C
CA-125 a glycoprotein found in the blood serum of patients with ovarian or other glandular cell carcinomas. Increasing levels of the antigen mean increasing tumour growths which may indicate poor prognosis. Also known as cancer cell surface antigen 125.
cachexia a condition of extreme debility typical of the late stages of chronic disease, symptoms include weight loss and general bodily deterioration.
cadaver a corpse. In a medical context it implies a dead body which is dissected in a medical school, or in a mortuary at a postmortem examination.
caecum the blind, pouch-like commencement of the colon in the right iliac fossa. To it is attached the vermiform appendix; it is separated from the ileum by the ileocaecal valve.
caesium-137 (137Cs) a radioactive substance which, when sealed in needles or tubes, can be used for interstitial and surface applications. It can also be employed as a source for treatment by Selectron. Historically has been used for external beam therapy.
caesium iodide crystal a crystal which used to be used in the detector of a CT scanner to detect any radiation passing through the patient. Now obsolete. See also ceramic detectors.
caisson disease results from sudden reduction in atmospheric pressure, as experienced by divers on return to surface, aircrew ascending to great heights. Caused by bubbles of nitrogen which are released from solution in the blood; symptoms vary according to the site of these. The condition is largely preventable by proper and gradual decompression technique. See also decompression illness.
calamine zinc carbonate with ferric oxide. Used in lotions and creams for the relief of itching; however, it is not generally effective.
calcaneus (calcaneum, os calcis) the heel bone.
calcareous chalky. Relating to lime or calcium.
calcification the hardening of an organic substance by a deposit of calcium salts within it. May be physiological, as in bone, or pathological, as in arteries.
calcitonin (thyrocalcitonin) hormone secreted by the thyroid gland. It has a fine-tuning role in calcium homeostasis. It opposes the action of parathyroid hormone and reduces levels of calcium and phosphate in the serum by its action on the kidneys and bone. It inhibits calcium reabsorption from bone and stimulates the excretion of calcium and phosphate in the urine. Calcitonin is released when the serum calcium level rises. Synthetic calcitonin is used in the management of metastatic bone cancer, Paget’s disease and osteoporosis.
calcitriol (1,25-dehydroxycholecalciferol) the active form of vitamin D concerned with calcium homeostasis.
calcium (Ca) a metallic element. Needed by the body for neuromuscular conduction and blood coagulation and as an important component of the skeleton and teeth. An essential nutrient.
calcium carbonate a calcium salt used in many antacid medicines.
calcium gluconate a calcium salt used to treat calcium deficiencies and disorders such as rickets.
calcium tungstate the main phosphor used in conventional intensifying screens now superseded by rare earth phosphors.
calculus a stone, small mineral deposits. Examples include gallstones and renal calculi. dental calculus a hard calcified deposit that forms on the surface of the teeth, also known as tartar.
Caldwell–Luc operation (radical antrostomy) a radical operation previously used for sinusitis.
calibrated stepwedge a piece of equipment which is made up of different thickness of aluminium with a layer of copper on the base, wedges are calibrated so that when radiographed each step produces an exact increase or decrease in density on the film. See also stepwedge.
caliper a two-pronged instrument for measuring the diameter of a round body, used chiefly in pelvimetry. A two-pronged instrument with sharp points which are inserted into the lower end of a fractured long bone, a weight is attached to the other end of the caliper, which maintains a steady pull on the distal end of the bone. Thomas’ walking caliper is similar to the Thomas’ splint, but the W-shaped junction at the lower end is replaced by two small iron rods which slot into holes made in the heel of the boot, the ring should fit the groin perfectly, and all weight is then borne by the ischial tuberosity.
callus the partly calcified tissue which forms about the ends of a broken bone and ultimately accomplishes repair of the fracture, when this is complete the bony thickening is known as permanent callus. corn (callosity, keratoma, mechanically induced hyperkeratosis) a yellowish plaque of hard skin caused by pressure or friction, the stratum corneum becomes hypertrophied, most commonly seen on the feet and palms of the hands. A painful, cone-shaped overgrowth and hardening of the epidermis, with the point of the cone in the deeper layers. Corns on the sole of the foot and over joints are often described as hard corns, and those occurring between the toes are described as soft corns.
calor heat: one of the five classic local signs and symptoms of inflammation, the others are dolor, loss of function, rubor and tumor.
calorie a unit of heat. In practice the calorie is too small a unit to be useful and the kilocalorie (kcal) is the preferred unit in studies in metabolism. A kcal is the amount of heat required to raise the temperature of 1kg of water by 1öC. In medicine, science and technology generally, the calorie has been replaced by the joule (derived SI unit) as a unit of energy, work and heat. For approximate conversion: 4.2kJ=1kcal.
calorific describes any phenomena that relate to heat production.
calorimetry the precise method of measuring the absorbed dose of radiation in a body by calculating the temperature rise when the body is irradiated.
Campylobacter a genus of Gram-negative motile bacteria. Campylobacter jejuni is a common cause of bacterial food poisoning. It causes abdominal pain and bloodstained diarrhoea that may last for 10–14 days. The microorganism is associated with raw meat and poultry, the fur of infected pet animals and unpasteurized milk. No reported person-to-person spread.
canaliculus a minute capillary passage. Any small canal, such as the passage leading from the edge of the eyelid to the lacrimal sac or one of the numerous small canals leading from the Haversian canals and terminating in the lacunae of bone.
canal of Schlemm a canal in the inner part of the sclera, close to its junction with the cornea, which it encircles. It drains excess aqueous humour to maintain normal intraocular pressure. Impaired drainage results in raised intraocular pressure.
cancellous resembling latticework; light and spongy; like a honeycomb. Describes a type of bone tissue.
cancer a general term which covers any malignant growth in any part of the body. The growth is purposeless, parasitic, and flourishes at the expense of the human host. Characteristics are the tendency to cause local destruction, to invade adjacent tissues and to spread by metastasis. Frequently recurs after removal. carcinoma refers to malignant tumours of epithelial tissue, sarcoma to malignant tumours of connective tissue.
cancerophobia obsessive fear of cancer.
candela (cd) one of the seven base units of the International System of Units (SI). Measures luminous intensity.
candida (Monilia) a type of fungi which is widespread in nature.
candidiasis (candidosis, moniliasis, thrush) infection caused by a species of Candida, usually Candida albicans. Infection may involve the mouth, gastrointestinal tract, skin, nails, respiratory tract or genitourinary tract (vulvovaginitis, balanitis), especially in individuals who are debilitated, for example, by cancer or diabetes mellitus, or immunosuppressed and after long-term or extensive treatment with antibiotics, which upsets the microbial flora, and other drugs, for example, corticosteroids. Oral infection can be caused by poor oral hygiene, including carious teeth and ill-fitting dentures.
canine of or resembling a dog.
canine tooth pointed tooth with a single cusp (cuspid) and root, placed third from the midline in both primary and secondary dentitions. A lay term for the upper permanent canine is ‘eye tooth’. There are four in all.
cannula a hollow tube, usually plastic, for the introduction or withdrawal of fluid from the body. In some types the lumen is fitted with a sharp-pointed trocar to facilitate insertion, which is withdrawn when the cannula is in situ.
cannulation insertion of a cannula, such as into a vein to facilitate the administration of intravenous fluids.
cans the container for the sodium iodide crystals of scintillation counters to prevent the absorption of moisture by the crystal which would make it cloudy.
canthus the angle formed by the junction of the eyelids. The inner one is known as the nasal canthus and the outer as the outer (temporal) canthus.
capacitance is the amount of charge a body can hold per unit potential difference. In a sphere the capacitance is the ratio of the total charge on the body to its potential. If there are two surfaces the capacitance is the ratio of the total charge of one sign on the body to the potential difference between the surfaces.
capacitor an electrical component consisting of two plates separated by a dielectric, when it receives a potential difference across the plates a charge is stored.
capelline bandage (divergent spica) a bandage applied in a circular fashion to the head or an amputated limb.
capillary literally, hair-like; any tiny thin-walled vessel forming part of a network which facilitates rapid exchange of substances between the contained fluid and the surrounding tissues. bile capillary begins in a space in the liver and joins others, eventually forming a bile duct. blood capillary unites an arteriole and a venule. capillary fragility an expression of the ease with which blood capillaries may rupture. lymph capillary begins in the tissue spaces throughout the body and joins others, eventually forming a lymphatic vessel.
capillary blockade the injection of large radioactive particles (20–50 μm) that are unable to pass through capillaries and therefore block the first capillary bed they reach. Used in radionuclide imaging to see the vascular bed of the lungs.
capital budget financial allocation for the purchase of items, such as equipment, that will last longer than 12 months, or items that cost more than an agreed level. See also revenue budget.
capitate forms one of the carpal bones of the wrist.
capitation funding method of allocating money and other resources based on the number of people living in a geographical area. See also weighted capitation.
capsule the ligaments which surround a joint. A gelatinous or rice paper container for a drug. The outer membranous covering of certain organs, such as the kidney, liver.
capsulectomy the surgical excision of a capsule. Refers to a joint or lens; less often to the kidney.
capsulitis inflammation of a capsule. Sometimes used as a synonym for frozen shoulder.
carbaminohaemoglobin a compound formed between carbon dioxide and haemoglobin. Some carbon dioxide in the blood is carried in this form.
carbohydrate an organic compound containing carbon, hydrogen and oxygen. Formed in nature by photosynthesis in plants. Carbohydrates are the major source of energy in most diets, on average 1g of carbohydrate is metabolized to produce 16kJ heat. They include starches, sugars and non-starch polysaccharides (NSP), and are classified in three groups – monosaccharides, disaccharides and polysaccharides.
carbon a non-metallic element found in all organic molecules and living matter. Carbon can bond with four other atoms and is able to form a huge number of complex molecules.
carbon dioxide a gas; a waste product of many forms of combustion and metabolism, excreted via the lungs. Builds up in respiratory insufficiency or failure and carbon dioxide tension in arterial blood (PaCO2) rises above normal levels.
carbon monoxide a poisonous gas that combines with haemoglobin to form a stable compound. This blocks the normal reversible oxygen-carrying function and leads to hypoxia. The onset of hypoxia may be insidious but it is associated with confusion, headache, increasing respiratory rate, flushed appearance, changes in conscious level, seizures and cardiac arrhythmias.
carbon tetrachloride colourless volatile liquid used in dry cleaning and some types of antifreeze. Exposure may result in toxicity and liver damage.
carbonic anhydrase an enzyme that assists the transfer of carbon dioxide from tissues to blood and to alveolar air by reversibly catalysing the decomposition of carbonic acid into carbon dioxide and water.
carbonic anhydrase inhibitors drugs that reduce the production of aqueous humour, thereby reducing intraocular pressure. They also have diuretic effects.
carboxyhaemoglobin a stable compound formed by the union of carbon monoxide and haemoglobin; the red blood cells then lose their respiratory function.
carboxyhaemoglobinaemia carboxyhaemoglobin in the blood.
carboxyhaemoglobinuria carboxyhaemoglobin in the urine.
carbuncle an acute inflammation (usually caused by Staphylococcus). There is a collection of boils causing necrosis in the skin and subcutaneous tissue.
carcinoembryonic antigen (CEA) increased amounts in the serum of adults can be a tumour marker for colorectal cancers and for non-malignant conditions, such as liver cirrhosis caused by alcohol misuse.
carcinogen agent, substance or environment causing cancer.
carcinogenesis the production of cancer.
carcinoid syndrome cluster of symptoms including flushing, palpitation, diarrhoea and bronchospasm from histological (usually low grade) malignancy; often originates in the appendix.
carcinoma a malignant tumour of epithelial tissue (for example, mucous membrane) and derivatives such as glands.
carcinoma in situ condition with cells closely resembling cancer cells. A very early cancer. Well described in uterus and prostate. Previously called preinvasive carcinoma.
carcinomatosis widespread malignancy affecting many organs.
cardia the oesophageal opening into the stomach.
cardiac associated with the heart, associated with the cardia of the stomach.
cardiac arrest complete cessation of effective output (of blood) from heart activity. Failure of the heart action to maintain an adequate circulation. The clinical picture of cessation of circulation in a patient who was not expected to die at the time.
cardiac bed one which can be manipulated so that the patient is supported in a sitting position.
cardiac bypass operation; the bypassing of atheromatous vessels supplying heart muscle (myocardium).
cardiac catheterization a long plastic catheter or tubing is inserted into an artery or vein and moved under X-ray guidance until it reaches the heart. A catheter inserted into the brachial or femoral artery gives access to the left side of the heart and those inserted into the brachial or femoral vein can be guided into the right atrium, ventricle and the pulmonary artery. Cardiac catheterization can be used for: (a) recording pressures and cardiac output; (b) the introduction of radiopaque contrast agent for angiography; (c) treatments, such as angioplasty and stent insertion. See also angioplasty.
cardiac cycle the series of movements through which the heart passes in performing one heart beat, which corresponds to one pulse beat and takes about one second. See also diastole, systole.
cardiac enzymes released from damaged myocardial cells. Abnormal levels found in the blood are suggestive of a diagnosis of myocardial infarction. Used to confirm or refute the diagnosis of myocardial infarction. The enzymes usually measured are troponins and creatine kinase (CK) but aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) may also be measured.
cardiac massage performed during cardiac arrest. With the person lying on his or her back on a firm surface, the lower part of the sternum (breastbone) is depressed to compress the heart and force blood into the circulation. See also cardiopulmonary resuscitation (CPR).
cardiac monitor equipment used to visually record the heart cycle and therefore monitor the activity of the heart.
cardiac oedema gravitational oedema. Such patients secrete excessive aldosterone which increases excretion of potassium and conserves sodium and chloride. Anti-aldosterone (aldosterone antagonists) drugs are useful, for example, spironolactone. See also oedema.
cardiac output (CO) the volume of blood ejected by the heart per minute, typically 4–5L/min at rest. It can be expressed as the cardiac index (CI), cardiac output divided by body surface area.
cardiac pacemaker an electrical device for maintaining myocardial contraction by stimulating the heart muscle. A pacemaker may be permanent or temporary. They are programmed in a variety of modes. Nowadays pacemakers can be programmed to alter their rate in response to physical activity.
cardiac tamponade excessive fluid surrounding the heart, usually blood when the cause is traumatic, causes compression of the heart especially the right ventricle leading to impaired cardiac function. Can occur in surgery and penetrating wounds or cardiac rupture.
cardialgia literally, pain in the heart. Often used to mean heartburn (pyrosis).
cardiogenic of cardiac origin.
cardiogenic shock shock caused when the action of the heart is impaired, for example, in heart failure, cardiac injury, disease of the heart muscles.
cardiograph an instrument for recording graphically the force and form of the heart beat.
cardiologist a medically qualified person who specializes in diagnosing and treating diseases of the heart.
cardiology study of the structure, function and diseases of the heart.
cardiomegaly enlargement of the heart.
cardiomyopathy a disease of the myocardium associated with cardiac dysfunction. It is classified as dilated cardiomyopathy, hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy or restrictive cardiomyopathy. Management includes treatment of the cause (if possible), treatment of heart failure and sometimes heart transplantation.
cardiophone a microphone strapped to a patient which allows audible and visual signal of heart sounds. By channelling pulses through an electrocardiograph, a graphic record can be made. Can be used for the fetus.
cardioplegia the use of an electrolyte solution to induce electromechanical cardiac arrest. cold cardioplegia combined with hypothermia to reduce the oxygen consumption of the myocardium during open heart surgery.
cardiopulmonary associated with the heart and lungs.
cardiopulmonary bypass used in open heart surgery. The heart and lungs are excluded from the circulation and replaced by a pump oxygenator.
cardiopulmonary resuscitation (CPR) the techniques used to maintain circulation and respiration following cardiopulmonary arrest. It involves (a) the maintenance of a clear airway, (b) artificial respiration using mouth-to-mouth or mouth-to-nose respiration, or with a bag and face mask, or by an endotracheal tube, and (c) maintenance of the circulation by external cardiac massage. See also resuscitation.
cardiorenal associated with the heart and kidney.
cardiorespiratory associated with the heart and the respiratory system.
cardiorrhaphy stitching of the heart wall: usually reserved for traumatic surgery.
cardiothoracic associated with the heart and thoracic cavity. A specialized branch of surgery.
cardiotocograph the instrument used in cardiotocography.
cardiotocography (CTG) a procedure whereby the fetal heart rate is measured either by an external microphone or by the application of an electrode to the fetal scalp, recording the fetal ECG and from it the fetal heart rate. An external transducer placed on the mother’s abdomen measures the uterine contractions.
cardiotomy syndrome pyrexia, pericarditis and pleural effusion following heart surgery. It may develop weeks or months after the operation and is thought to be an autoimmune reaction.
cardiotoxic describes any agent that has an injurious effect on the heart.
cardiovascular associated with the heart and blood vessels.
cardiovascular endurance the ability to sustain exercise without undue fatigue, cardiac distress or respiratory distress.
cardioversion use of electrical countershock for restoring the heart rhythm to normal.
carditis inflammation of the heart. A word seldom used without the appropriate prefix, for example, endo-, myo-, peri-.
caries inflammatory decay of bone, usually associated with pus formation. In dentistry tooth decay. See also dental caries.
carina a keel-like structure exemplified by the keel-shaped cartilage at the bifurcation of the trachea into two bronchi.
cariogenic causing caries, by convention referring to dental caries.
carneous mole a fleshy mass in the uterus comprising blood clot and a dead fetus or parts of a dead fetus that have not been expelled with miscarriage.
carotid the principal artery on each side of the neck. At the bifurcation of the common carotid into the internal and external carotids there are: (a) the carotid bodies a collection of chemoreceptors which, being sensitive to chemical changes in the blood, protect the body against lack of O2; (b) the carotid sinus a collection of baroreceptors; increased pressure causes slowing of the heart beat and lowering of blood pressure.
carotid angiography the demonstration of the brain circulation by direct injection of a contrast agent into the carotid artery or via a catheter in the femoral vein which is passed to the carotid artery.
carpal associated with the wrist.
carpal bones the eight bones that lie between the distal end for the radius and ulna and the metacarpals.
carpal tunnel syndrome nocturnal pain, numbness, weakness of the thumb and tingling in the area of distribution of the median nerve in the hand. Due to compression as the nerve passes under the fascial band. Most common in middle-aged women.
carpometacarpal associated with the carpal and metacarpal bones.
carpopedal associated with the hands and feet.
carpopedal spasm painful spasm of hands and feet in tetany. See also hypocalcaemia.
carpus the bones of the wrist.
carrier a person who harbours microorganisms of an infectious disease without showing symptoms and who can transmit infection to others. A person who carries a recessive gene at a specific chromosome location (locus) and therefore passes on a hereditary abnormality.
cartesian co-ordinate the point on a graph where the value of x meets the value of y.
cartilage a dense connective tissue capable of withstanding pressure. There are several types according to the function it has to fulfil. There is relatively more cartilage in a child’s skeleton but much of it has been converted into bone by adulthood.
cartilaginous joints (amphiarthroses) joints with either no movement or minimal movement and joined by a layer of cartilage.
caruncle a red fleshy projection. Hymenal caruncles surround the entrance to the vagina after rupture of the hymen. The lacrimal caruncle is the fleshy prominence at the inner angle of the eye.
case–control study a retrospective research study that compares outcomes for a group with a particular condition with those of a control group who do not have the condition.
case study research that studies data from one case, or a small group of cases.
caseation the formation of a soft, cheese-like mass, as occurs in tuberculosis.
caseous degeneration cheese-like tissue resulting from atrophy in a tuberculoma or gumma.
Casoni test intradermal injection of fresh, sterile hydatid fluid. A white papule indicates a hydatid cyst.
cassette a piece of equipment to hold either an imaging plate or radiographic film. It may also contain intensifying screens and a grid.
cast material or exudate that has been moulded to the form of the cavity or tube in which it has collected. A rigid casing often made with plaster of Paris and applied to immobilize a part of the body.
castration surgical removal of the testes in the male, or of the ovaries in the female. Castration can be part of the treatment for a hormone-dependent cancer.
CAT computed axial tomography.
catabolism (katabolism) the series of chemical reactions in the living body whereby complex substances are broken down into simpler ones accompanied by the release of energy. This energy is needed for converting simple compounds into complex compounds in the body (anabolism), and the other activities of the body.
catalyst any substance that regulates or accelerates the rate of a chemical reaction without itself undergoing a permanent change.
cataplexy a condition of muscular rigidity induced by severe mental shock or fear. The patient remains conscious.
cataract opacity of the lens of the eye causing partial or complete blindness. Usually age-related, but many causes including congenital, traumatic or metabolic such as diabetes mellitus.
catarrh chronic inflammation of a mucous membrane with constant flow of a thick sticky mucus.
catecholamines a group of important physiological amines, such as adrenaline (epinephrine), noradrenaline (norepinephrine) and dopamine. They act as hormones and neurotransmitters and affect blood pressure, heart rate, respiratory rate and blood sugar. Abnormally high levels are secreted by adrenal and other tumours and can be detected in the urine. See also phaeochromocytoma.
categorical data data that can be categorized, for example, hair colour. See also nominal data, ordinal data.
CAT scanner computer assisted tomography or computed axial tomography. See also CT scanner.
cat scratch fever a virus infection resulting from a cat scratch or bite. There is fever and lymph node swelling about a week after the incident. Recovery is usually complete, although an abscess may develop.
catheter a hollow tube of variable length and bore, usually having one fluted end and a tip of varying size and shape according to function. Catheters are made of many substances including soft and hard rubber, gum elastic, glass, silver, other metals and plastic materials, some of which are radiopaque. They have many uses including: blowing gas, air or powder into a cavity, cardiac catheterization, introduction of contrast agent for angiography, withdrawal of fluid from body cavities, for example, urinary catheter and the administration of drugs, fluids and nutrients.
catheterization insertion of a catheter, most usually into the urinary bladder. See also cardiac catheterization.
cathetron unit a high-rate dose, remotely controlled, afterloading device for radiotherapy. Hollow steel catheters are placed in the desired position. They are then connected to a protective safe by hollow cables. The radioactive cobalt moves from the safe into the catheters. After delivery of the required dose, the cobalt returns to the safe, thus avoiding radiation hazard to staff. Currently superseded by units such as the Selectron.
cathode is the assembly that contains the negatively charged filament, focussing cup, supporting wires and cathode support in an X-ray tube.
cathode rays streams of electrons coming from the heat filament or cathode.
cathode ray tube used in older computer monitors where an electron gun is focussed on a fluorescent screen, where electrons hit the screen light is produced and therefore an image is formed. See also glass plasma display, liquid crystal display.
cation a positively charged ion which moves towards the cathode when an electric current is passed through an electrolytic solution. See also anion.
cauda a tail or tail-like appendage.
cauda equina lower part of the spinal cord where the nerves for the legs and bladder originate.
caudal anaesthesia injection of local anaesthetic into the epidural space at the level of the sacrum causing loss of sensation in the lower abdomen and pelvis.
cauterize to cause tissue destruction by applying a heated instrument.
cautery an agent or device, for example, electricity, chemicals or extremes of temperature, which destroys cells and tissues. Uses include the prevention of blood loss during surgery, or to remove abnormal tissue.
cavernous having hollow spaces.
cavernous sinus a channel for venous blood, on either side of the sphenoid bone. It drains blood from the cerebral hemispheres, orbits and the bones of the skull. Sepsis around the eyes or nose can cause cavernous sinus thrombosis.
cavitation the formation of a cavity, as in pulmonary tuberculosis. When gas bubbles expand, contract, increase in pressure or temperature due to the passage of ultrasound.
cavity a hollow; an enclosed area.
CDROM (Compact Disk Read-Only Memory) an object for storing computer data; once the data have been stored they cannot be changed.
CDRW (Compact Disk Re-Writer) an object for storing computer data; the data can be re-written if required.
celestin tube a soft rubber intubation tube which is pulled through an oesophageal tumour by the use of a string or guidewire and is attached to the stomach with a suture. Used to maintain a free passage of food and fluid.
cell basic structural unit of living organisms. A mass of protoplasm (cytoplasm) and usually a nucleus within a plasma or cell membrane. Some cells, for example, erythrocytes, are non-nucleated whereas others, such as voluntary muscle, may be multinucleated. The cytoplasm contains various subcellular organelles – mitochondria, ribosomes, etc. – that undertake the metabolic processes of the cell.
cell cycle the events occurring within a cell from one mitotic division to the next. Comprises the dynamic course of division of normal and cancer cells incorporating phases of DNA synthesis (S-phase), growth phases (GI and GII), mitosis (M) and ‘rest phase’ (G0).
cell cycle phase non-specific describes a cytotoxic drug that acts at any time in the cell cycle.
cell cycle phase specific describes a cytotoxic drug that acts during a specific phase of the cell cycle.
Celsius the derived SI unit (International System of Units) for temperature. Named after Anders Celsius (1701–1744) who constructed the first centigrade thermometer. See also centigrade.
cement the outer layer covering the root of a tooth and continuous with the enamel.
cementum calcified organic hard tissue forming on the surface of a root of a tooth, and providing attachment for the periodontal ligament.
Centers for Disease Control and Prevention (CDC) a federal agency in the USA (Atlanta). Its functions include the investigation, identification, prevention and control of disease.
centigrade a scale with one hundred divisions or degrees. Most often refers to the thermometric scale in which the freezing point of water is fixed at 0öC and the boiling point at 100öC. It is usually called Celsius for medical and scientific purposes. See also Celsius.
central limit theorem in research: sampling distribution becomes more normal the more samples that are taken.
central sterile supplies department (CSSD) designated an area where packets are prepared containing the equipment and/or swabs and dressings necessary to perform activities requiring aseptic technique. See also hospital sterilization and disinfection unit (HSDU).
central tendency statistic averages. The tendency for observations to centre around a specific value rather than across the entire range. See also mean, median, mode.
central venous catheter/line specialized intravenous cannula placed in a large vein (jugular, subclavian or femoral). Used for the measurement of central venous pressure, and fluids and drugs. Also allows long-term vascular access for the administration of drugs, blood products or nutritional support.
central venous pressure (CVP) the pressure of the blood within the right atrium. It is measured using a central venous catheter attached to a manometer or pressure transducer.
centralized daylight system a system where the loading and unloading of a cassette or film magazine is directly linked to an automatic film processor.
centric occlusion contact of the upper and lower teeth with maximum contact of the cusps.
centrifugal efferent. Having a tendency to move outwards from the centre, as the nerve impulses from the brain to the peripheral structures.
centrifuge an apparatus which subjects solutions to centrifugal forces by high-speed rotation, thereby separating substances of different densities into discrete bands within the liquid phase. It is usually used to separate (‘spin down’) particulate material (for example, subcellular particles) from a suspending liquid.
centriole a subcellular organelle that aids spindle formation during nuclear division. See also meiosis, mitosis.
centronics a type of standard interface between computer and peripheral.
cephalalgia pain in the head; headache.
cephalic associated with the head; near the head.
cephalocele hernia of the brain; protrusion of part of the brain through the skull.
cephalometric radiograph a lateral projection of the skull and mandible for making cranial measurements to estimate the degree of any facial abnormality.
cephalometry measurement of the living human head.
ceramic detector a modern device used in CT scanning to measure the amount of radiation transmitted through a patient, giving a reduction in noise compared with earlier detectors and in chest scans there is said to be a reduction in beam hardening artefacts.
cerebellar gait a staggering, unsteady, wide-based walk seen in patients with damage to the cerebellum or its connections. See also gait.
cerebellum that part of the brain which lies behind and below the cerebrum. Its chief functions are the coordination of fine voluntary movements and the control of posture.
cerebral associated with the cerebrum.
cerebral cavity the ventricles of the brain.
cerebral compression arises from any space-occupying intracranial lesion.
cerebral cortex the outer layer of cells (grey matter) in the cerebral hemispheres.
cerebral hemisphere one side of the cerebrum, right or left.
cerebral palsy non-progressive brain damage that typically occurs at, or shortly after, birth resulting in a range of mainly motor conditions ranging from clumsiness to severe spasticity.
cerebral function monitor (CFM) equipment for continuous monitoring of brain wave activity, for example, to detect seizures in sedated and paralysed patients.
cerebral perfusion pressure (CPP) the pressure which drives blood through the brain. It is the difference between the arterial blood pressure and the intracranial pressure. If CPP is too low the blood flow to the brain may be inadequate and the brain deprived of oxygen.
cerebrospinal associated with the brain and spinal cord.
cerebrospinal fluid the clear fluid found within the ventricles (cavities) of the brain, central canal of the spinal cord and beneath the cranial and spinal meninges in the subarachnoid space. Protects and nourishes the brain and spinal cord. It is formed by the choroid plexus in the ventricles and circulates around the brain and spinal cord before it is reabsorbed on the outside of the brain.
cerebrovascular associated with the blood vessels of the brain.
cerebrovascular accident (stroke) (CVA) interference with the cerebral blood flow due to embolism, haemorrhage or thrombosis. Signs and symptoms vary according to the duration, extent and site of tissue damage; there may be only a passing, even momentary inability to move a hand or foot; weakness or tingling in a limb; stertorous breathing; incontinence of urine and faeces; coma; paralysis of a limb or limbs; and speech deficiency (aphasia). See also transient ischaemic attack.
cerebrum the largest and uppermost part of the brain. The longitudinal fissure divides it into two hemispheres, each containing a lateral ventricle. A mass of nerve fibres (white matter) is covered by a thin layer of nerve cells (grey matter). It controls the higher functions and contains major motor and sensory areas. The outer surface is convoluted.
cerumen ear wax, sticky brown secretion from glands in the external auditory canal. Traps dust and other particles entering the ear.
cervical associated with the neck. Associated with the cervix (neck) of an organ.
cervical canal the lumen of the cervix uteri, from the internal to the external os.
cervical intraepithelial neoplasm (CIN) abnormal changes in the basal layer of the squamous epithelial layers of the uterus and is divided into three grades, CIN 1 is pre-malignant through to CIN3 which is early cancer.
cervical rib an additional rib articulating with the seventh cervical vertebra.
cervical smear see cervical intraepithelial neoplasia.
cervical vertebrae the seven bones that form the neck.
cervicectomy amputation of the uterine cervix.
cervicitis inflammation of the uterine cervix.
cervix uteri uterine cervix, the neck of the uterus.
cetrimide a disinfectant with detergent properties. Used for wound cleansing and skin preparation.
chancre the primary syphilitic ulcer developing at the site of infection with Treponema pallidum. It is associated with swelling of local lymph nodes. The chancre is painless, hard (indurated), solitary and highly infectious.
characteristic curve applies to a particular film or film/screen combination and is the curve which results when the density is plotted against the log of relative exposure. It is also called D log E curve, a Hurter and Driffield curve, a log It curve. The curve is used to determine the basic fog level, threshold, toe, straight line portion, shoulder and maximum density of the film. See also basic fog level, threshold, toe, straight line portion, shoulder, maximum density. (See figure on p. 80).
charcoal used therapeutically for its adsorptive and deodorant properties. Can be taken to absorb abdominal gas. Activated charcoal incorporated into dressings is used to reduce odour in discharging wounds.
Charcot’s joint complete disorganization of a joint associated with fluid-filled cavities in the spinal cord (syringomyelia), diabetes mellitus, or advanced cases of wasting away of the posterior nerve roots of the spinal cord (tabes dorsalis, locomotor ataxia). The condition is painless.
continuous hyperfractionated accelerated radiotherapy.
chelate a compound composed of a central metal ion and an organic molecule with multiple bonds, formed in a ring formation.
chemonucleolysis injection of an enzyme, usually into an intervertebral disc, for dissolution of same.
chemoradiation giving chemotherapy and radiotherapy at the same time.
chemoreceptor a sensory nerve ending or a cell having an affinity for, and capable of reacting to, a chemical stimuli, for example, taste, oxygen levels in the blood.
chemoresistant describes a tumour that does not usually shrink with chemotherapy.
chemosensitive describes a tumour that shrinks following chemotherapy administration.
chemotaxis movements of a cell (for example, leucocyte) or a microorganism in response to chemical stimuli; attraction is termed positive chemotaxis, repulsion is negative.
chemotherapy chemical agents of various types; prescribed to delay or arrest growth of cancer cells through interruption/inhibition of cell cycle; on a selective basis by impairing their ability to replicate. Usually given in combination rather than as single agents. They are non-selective and non-specific and therefore affect all cycling cells whether benign or malignant. Administration is by oral, intramuscular, intravenous, intracavitary, or intra-arterial routes. See also alkylating agents, antimetabolites, antitumour antibiotics, vinca alkaloids.
chenodeoxycholic acid a bile acid. It can be taken orally to dissolve certain types of gallstones.
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