a vasectomy or has not ejaculated, do you know what region of the testis they remain in?
Used consistently and effectively based on the individual methods and instructions, pregnancy can be prevented. Coupling hormonal methods (pill, patch, etc.) with barrier methods (condoms) increases the effectiveness rate AND prevents the spread of STIs, so doubling up is always a good option. When preventative birth control fails, there are also emergency contraceptive options sometimes referred to as plan b that are available.
A Brief History of The Pill
It is important to note that while humans sought to enjoy sex without a desire to procreate, for most of history there was not an option that gave women autonomy over their reproductive health in the way that the pill did. “The birth control pill separated sexual practice from conception, forcing re-assessment and reevaluation of social, political, and religious viewpoints” (Liao & Dollin, 2012, para 1). In essence, the pill changed the power dynamic which was part of women’s liberation. After animal experiments in the 1930s demonstrated that high levels of progesterone could stop ovulation, Mexican Chemist Dr. Carl Djerassi synthesized progestin from Mexican Yam root. Dr. Djerassi did this work in the late 1940s, at a time when women’s rights and reproductive freedom were not a cultural norm for most women in the U.S. and in most places worldwide. Despite this, the first birth control pill was approved by the United States Food and Drug Administration (FDA) in 1960 and control over reproductive rights became possible for women. Depending on the nation and its date of approval of the drug, worldwide dates of pill availability vary. More on the history of the pill here .
A name to know in the development of hormonal birth control is Dr. Percy Julian . Dr Julian was the grandchild of slaves who went on to work on the chemical synthesis of medicinal drugs from plants. This work led to the synthetic chemicals used in hormonal birth control pills. His work to advance the birth control pill was just one area of contribution to the field yet his path was fraught with roadblocks because he was Black.
A Bit more on Hormonal Birth Control
Birth control pills take advantage of the negative feedback system that regulates the ovarian and menstrual cycles to stop ovulation and prevent pregnancy. Typically they work by providing a constant level of both estrogen and progesterone, which negatively feeds back onto the hypothalamus and pituitary, thus preventing the release of FSH and LH. Without FSH, the follicles do not mature, and without the LH surge, ovulation does not occur. Although the estrogen in birth control pills does stimulate some thickening of the endometrial wall, it is reduced compared with a normal cycle and is less likely to support implantation.
Some birth control pills contain 21 active pills containing hormones, and 7 inactive pills (placebos). The decline in hormones during the week that the woman takes the placebo pills triggers menses, although it is typically lighter than a normal menstrual flow because of the reduced endometrial thickening. Newer types of birth control pills have been developed that deliver low-dose estrogens and progesterone for the entire cycle (these are meant to be taken 365 days a year), and menses never occurs. While some women prefer to have the proof of a lack of pregnancy that a monthly period provides, menstruation every 28 days is not required for health reasons, and there are no reported adverse effects of not having a menstrual period in an otherwise healthy individual.
Because birth control pills function by providing constant estrogen and progesterone levels and disrupting negative feedback, skipping even just one or two pills at certain points of the cycle (or even being several hours late taking the pill) can lead to an increase in FSH and LH and result in ovulation. It is important, therefore, that the woman follow the directions on the birth control pill package to successfully prevent pregnancy.


10.5I: Types of Neurotransmitters by Function
Neurotransmitters are endogenous chemicals that transmit signals from a neuron to a target cell across a synapse.
- Describe types of neurotransmitters by their function
Key Points
- Neurotransmitters are endogenous chemicals that transmit signals from a neuron to a target cell across a synapse.
- Release of neurotransmitters usually follows arrival of an action potential at the synapse, but may also follow a graded electrical potential.
- The major types of neurotransmitters include acetylcholine, biogenic amines, and amino acids.
- Biogenic amines include the catecholamines such as dopamine, norepinephrine (NE), and epinephrine, as well as indolamines such as serotonin and histamine.
Key Terms
- neurotransmitter : An endogenous chemical that transmits signals from a neuron to a target cell across a synapse.
-
acetylcholine
: This neurotransmitter acts on the neuromuscular juncture and is
synthesized from acetic acid and choline. - Biogenic amines : Neurotransmitters distributed in the brain, where they play a role in emotional behavior and help in regulating the biological clock.
-
glutamate
: An amino acid that
promotes excitatory effects by increasing the probability that the target cell will fire an action potential.
Neurotransmitters are endogenous chemicals that transmit signals from a neuron to a target cell across a synapse. Although some neurons produce and release only one kind of neurotransmitter, most make two or more and may release one or more at any given time. The coexistence of more than one neurotransmitter in the synapse makes it possible for the cell to exert several influences at the same time.
Neurotransmitter Structure
Major elements in neuron-to-neuron communication : Chemical synapses are specialized junctions through which neurons signal to each other and to non-neuronal cells such as those in muscles or glands.
Neurotransmitters are packaged into synaptic vesicles clustered beneath the membrane in the axon terminal on the presynaptic side of a synapse. They are released into and diffuse across the synaptic cleft, where they bind to specific receptors in the membrane on the postsynaptic side of the synapse. Release of neurotransmitters usually follows arrival of an action potential at the synapse, but may also follow a graded electrical potential. Low-level baseline release also occurs without electrical stimulation.
Neurotransmitters are synthesized from plentiful and simple precursors such as amino acids, which are readily available from the diet and require only a small number of biosynthetic steps to convert.
Classification of Neurotransmitters
Neurotransmitters fall into several chemical classes based on the molecular structure. The major types of neurotransmitters include acetylcholine, biogenic amines, and amino acids. The neurotransmitters can also be classified based on function (excitatory or inhibitory) and action (direct or neuromodulatory).
Acetylcholine
Acetylcholine, which acts on the neuromuscular junction, was the first neurotransmitter identified. It is synthesized from acetic acid and choline. Once released, acetylcholine binds to post-synaptic receptors and is degraded by acetylcholinesterase. Acetylcholine-releasing neurons are also found in the central nervous system (CNS).
Biogenic Amines
Biogenic amines include the catecholamines, such as dopamine, norepinephrine (NE), and epinephrine, as well as indolamines such as serotonin and histamine. Dopamine and NE are synthesized from amino acid tyrosine. Serotonin is synthesized from tryptophan. Histamine is synthesized from amino acid
histidine.
Biogenic amines are distributed in the brain, where they play a role in emotional behavior and help in regulating the biological clock. Additionally, some motor neurons of the ANS release catecholamines like NE. NE, dopamine, and histamine can be excitatory or inhibitory depending on the receptor type. Addictive drugs such as cocaine and amphetamine exert their effects primarily on the dopamine system, while addictive opiates and functional analogs of opioid peptides which regulate dopamine levels.
Amino Acids
Glutamate and gamma-aminobutyric acid (GABA) are amino acid-based neurotransmitters. The most prevalent transmitter in the human brain is glutamate, which promotes excitatory effects by increasing the probability that the target cell will fire an action potential. The next most prevalent is GABA, which is inhibitory at more than 90% of the synapses that do not use glutamate.
Neuropeptides such as Substance P and endorphins are strings of amino acids that are important in the mediation of pain signals. Enkephalin activity increases dramatically in pregnant women in labor. Endorphins are released in the so called “runner’s high.” There is also evidence that neuropeptides such as gut-brain peptides are produced by non-neural tissues in the gastrointestinal tract.


6.16: Discussion- Merging and Centering Cells
We have learned a variety of tips you can use to create visually appealing tables in Excel, including applying table and cell styles and changing the size of rows and columns.
Another helpful Excel tool is the ability to merge and center cells and to wrap text within a cell.
- Select the cells you wish to merge into one larger cell.
- Click “Merge & Center” from the “Alignment” group of the ribbon.
- When you type in this merged cell, the text will automatically be centered left to right in the cell.
Discussion Questions
- In what situations would this feature be useful?
- Would you ever use this feature? Why or why not?
Share your opinions below and respond to two of your classmates’ thoughts.
Contributors and Attributions
CC licensed content, Original
- Discussion Forum: Merging and Centering Cells. Authored by : Shelli Carter. Provided by : Lumen Learning. License : CC BY: Attribution


17.7: Ultrasound
Learning Objectives
By the end of this section, you will be able to:
- Define acoustic impedance and intensity reflection coefficient.
- Describe medical and other uses of ultrasound technology.
- Calculate acoustic impedance using density values and the speed of ultrasound.
- Calculate the velocity of a moving object using Doppler-shifted ultrasound.
Any sound with a frequency above 20,000 Hz (or 20 kHz)—that is, above the highest audible frequency—is defined to be ultrasound. In practice, it is possible to create ultrasound frequencies up to more than a gigahertz. (Higher frequencies are difficult to create; furthermore, they propagate poorly because they are very strongly absorbed.) Ultrasound has a tremendous number of applications, which range from burglar alarms to use in cleaning delicate objects to the guidance systems of bats. We begin our discussion of ultrasound with some of its applications in medicine, in which it is used extensively both for diagnosis and for therapy.
Characteristics of Ultrasound
Any sound with a frequency above 20,000 Hz (or 20 kHz)—that is, above the highest audible frequency—is defined to be ultrasound. In practice, it is possible to create ultrasound frequencies up to more than a gigahertz. (Higher frequencies are difficult to create; furthermore, they propagate poorly because they are very strongly absorbed.) Ultrasound has a tremendous number of applications, which range from burglar alarms to use in cleaning delicate objects to the guidance systems of bats. We begin our discussion of ultrasound with some of its applications in medicine, in which it is used extensively both for diagnosis and for therapy.
Ultrasound in Medical Therapy
Ultrasound, like any wave, carries energy that can be absorbed by the medium carrying it, producing effects that vary with intensity. When focused to intensities of \(10^3\) to \(10^5 \, W/m^2\) ultrasound can be used to shatter gallstones or pulverize cancerous tissue in surgical procedures (Figure \(\PageIndex{2}\)). Intensities this great can damage individual cells, variously causing their protoplasm to stream inside them, altering their permeability, or rupturing their walls through cavitation . Cavitation is the creation of vapor cavities in a fluid—the longitudinal vibrations in ultrasound alternatively compress and expand the medium, and at sufficient amplitudes the expansion separates molecules. Most cavitation damage is done when the cavities collapse, producing even greater shock pressures.
Most of the energy carried by high-intensity ultrasound in tissue is converted to thermal energy. In fact, intensities of \(10^3\) to \(10^4 \, W/m^2\) are commonly used for deep-heat treatments called ultrasound diathermy. Frequencies of 0.8 to 1 MHz are typical. In both athletics and physical therapy, ultrasound diathermy is most often applied to injured or overworked muscles to relieve pain and improve flexibility. Skill is needed by the therapist to avoid “bone burns” and other tissue damage caused by overheating and cavitation, sometimes made worse by reflection and focusing of the ultrasound by joint and bone tissue.
In some instances, you may encounter a different decibel scale, called the sound pressure level, when ultrasound travels in water or in human and other biological tissues. We shall not use the scale here, but it is notable that numbers for sound pressure levels range 60 to 70 dB higher than you would quote for \(β\), the sound intensity level used in this text. Should you encounter a sound pressure level of 220 decibels, then, it is not an astronomically high intensity, but equivalent to about 155 dB—high enough to destroy tissue, but not as unreasonably high as it might seem at first.
Ultrasound in Medical Diagnostics
When used for imaging, ultrasonic waves are emitted from a transducer, a crystal exhibiting the piezoelectric effect (the expansion and contraction of a substance when a voltage is applied across it, causing a vibration of the crystal). These high-frequency vibrations are transmitted into any tissue in contact with the transducer. Similarly, if a pressure is applied to the crystal (in the form of a wave reflected off tissue layers), a voltage is produced which can be recorded. The crystal therefore acts as both a transmitter and a receiver of sound. Ultrasound is also partially absorbed by tissue on its path, both on its journey away from the transducer and on its return journey. From the time between when the original signal is sent and when the reflections from various boundaries between media are received, (as well as a measure of the intensity loss of the signal), the nature and position of each boundary between tissues and organs may be deduced.
Reflections at boundaries between two different media occur because of differences in a characteristic known as the acoustic impedance \(Z\) of each substance. Impedance is defined as
\[Z = \rho v,\]
where \(\rho\) is the density of the medium (in kg/m^3\) ) and \(v\) is the speed of sound through the medium (in m/s). The units for \(Z\) are therefore \(kg/(m^2 \cdot s)\).
Table \(\PageIndex{1}\) shows the density and speed of sound through various media (including various soft tissues) and the associated acoustic impedances. Note that the acoustic impedances for soft tissue do not vary much but that there is a big difference between the acoustic impedance of soft tissue and air and also between soft tissue and bone.
| Medium | Density \((kg/m^3)\) | Speed of Ultrasound (m/s) | Acoustic Impedence \((kg/(m^2\cdot s))\) |
|---|---|---|---|
| Air | 1.3 | 330 | 429 |
| Water | 1000 | 1500 | \(1.5 \times 10^6\) |
| Blood | 1060 | 1570 | \(1.66 \times 10^6\) |
| Fat | 925 | 1450 | 1.34(1000000) |
| Muscle (average) | 1075 | 1590 | 1.7(1000000) |
| Bone (varies) | 1400–1900 | 4080 | 5.7 to 7.8(1000000 |
| Barium titanate (transducer material) | 5600 | 5500 | 30.8(1000000) |
At the boundary between media of different acoustic impedances, some of the wave energy is reflected and some is transmitted. The greater the difference in acoustic impedance between the two media, the greater the reflection and the smaller the transmission.
The intensity reflection coefficien t \(a\) is defined as the ratio of the intensity of the reflected wave relative to the incident (transmitted) wave. This statement can be written mathematically as
\[a = \frac{\left(Z_{2} - Z_{1}\right)^2}{\left(Z_{1} + Z_{2}\right)^{2}},\]
where \(Z_{1}\) and \(Z_{2}\) are the acoustic impedances of the two media making up the boundary. A reflection coefficient of zero (corresponding to total transmission and no reflection) occurs when the acoustic impedances of the two media are the same. An impedance “match” (no reflection) provides an efficient coupling of sound energy from one medium to another. The image formed in an ultrasound is made by tracking reflections (as shown in Figure \(\PageIndex{3}\)) and mapping the intensity of the reflected sound waves in a two-dimensional plane.
Example \(\PageIndex{1}\): Calculate Acoustic Impedance and Intensity Reflection Coefficient: Ultrasound and Fat Tissue
(a) Using the values for density and the speed of ultrasound given in Table \(\PageIndex{1}\), show that the acoustic impedance of fat tissue is indeed \(1.34 \times 10^{6}kg / \left( m^{2} \cdot s \right)\).
(b) Calculate the intensity reflection coefficient of ultrasound when going from fat to muscle tissue.
Strategy for (a)
The acoustic impedance can be calculated using \(Z = \rho v\) and the values for \(\rho\) and \(v\) found in Table \(\PageIndex{1}\).
Solution for (a)
(1) Substitute known values from Table \(\PageIndex{1}\) into \(Z = \rho v\).
\[Z = \rho v = \left(925 kg/m^{3}\right)\left(1450 m/s\right)\]
(2) Calculate to find the acoustic impedance of fat tissue.
\[1.34 \times 10^{6} kg/\left(m^{2} \cdot s\right)\]
This value is the same as the value given for the acoustic impedance of fat tissue.
The intensity reflection coefficient for any boundary between two media is given by \(a = \frac{\left(Z_{2} - Z_{1}\right)^{2}}{\left(Z_{2} + Z_{1}\right)^{2}}\), and the acoustic impedance of muscle is given in Table \(\PageIndex{1}\).
Solution for (b)
Substitute known values into \(a = \frac{\left(Z_{2} - Z_{1}\right)^{2}}{\left(Z_{2} + Z_{1}\right)^{2}}\) to find the intensity reflection coefficient:
\[a = \frac{\left(Z_{2} - Z_{1}\right)^{2}}{\left(Z_{2} + Z_{1}\right)^{2}} = \frac{\left(1.34 \times 10^{6} kg/\left(m^{2} \cdot s\right) - 1.70 \times 10^{6} kg/\left(m^{2} \cdot s\right) \right)^{2}}{\left(1.70 \times 10^{6} kg / \left(m^{2}\cdot s\right) + 1.34 \times 10^{6} kg/ \left(m^{2} \cdot s \right) \right)^{2}} = 0.014\]
Discussion
This result means that only 1.4% of the incident intensity is reflected, with the remaining being transmitted.
The applications of ultrasound in medical diagnostics have produced untold benefits with no known risks. Diagnostic intensities are too low (about \(10^{-2} W/m^{2}\)) to cause thermal damage. More significantly, ultrasound has been in use for several decades and detailed follow-up studies do not show evidence of ill effects, quite unlike the case for x-rays.
The most common ultrasound applications produce an image like that shown in Figure \(\PageIndex{4}\). The speaker-microphone broadcasts a directional beam, sweeping the beam across the area of interest. This is accomplished by having multiple ultrasound sources in the probe’s head, which are phased to interfere constructively in a given, adjustable direction. Echoes are measured as a function of position as well as depth. A computer constructs an image that reveals the shape and density of internal structures.
How much detail can ultrasound reveal? The image in Figure \(\PageIndex{4}\) is typical of low-cost systems, but that in \(\PageIndex{5}\) shows the remarkable detail possible with more advanced systems, including 3D imaging. Ultrasound today is commonly used in prenatal care. Such imaging can be used to see if the fetus is developing at a normal rate, and help in the determination of serious problems early in the pregnancy. Ultrasound is also in wide use to image the chambers of the heart and the flow of blood within the beating heart, using the Doppler effect (echocardiology).
Whenever a wave is used as a probe, it is very difficult to detect details smaller than its wavelength \(\lambda\). Indeed, current technology cannot do quite this well. Abdominal scans may use a 7-MHz frequency, and the speed of sound in tissue is about 1540 m/s -- so the wavelength limit to detail would be \(\lambda = \frac{v_{w}}{f} = \frac{1540 m/s}{7 \times 10^{6} Hz} = 0.22mm\). In practice, 1-mm detail is attainable, which is sufficient for many purposes. Higher-frequency ultrasound would allow greater detail, but it does not penetrate as well as lower frequencies do. The accepted rule of thumb is that you can effectively scan to a depth of about \(500 \lambda\) into tissue. For 7 MHz, this penetration limit is \(500 \times 0.22 mm\), which is 0.11 m. Higher frequencies may be employed in smaller organs, such as the eye, but are not practical for looking deep into the body.
In addition to shape information, ultrasonic scans can produce density information superior to that found in X-rays, because the intensity of a reflected sound is related to changes in density. Sound is most strongly reflected at places where density changes are greatest.
Another major use of ultrasound in medical diagnostics is to detect motion and determine velocity through the Doppler shift of an echo, known as Doppler-shifted ultrasound . This technique is used to monitor fetal heartbeat, measure blood velocity, and detect occlusions in blood vessels, for example. (See Figure \(\PageIndex{6}\).)
A clever technique is used to measure the Doppler shift in an echo. The frequency of the echoed sound is superimposed on the broadcast frequency, producing beats. The beat frequency is \(F_{B} = \vert f_{1} - f_{2} \vert \), and so it is directly proportional to the Doppler shift ( \(f_{1} - f_{2}\) ) and hence, the reflector’s velocity. The advantage in this technique is that the Doppler shift is small (because the reflector’s velocity is small), so that great accuracy would be needed to measure the shift directly. But measuring the beat frequency is easy, and it is not affected if the broadcast frequency varies somewhat. Furthermore, the beat frequency is in the audible range and can be amplified for audio feedback to the medical observer.
USES FOR DOPPLER-SHIFTED RADAR
Doppler-shifted radar echoes are used to measure wind velocities in storms as well as aircraft and automobile speeds. The principle is the same as for Doppler-shifted ultrasound. There is evidence that bats and dolphins may also sense the velocity of an object (such as prey) reflecting their ultrasound signals by observing its Doppler shift.
Example \(\PageIndex{2}\): Calculate Velocity of Blood: Doppler-Shifted Ultrasound
Ultrasound that has a frequency of 2.50 MHz is sent toward blood in an artery that is moving toward the source at 20.0 cm/s, as illustrated in Figure \(\PageIndex{7}\). Use the speed of sound in human tissue as 1540 m/s. (Assume that the frequency of 2.50 MHz is accurate to seven significant figures.)
- What frequency does the blood receive?
- What frequency returns to the source?
- What beat frequency is produced if the source and returning frequencies are mixed?
Strategy
The first two questions can be answered using \(f_{obs} = f_{s} \left(\frac{v_{w}}{v_{w} \pm v_{s}}\right)\) and \(f_{obs} = f_{s} \left(\frac{v_{w} \pm v_{obs}}{v_{w}}\right)\) for the Doppler shift. The last question asks for beat frequency, which is the difference between the original and returning frequencies.
Solution for (a)
-
Identify knowns:
- The blood is a moving observer, and so the frequency it receives is given by \[f_{obs} = f_{s} \left(\frac{v_{w} \pm v_{obs}}{v_{w}}\right)\].
- \(v_{b}\) is the blood velocity (\(v_{obs}\) here) and the plus sign is chosen because the motion is toward the source.
- Enter the given values into the equation. \[f_{obs} = \left(2,500,000 Hz\right) \left( \frac{1540 m/s + 0.2 m/s}{1540 m/s}\right)\]
- Calculate to find the frequency: 2,500,325 Hz.
Solution for (b)
-
Identify knowns:
- The blood acts as a moving source.
- The microphone acts as a stationary observer.
-
The frequency leaving the blood is 2,500,325 Hz, but it is shifted upward as given by \[f_{obs} = f_{s} \left(\frac{v_{w}}{v_{w} - v_{b}}\right).\]
- \(f_{obs}\) is the frequency received by the speaker-microphone.
- The source velocity is \(v_{b}\).
- The minus sign is used because the motion is toward the observer.
- Enter the given values into the equation: \[f_{obs} = \left(2,500,325 Hz\right) \left( \frac{1540 m/s}{1540 m/s - 0.200 m/s}\right)\]
- Calculate to find the frequency returning to the source: 2,500,649 Hz.
Solution for (c)
-
Identify knowns:
- The beat frequency is simply the absolute value of the difference between \(f_{s}\) and \(f_{obs}\) as stated in: \[f_{B} = \vert f_{obs} - f_{s}\vert.\]
- Substitute known values: \[\vert 2,500,649 Hz - 2,500,000 Hz\vert\]
- Calculate to find the beat frequency: 649 Hz.
Discussion
The Doppler shifts are quite small compared with the original frequency of 2.50 MHz. It is far easier to measure the beat frequency than it is to measure the echo frequency with an accuracy great enough to see shifts of a few hundred hertz out of a couple of megahertz. Furthermore, variations in the source frequency do not greatly affect the beat frequency, because both \(f_{s}\) and \(f_{obs}\) would increase or decrease. Those changes subtract out in \(f_{B} = \vert f_{obs} - f_{s} \vert\).
INDUSTRIAL AND OTHER APPLICATIONS OF ULTRASOUND
Industrial, retail, and research applications of ultrasound are common. A few are discussed here. Ultrasonic cleaners have many uses. Jewelry, machined parts, and other objects that have odd shapes and crevices are immersed in a cleaning fluid that is agitated with ultrasound typically about 40 kHz in frequency. The intensity is great enough to cause cavitation, which is responsible for most of the cleansing action. Because cavitation-produced shock pressures are large and well transmitted in a fluid, they reach into small crevices where even a low-surface-tension cleaning fluid might not penetrate.
Sonar is a familiar application of ultrasound. Sonar typically employs ultrasonic frequencies in the range from 30.0 to 100 kHz. Bats, dolphins, submarines, and even some birds use ultrasonic sonar. Echoes are analyzed to give distance and size information both for guidance and finding prey. In most sonar applications, the sound reflects quite well because the objects of interest have significantly different density than the medium in which they travel. When the Doppler shift is observed, velocity information can also be obtained. Submarine sonar can be used to obtain such information, and there is evidence that some bats also sense velocity from their echoes.
Similarly, there are a range of relatively inexpensive devices that measure distance by timing ultrasonic echoes. Many cameras, for example, use such information to focus automatically. Some doors open when their ultrasonic ranging devices detect a nearby object, and certain home security lights turn on when their ultrasonic rangers observe motion. Ultrasonic “measuring tapes” also exist to measure such things as room dimensions. Sinks in public restrooms are sometimes automated with ultrasound devices to turn faucets on and off when people wash their hands. These devices reduce the spread of germs and can conserve water.
Ultrasound is used for nondestructive testing in industry and by the military. Because ultrasound reflects well from any large change in density, it can reveal cracks and voids in solids, such as aircraft wings, that are too small to be seen with x-rays. For similar reasons, ultrasound is also good for measuring the thickness of coatings, particularly where there are several layers involved.
Basic research in solid state physics employs ultrasound. Its attenuation is related to a number of physical characteristics, making it a useful probe. Among these characteristics are structural changes such as those found in liquid crystals, the transition of a material to a superconducting phase, as well as density and other properties.
These examples of the uses of ultrasound are meant to whet the appetites of the curious, as well as to illustrate the underlying physics of ultrasound. There are many more applications, as you can easily discover for yourself.
Exercise \(\PageIndex{1}\)
Why is it possible to use ultrasound both to observe a fetus in the womb and also to destroy cancerous tumors in the body?
- Answer
-
Ultrasound can be used medically at different intensities. Lower intensities do not cause damage and are used for medical imaging. Higher intensities can pulverize and destroy targeted substances in the body, such as tumors.
Summary
- The acoustic impedance is defined as \(Z = \rho v\), where \(\rho\) is the density of a medium through which the sound travels and \(v\) is the speed of sound through that medium.
- The intensity reflection coefficient \(a\), a measure of the ratio of the intensity of the wave reflected off a boundary between two media relative to the intensity of the incident wave, is given by \(a = \frac{\left(Z_{2} - Z_{1}\right)^{2}}{\left(Z_{1} + Z_{2}\right)^{2}}\).
- The intensity reflection coefficient is a unitless quantity.
Glossary
- acoustic impedance
- property of medium that makes the propagation of sound waves more difficult
- intensity reflection coefficient
- a measure of the ratio of the intensity of the wave reflected off a boundary between two media relative to the intensity of the incident wave
- Doppler-shifted ultrasound
- a medical technique to detect motion and determine velocity through the Doppler shift of an echo


6.10: Another Look at Probability (2 of 2)
Source: GeoGebra , license: CC BY SA
Note that by clicking the GeoGebra link above you can launch a new window with this simulation in it if you would like to position it closer to the questions you’ll be answering below to avoid scrolling so much.
- Make sure Coins = 1 and P(heads) = 0.2 .
- Click the Auto button and watch the count of heads and tails change.
- Click the Pause (II) button once Total Flips is over 100 or so.
- Record the total number of Heads (1’s) and the total number of flips.
- Calculate P(H) (Number of heads / Total Flips) when Total Flips is about 100.
- Click the Auto button again to continue the flips.
- Click the Pause (II) once Total Flips is over 1,000 or so.
- Record the total number of Heads (1’s) and the total number of flips.
- Calculate P(H) (Number of heads / Total Flips) when Total Flips is about 1,000.
Let’s summarize what we have learned from these activities:
- The empirical probability will approach the theoretical probability after a large number of repetitions. In some situations, such as in flipping an unfair coin, we cannot calculate the theoretical probability. In these cases, we have to depend on data.
- There is less variability in a large number of repetitions. This means that in the long run, we will see a pattern, so we are more confident about estimating the probability of an event using empirical probability with a large number of repetitions.
What Do We Mean When We Say an Event Is Random or Due to Chance?
In the discussion of the role of probability in the Big Picture of Statistics, we said that probability is the machinery that allows us to draw conclusions about a population on the basis of a random sample. To understand why we can trust random selection in an observational study and random assignment in an experiment, we need to look more closely at what we mean by random or chance behavior.
When we say that an event is random or due to chance, we mean that the event is unpredictable in the short run but has a regular and predictable behavior in the long run. This is obviously true for the coin-tossing activity. We cannot predict whether an individual toss will be heads, but in the long run, the outcomes have a predictable pattern. The relative frequency of heads is very close to 0.5 for a fair coin.
We can make probability statements only about random events.
What Is the Connection between the Coin-Flipping Activities and the Discussion of Probability in the Previous Module?
Let’s look at two probability questions that we might answer using the familiar data set from Relationships in Categorical Data with Intro to Probability . Recall that 6,198 of the 12,000 students at a West Coast community college are female. Previously, we calculated P (female) = 6,198 / 12,000 = 0.5165. What is the random event in this case? Let’s be very specific about the question this calculation is meant to answer.
What is the probability that a student at the West Coast community college is a female?
- In this case, the relative frequency 6,198 / 12,000 is the actual proportion of females at the college. This is like the fair coin situation. Because we know the gender distribution at the college, we can think of 0.5165 as the theoretical probability that a randomly selected student at this particular college is a female. Tossing the fair coin in the simulation is like randomly selecting a student from the spreadsheet of data. We do not know if a randomly selected student will be female. But if we repeat this process many, many times, in the long run, the relative frequency of females will have a predictable pattern. The relative frequency will be very close to the proportion of females in the data set.
What is the probability that a community college student in the United States is female?
- In this case, we are using the data from the 12,000 West Coast community college students to represent students at all community colleges in the United States. The relative frequency is an estimate for the chance that a randomly selected U.S. student is female. This is like tossing the unfair coin 12,000 times and using the relative frequency of heads as an estimate of P (head). We do not know P (female) for all community colleges, just as we did not know the P (heads) with an unfair coin. But if the sample is random, we can use the relative frequency of females in the sample as an estimate of P (female) in all community colleges.
The main points are these:
- We can make probability statements only about random events.
- Probability of an event A is the relative frequency with which that event occurs in a long series of repetitions.
Contributors and Attributions
- Concepts in Statistics. Provided by : Open Learning Initiative. Located at : http://oli.cmu.edu . License : CC BY: Attribution


2.4: Toulmin’s Schema
Stephen Edelston Toulmin (born March 25, 1922) is a British philosopher, author, and educator. Influenced by the Austrian philosopher Ludwig Wittgenstein, Toulmin devoted his works to the analysis of moral reasoning. Throughout his writings, he seeks to develop practical arguments which can be used effectively in evaluating the ethics behind moral issues. The Toulmin Model of Argumentation, a diagram containing six interrelated components used for analyzing arguments, was considered his most influential work, particularly in the field of rhetoric and communication, and in computer science.
Figure \(\PageIndex{1}\)
Stephen Toulmin is a British philosopher and educator who devoted to analyzing moral reasoning. Throughout his writings, he seeks to develop practical arguments which can be used effectively in evaluating the ethics behind moral issues. His most famous work was his Model of Argumentation(sometimes called “Toulmin’s Schema,” which is a method of analyzing an argument by breaking it down into six parts. Once an argument is broken down and examined, weaknesses in the argument can be found and addressed.
Toulmin’s Schema:
- Claim: conclusions whose merit must be established. For example, if a person tries to convince a listener that he is a British citizen, the claim would be “I am a British citizen.”
- Data: the facts appealed to as a foundation for the claim. For example, the person introduced in 1 can support his claim with the supporting data “I was born in Bermuda.”
- Warrant: the statement authorizing the movement from the data to the claim. In order to move from the data established in 2, “I was born in Bermuda,” to the claim in 1, “I am a British citizen,” the person must supply a warrant to bridge the gap between 1 & 2 with the statement “A man born in Bermuda will legally be a British Citizen.” Toulmin stated that an argument is only as strong as its weakest warrant and if a warrant isn’t valid, then the whole argument collapses. Therefore, it is important to have strong, valid warrants.
- Backing: facts that give credibility to the statement expressed in the warrant; backing must be introduced when the warrant itself is not convincing enough to the readers or the listeners. For example, if the listener does not deem the warrant as credible, the speaker would supply legal documents as backing statement to show that it is true that “A man born in Bermuda will legally be a British Citizen.”
- Rebuttal: statements recognizing the restrictions to which the claim may legitimately be applied. The rebuttal is exemplified as follows, “A man born in Bermuda will legally be a British citizen, unless he has betrayed Britain and become a spy of another country.”
- Qualifier: words or phrases expressing how certain the author/speaker is concerning the claim. Such words or phrases include “possible,” “probably,” “impossible,” “certainly,” “presumably,” “as far as the evidence goes,” or “necessarily.” The claim “I am definitely a British citizen” has a greater degree of force than the claim “I am a British citizen, presumably.”
- The first three elements “claim,” “data,” and “warrant” are considered as the essential components of practical arguments, while the 4-6 “Qualifier,” “Backing,” and “Rebuttal” may not be needed in some arguments. When first proposed, this layout of argumentation is based on legal arguments and intended to be used to analyze arguments typically found in the courtroom; in fact, Toulmin did not realize that this layout would be applicable to the field of rhetoric and communication until later. 1
Here are a few more examples of Toulmin’s Schema:
Suppose you see a one of those commercials for a product that promises to give you whiter teeth. Here are the basic parts of the argument behind the commercial:
Figure \(\PageIndex{2}\)
- Claim: You should buy our tooth-whitening product.
- Data: Studies show that teeth are 50% whiter after using the product for a specified time.
- Warrant: People want whiter teeth.
- Backing: Celebrities want whiter teeth.
- Rebuttal: Commercial says “unless you don’t want to attract guys.”
- Qualifier: Fine print says “product must be used six weeks for results.”
Notice that those commercials don’t usually bother trying to convince you that you want whiter teeth; instead, they assume that you have bought into the value our culture places on whiter teeth. When an assumption–a warrant in Toulmin’s terms–is unstated, it’s called an implicit warrant. Sometimes, however, the warrant may need to be stated because it is a powerful part of the argument. When the warrant is stated, it’s called an explicit warrant. 2
- Claim: People should probably own a gun.
- Data: Studies show that people who own a gun are less likely to be mugged.
- Warrant: People want to be safe.
- Backing: May not be necessary. In this case, it is common sense that peoplewant to be safe.
- Rebuttal: Not everyone should own a gun. Children and those will mentaldisorders/problems should not own a gun.
- Qualifier: The word “probably” in the claim.
- Claim: Flag burning should be unconstitutional in most cases.
- Data: A national poll says that 60% of Americans want flag burningunconstitutional
- Warrant: People want to respect the flag.
- Backing: Official government procedures for the disposal of flags.
- Rebuttal: Not everyone in the U.S. respects the flag.
- Qualifier: The phrase “in most cases”
Toulmin says that the weakest part of any argument is its weakest warrant. Remember that the warrant is the link between the data and the claim. If the warrant isn’t valid, the argument collapses. 2


1: Prerequisites
In this chapter, we will review sets of numbers and properties of operations used to manipulate numbers. This understanding will serve as prerequisite knowledge throughout our study of algebra and trigonometry.
-
- 1.0: Prelude to Prerequisites
- Measuring and recording the characteristics of weather conditions requires a use of different kinds of numbers. Calculating with them and using them to make predictions requires an understanding of relationships among numbers. In this chapter, we will review sets of numbers and properties of operations used to manipulate numbers. This understanding will serve as prerequisite knowledge throughout our study of algebra and trigonometry.
-
- 1.5: Factoring Polynomials
- The greatest common factor, or GCF, can be factored out of a polynomial. Checking for a GCF should be the first step in any factoring problem. Trinomials with leading coefficient 1 can be factored by finding numbers that have a product of the third term and a sum of the second term. Trinomials can be factored using a process called factoring by grouping. Perfect square trinomials and the difference of squares are special products and can be factored using equations.
-
- 1.6: Rational Expressions
- The quotient of two polynomial expressions is called a rational expression. We can apply the properties of fractions to rational expressions, such as simplifying the expressions by canceling common factors from the numerator and the denominator. To do this, we first need to factor both the numerator and denominator.
Thumbnail: A shortcut called FOIL is sometimes used to find the product of two binomials. It is called FOIL because we multiply the first terms, the outer terms, the inner terms, and then the last terms of each binomial.


28.4D: Subphyla of Arthropoda
- Differentiate among the subphylums hexapoda, myriapoda, crustacea, and chelicerata
Representatives of Phylum Arthropoda
Subphylum Hexapoda
The name Hexapoda denotes the presence of six legs (three pairs) in these animals, which differentiates them from the number of pairs present in other arthropods. Hexapods are characterized by the presence of a head, thorax, and abdomen, constituting three tagma. The thorax bears the wings as well as six legs in three pairs. Many of the common insects we encounter on a daily basis, including ants, cockroaches, butterflies, and flies, are examples of Hexapoda.
Among the hexapods, the insects are the largest class in terms of species diversity as well as biomass in terrestrial habitats ). Typically, the head bears one pair of sensory antennae, mandibles as mouthparts, a pair of compound eyes, and some ocelli (simple eyes), along with numerous sensory hairs. The thorax bears three pairs of legs (one pair per segment) and two pairs of wings, with one pair each on the second and third thoracic segments. The abdomen usually has eleven segments and bears reproductive apertures. Hexapoda includes insects that are winged (like fruit flies) and wingless (like fleas).
Subphylum Myriapoda
Subphylum Myriapoda includes arthropods with numerous legs. Although the name is hyperbolic in suggesting that myriad legs are present in these invertebrates, the number of legs may vary from 10 to 750. This subphylum includes 13,000 species; the most commonly-found examples are millipedes and centipedes. All myriapods are terrestrial animals, prefering a humid environment.
Myriapods are typically found in moist soils, decaying biological material, and leaf litter. Centipedes, such as Scutigera coleoptrata, are classified as chilopods. These animals bear one pair of legs per segment, mandibles as mouthparts, and are somewhat dorsoventrally flattened. The legs in the first segment are modified to form forcipules (poison claws) that deliver venom to prey such as spiders and cockroaches, as centipedes are predatory. Millipedes bear two pairs of legs per diplosegment, a feature that results from embryonic fusion of adjacent pairs of body segments, are usually rounder in cross-section, and are herbivores or detritivores. Millipedes have visibly more numbers of legs as compared to centipedes, although they do not bear a thousand legs.
Subphylum Crustacea
Crustaceans are the most dominant aquatic arthropods since the total number of marine crustacean species stands at 67,000. However, there are also freshwater and terrestrial crustacean species. Krill, shrimp, lobsters, crabs, and crayfish are all examples of crustaceans. Terrestrial species like the wood lice ( Armadillidium spp.) (also called pill bugs, rolly pollies, potato bugs, or isopods) are also crustaceans, although the number of non-aquatic species in this subphylum is relatively low.
Crustaceans possess two pairs of antennae, mandibles as mouthparts, and biramous (“two branched”) appendages: their legs are formed in two parts, as distinct from the uniramous (“one branched”) myriapods and hexapods.
Unlike that of the Hexapoda, the head and thorax of most crustaceans is fused to form a cephalothorax, which is covered by a plate called the carapace, thus producing a body structure of two tagma. Crustaceans have a chitinous exoskeleton that is shed by molting whenever the animal increases in size. The exoskeletons of many species are also infused with calcium carbonate, which makes them even stronger than in other arthropods. Crustaceans have an open circulatory system where blood is pumped into the hemocoel by the dorsally-located heart. Hemocyanin and hemoglobin are the respiratory pigments present in these animals.
Subphylum Chelicerata
This subphylum includes animals such as spiders, scorpions, horseshoe crabs, and sea spiders and is predominantly terrestrial, although some marine species also exist. An estimated 77,000 species, found in almost all habitats, are included in subphylum Chelicerata.
The body of chelicerates may be divided into two parts: prosoma and opisthosoma, which are basically the equivalents of cephalothorax (usually smaller) and abdomen (usually larger). A “head” tagmum is not usually discernible. The phylum derives its name from the first pair of appendages, the chelicerae, which are specialized claw-like or fang-like mouthparts. These animals do not possess antennae. The second pair of appendages is known as pedipalps. In some species, such as sea spiders, an additional pair of appendages, called ovigers, is present between the chelicerae and pedipalps.
Chelicerae are used primarily for feeding, but in spiders, these are often modified into fangs that inject venom into their prey before feeding. Members of this subphylum have an open circulatory system with a heart that pumps blood into the hemocoel. Aquatic species have gills, whereas terrestrial species have either trachea or book lungs for gaseous exchange.
The nervous system in chelicerates consists of a brain and two ventral nerve cords. These animals use external as well as internal fertilization strategies for reproduction, depending upon the species and its habitat. Parental care for the young ranges from absolutely none to relatively-prolonged care.
Contributions and Attributions
- OpenStax College, Biology. October 17, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44667/latest...ol11448/latest . License : CC BY: Attribution
- Ecdysozoa. Provided by : Wikipedia. Located at : en.Wikipedia.org/wiki/Ecdysozoa . License : CC BY-SA: Attribution-ShareAlike
- ecdysis. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/ecdysis . License : CC BY-SA: Attribution-ShareAlike
- cuticle. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/cuticle . License : CC BY-SA: Attribution-ShareAlike
- coelomate. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/coelomate . License : CC BY-SA: Attribution-ShareAlike
- Cicada Molting. Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/Fi...da_Molting.jpg . License : CC BY-SA: Attribution-ShareAlike
- OpenStax College, Biology. October 17, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44667/latest...ol11448/latest . License : CC BY: Attribution
- exoskeleton. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/exoskeleton . License : CC BY-SA: Attribution-ShareAlike
- Cicada Molting. Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/Fi...da_Molting.jpg . License : CC BY-SA: Attribution-ShareAlike
- Soybean cyst nematode and egg SEM. Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/Fi...nd_egg_SEM.jpg . License : CC BY: Attribution
- malpighian tubule. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/malpighian+tubule . License : CC BY-SA: Attribution-ShareAlike
- OpenStax College, Biology. October 17, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44667/latest...ol11448/latest . License : CC BY: Attribution
- spiracle. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/spiracle . License : CC BY-SA: Attribution-ShareAlike
- tagma. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/tagma . License : CC BY-SA: Attribution-ShareAlike
- Cicada Molting. Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/Fi...da_Molting.jpg . License : CC BY-SA: Attribution-ShareAlike
- Soybean cyst nematode and egg SEM. Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/Fi...nd_egg_SEM.jpg . License : CC BY: Attribution
- BLW Trilobite (Paradoxides sp.). Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/Fi...xides_sp.).jpg . License : CC BY-SA: Attribution-ShareAlike
- Horseshoecrab2. Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/Fi...eshoecrab2.jpg . License : CC BY: Attribution
- OpenStax College, Biology. October 17, 2013. Provided by : OpenStax CNX. Located at : http://cnx.org/content/m44667/latest...ol11448/latest . License : CC BY: Attribution
- cephalothorax. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/cephalothorax . License : CC BY-SA: Attribution-ShareAlike
- forcipule. Provided by : Wiktionary. Located at : en.wiktionary.org/wiki/forcipule . License : CC BY-SA: Attribution-ShareAlike
- Cicada Molting. Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/Fi...da_Molting.jpg . License : CC BY-SA: Attribution-ShareAlike
- Soybean cyst nematode and egg SEM. Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/Fi...nd_egg_SEM.jpg . License : CC BY: Attribution
- BLW Trilobite (Paradoxides sp.). Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/Fi...xides_sp.).jpg . License : CC BY-SA: Attribution-ShareAlike
- Horseshoecrab2. Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/Fi...eshoecrab2.jpg . License : CC BY: Attribution
- House centipede. Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/Fi..._centipede.jpg . License : CC BY: Attribution
- Proteatia vol. Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/Fi...teatia_vol.jpg . License : CC BY-SA: Attribution-ShareAlike
- Carcinus aestuarii 2009 G1. Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/Fi...ii_2009_G1.jpg . License : CC BY-SA: Attribution-ShareAlike
- Solifugae Chelicera lateral aspect 2012 01 24 0999s. Provided by : Wikimedia. Located at : commons.wikimedia.org/wiki/Fi...1_24_0999s.JPG . License : CC BY: Attribution
Key Points
- The Hexapoda include insects; the Crustacea include lobster, crabs, and shrimp; the Myriapoda include centipedes and millipedes; and the Chelicerata include spiders, scorpions.
- The Hexapoda are the largest grouping of Arthropods, containing the more than one million species of insects, having representatives with six legs and one pair of antennae.
- The Myriapoda are terrestrial, prefering humid environments; they have between 10 and 750 legs.
- The Crustacea are primarily aquatic arthropods, but also include terrestrial forms, which have a cephalothorax covered by a carapace.
- The Chelicerata, which includes the spiders, horseshoe crabs, and scorpions, have mouth parts that are fang-like and used for capturing prey.
Key Terms
- cephalothorax : the fused head and thorax of spiders and crustaceans
- forcipule : a modified pincer-like foreleg in centipedes, capable of injecting venom