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Circadian rhythm
Circadian rhythm
Biological timing and rhythmicity that, in humans, is characterised by cycles of approximately 24 hours. Synonym: biological clock.
SIMILAR TERMS--------------------------------------
Circadian
Fluctuating regularly on a time basis usually entrained to a metabolic, endocrine, neurochemical, light-dark, temperature, or seasonal cycle (see also diurnal, ultradian). There are very fast biorhythm cycles such as in the EEG and ECG, a 90-minute cycle seen in REM-NREM sleep or in waking attentive/alert-drowsy/inattentive swing, a twice daily body temperature peak and slump. a 24-hour ACTH cycle, a monthly menstrual cycle, and possibly longer seasonal cycles not yet thoroughly described.
Circanol
Circanol is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): ergoloid mesylates.
Circle of Willis
An arterial circle at the base of the brain that is of critical importance. The circle of Willis receives all the blood that is pumped up the two internal carotid arteries that come up the front of the neck and that is pumped from the basilar artery formed by the union of the two vertebral arteries that come up the back of the neck. All the principal arteries that supply cerebral hemispheres of the brain branch off from the circle of Willis.
Circular breathing
Inhaling through the nose and inflating the cheeks and neck with air at the same time.Some saxophone players do circular breathing; this may not be a safe practice since it may reduce blood flow to the brain.
Circulation
The flow of blood through the body. Includes the heart, arteries, veins and capillaries.
Circulation, fetal
The blood circulation in the fetus (the unborn baby). Before birth, the blood from the heart that is destined (in the pulmonary artery) for the lungs is shunted away from the lungs and returned to the greatest of arteries (the aorta). The shunt is through a short vessel called the ductus arteriosus. When this shunt is open, it is said to be a patent (pronounced pá tent) ductus arteriosus (PDA). The PDA usually closes at or shortly after birth and blood is permitted to course freely to the lungs.
Circulatory
Having to do with the circulation, the movement of fluid in a regular or circuitous course. Although the adjective "circulatory" need not necessarily refer to the circulation of the blood, for all practical purposes today it does. A circulatory problem is taken usually to be a problem with the blood circulation, for example with heart failure.
Circulatory system
Pertaining to the heart and blood vessels, and the circulation of blood.
Circum-
Prefix meaning around, surrounding, or encircling. As in circumcision, circumflex, and circumjacent. From the Latin preposition circum meaning round.
Circumcision
The surgical removal of the sheath of skin (called a foreskin) that covers the head of the penis.
Circumflex
Curved like a bow. In anatomy, circumflex describes a structure that bends around like a bow. For example, the circumflex branch of the left coronary artery.
Circumscribed
Having a border, localized. Often associated with a capsule and benign tumors of the brain, for example, meningiomas, pituitary adenomas and acoustic neuromas. See diffuse.
Circumstantiality
Pattern of speech that is indirect and delayed in reaching its goal because of excessive or irrelevant detail or parenthetical remarks. The speaker does not lose the point, as is characteristic of loosening of associations, and clauses remain logically connected, but to the listener it seems that the end will never be reached.
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Carotid endarterectomy
Surgical removal of deposits (which cause restricted blood flow, or are the source of an embolus) in the walls of the carotid artery.
Case report form (CRF)
A printed, optical, or electronic document designed to record all of the protocol-required information to be reported to the sponsor on each trial subject.
Categorical data
Data evaluated by sorting values into various categories (for example, severe, moderate, and mild).
Casuality assessment
Determining whether there is a reasonable possibility that the drug caused or contributed to an adverse event. It includes assessing temporal relationships, dechallenge/rechallenge information, association (or lack of association) with underlying disease, and the presence (or absence) of a more likely cause.
Cerebral infarct
A localised area of cell death in the brain due to inadequate blood flow.
Circadian rhythm
Clean database (or file)
One from which errors have been eliminated and in which measurements and other values are provided in the same units.
Clinical trial
A research study that involves the administration of a test regimen or experimental treatment (eg. a new drug or therapy), to humans to evaluate its efficacy and safety. See also phases of clinical trials.
Clinical trial/study report
A written description of a trial/study of any therapeutic, prophylactic, or diagnostic agent conducted in human subjects, in which the clinical and statistical description, presentations, and analyses are fully integrated into a single report (see the ICH Guideline for Structure and Content of Clinical Study Reports).
Coding in clinical trials
The process of assigning data to categories for analysis.
Cognition (or cognitive function)
Higher intellectual functioning including awareness, perception, reasoning, memory, and problem solving.
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