calcium is also important for maintaining the potential difference across excitable cell membranes, as well as proper bone formation. calf – is the back portion of the lower leg in human anatomy. the muscles within the calf correspond to the posterior compartment of the leg. the two largest muscles within this compartment are known together as the calf muscle and attach to the heel via the achilles tendon. several other, smaller muscles attach to the knee, the ankle, and via long tendons to the toes. cancer – is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. these contrast with benign tumors, which do not spread to other parts of the body. capillary – is a small blood vessel from 5 to 10 micrometres (µm) in diameter, and having a wall one endothelial cell thick. they are the smallest blood vessels in the body: they convey blood between the arterioles and venules. these microvessels are the site of exchange of many substances with the interstitial fluid surrounding them. carcinogen – is any substance, radionuclide, or radiation that promotes carcinogenesis, the formation of cancer. this may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. carcinogenesis – also called oncogenesis or tumorigenesis, is the formation of a cancer, whereby normal cells are transformed into cancer cells. cardiac arrest – a sudden loss of blood flow resulting from the failure of the heart to effectively pump. symptoms include loss of consciousness and abnormal or absent breathing. some individuals may experience chest pain, shortness of breath, or nausea before cardiac arrest. if not treated within minutes, it typically leads to death. cardiac catheterization – (heart cath or just cath), is the insertion of a catheter into a chamber or vessel of the heart. this is done both for diagnostic and interventional purposes. cardiac muscle – (also called heart muscle or myocardium), is one of three types of vertebrate muscles, with the other two being skeletal and smooth muscles. it is an involuntary, striated muscle that constitutes the main tissue of the walls of the heart. the myocardium forms a thick middle layer between the outer layer of the heart wall (the epicardium) and the inner layer (the endocardium), with blood supplied via the coronary circulation. it is composed of individual heart muscle cells (cardiomyocytes) joined by intercalated discs, encased by collagen fibres and other substances that form the extracellular matrix. cardiac surgery – or cardiovascular surgery, is surgery on the heart or great vessels performed by cardiac surgeons. it is often used to treat complications of ischemic heart disease (for example, with coronary artery bypass grafting); to correct congenital heart disease; or to treat valvular heart disease from various causes, including endocarditis, rheumatic heart disease, and atherosclerosis. it also includes heart transplantation. cardiology – is a branch of medicine dealing with disorders of the heart as well as parts of the circulatory system. cardiothoracic surgery – (also known as thoracic surgery) is the field of medicine involved in surgical treatment of organs inside the thorax (the chest)—generally treatment of conditions of the heart (heart disease) and lungs (lung disease). cardiovascular disease – (cvd), is a class of diseases that involve the heart or blood vessels. cvd includes coronary artery diseases (cad) such as angina and myocardial infarction (commonly known as a heart attack). other cvds include stroke, heart failure, hypertensive heart disease, rheumatic heart disease, cardiomyopathy, heart arrhythmia, congenital heart disease, valvular heart disease, carditis, aortic aneurysms, peripheral artery disease, thromboembolic disease, and venous thrombosis. carotid artery, common – in anatomy, the left and right common carotid arteries (carotids) ) are arteries that supply the head and neck with oxygenated blood; they divide in the neck to form the external and internal carotid arteries. carotid artery, external – the external carotid artery is a major artery of the head and neck. it arises from the common carotid artery when it splits into the external and internal carotid artery. it supplies blood to the face and neck. carotid artery, internal – the internal carotid artery is a major paired artery, one on each side of the head and neck, in human anatomy. they arise from the common carotid arteries where these bifurcate into the internal and external carotid arteries at cervical vertebral level 3 or 4; the internal carotid artery supplies the brain, while the external carotid nourishes other portions of the head, such as face, scalp, skull, and meninges. carotid artery stenosis – is a narrowing or constriction of any part of the carotid arteries, usually caused by atherosclerosis. carpal bones – are the eight small bones that make up the wrist (or carpus) that connects the hand to the forearm. in human anatomy, the main role of the wrist is to facilitate effective positioning of the hand and powerful use of the extensors and flexors of the forearm, and the mobility of individual carpal bones increase the freedom of movements at the wrist. carpal tunnel syndrome – (cts), is a medical condition due to compression of the median nerve as it travels through the wrist at the carpal tunnel. the main symptoms are pain, numbness and tingling in the thumb, index finger, middle finger and the thumb side of the ring fingers. cartilage – is a resilient and smooth elastic tissue, a rubber-like padding that covers and protects the ends of long bones at the joints, and is a structural component of the rib cage, the ear, the nose, the bronchial tubes, the intervertebral discs, and many other body components. it is not as hard and rigid as bone, but it is much stiffer and much less flexible than muscle. the matrix of cartilage is made up of chondrin. cartilaginous joint – cartilaginous joints are connected entirely by cartilage (fibrocartilage or hyaline). cartilaginous joints allow more movement between bones than a fibrous joint but less than the highly mobile synovial joint. cartilaginous joints also forms the growth regions of immature long bones and the intervertebral discs of the spinal column. catheter – is a thin tube made from medical grade materials serving a broad range of functions. catheters are medical devices that can be inserted in the body to treat diseases or perform a surgical procedure. by modifying the material or adjusting the way catheters are manufactured, it is possible to tailor catheters for cardiovascular, urological, gastrointestinal, neurovascular, and ophthalmic applications. celiac disease – another way of spelling coeliac disease cell biology – also called cytology, is a branch of biology that studies the structure and function of the cell, which is the basic unit of life. cell biology is concerned with the physiological properties, metabolic processes, signaling pathways, life cycle, chemical composition and interactions of the cell with their environment. central nervous system – (cns), is the part of the nervous system consisting of the brain and spinal cord. cephalic vein – is a superficial vein in the arm. it communicates with the basilic vein via the median cubital vein at the elbow and is located in the superficial fascia along the anterolateral surface of the biceps brachii muscle. near the shoulder, the cephalic vein passes between the deltoid and pectoralis major muscles (deltopectoral groove) and through the deltopectoral triangle, where it empties into the axillary vein. cerebellum – (latin for "little brain"), is a major feature of the hindbrain of all vertebrates. although usually smaller than the cerebrum, in some animals such as the mormyrid fishes it may be as large as or even larger. in humans, the cerebellum plays an important role in motor control. it may also be involved in some cognitive functions such as attention and language as well as in regulating fear and pleasure responses, but its movement-related functions are the most solidly established. the human cerebellum does not initiate movement, but contributes to coordination, precision, and accurate timing: it receives input from sensory systems of the spinal cord and from other parts of the brain, and integrates these inputs to fine-tune motor activity. cerebellar damage produces disorders in fine movement, equilibrium, posture, and motor learning in humans. cerebrum – is a large part of the brain containing the cerebral cortex (of the two cerebral hemispheres), as well as several subcortical structures, including the hippocampus, basal ganglia, and olfactory bulb. in the human brain, the cerebrum is the uppermost region of the central nervous system. the prosencephalon is the embryonic structure from which the cerebrum develops prenatally. in mammals, the dorsal telencephalon, or pallium, develops into the cerebral cortex, and the ventral telencephalon, or subpallium, becomes the basal ganglia. the cerebrum is also divided into approximately symmetric left and right cerebral hemispheres. with the assistance of the cerebellum, the cerebrum controls all voluntary actions in the body. cervical cancer – is a cancer arising from the cervix. it is due to the abnormal growth of cells that have the ability to invade or spread to other parts of the body. early on, typically no symptoms are seen. later symptoms may include abnormal vaginal bleeding, pelvic pain, or pain during sexual intercourse. while bleeding after sex may not be serious, it may also indicate the presence of cervical cancer. cervix – or cervix uteri, is the lower part of the uterus in the human female reproductive system. the cervix is usually 2 to 3 cm long (~1 inch) and roughly cylindrical in shape, which changes during pregnancy. the narrow, central cervical canal runs along its entire length, connecting the uterine cavity and the lumen of the vagina. the opening into the uterus is called the internal os, and the opening into the vagina is called the external os. the lower part of the cervix, known as the vaginal portion of the cervix (or ectocervix), bulges into the top of the vagina. cheek – the cheeks constitute the area of the face below the eyes and between the nose and the left or right ear. "buccal" means relating to the cheek. in humans, the region is innervated by the buccal nerve. the area between the inside of the cheek and the teeth and gums is called the vestibule or buccal pouch or buccal cavity and forms part of the mouth. chin – is the area of the face below the lower lip and including the mandibular prominence. it is formed by the lower front of the mandible. chronic fatigue syndrome – (cfs), also referred to as myalgic encephalomyelitis (me), is a medical condition characterized by long-term fatigue and other persistent symptoms that limit a person's ability to carry out ordinary daily activities. ciliary muscle – is a ring of smooth muscle in the eye's middle layer (vascular layer) that controls accommodation for viewing objects at varying distances and regulates the flow of aqueous humor into schlemm's canal. it changes the shape of the lens within the eye, not the size of the pupil which is carried out by the sphincter pupillae muscle and dilator pupillae. circulatory system – the circulatory system, also called the cardiovascular system or the vascular system, is an organ system that permits blood to circulate and transport nutrients (such as amino acids and electrolytes), oxygen, carbon dioxide, hormones, and blood cells to and from the cells in the body to provide nourishment and help in fighting diseases, stabilize temperature and ph, and maintain homeostasis. clavicle – also known as the collar bone, is a long bone that serves as a strut between the shoulder blade and the sternum. there are two, one on the right, and one on the left side of the trunk. along with the shoulder blade, the clavicles make up the shoulder girdle. the clavicle has many functions. it connects the axial and appendicular skeleton in conjunction with the scapula, helps extend range of motion, and protects neurovascular structures. clinic – (or outpatient clinic or ambulatory care clinic) is a healthcare facility that is primarily focused on the care of outpatients. clinics can be privately operated or publicly managed and funded. clinical research – is a branch of healthcare science that determines the safety and effectiveness (efficacy) of medications, devices, diagnostic products and treatment regimens intended for human use. these may be used for prevention, treatment, diagnosis or for