9.5: Act V
Act V, Scene 1
Before OLIVIA’s house.
[Enter Clown and FABIAN]
Fabian
.
Now, as thou lovest me, let me see his letter.
2190
Feste . Good Master Fabian, grant me another request.
Fabian . Any thing.
Feste . Do not desire to see this letter.
Fabian
.
This is, to give a dog, and in recompense desire my
dog again.
2195
[Enter DUKE ORSINO, VIOLA, CURIO, and Lords]
Orsino . Belong you to the Lady Olivia, friends?
Feste . Ay, sir; we are some of her trappings.
Orsino . I know thee well; how dost thou, my good fellow?
Feste
.
Truly, sir, the better for my foes and the worse
2200
for my friends.
Orsino . Just the contrary; the better for thy friends.
Feste . No, sir, the worse.
Orsino . How can that be?
Feste
.

Orsino . Why, this is excellent.
Feste
.
By my troth, sir, no; though it please you to be
one of my friends.
Orsino
.
Thou shalt not be the worse for me: there’s gold.
2215
Feste
.
But that it would be double-dealing, sir, I would
you could make it another.
Orsino .
Feste
.
Put your grace in your pocket, sir, for this once,
and let your flesh and blood obey it.
2220
Orsino
.
Well, I will be so much a sinner, to be a
double-dealer: there’s another.
Feste
.
Primo, secundo, tertio, is a good play; and the old
saying is, the third pays for all: the triplex,
sir, is a good tripping measure; or the bells of
2225
Saint Bennet, sir, may put you in mind; one, two, three.
Orsino
.
You can fool no more money out of me at this throw:
if you will let your lady know I am here to speak
with her, and bring her along with you, it may awake
my bounty further.
2230
Feste
.
Marry, sir, lullaby to your bounty till I come
again. I go, sir; but I would not have you to think
that my desire of having is the sin of covetousness:
but, as you say, sir, let your bounty take a nap, I
will awake it anon.
2235
[Exit]
Viola . Here comes the man, sir, that did rescue me.
[Enter ANTONIO and Officers]
Orsino
.
That face of his I do remember well;
Yet, when I saw it last, it was besmear’d
2240
As black as Vulcan in the smoke of war:
A bawbling vessel was he captain of,
For shallow draught and bulk unprizable;
With which such scathful grapple did he make
With the most noble bottom of our fleet,
2245
That very envy and the tongue of loss
Cried fame and honour on him. What’s the matter?
First Officer
.
Orsino, this is that Antonio
That took the Phoenix and her fraught from Candy;
And this is he that did the Tiger board,
2250
When your young nephew Titus lost his leg:
Here in the streets, desperate of shame and state,
In private brabble did we apprehend him.
Viola
.
He did me kindness, sir, drew on my side;
But in conclusion put strange speech upon me:
2255
I know not what ’twas but distraction.
Orsino
.
Notable pirate! thou salt-water thief!

Orsino, noble sir,
Be pleased that I shake off these names you give me:
Antonio never yet was thief or pirate,
Though I confess, on base and ground enough,
Orsino’s enemy. A witchcraft drew me hither:
2265
That most ingrateful boy there by your side,
From the rude sea’s enraged and foamy mouth
Did I redeem; a wreck past hope he was:
His life I gave him and did thereto add
My love, without retention or restraint,
2270
All his in dedication; for his sake
Did I expose myself, pure for his love,
Into the danger of this adverse town;
Drew to defend him when he was beset:
Where being apprehended, his false cunning,
2275
Not meaning to partake with me in danger,
Taught him to face me out of his acquaintance,
And grew a twenty years removed thing
While one would wink; denied me mine own purse,
Which I had recommended to his use
2280
Not half an hour before.
Viola . How can this be?
Orsino . When came he to this town?
Antonio
.
To-day, my lord; and for three months before,
No interim, not a minute’s vacancy,
2285
Both day and night did we keep company.
[Enter OLIVIA and Attendants]
Orsino
.
Here comes the countess: now heaven walks on earth.
But for thee, fellow; fellow, thy words are madness:
Three months this youth hath tended upon me;
2290
But more of that anon. Take him aside.
Olivia
.
What would my lord, but that he may not have,
Wherein Olivia may seem serviceable?
Cesario, you do not keep promise with me.
Viola
.
Madam!
2295
Orsino . Gracious Olivia,—
Olivia . What do you say, Cesario? Good my lord,—
Viola . My lord would speak; my duty hushes me.
Olivia
.
If it be aught to the old tune, my lord,
It is as fat and fulsome to mine ear
2300
As howling after music.
Orsino . Still so cruel?
Olivia . Still so constant, lord.
Orsino
.
What, to perverseness? you uncivil lady,
To whose ingrate and unauspicious altars
2305
My soul the faithfull’st offerings hath breathed out
That e’er devotion tender’d! What shall I do?
Olivia . Even what it please my lord, that shall become him.
Orsino
.
Why should I not, had I the heart to do it,
Like to the Egyptian thief at point of death,
2310
Kill what I love?—a savage jealousy
That sometimes savours nobly.
Viola
.
And I, most jocund, apt and willingly,
To do you rest, a thousand deaths would die.
2325
Olivia . Where goes Cesario?
Viola
.
After him I love
More than I love these eyes, more than my life,
More, by all mores, than e’er I shall love wife.
If I do feign, you witnesses above
2330
Punish my life for tainting of my love!
Olivia . Ay me, detested! how am I beguiled!
Viola . Who does beguile you? who does do you wrong?
Olivia
.
Hast thou forgot thyself? is it so long?
Call forth the holy father.
2335
Orsino . Come, away!
Olivia . Whither, my lord? Cesario, husband, stay.
Orsino . Husband!
Olivia . Ay, husband: can he that deny?
Orsino
.
Her husband, sirrah!
2340
Viola . No, my lord, not I.
Olivia
.
Alas, it is the baseness of thy fear
That makes thee strangle thy propriety:
Fear not, Cesario; take thy fortunes up;
Be that thou know’st thou art, and then thou art
2345
As great as that thou fear’st.
[Enter Priest]
O, welcome, father!
Father, I charge thee, by thy reverence,
Here to unfold, though lately we intended
2350
To keep in darkness what occasion now
Reveals before ’tis ripe, what thou dost know
Hath newly pass’d between this youth and me.
Priest
.
A contract of eternal bond of love,
Confirm’d by mutual joinder of your hands,
2355
Attested by the holy close of lips,
Strengthen’d by interchangement of your rings;
And all the ceremony of this compact
Seal’d in my function, by my testimony:
Since when, my watch hath told me, toward my grave
2360
I have travell’d but two hours.
Orsino
.
O thou dissembling cub! what wilt thou be
When time hath sow’d a grizzle on thy case?
Or will not else thy craft so quickly grow,
That thine own trip shall be thine overthrow?
2365
Farewell, and take her; but direct thy feet
Where thou and I henceforth may never meet.
Viola . My lord, I do protest—
Olivia
.
O, do not swear!
Hold little faith, though thou hast too much fear.
2370
[Enter SIR ANDREW]
Sir Andrew Aguecheek
.
For the love of God, a surgeon! Send one presently
to Sir Toby.
Olivia . What’s the matter?
Sir Andrew Aguecheek
.
 I had rather than forty pound I were at home.
Olivia . Who has done this, Sir Andrew?
Sir Andrew Aguecheek
.
The count’s gentleman, one Cesario: we took him for
a coward, but he’s the very devil incardinate.
2380
Orsino . My gentleman, Cesario?
Sir Andrew Aguecheek
.
‘Od’s lifelings, here he is! You broke my head for
nothing; and that that I did, I was set on to do’t
by Sir Toby.
Viola
.
Why do you speak to me?
Sir Andrew Aguecheek
.

[Enter SIR TOBY BELCH and Clown]
2390
Here comes Sir Toby halting; you shall hear more:
but if he had not been in drink, he would have
tickled you othergates than he did.
Orsino . How now, gentleman! how is’t with you?
Sir Toby Belch
.
That’s all one: has hurt me, and there’s the end
2395
on’t. Sot, didst see Dick surgeon, sot?
Feste
.
O, he’s drunk, Sir Toby, an hour agone; his eyes
were set at eight i’ the morning.
Sir Toby Belch
.
 Away with him! Who hath made this havoc with them?
Sir Andrew Aguecheek . I’ll help you, Sir Toby, because well be dressed together.
Sir Toby Belch
.
Will you help? an ass-head and a coxcomb and a
knave, a thin-faced knave, a gull!
Olivia
.
Get him to bed, and let his hurt be look’d to.
2405
[Exeunt Clown, FABIAN, SIR TOBY BELCH, and SIR ANDREW]
[Enter SEBASTIAN]
Sebastian
.
I am sorry, madam, I have hurt your kinsman:
But, had it been the brother of my blood,
I must have done no less with wit and safety.
2410
You throw a strange regard upon me, and by that
I do perceive it hath offended you:
Pardon me, sweet one, even for the vows
We made each other but so late ago.
Orsino
.
One face, one voice, one habit, and two persons,
2415
A natural perspective, that is and is not!
Sebastian
.
Antonio, O my dear Antonio!
How have the hours rack’d and tortured me,
Since I have lost thee!
Antonio
.
Sebastian are you?
2420
Sebastian . Fear’st thou that, Antonio?
Antonio
.
How have you made division of yourself?
An apple, cleft in two, is not more twin
Than these two creatures. Which is Sebastian?
Olivia
.
Most wonderful!
2425
Sebastian
.
Do I stand there? I never had a brother;
Nor can there be that deity in my nature,
Of here and every where. I had a sister,
Whom the blind waves and surges have devour’d.
Of charity, what kin are you to me?
2430
What countryman? what name? what parentage?
Viola
.
Of Messaline: Sebastian was my father;
Such a Sebastian was my brother too,
So went he suited to his watery tomb:
If spirits can assume both form and suit
2435
You come to fright us.
Sebastian
.
A spirit I am indeed;
But am in that dimension grossly clad
Which from the womb I did participate.

Viola . My father had a mole upon his brow.
Sebastian . And so had mine.
Viola
.
And died that day when Viola from her birth
2445
Had number’d thirteen years.
Sebastian
.
O, that record is lively in my soul!
He finished indeed his mortal act
That day that made my sister thirteen years.
Viola
.
If nothing lets to make us happy both
2450
But this my masculine usurp’d attire,
Do not embrace me till each circumstance
Of place, time, fortune, do cohere and jump
That I am Viola: which to confirm,
I’ll bring you to a captain in this town,
2455
Where lie my maiden weeds; by whose gentle help
I was preserved to serve this noble count.
All the occurrence of my fortune since
Hath been between this lady and this lord.
Sebastian
.
[To OLIVIA]
So comes it, lady, you have been mistook:
2460
But nature to her bias drew in that.
You would have been contracted to a maid;
Nor are you therein, by my life, deceived,
You are betroth’d both to a maid and man.
Orsino
.
Be not amazed; right noble is his blood.
2465
If this be so, as yet the glass seems true,
I shall have share in this most happy wreck.
[To VIOLA]
Boy, thou hast said to me a thousand times
Thou never shouldst love woman like to me.
2470
Viola
.
And all those sayings will I overswear;
And those swearings keep as true in soul
As doth that orbed continent the fire
That severs day from night.
Orsino
.
Give me thy hand;
2475
And let me see thee in thy woman’s weeds.
Viola
.
The captain that did bring me first on shore
Hath my maid’s garments: he upon some action
Is now in durance, at Malvolio’s suit,
A gentleman, and follower of my lady’s.
2480
Olivia
.
He shall enlarge him: fetch Malvolio hither:
And yet, alas, now I remember me,
They say, poor gentleman, he’s much distract.
[Re-enter Clown with a letter, and FABIAN]
A most extracting frenzy of mine own
2485
From my remembrance clearly banish’d his.
How does he, sirrah?
Feste
.
Truly, madam, he holds Belzebub at the staves’s end as
well as a man in his case may do: has here writ a
letter to you; I should have given’t you to-day
2490
morning, but as a madman’s epistles are no gospels,
so it skills not much when they are delivered.
Olivia . Open’t, and read it.
Feste
.
Look then to be well edified when the fool delivers
the madman.
2495
[Reads]
‘By the Lord, madam,’—
Olivia . How now! art thou mad?
Feste
.
No, madam, I do but read madness: an your ladyship
will have it as it ought to be, you must allow Vox.
2500
Olivia . Prithee, read i’ thy right wits.
Feste
.
So I do, madonna; but to read his right wits is to
read thus: therefore perpend, my princess, and give ear.
Olivia . Read it you, sirrah.
[To FABIAN]
Fabian
.
[Reads]
‘By the Lord, madam, you wrong me, and the
world shall know it: though you have put me into
darkness and given your drunken cousin rule over
me, yet have I the benefit of my senses as well as
your ladyship. I have your own letter that induced
2510
me to the semblance I put on; with the which I doubt
not but to do myself much right, or you much shame.
Think of me as you please. I leave my duty a little
unthought of and speak out of my injury.
THE MADLY-USED MALVOLIO.’
2515
Olivia . Did he write this?
Feste . Ay, madam.
Orsino . This savours not much of distraction.
Olivia
.
See him deliver’d, Fabian; bring him hither.
[Exit FABIAN]
2520
My lord so please you, these things further
thought on,
To think me as well a sister as a wife,
One day shall crown the alliance on’t, so please you,
Here at my house and at my proper cost.
2525
Orsino
.
Madam, I am most apt to embrace your offer.

Olivia . A sister! you are she.
[Re-enter FABIAN, with MALVOLIO]
Orsino . Is this the madman?
Olivia
.
Ay, my lord, this same.
How now, Malvolio!
Malvolio
.
Madam, you have done me wrong,
Notorious wrong.
2540
Olivia . Have I, Malvolio? no.
Malvolio
.
Lady, you have. Pray you, peruse that letter.
You must not now deny it is your hand:
Write from it, if you can, in hand or phrase;
Or say ’tis not your seal, nor your invention:
2545
You can say none of this: well, grant it then
And tell me, in the modesty of honour,
Why you have given me such clear lights of favour,
Bade me come smiling and cross-garter’d to you,
To put on yellow stockings and to frown
2550
Upon Sir Toby and the lighter people;
And, acting this in an obedient hope,
Why have you suffer’d me to be imprison’d,
Kept in a dark house, visited by the priest,
And made the most notorious geck and gull
2555
That e’er invention play’d on? tell me why.
Olivia
.
Alas, Malvolio, this is not my writing,
Though, I confess, much like the character
But out of question ’tis Maria’s hand.
And now I do bethink me, it was she
2560
First told me thou wast mad; then camest in smiling,
And in such forms which here were presupposed
Upon thee in the letter. Prithee, be content:
This practise hath most shrewdly pass’d upon thee;
But when we know the grounds and authors of it,
2565
Thou shalt be both the plaintiff and the judge
Of thine own cause.
Fabian
.
Good madam, hear me speak,
And let no quarrel nor no brawl to come
Taint the condition of this present hour,
2570
Which I have wonder’d at. In hope it shall not,
Most freely I confess, myself and Toby
Set this device against Malvolio here,
Upon some stubborn and uncourteous parts
We had conceived against him: Maria writ
2575
The letter at Sir Toby’s great importance;
In recompense whereof he hath married her.
How with a sportful malice it was follow’d,
May rather pluck on laughter than revenge;
If that the injuries be justly weigh’d
2580
That have on both sides pass’d.
Olivia . Alas, poor fool, how have they baffled thee!
Feste
.
Why, ‘some are born great, some achieve greatness,
and some have greatness thrown upon them.’ I was
one, sir, in this interlude; one Sir Topas, sir; but
2585
that’s all one. ‘By the Lord, fool, I am not mad.’
But do you remember? ‘Madam, why laugh you at such
a barren rascal? an you smile not, he’s gagged:’
and thus the whirligig of time brings in his revenges.
Malvolio
.
I’ll be revenged on the whole pack of you.
2590
[Exit]
Olivia . He hath been most notoriously abused.
Orsino
.
Pursue him and entreat him to a peace:
He hath not told us of the captain yet:
When that is known and golden time convents,
2595
A solemn combination shall be made
Of our dear souls. Meantime, sweet sister,
We will not part from hence.
[Exeunt all, except Clown]
Feste
.

But when I came to man’s estate,
With hey, ho, &c.
‘Gainst knaves and thieves men shut their gate,
2610
For the rain, &c.
But when I came, alas! to wive,
With hey, ho, &c.
By swaggering could I never thrive,
For the rain, &c.
2615
But when I came unto my beds,
With hey, ho, &c.
With toss-pots still had drunken heads,
For the rain, &c.
A great while ago the world begun,
2620
With hey, ho, &c.
But that’s all one, our play is done,
And we’ll strive to please you every day.
[Exit]
- Twelfth Night, Or What You Will. Authored by : William Shakespeare. Located at : http://www.opensourceshakespeare.org/views/plays/playmenu.php?WorkID=12night . License : Public Domain: No Known Copyright
- Image of Twelfth Night Scene. Authored by : William Hamilton. Located at : https://commons.wikimedia.org/wiki/File:William_Hamilton,_A_Scene_from_Twelfth_Night.jpg . License : Public Domain: No Known Copyright


5.3: Fungi
- Explain why the study of fungi such as yeast and molds is within the discipline of microbiology
- Describe the unique characteristics of fungi
- Describe examples of asexual and sexual reproduction of fungi
- Compare the major groups of fungi in this chapter, and give examples of each
- Identify examples of the primary causes of infections due to yeasts and molds
- Identify examples of toxin-producing fungi
- Classify fungal organisms according to major groups
The fungi comprise a diverse group of organisms that are heterotrophic and typically saprozoic. In addition to the well-known macroscopic fungi (such as mushrooms and molds), many unicellular yeasts and spores of macroscopic fungi are microscopic. For this reason, fungi are included within the field of microbiology.
Fungi are important to humans in a variety of ways. Both microscopic and macroscopic fungi have medical relevance, with some pathogenic species that can cause mycoses (illnesses caused by fungi). Some pathogenic fungi are opportunistic, meaning that they mainly cause infections when the host’s immune defenses are compromised and do not normally cause illness in healthy individuals. Fungi are important in other ways. They act as decomposers in the environment, and they are critical for the production of certain foods such as cheeses. Fungi are also major sources of antibiotics, such as penicillin from the fungus Penicillium .
Characteristics of Fungi
Fungi have well-defined characteristics that set them apart from other organisms. Most multicellular fungal bodies, commonly called molds, are made up of filaments called hyphae. Hyphae can form a tangled network called a mycelium and form the thallus (body) of fleshy fungi. Hyphae that have walls between the cells are called septate hyphae; hyphae that lack walls and cell membranes between the cells are called nonseptate or coenocytic hyphae). (Figure \(\PageIndex{1}\)).
In contrast to molds, yeasts are unicellular fungi. The budding yeasts reproduce asexually by budding off a smaller daughter cell; the resulting cells may sometimes stick together as a short chain or pseudohypha (Figure \(\PageIndex{1}\)). Candida albicans is a common yeast that forms pseudohyphae; it is associated with various infections in humans, including vaginal yeast infections, oral thrush, and candidiasis of the skin.
Some fungi are dimorphic, having more than one appearance during their life cycle. These dimorphic fungi may be able to appear as yeasts or molds, which can be important for infectivity. They are capable of changing their appearance in response to environmental changes such as nutrient availability or fluctuations in temperature, growing as a mold, for example, at 25 °C (77 °F), and as yeast cells at 37 °C (98.6 °F). This ability helps dimorphic fungi to survive in diverse environments. Histoplasma capsulatum , the pathogen that causes histoplasmosis, a lung infection, is an example of a dimorphic fungus (Figure \(\PageIndex{2}\)).
There are notable unique features in fungal cell walls and membranes. Fungal cell walls contain chitin, as opposed to the cellulose found in the cell walls of plants and many protists. Additionally, whereas animals have cholesterol in their cell membranes, fungal cell membranes have different sterols called ergosterols. Ergosterols are often exploited as targets for antifungal drugs.
Fungal life cycles are unique and complex. Fungi reproduce sexually either through cross- or self-fertilization. Haploid fungi form hyphae that have gametes at the tips. Two different mating types (represented as “+ type” and “– type”) are involved. The cytoplasms of the + and – type gametes fuse (in an event called plasmogamy), producing a cell with two distinct nuclei (a dikaryotic cell). Later, the nuclei fuse (in an event called karyogamy) to create a diploid zygote. The zygote undergoes meiosis to form spores that germinate to start the haploid stage, which eventually creates more haploid mycelia (Figure \(\PageIndex{3}\)). Depending on the taxonomic group, these sexually produced spores are known as zygospores (in Zygomycota), ascospores (in Ascomycota), or basidiospores (in Basidiomycota) (Figure \(\PageIndex{4}\)).
Fungi may also exhibit asexual reproduction by mitosis, mitosis with budding, fragmentation of hyphae, and formation of asexual spores by mitosis. These spores are specialized cells that, depending on the organism, may have unique characteristics for survival, reproduction, and dispersal. Fungi exhibit several types of asexual spores and these can be important in classification.
Is a dimorphic fungus a yeast or a mold? Explain.
Fungal Diversity
The fungi are very diverse, comprising seven major groups. Not all of the seven groups contain pathogens. Some of these groups are generally associated with plants and include plant pathogens. For example, Urediniomycetes and Ustilagomycetes include the plant rusts and smuts, respectively. These form reddish or dark masses, respectively, on plants as rusts (red) or smuts (dark). Some species have substantial economic impact because of their ability to reduce crop yields. Glomeromycota includes the mycorrhizal fungi, important symbionts with plant roots that can promote plant growth by acting like an extended root system. The Glomeromycota are obligate symbionts, meaning that they can only survive when associated with plant roots; the fungi receive carbohydrates from the plant and the plant benefits from the increased ability to take up nutrients and minerals from the soil. The Chytridiomycetes (chytrids) are small fungi, but are extremely ecologically important. Chytrids are generally aquatic and have flagellated, motile gametes; specific types are implicated in amphibian declines around the world. Because of their medical importance, we will focus on Zygomycota, Ascomycota, Basidiomycota, and Microsporidia. Figure \(\PageIndex{9}\) summarizes the characteristics of these medically important groups of fungi.
The Zygomycota (zygomycetes) are mainly saprophytes with coenocytic hyphae and haploid nuclei. They use sporangiospores for asexual reproduction. The group name comes from the zygospores that they use for sexual reproduction (Figure \(\PageIndex{3}\)), which have hard walls formed from the fusion of reproductive cells from two individuals. Zygomycetes are important for food science and as crop pathogens. One example is Rhizopus stolonifer (Figure \(\PageIndex{4}\)), an important bread mold that also causes rice seedling blight. Mucor is a genus of fungi that can potentially cause necrotizing infections in humans, although most species are intolerant of temperatures found in mammalian bodies (Figure \(\PageIndex{4}\)).
The Ascomycota include fungi that are used as food (edible mushrooms, morels, and truffles), others that are common causes of food spoilage (bread molds and plant pathogens), and still others that are human pathogens. Ascomycota may have septate hyphae and cup-shaped fruiting bodies called ascocarps. Some genera of Ascomycota use sexually produced ascospores as well as asexual spores called conidia, but sexual phases have not been discovered or described for others. Some produce an ascus containing ascospores within an ascocarp (Figure \(\PageIndex{5}\)).
Examples of the Ascomycota include several bread molds and minor pathogens, as well as species capable of causing more serious mycoses. Species in the genus Aspergillus are important causes of allergy and infection, and are useful in research and in the production of certain fermented alcoholic beverages such as Japanese sake . The fungus Aspergillus flavus , a contaminant of nuts and stored grains, produces an aflatoxin that is both a toxin and the most potent known natural carcinogen. Neurospora crassa is of particular use in genetics research because the spores produced by meiosis are kept inside the ascus in a row that reflects the cell divisions that produced them, giving a direct view of segregation and assortment of genes (Figure \(\PageIndex{6}\)). Penicillium produces the antibiotic penicillin (Figure \(\PageIndex{5}\)).
Many species of ascomycetes are medically important. A large number of species in the genera Trichophyton , Microsporum , and Epidermophyton are dermatophytes, pathogenic fungi capable of causing skin infections such as athlete’s foot, jock itch, and ringworm. Blastomyces dermatitidis is a dimorphic fungus that can cause blastomycosis, a respiratory infection that, if left untreated, can become disseminated to other body sites, sometimes leading to death. Another important respiratory pathogen is the dimorphic fungus Histoplasma capsulatum (Figure \(\PageIndex{2}\)) , which is associated with birds and bats in the Ohio and Mississippi river valleys. Coccidioides immitis causes the serious lung disease Valley fever. Candida albicans , the most common cause of vaginal and other yeast infections, is also an ascomycete fungus; it is a part of the normal microbiota of the skin, intestine, genital tract, and ear (Figure \(\PageIndex{5}\)). Ascomycetes also cause plant diseases, including ergot infections, Dutch elm disease, and powdery mildews.
Saccharomyces yeasts, including the baker’s yeast S. cerevisiae , are unicellular ascomycetes with haploid and diploid stages (Figure \(\PageIndex{7}\)). This and other Saccharomyces species are used for brewing beer.
The Basidiomycota (basidiomycetes) are fungi that have basidia (club-shaped structures) that produce basidiospores(spores produced through budding) within fruiting bodies called basidiocarps (Figure \(\PageIndex{8}\)). They are important as decomposers and as food. This group includes rusts, stinkhorns, puffballs, and mushrooms. Several species are of particular importance. Cryptococcus neoformans , a fungus commonly found as a yeast in the environment, can cause serious lung infections when inhaled by individuals with weakened immune systems. The edible meadow mushroom, Agricus campestris , is a basidiomycete, as is the poisonous mushroom Amanita phalloides , known as the death cap. The deadly toxins produced by A. phalloides have been used to study transcription.
Finally, the Microsporidia are unicellular fungi that are obligate intracellular parasites. They lack mitochondria, peroxisomes, and centrioles, but their spores release a unique polar tubule that pierces the host cell membrane to allow the fungus to gain entry into the cell. A number of microsporidia are human pathogens, and infections with microsporidia are called microsporidiosis. One pathogenic species is Enterocystozoan bieneusi , which can cause symptoms such as diarrhea, cholecystitis (inflammation of the gall bladder), and in rare cases, respiratory illness.
Which group of fungi appears to be associated with the greatest number of human diseases?
When we think about antimicrobial medications, antibiotics such as penicillin often come to mind. Penicillin and related antibiotics interfere with the synthesis of peptidoglycan cell walls, which effectively targets bacterial cells. These antibiotics are useful because humans (like all eukaryotes) do not have peptidoglycan cell walls.
Developing medications that are effective against eukaryotic cells but not harmful to human cells is more difficult. Despite huge morphological differences, the cells of humans, fungi, and protists are similar in terms of their ribosomes, cytoskeletons, and cell membranes. As a result, it is more challenging to develop medications that target protozoans and fungi in the same way that antibiotics target prokaryotes.
Fungicides have relatively limited modes of action. Because fungi have ergosterols(instead of cholesterol) in their cell membranes, the different enzymes involved in sterol production can be a target of some medications. The azole and morpholine fungicidesinterfere with the synthesis of membrane sterols. These are used widely in agriculture (fenpropimorph) and clinically (e.g., miconazole). Some antifungal medications target the chitin cell walls of fungi. Despite the success of these compounds in targeting fungi, antifungal medications for systemic infections still tend to have more toxic side effects than antibiotics for bacteria.
Sarah is relieved the ringworm is not an actual worm, but wants to know what it really is. The physician explains that ringworm is a fungus. He tells her that she will not see mushrooms popping out of her skin, because this fungus is more like the invisible part of a mushroom that hides in the soil. He reassures her that they are going to get the fungus out of her too.
The doctor cleans and then carefully scrapes the lesion to place a specimen on a slide. By looking at it under a microscope, the physician is able to confirm that a fungal infection is responsible for Sarah’s lesion. In Figure \(\PageIndex{10}\), it is possible to see macro- and microconidia in Trichophyton rubrum . Cell walls are also visible. Even if the pathogen resembled a helminth under the microscope, the presence of cell walls would rule out the possibility because animal cells lack cell walls.
The doctor prescribes an antifungal cream for Sarah’s mother to apply to the ringworm. Sarah’s mother asks, “What should we do if it doesn’t go away?”
Can all forms of ringworm be treated with the same antifungal medication?
Key Concepts and Summary
- The fungi include diverse saprotrophic eukaryotic organisms with chitin cell walls
- Fungi can be unicellular or multicellular; some (like yeast) and fungal spores are microscopic, whereas some are large and conspicuous
- Reproductive types are important in distinguishing fungal groups
- Medically important species exist in the four fungal groups Zygomycota, Ascomycota, Basidiomycota, and Microsporidia
- Members of Zygomycota, Ascomycota, and Basidiomycota produce deadly toxins
- Important differences in fungal cells, such as ergosterols in fungal membranes, can be targets for antifungal medications, but similarities between human and fungal cells make it difficult to find targets for medications and these medications often have toxic adverse effects


10.4: Levels of Evaluation
Your friend Amal is struggling.  How do we explain what is going on with her?
Well, we have three basic options and the choice between them will determine how we evaluate Amal: is she a victim of circumstance? Is she maladjusted and in need of medical intervention? Or is she simply making bad choices?
The three levels of evaluation, as I like to call them are the different lenses through which we can view Amal’s situation.
Material evaluation
At the material level of evaluation, we look at what sorts of resources Amal has access to and how Amal is put together as an organism. Is Amal’s hypothalamus being impinged on by a benign tumor? If so, then the tumor is the best explanation for her lack of motivation—there’s something materially wrong with her. Is she chronically malnourished? Does she lack the financial resources necessary to make the changes she’d otherwise make? If so, she’s got a material deficit —not having enough resources of one kind or another is getting in the way of her doing what she’d like to do.
- “He’s missing some capacity that the rest of us have”
- “If she had a little bit more resources, she could do great things.”
- “He’s got good genes, comes from a long line of distance runners.”
- “It wasn’t her saying all those things, that was the brain tumor.”
- “They weren’t ignoring you because they were mad at you, they were doing it because their brain was low on serotonin and so they were catatonic.”
- “He was malnourished as a child, so now he has trouble with impulse control.”
- “I’m sorry, I’m just really tired/in a bad mood/really hangry.”
- “She didn’t mean to do it, it was just a reflex!”
Agential evaluation
At the agential level of evaluation, we treat people like rational agents, who are responding to reasons for acting and making a more or less free choice. Agents are in charge of their actions, they have responsibility for the outcomes of those actions, and they are acting so as to express their values or reasons. Their own convictions and commitments determine what they end up doing rather than any material deficits or deficiencies. We spend a lot of time at this level of evaluation, especially when it comes to our negative evaluations of the actions and situations of other people and our positive evaluations of our own situations and actions.
- “She meant to do that”
- “They always go out of their way to make me feel welcome.”
- “A lot of hard work and good choices got me where I am today.”
- “You were ignoring me on purpose!”
- “What reason would someone have to do such a thing? What were they thinking?”
- “He knew what he was doing and he should take responsibility for his actions.”
Structural evaluation
At the structural level of evaluation, we are interested in the contexts or structures in which people are embedded in evaluating their situations or choices. Why doesn’t she eat healthier? Well, she lives in a food desert where the only food to buy for miles is at quickee marts and fast food restaurants. We’re pointing to facts about the way society is ordered or the roles or situations people find themselves in to explain their behavior or situation. Why doesn’t he study harder for his math exams? Well, his father left a few years ago, so he has to take care of his siblings after school and then work after dinner until midnight each night. It’s a particular role that this character plays and all of the responsibilities that go along with it that explain why he does what he does.
Notice how we haven’t talked at all about choices here. We’re not interested necessarily in why people make the choices they do, because sometimes when we talk about the structures in which they’re embedded, it becomes clear that they don’t really have a choice. Other times structures merely make it so that someone’s apparently irrational or imprudent choices are actually the best choice available. Here’s an example: Sam works hard at their job, often picking up overtime and working extra shifts. Sam still, though, doesn’t have any hope of saving for retirement or saving to buy a house, etc. They are stuck. So when Sam finally is able to save $200 in the bank after six months of skimping and saving, they face the choice of either a) keeping it in the bank so that in 30 years of scraping they can finally afford to get a more solid financial footing under their feet, or b) spend it on something nice for theirself now, so that they can do more than simply survive for the next 30 years. We could talk about personal responsibility here, but we could also recognize that the structures within society sometimes make a bad choice—buying a new phone or video game instead of saving for the future—the best available choice—living life while you have it so that you don’t suffer your whole life waiting for a financially stable future that may never come. If a person’s seemingly irresponsible choice is actually the best choice available to them, then we have good reason to think that a structural evaluation of their circumstances will be helpful in understanding their actions and life situation.
So when we engage in structural evaluation, we’re evaluating a person’s actions and circumstances insofar as they were caused by or constrained by the structures, contexts, systems, etc. in which that person is embedded and therefore also by reference to the roles that that person plays in those structures.
- “Of course they ended up doing that, they didn’t have a choice!”
- “She never has time for brunch anymore because she’s a mother.”
- “Anyone in those circumstances would have done the same thing.”
- “How can we hold someone responsible for doing what society has forced them to do?”
- “Growing up, we only had two options available to us: work at a fast food joint or deal drugs.”
- “They live deep in rural California and so don’t always have the easiest of access to fast internet.”
- “She suffers from depression because she is constantly faced with hurtles that keep her from advancing at work and threats of violence and harassment when she’s not at work.”
When we’re thinking at either the material or structural level, we’re thinking about someone in a way that brackets or temporarily disregards their role in their life as responsible actors. Thich Nhat Hanh, a Vietnamese Buddhist Monk, gave the analogy of a head of lettuce growing in the ground. If it starts to shrivel or wither, we will think “it needs more water” rather than “it needs to make better decisions.” If it is too small, we’ll think “oh its genes code for less growth” or “maybe it didn’t get enough sunlight.” We won’t think “that head of lettuce is at fault for being so small. If only it would’ve tried harder.” Get it? By treating other people like heads of lettuce we ignore something important about them: that they have reasons for their actions and are often deliberately making the decisions they make. But we also open up a whole way of understanding their behavior that doesn’t necessitate that they be at fault for everything bad that happens in their life.
A few upshots
First, we should note that we often think of ourselves as victims of circumstance or as people struggling to do our best with the resources at our disposal. We often, though, see other people as agents —as acting on purpose and for reasons. This is a pretty problematic way to go about our lives. We make excuses for ourselves while refusing to do so for others. Instead, I believe we should reverse this dynamic: we should see ourselves as agents and always hold ourselves accountable for our actions (except maybe give ourselves a break when we need it) and see other people as victims of circumstance or people determined to do what they do by habits, reflexes, and sometimes by the fact that they lack material resources.
A related point is that we’re, empirically speaking, not good at this. We suffer from a cognitive bias called fundamental attribution error , where we tend to think of the actions of ourselves and of people in our “in groups” as excusable by appeal to circumstances or material resources/makeup; but we tend to think of the actions of people who aren’t like us or are from an outgroup (even fans of a rival sports team, for instance) as agents who make bad choices and/or have bad intentions.
Our goal should be to reverse fundamental attribution error and instead be harder on those around us and strive to understand those who are not like us with as much empathy, understanding, and patience as we can muster.  Everyone messes up sometimes.
A different upshot is somewhat political: it’s tempting to think that it is only our choices and hard work that determine our lot in life (where we end up in the social hierarchy), but if we take the material and structural perspectives seriously, it becomes harder to hold onto this absolutist view. We must admit, it seems like everyone would agree upon reflection, that sometimes circumstances or material resources determine how things go for someone. Some people are fantastically successful because their parents had a lot of connections (structural/relational perspective) and/or because they were given a large inheritance (material perspective) or maybe because their brains just naturally work well or their bodies are naturally fit and shapely or their hand-eye coordination is naturally fantastic without any training (still in the material perspective). The same goes for those who are unsuccessful. Life isn’t only about the choices we make, but obviously our choices play a large role in shaping who we become and where we end up.
Finally, we have to be careful in choosing when to apply moral reasoning, or moralizing about a situation. A person may be simply making the best decision offered them by the circumstances or acting out an impulse brought on by the material structure of their brain. If that’s the case, then moralizing or judging them on moral grounds might be inappropriate. We aren’t always rational actors making rational decisions or acting for reasons; and furthermore what sorts of things a rational person would do changes dramatically with circumstances and context. Don’t be too quick to judge other folks on moral grounds!


4.3: Editing a Transcluded (Reused) Page
Sometimes in editing pages on the Library, a page will be edited and it may look something like the page shown below for the first chapter's exercise set in the OpenStax Calculus text.
This is a transcluded page like the procedure outlined in Section 2.8 . To edit the content on this page (to fix a typo or incorrect image, etc.), the source page must be located and edited directly. If you are not the textbook's author, remember to only fix errors on the original source pages and only customize pages that are located in your school's Course Shell.
To quickly navigate to the corresponding source page to edit it, double click on the purple "Content Reuse" box and a Content Reuse window will pop up.
Copy and paste the URL in the "Article to reuse" which is the source page. Then paste it in the URL wtih the after appending it to the name of the library (Math library in this case).
When the new page (source) opens up, you can edit it as with other pages. Any edits on this source page will be reflected on the transcluded page as well, once it is refreshed.


13.4: Mutagens and Carcinogens
A carcinogen is any agent that directly increases the incidence of cancer. Most, but not all carcinogens are mutagens. Carcinogens that do not directly damage DNA include substances that accelerate cell division, thereby leaving less opportunity for cell to repair induced mutations, or errors in replication. Carcinogens that act as mutagens may be biological, physical, or chemical in nature, although the term is most often used in relation to chemical substances.
Human Papilloma Virus ( HPV , Figure \(\PageIndex{4}\)) is an example of a biological carcinogen. Almost all cervical cancers begin with infection by HPV, which contains genes that disrupt the normal pattern of cell division within the host cell. Any gene that leads to an uncontrolled increase in cell division is called an oncogene . The HPV E6 and E7 genes are considered oncogenes because they inhibit the host cell’s natural tumor suppressing proteins (include p53, described below). The product of the E5 gene mimics the host’s own signals for cell division, and these and other viral gene products may contribute to dysplasia, which is detected during a Pap smear (Figure \(\PageIndex{5}\)). Detection of abnormal cell morphology in a Pap smear is not necessarily evidence of cancer. It must be emphasized again that cells have many regulatory mechanisms to limit division and growth, and for cancer to occur, each of these mechanisms must be disrupted. This is one reason why only a minority of individuals with HPV infections ultimately develop cancer. Although most HPV-related cancers are cervical, HPV infection can also lead to cancer in other tissues, in both women and men.
Figure \(\PageIndex{4}\): Electron micrograph of HPV. (Wikipedia-Unknown-PD)
Figure \(\PageIndex{5}\): Dysplastic (left) and normal (right) cells from a Pap smear. (Flickr-Ed Uthman-CC:AS)
Radiation is a well-known physical carcinogen, because of its potential to induce DNA damage within the body. The most damaging type of radiation is ionizing , meaning waves or particles with sufficient energy to strip electrons from the molecules they encounter, including DNA or molecules that can subsequently react with DNA. Ionizing radiation, which includes x-rays, gamma rays, and some wavelengths of ultraviolet rays, is distinct from the non-ionizing radiation of microwave ovens, cell phones, and radios. As with other carcinogens, mutation of multiple, independent genes that normally regulate cell division is required before cancer develops.
Chemical carcinogens (Table \(\PageIndex{2}\)) can be either natural or synthetic compounds that, based on animal feeding trials or epidemiological (i.e. human population) studies, increase the incidence of cancer. The definition of a chemical as a carcinogen is problematic for several reasons. Some chemicals become carcinogenic only after they are metabolized into another compound in the body; not all species or individuals may metabolize chemicals in the same way. Also, the carcinogenic properties of a compound are usually dependent on its dose. It can be difficult to define a relevant dose for both lab animals and humans. Nevertheless, when a correlation between cancer incidence and chemical exposure is observed, it is usually possible to find ways to reduce exposure to that chemical.
|
Table \(\PageIndex{2}\): Some classes of chemical carcinogens (Pecorino 2008) |
|
1. PAHs (polycyclic aromatic hydrocarbons) e.g. benzo[a]pyrene and several other components of the smoke of cigarettes, wood, and fossil fuels 2. Aromatic amines e.g. formed in food when meat (including fish, poultry) are cooked at high temperature 3. Nitrosamines and nitrosamides e.g. found in tobacco and in some smoked meat and fish 4. Azo dyes e.g. various dyes and pigments used in textiles, leather, paints. 5. Carbamates e.g. ethyl carbamate (urethane) found in some distilled beverages and fermented foods 6. Halogenated compounds e.g. pentachlorophenol used in some wood preservatives and pesticides. 7. Inorganic compounds e.g. asbestos; may induce chronic inflammation and reactive oxygen species 8. Miscellaneous compounds e.g. alkylating agents, phenolics |


8.2: Wound Assessment
By the end of this section, you will be able to:
- Describe the clinical guidelines used for wound assessment
- Recognize the different tools available for wound assessment
- Identify important aspects of nursing documentation of the wound assessment
Clinical Guidelines for Wound Assessment
Wound treatment varies widely depending on the type, location, age, and appearance of the wound, as well as the characteristics of the patient, type of wound care specialist, and setting of the patient care. Thus, prior to planning for treatment of any wound, initial, thorough wound assessment must take place. The nurse must also consider that wound treatment is also affected by the needs and abilities of the patient as well as family support for ongoing wound care. Consider the wound pictures in Figure 8.7. Each image shows a different type of wound and each type requires different treatment and management strategies on the part of healthcare providers. However, before treatment can begin, assessment must occur.
Type of Wound
Determining how the wound was created helps to determine the type of wound (Nagle et al., 2023). In some cases, the type may be very clear. For example, in Figure 8.7, image (d) is clearly a traumatic wound of some type. The patient can easily state to providers how it occurred (a table saw) and providers know how to manage it appropriately. However, other wounds may be more difficult to manage. Images (a) and (c) both show wounds that require additional investigation before the type can actually be assessed. Image (a) shows an ulcer of some type and image (c) shows a skin infection, but without additional assessment, the exact type of ulcer or infection remains unknown.
Wound Location
Wound locations dramatically impact the strategies providers can use in wound treatment (Nagle et al., 2023). Wounds on skin surfaces that are difficult to keep clean and/or dry, such as skin folds, the perineal area, hands, feet, and/or face, will be managed differently than those that are easier to keep clean and dry, such as the abdomen or arm. Other location concerns include the amount of weight-bearing performed at or near the wound’s location. Wound healing requires oxygenation of the surrounding tissue, and areas that bear consistent weight, such as bony prominences such as the coccyx, may heal more slowly or require alternative strategies. Other locations, such as being near major arteries or vessels, may impact the types of interventions that can be utilized (Nagle et al., 2023).
Visual inspection should include inspecting the wound and surrounding area. Note any visible landmarks or anatomical structures that can help accurately describe the wound location. Use adequate lighting to enhance visibility. Identify nearby anatomical landmarks to describe the wound’s location accurately. These landmarks may include bones, joints, muscles, and other structures. For example, a wound could be described as “located on the anterior aspect of the lower leg, approximately 2 in (5 cm) above the medial malleolus.” Use of a clock face or grid system is also recommended. If applicable, use a clock face analogy or a grid system to precisely pinpoint the wound location. For instance, you might describe a wound as “located at the two-o’clock position on the dorsal aspect of the right foot” or “in the upper left quadrant of the abdomen.”
Wound Characteristics
There are a variety of wound characteristics that also impact diagnosis and treatment interventions (Table 8.4). Each of these must be assessed and documented as part of the initial treatment process.
| Characteristic | Examples | Importance |
|---|---|---|
| Appearance | Color, depth, surrounding skin, shape, presence of foreign bodies, and exposed muscle or bone |
|
| Measurement | Circumference, depth, length, and width |
|
| Edges | Smooth, jagged, rounded edges, presence of undermining (erosion beneath skin surface beyond visible edges) or tunneling (erosion in channels beneath intact skin surrounding a wound) should be noted. Approximated (clean edges, that close easily) versus not approximated (jagged edges) should be documented. |
|
| Exudate (liquid that secretes from the wound) | Purulent (pus, tan to yellow), foul purulent (purulent with foul odor), serous (thin, watery, clear), serosanguineous (mix of serous fluid and blood), sanguineous (bloody) |
|
Skin Tone
Skin tone is another critical piece of wound assessment. Identifying a baseline skin tone enables changes to be identified quickly. Also, different skin tones reflect wounds and injuries in different ways. Consider erythema , a change in skin color due to a change in blood flow. Traditionally, erythema has been described by “redness.” However, erythema generally only appears red for individuals with pale skin tones (Dhoonmoon et al., 2023). For patients with darker skin tones, erythema may also be pink or purple, or simply a darkening of the surrounding skin. Thus, particularly for patients with darker skin tones, textural or temperature-based skin changes may be more important than appearance (Dhoonmoon et al., 2023).
Wound Assessment Tools
Wounds may include intentional wound s such as surgical sites that are prone to infection and complicated wounds such as pressure injuries, traumatic injuries, and various types of venous ulcers. There is a variety of wound assessment tools used to confirm the risk of developing wounds or to monitor healing. Different strategies can be employed depending on the risks various patients experience. For wounds that are more difficult to heal, providers must have reliable assessment methods to ensure appropriate and accurate communication among team members and allow for accurate assessment of changes between visits (Bates-Jensen et al., 2019).
Braden Scale
The Braden Scale is the most used pressure injury risk assessment tool in the United States and is used across many healthcare settings, including critical and acute care, long-term care, rehabilitation, and even by home-based nursing (Kennerly et al., 2022). It evaluates the relative risk of a patient developing skin breakdown and pressure injuries. The scores can be used to tailor pressure injury prevention interventions to patients at risk of injuries (Kennerly et al., 2022).
The Braden Scale uses six subscales: mobility, activity, sensory perception, nutrition, friction / shear , moisture (Kennerly et al., 2022). Each of these six factors is scored on a scale from 1 to 4, depending on the factor. After each item is decided, the ratings are added together for a possible score between 6 and 23. The lower the score, the greater the risk for development of a pressure injury. All patients scoring 18 and below should be reassessed regularly, on a schedule dictated by facility and healthcare setting. Patients scoring above 18 should be reassessed when they experience condition-related changes.
The Braden Scale is a very helpful tool to establish the relative risk of a patient experiencing issues with skin breakdown.
The Braden Scale is a tool used by nurses to identify a patient’s risk of developing pressure injuries and is typically completed on admission to a hospital or other healthcare facility (Table 8.5). This evidence-based assessment tool rates the patient on a scale of 1 (completely limited) to 4 (no impairment) in the following categories: sensory perception, moisture, activity, mobility, nutrition, and friction and shear. The ranges for the scores are mild risk (15–18), moderate risk (13–14), high risk (10–12), and severe risk (9 or less).
| Category | 1 (most severe) | 2 | 3 | 4 |
|---|---|---|---|---|
| Sensory perception | Completely limited, unresponsive | Very limited, only responds to painful stimuli | Responds to verbal commands but limited communication | No impairment, responds and communicates |
| Moisture | Constant moisture | Frequent moisture/linen changes | Occasional moisture/extra linen change | Usually dry/routine linen change |
| Activity | Bedbound | Chairbound, limited walking | Short-distance walking | Frequent walking |
| Mobility | Immobile | Very limited | Slight limitations | No limitations |
| Nutrition | Very poor | Likely inadequate | Adequate | Excellent |
| Friction, shear | Constant friction, requires assistance | Movement with minimal assistance | Independent movement | N/a |
Simplified Surgical Site Event Risk Assessment (SSERA) Model
Despite the use of best practices in surgeries, there remains a risk for surgical site infections (SSIs) for everyone undergoing major surgery. In the United States alone, there is are estimated 200,000 SSIs annually, with a cost of up to $10 billion a year (SSERA Group, 2023). The simplified Surgical Site Event Risk Assessment (SSERA) model uses six risk factors to individually evaluate a patient’s risk for an SSI and each risk factor is assigned a color (green, orange, or red) based on the relative risk for an SSI.
You can view the Surgical Site Event Risk Assessment (SSERA) model in Figure 1 of this publication. The SEERA model helps surgeons determine an individual patient’s risk for surgical site infection, based on six risk factors.
A patient’s risk for SSI is evaluated based on the data in the table. If a patient is positive for any red box or three orange boxes, they are considered a high risk for SSI. Any two orange boxes make them an elevated risk for SSI (SSERA Group, 2023). Once a patient’s risk for SSI is known, additional protections can be used (where possible) to monitor for and prevent SSIs.
Wagner Ulcer Classification System
In patients with diabetes, foot infections are common, due to peripheral neuropathy (loss of feeling in the extremities that keeps patients from recognizing they have a wound ) and may result in amputations (Bhowmik, 2023). Long-term glucose changes related to diabetes affects circulation and blood vessels, increasing the healing time for wounds and the risk of infection and gangrene (Shah et al., 2022). The Wagner Ulcer Classification System is one of many types of assessment tools used for patients with diabetic foot ulcers.
The Wagner system is used to determine the severity of a diabetic ulcer by looking at depth, amount of tissue necrosis (tissue death), and presence of osteomyelitis (bone infection) (Bhowmik, 2023). It classifies diabetic foot ulcers into grades between 0 and 5 (Table 8.6) (Song et al., 2022; Shah et al., 2022).
| Wagner Grade | Description |
|---|---|
| 0 | Intact skin that may have bunions, claw toes, or Charcot breakdown. There may also be hyperkeratotic lesions near bony deformities, indicating the foot is at risk of breakdown. |
| 1 | Superficial ulcer with no penetration to deep layers. The base of the ulcer may be necrotic or granulating (tissue regrowth). |
| 2 | Deeper lesion extending to bone, ligament, tendon, or deep fascia. There is no abscess or osteomyelitis at this stage. |
| 3 | Deep abscess, osteomyelitis, or infection of tendon. This stage often requires imaging, probing to the bone, and/or bone biopsy to assess the extent. |
| 4 | Some portion of the forefoot or toes is gangrenous. Gangrene may be classified as wet or dry. |
| 5 | Severe gangrene with no potential for healing, necessitating the amputation of all of the gangrenous area. |
Sometimes the best way to understand wound classifications is to see examples. You can see images of the Wagner staging and learn more about the Wagner classification system in this helpful reference guide. Please be prepared; some of the images are very graphic.
Bates-Jensen Wound Assessment Tool (BWAT)
The Bates-Jensen Wound Assessment Tool (BWAT) is used to evaluate wound status and healing; it measures thirteen wound characteristics. The BWAT was initially developed to be used with pressure injuries; however, it has been widely used with a variety of wounds including post-surgical, infected, and various ulcerative wounds (Bates-Jensen et al., 2019). The BWAT (Table 8.7) is a good assessment tool because it can be used by individuals with limited wound care experience; however, it is slightly less accurate when used on patients with darker skin tones.
| Item | Assessment |
|---|---|
| Size | Use a ruler to measure length and width and then multiply to get the area. |
| Depth | Choose the appropriate depth ranging from intact, nonblanchable skin to underlying structural damage, such as damage to tendons and bone. |
| Edges | Describe edges from indistinct, attached but flat and flush with wound base, not attached (base of wound is deeper than the edge), thickened or rolled under, callous-like, or fibrotic (hard, and rigid to the touch). |
| Undermining | Assess by using a cotton applicator under the wound edge and advance as far as possible without adding pressure. Measure the distance between the edge and end of cotton applicator. Continue around the wound to look for undermining at all points. |
| Necrotic tissue | Choose the predominant type of necrotic tissue according to color, consistency, and attachment to wound: white/grey nonviable tissue, yellow slough that does not adhere to the wound but lifts out easily, yellow slough that is loosely attached to wound, boggy black eschar attached to wound bed, or firm crusty hard/black eschar tissue attached to base and edges. |
| Necrotic tissue amount | Use a transparent measuring guide to determine the percentage of necrotic involvement. |
| Exudate type | Cleanse wound with normal saline or water before assessing due to the way some dressings work. Choose the most predominant from bloody, serosanguineous, serous, purulent, and foul purulent (thick yellow to green with odor). |
| Exudate amount | Determine the amount of exudate based on wound bed and used patient’s dressing; range from none to large (> 75 percent of dressing saturated or wound bathed in fluids). |
| Skin color of surrounding wound | Assess tissues within 1.6 in (4 cm) of edges. People with darker skin will show deepening of normal skin color or purple. When healing, their new skin may be pink and may not darken. |
| Peripheral tissue edema | Assess tissue within 1.6 in (4 cm) of wound edges. Observe for skin that is puffy, shiny, and tight. Press fingertip into intact tissue for five seconds and observe for indentation. Measure how far edema expands from wound edge. |
| Peripheral issue induration | Assess tissue within 1.6 in (4 cm) of wound edges. Observe for areas of abnormal firmness with clear boundaries (such as bumps under the skin). Measure size and distance from wound edge. |
| Granulation tissue | Early tissue regrowth: Health granulation is bright, beefy red, and shiny. Poor circulation appears pale pink or blanched to a dull color. |
| Epithelialization | Skin regrowth: Young skin is usually pink or red; may be in base of wound or only growing in from the edges. Measure percentage with a transparent measurement tape. |
Scenario: In this clinical narrative, a wound care nurse answers a patient’s questions about using the BWAT.
Nurse: Hi, Mr. Johnson. How are you feeling today?
Patient: Oh, not too bad, I guess.
Nurse: Can I take a look at your wound?
Patient: Well, you can, but I don’t know why you’d want to! Gives me the heebie-jeebies.
Nurse: I can understand if you’re feeling a little squeamish, but it’s important that we keep an eye on it and make sure it’s healing. Let me go ahead and put on my gloves, and we’ll see how it’s doing, okay?
Patient: Sure.
[After putting on sterile gloves, the nurse starts to gently uncover the patient’s wound.]
Nurse: Okay, let’s have a look.
Patient: What are you looking for, anyway? [chuckles] Bugs?
Nurse: Not exactly! When I check your wound, I’m looking for signs that it’s not healing well or is infected. So, I want to see if your skin is red and swollen, if there’s any pus or blood coming out.
Patient: It isn’t bleeding anymore, but sometimes the bandage feels a little damp.
Nurse: That’s good to know! Paying attention to how your wound looks and feels is very helpful for me. It can be normal for there to be some fluid coming out of the wound as it heals, but we still want to see how much there is and what it looks like. Even what it smells like!
Patient: I think that’s a little too much for me! I’ll let you do a sniff test.
Nurse: Fortunately, I think your wound is in pretty good shape. See how the edges are starting to come together? That’s a sign that your skin is doing its job to heal and close up the wound. I don’t see any signs of an infection, which is great. How’s your pain?
Patient: Not as bad as it was, but it still twinges sometimes.
Nurse: That can be a normal part of the healing process—but tell me if it starts to hurt more or you think the discomfort is getting worse.
Patient: Okay.
Nurse: Before we get a new dressing on there, do you mind if I snap a picture?
Patient: Ha! For your personal collection?
Nurse: No, photos are kept in your file for medical purposes only. Remember last time I took a photo for your record? I’ll compare the one I take today to that one to get a better idea of how your healing is progressing. I can’t remember every detail of all the wounds I treat, so having pictures is very helpful.
Scenario follow-up: In this example, the nurse has efficiently performed a wound check on a patient while also answering his questions about the importance of tracking progress.
Nursing Documentation of Wound Assessment
When documenting wound assessments, nurses must be careful to document accurately and without assumption. Incorrect documentation may negatively impact patients as clinicians reviewing the documents will be unable to accurately evaluate the severity of the wound and information about the healing process. Documentation is also important for regulatory agencies such as departments of health, third-party payers such as private insurance and the Centers for Medicare & Medicaid Services, accreditation bodies such as the Joint Commission and the Long-Term Care Institute, and even for potential legal proceedings (WoundSource, 2022). Ensure the following information is included in wound documentation (Song et al., 2022; WoundSource, 2022):
- type of wound or cause, such as pressure injury, surgical site, traumatic wound
- any related healthcare conditions such as diabetes, neuropathy, or gangrene
- location information including anatomical body part and information, such as right/left, front/back, top/bottom, midway between
- wound size: length, width, depth in centimeters
- wound thickness : amount of skin breakdown, fat exposure, and bone and/or muscle involvement
- any indication of infection, such as fever, increased drainage, odor, heat, swelling, or pain
- patient variables including refusal to participate in care or adhere to treatment plans
- photographic evidence of the wound (both for legal reasons and to monitor wound-healing progress
Correct Terminology
When documenting a wound, always use the correct terminology and location information (Table 8.8).
| Description Type | Terms |
|---|---|
| Wound bed characteristics | Granulation: healing state in which new tissue begins to form |
| Slough: wet yellow to white tissue in wound bed made of dead cells; may or may not be attached to wound bed | |
| Eschar: dead tissue formed over healthy skin | |
| Epithelialization : growth of epidermis (skin cells) over skin and wound surface; healing to close wound | |
| Wound edges | Defined versus undefined: how clear are the boundaries of the wound from the surrounding skin? |
| Attached versus unattached: are the edges of the wound attached to the underlying tissue or can a cotton swab or instrument slide between the layers? | |
| Approximated versus not approximated: are wound edges brought together and aligned in a close or near-close manner or are do they remain separated or open? | |
| Epibole | |
| Maceration | |
| Callused or fibrotic edge (toughened skin around wound edges) | |
| Wound margin (edges of wound) | |
| Skin beyond the wound | Color |
| Temperature | |
| Edema (swelling): present or absent | |
| Boggy (spongy) | |
| Induration (thickened or hardened area): provide a location and size | |
| Undermining, tunneling, or sinus tracts (cavity leading from an abscess beneath the wound to the surface) | |
| Exudate type | Serous |
| Sanguineous | |
| Serosanguineous | |
| Purulent | |
| Foul purulent | |
| Exudate amount | Scant: wound tissue moist, no drainage on dressings |
| Minimal: tissue moist, light exudate on dressing | |
| Moderate: tissue wet, up to 75 percent of dressing saturated over twenty-four hours | |
| Large: wound filled with fluid; > 75 percent of dressing saturated |
Restorix Health and American Medical Technologies published a document to help study and learn appropriate documentation of wounds in patients.
Recommendation for Reevaluation
Most wounds progress normally through the four stages of healing: hemostasis , inflammatory, proliferation, and maturation. They should be reevaluated throughout the healing process to ensure they are healing effectively and appropriately. This process is described further in 8.3 Wound Management. When issues occur at any stage, additional steps may be required to ensure wound healing.


1.4: Medieval Music Overview
Please begin your reading on the music of the Middle Ages with this web summary of some of the most important developments of this period. We will have more detailed reading assignments on the terms and composers discussed on this page, but this provides a good sense of the historical flow of this period of music history, which is considerably longer than most other periods.
You’ll notice that the author makes reference to a number of pieces of music in this text. While these pieces mentioned are good examples, they do not always align with our listening assignments. Be sure you focus your listening study on the pieces on the playlist for this module.
Contributors and Attributions
- Authored by : Elliott Jones. Provided by : Santa Ana College. Located at : http://www.sac.edu . License : CC BY: Attribution


6.7: Logistics and Communication
Logistics
Logistics refers to the activities of coordinating and moving resources, particularly inputs into the transformation process, and finished goods out to customers. Originally, the term logistics was from the military and referred to moving troops, equipment and supplies. Managing logistics involves making decisions such as the following:
- Choosing to operate and manage the firm’s own transportation, or whether to outsource this activity
- Selecting suppliers that have the capability to ship goods safely and securely within the required time frame
- Choosing the correct mode of transportation and the most effective route
- Negotiating the shipping rate
Modes of Transportation
There are several modes of transportation available to companies. We discuss them in the following:
Trucking
The majority of goods are shipped by truck completely or at some point during the shipping. Trucking is the most flexible of all modes of transportation. Trucking is categorized by “truck-load” (TL) when the entire truck is hired and delivered directly, or “less-than-truckload” (LTL) which generally includes using several orders to increase the utilization of the truck. A serious issue facing Canada at this time is the expected shortage of qualified drivers. Demand for drivers continues to increase every year, and the average age of drivers is increasing. The trucking industry will face challenges to make driving more attractive to entice new workers into trucking jobs. [3]
Railroads
Rail can be a very cost effective means of transporting goods that need to travel long distances. Goods in containers, or products that are bulky and heavy are ideal for train transport. Canadian rail ships products including cars, fertilizer, food and beverages, forest products, grain, metals and minerals and petroleum products. Often, large manufacturers locate themselves near rail lines to make for easy shipment of raw material into, and finished goods out of their facilities. Compared to trucking, shipping by rail is very energy efficient, and removes many trucks from congested highways. Canada has a very old and well-established rail system. [4]
Airfreight
For goods that are expensive, small and light, air shipping may be a good choice. Air carriers charge by a combination of the weight and size of the shipment. This mode of transport is generally used when speed is more important than cost. Shipping by air is very reliable. Firms may want to consider the environmental impact of regular use of air shipping.
Waterway
This is a very common way of shipping goods. The goods that travel by water include chemicals, stone, cement, sugar, coal and other heavy commodities. Millions of containers travel by ship each year. Do you know what goods travel by ship? Read here.
The Great Lakes St. Lawrence Seaway System is a 3,700 kilometer marine highway that runs between Canada and the United States. Opening in 1959 the seaway is a major trade artery that serves many industries to ship iron ore, coal, limestone, steel, grain and cement. The cost for shipping by waterways is inexpensive. Most low-cost products are shipped by waterways. [5]
Pipelines
Crude oil, natural gas and other petroleum products are shipped by pipelines. Once the pipelines are built, the cost per kilometre for shipping is very inexpensive. There is a lot of opposition and concern over new pipelines because of worry over spills and leaks that may contaminate land and waterways. [6]
Multimodal/Intermodal shipping
This refers to the use of a combination of different types of transportation to move goods from origin to destination. A common example is a combination of truck/ship/train. The goal is to ship the goods as efficiently as possible. The goods are shipped under a single contract with a carrier, and can be easily tracked. It also uses several modes of transportation but also uses a container so that freight does not have to be handled each time it changes modes. Each mode will have a carrier responsible for the shipment. The use of containers increases the security, reduces loss and damage and increases the speed of shipment.
Distribution Management
Distribution management refers to the process of overseeing the movement of goods from supplier or manufacturer to point of sale. Distribution management is an important part of the business cycle for distributors and wholesalers. The profit margins of businesses depend on how quickly they can turn over their goods. The more they sell, the more they earn, which means a better future for the business. Having a successful distribution management system is also important for businesses to remain competitive and to keep customers satisfied.
Distribution involves diverse functions such as customer service, shipping, warehousing, inventory control, private trucking-fleet operations, packaging, receiving, materials handling, along with plant, warehouse, store location planning, and the integration of information.
The goal is to achieve ultimate efficiency in delivering raw materials and parts, both partially and completely finished products to the right place and time in the proper condition. [7]
The combination of distribution and transportation is logistics . The most important factor in any logistics is quickly delivering product in perfect condition. Read here how Amazon has used its supply chain management to fuel its rise to the top.
Crossdocking
A broad definition of crossdocking is the transfer of goods and materials from an inbound carrier to an outbound carrier without the products actually entering the warehouse or being put away into storage. Thus, the products “cross the docks” from the receiving dock area to the shipping dock area. It can provide significant inventory savings, and the cost of holding inventory and the costs of handling the inventory are reduced. Crossdocking helps to provide excellent customer service by speeding up customer deliveries. [8]
Communication and Technology in the Supply Chain
Electronic Data Interchange (EDI)
Electronic Data Interchange (EDI) is the computer-to-computer exchange of business documents, such as purchase orders and invoices, in a standard electronic format between business partners, such as retailers and their suppliers, banks and their corporate clients, or car-makers and their parts suppliers.
EDI enables the companies to transfer the documents without having any people involved. The documents are automatically transferred from one computer (account) to another. As a result, there are many advantages to using EDI. The primary benefit is the speed and accuracy of the information transmitted. Information is made available in real time and errors that may have previously been caused during the data entry process are eliminated.
Common information exchanged using EDI include:
- Purchase orders
- Invoices
- Advance shipment notices (ASN)
- Customs documents
- Inventory information
- Shipping status
- Payment documents
- Bill of lading
- Sales/price catalogues
- Shipment status messages
Barcodes
Barcodes have been used extensively since the 1970s, and consist of data that is displayed in a machine-readable form that can be scanned by barcode readers. The information contained on the barcode is typically pricing information, product number and description and any other pertinent information. Barcodes have become the norm in retail operations allowing for pricing accuracy and easy price changes. This data provides point-of-sale information to allow retailers to track items being sold, update inventory, identify fast and slow moving products and assist in forecasting.
QR
Quick Response (known as QR) is using bar codes and EDI to make sales data available to vendors so that vendors can quickly replenish goods in the correct quantity. This is thought of as JIT in the retail industry. The goal is to reduce out-of stock incidents, as well as using smaller more frequent deliveries to reduce inventory and operating expenses.
Radio Frequency Identification Device (RFID)
This technology uses radio waves to communicate information contained on a tag attached to an object. The information contained on a tag may include things such as the products origin, date of production, shipment information, pricing info, and any other pertinent info. In order to transfer this info, both a tag and a reader are needed. There are two types of tags, active and passive. An active tag contains a power source such as a battery and can operate a great distance from the reader. Passive tags use energy from the reader. Unlike barcodes, the RFID tag and reader do not require line of site in order to transmit the information.
RFID applications include the following plus many more:
- Retail use to protect from theft
- Toll road payments
- Identification (i.e. tracking of animals and people)
- Passports
- Shipping tracking – to identify location and contents of orders
- Asset tracking (e.g. laptops, expensive tools, medical devices in hospitals)
- Race timing for marathons
- Tracking luggage during travel
Supply Chain Collaboration
Vendor Managed Inventory (VMI)
Vendor Managed Inventory (VMI) is an advanced supply chain relationship whereby a vendor (often a manufacturer) has access to their customer’s inventory information and the vendor takes the responsibility for maintaining an agreed-upon level of product at the customers location. This arrangement can be used with manufacturers, distributors and retailers.
VMI has numerous benefits for both the supplier (vendor) and the customer. The vendor has strong motivation to ensure that shelves are fully stocked, any slow-moving stock is discontinued and that employees have full understanding of the product offerings. The customer benefits from these VMI relationships because less work is involved on the buyers’ end. Due to EDI, there are few errors and goods flow quickly. Point-of-sale data updates the inventory and determines what items are needed. Salespeople from the vendor often provide assistance by training sales staff and assisting customers when possible.
Collaborative Planning, Forecasting and Replenishment (CPFR)
Collaborative Planning, Forecasting and Replenishment (CPFR) is an arrangement where two trading partners in a supply chain collaborate to agree on forecasts and orders between the manufacturer and distributor/retailer. The distributor/retailer will have collected POS data and added any additional information, such as promotion plans, inventory status or forecasts. That information gets shared with manufacturers who will then compare it with their own forecasts and capacity. Both teams can collaborate to solve any discrepancies, eliminate gaps and agree on a final set of numbers. Collaborating in this way will enable both firms to reduce inventory as well as reducing problems such as shortages and capacity problems.
"Supply Chain" Introduction to Operations Management Copyright © by Hamid Faramarzi and Mary Drane is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.


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central bulge
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(or nuclear bulge) the central (round) part of the Milky Way or a similar galaxy
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dark matter
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nonluminous mass, whose presence can be inferred only because of its gravitational influence on luminous matter; the composition of the dark matter is not known
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dark matter halo
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the mass in the Milky Way that extends well beyond the boundary of the luminous stars to a distance of at least 200,000 light-years from the center of the Galaxy; although we deduce its existence from its gravity, the composition of this matter remains a mystery
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differential galactic rotation
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the idea that different parts of the Galaxy turn at different rates, since the parts of the Galaxy follow Kepler’s third law: more distant objects take longer to complete one full orbit around the center of the Galaxy
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halo
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the outermost extent of our Galaxy (or another galaxy), containing a sparse distribution of stars and globular clusters in a more or less spherical distribution
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Milky Way Galaxy
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the band of light encircling the sky, which is due to the many stars and diffuse nebulae lying near the plane of the Milky Way Galaxy
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population I star
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a star containing heavy elements; typically young and found in the disk
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population II star
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a star with very low abundance of heavy elements; found throughout the Galaxy
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spiral arm
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a spiral-shaped region, characterized by relatively dense interstellar material and young stars, that is observed in the disks of spiral galaxies
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supermassive black hole
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the object in the center of most large galaxies that is so massive and compact that light cannot escape from it; the Milky Way’s supermassive black hole contains 4.6 millions of Suns’ worth of mass


11.3A: Phagocyte Migration and Phagocytosis
- Summarize phagocytosis and phagocyte migration
Phagocytosis is the process by which a cell takes in particles such as bacteria, parasites, dead host cells, and cellular and foreign debris. It involves a chain of molecular processes. Phagocytosis occurs after the foreign body, a bacterial cell, for example, has bound to molecules called “receptors” that are on the surface of the phagocyte. The phagocyte then stretches itself around the bacterium and engulfs it. Phagocytosis of bacteria by human neutrophils takes on average nine minutes to occur. Once inside the phagocyte, the bacterium is trapped in a compartment called a phagosome. Within one minute the phagosome merges with either a lysosome or a granule, to form a phagolysosome. The bacterium is then subjected to an overwhelming array of killing mechanisms and is dead a few minutes later. Dendritic cells and macrophages, on the other hand, are not so fast, and phagocytosis can take many hours in these cells. Macrophages are slow and untidy eaters; they engulf huge quantities of material and frequently release some undigested material back into the tissues. This debris serves as a signal to recruit more phagocytes from the blood. Phagocytes have voracious appetites; scientists have even fed macrophages with iron filings and then used a small magnet to separate them from other cells.
All phagocytes, and especially macrophages, exist in degrees of readiness. Macrophages are usually relatively dormant in the tissues and proliferate slowly. In this semi-resting state, they clear away dead host cells and other non-infectious debris and rarely take part in antigen presentation. But, during an infection, they receive chemical signals—usually interferon gamma—which increases their production of MHC II molecules and which prepares them for presenting antigens. In this state, macrophages are good antigen presenters and killers. However, if they receive a signal directly from an invader, they become “hyperactivated”, stop proliferating, and concentrate on killing. Their size and rate of phagocytosis increases—some become large enough to engulf invading protozoa. In the blood, neutrophils are inactive but are swept along at high speed. When they receive signals from macrophages at the sites of inflammation, they slow down and leave the blood. In the tissues, they are activated by cytokines and arrive at the battle scene ready to kill.
When an infection occurs, a chemical “SOS” signal is given off to attract phagocytes to the site. These chemical signals may include proteins from invading bacteria, clotting system peptides, complement products, and cytokines that have been given off by macrophages located in the tissue near the infection site. Another group of chemical attractants are cytokines that recruit neutrophils and monocytes from the blood. To reach the site of infection, phagocytes leave the bloodstream and enter the affected tissues. Signals from the infection cause the endothelial cells that line the blood vessels to make a protein called selectin, which neutrophils stick to when they pass by. Other signals called vasodilators loosen the junctions connecting endothelial cells, allowing the phagocytes to pass through the wall. Chemotaxis is the process by which phagocytes follow the cytokine “scent” to the infected spot. Neutrophils travel across epithelial cell-lined organs to sites of infection, and although this is an important component of fighting infection, the migration itself can result in disease-like symptoms. During an infection, millions of neutrophils are recruited from the blood, but they die after a few days.
Key Points
- Phagocytosis is needed to clear many things from a body, especially during an infection, when specialized cells “eat” things such as cellular debris or invading microbes.
- There are different cells that can engulf or phagocytose material in the body, these include macrophages, dendritic cells, and neutrophils.
- Phagocytic cells can migrate to a location where they are needed, through signaling events in the body.
Key Terms
- neutrophil : Neutrophil granulocytes are the most abundant type of white blood cells in mammals and form an essential part of the innate immune system.
- metachromatic granule : a granular cell inclusion present in many bacterial cells, having an avidity for basic dyes and causing irregular staining of the cell
- macrophage : A white blood cell that phagocytizes necrotic cell debris and foreign material, including viruses, bacteria, and tattoo ink. It presents foreign antigens on MHC II to lymphocytes. Part of the innate immune system.


12.5I: Vestibulocochlear (VIII) Nerve
The vestibulocochlear nerve (cranial nerve VIII) carries information about hearing and balance.
- Describe the vestibulocochlear nerve (cranial nerve VIII)
Key Points
- The vestibulocochlear nerve comprises the cochlear nerve that transmits hearing information, and the vestibular nerve that transmits balance information.
- The cochlear nerve travels away from the cochlea of the inner ear where it starts as the spiral ganglia.
- The vestibular nerve travels from the vestibular system of the inner ear.
Key Terms
- cochlear nerve : A sensory nerve that conducts information about the environment to the brain, in this case acoustic energy impinging on the tympanic membrane (sound waves reaching the ear drum). The cochlear nerve arises from within the cochlea and extends to the brainstem where its fibers make contact with the cochlear nucleus, the next stage of neural processing in the auditory system.
- vestibulocochlear nerve : Also known as the auditory vestibular nerve, this is the eighth of twelve cranial nerves, and it is responsible for transmitting sound and equilibrium (balance) information from the inner ear to the brain.
- vestibular nerve : One of the two branches of the vestibulocochlear nerve (the cochlear nerve being the other). It connects to the semicircular canals via the vestibular ganglion and receives positional information.
The vestibulocochlear nerve (also known as the auditory vestibular nerve and cranial nerve VIII) has axons that carry the modalities of hearing and equilibrium.
It consists of the cochlear nerve that carries information about hearing, and the vestibular nerve that carries information about balance.
This is the nerve along which the sensory cells (the hair cells) of the inner ear transmit information to the brain. It emerges from the pons and exits the inner skull via the internal acoustic meatus (or internal auditory meatus) in the temporal bone.
Vestibular system’s semicircular canal : An illustration of the inner ear showing its semicircular canal, hair cells, ampulla, cupula, vestibular nerve, and fluid.
The vestibulocochlear nerve consists mostly of bipolar neurons and splits into two large divisions: the cochlear nerve and the vestibular nerve. The cochlear nerve travels away from the cochlea of the inner ear where it starts as the spiral ganglia.
Processes from the organ of Corti (the receptor organ for hearing) conduct afferent transmission to the spiral ganglia. It is the inner hair cells of the organ of Corti that are responsible for activating the afferent receptors in response to pressure waves reaching the basilar membrane through the transduction of sound.
The vestibular nerve travels from the vestibular system of the inner ear. The vestibular ganglion houses the cell bodies of the bipolar neurons and extends processes to five sensory organs.
Three of these are the cristae, located in the ampullae of the semicircular canals. Hair cells of the cristae activate afferent receptors in response to rotational acceleration.
The other two sensory organs supplied by the vestibular neurons are the maculae of the saccule and utricle. Hair cells of the maculae activate afferent receptors in response to linear acceleration.
The vestibulocochlear nerve has axons that carry the modalities of hearing and equilibrium. Damage to the vestibulocochlear nerve may cause hearing loss, vertigo, a false sense of motion, loss of equilibrium in dark places, nystagmus, motion sickness, and gaze-evoked tinnitus.
A benign primary intracranial tumor of vestibulocochlear nerve is called a vestibular schwannoma (also called acoustic neuroma).