biological clock

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Related to biological clock: circadian rhythm


1. pertaining to biology.
2. a medicinal preparation made from living organisms and their products, such as a serum or vaccine.
biological clock the physiologic mechanism that governs the rhythmic occurrence of certain biochemical, physiologic, and behavioral phenomena in living organisms. See also biological rhythms.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

biological clock

1. An internal mechanism in organisms that controls the periodicity of various functions or activities, such as metabolic changes, sleep cycles, or photosynthesis.
a. The time period during which a person who desires to have a biological child, especially a woman approaching the decline of reproductive capability, is still able to do so.
b. The capacity to be fertile, especially in such a woman: She was eager to have a child before her biological clock stopped working.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.
Physiology An organism’s internal timer that sets biological rhythms—e.g., metabolism, sleep-wake cycles, and photosynthesis
Vox populi As currently used, that which ticks away the time left for a woman to have babies, ideally before age 40
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.

biological clock


internal clock

an internal mechanism (as yet poorly understood) by which many plants and animals keep a sense of time, making possible a rhythmic pattern of behavour. Many organisms have such ‘clocks’ producing activity cycles of approximately 24 hours (CIRCADIAN RHYTHMS) which, however, can be affected by external influences that ‘set’ the clock (entrainment). An individual's clock can be re-entrained if placed in a new time zone, but after rapid, long-distance travel the process can take several cycles, creating ‘jet-lag’ until internal and external rhythms are synchronized. Biological clocks affect not only whole organism activities (e.g. sleeping) but also cellular patterns of activity (e.g. varying METABOLIC RATES). See also DIURNAL RHYTHM.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005

Biological clock

A synonym for the body's circadian rhythm, the natural biological variations that occur over the course of a day.
Mentioned in: Cluster Headache
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
The biological clock in a normal person oscillates with an endogenously adjusted period of 24 hours.
According to neuroscientists, mice have a biological clock which is almost identical to that of humans with the difference that it is finetuned for nocturnal life.
Dr Riccardo Marioni, of the University of Edinburgh's Centre for Cognitive Ageing and Cognitive Epidemiology, said: "The same results in four studies indicated a link between the biological clock and deaths from all causes.
The female biological clock actually benefited some of us men.
The proper reestablishment of the biological clock increases the long-term regenerative capacity of the tissue and decreases the probability of developing tumors.
Our study shows the biological clock determines how well these hormones work," said Marc Montminy, of the Salk Institute for Biological Studies, who led the study.
Scientists are claiming this will effectively stop the biological clock.
They cover the human biological clock from genes to chronotherapy, photosensitivity as a disregarded attribute to analyze photo-periodic clocks, respiration rhythm and quality of sleep in the total wellness and development of a child, circadian sleep-wake rhythms in pre-term infants, interactions between the circadian and the immune systems as a framework for understanding disease, the spider monkey Ateles geoffroyi as a case study in the chronoecology of neotropical primates, the role of clocks and chaos in a biodynamic approach to cancer, and experimental findings and analytical properties of a klepsydraic model of internal time presentation.
A pal of hers tells me: "Naomi knows her biological clock is
The She Wolf star admits her biological clock is ticking and she's desperate to start a family.
Dunford really believe that putting a woman in a position of power in the banking sector will start off her biological clock, (ECHO letters, May 26)?
There is a natural gift which God almighty has installed in your body and it is called a biological clock. A good and devout Muslim doesn't need loudspeakers to wake him up at dawn and remind him of Allah and prayer and if you endure a little discomfort and set and adjust your biological clock to wake you up at dawn, then as a good and devout Muslim you will wake up and perform your duty towards Allah, without relying on loudspeakers.

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