LEVY, B. Cardiovascular Res. Vanhoutte and I. Leusen Eds. Shepherd and F. Abboud Eds. TAM, H. The Cardiovascular System. Bohr, A. Somlyo, and H. Sparks, Jr. WYSS, C. Loring B. Rowell 1 1. Personalised recommendations. Cite chapter How to cite? Reptiles are popularly deisgnated "cold-blooded", when in fact they can sustain high and steady bpdy temperatures just as mammals and birds do. Reptiles accomplish this not through high rates of internal heat production, as do mammals and birds.
Rather, they engage in quite sophisticated exploitation of heat exchange between their bodies and their environment. This is sometimes called behavioral thermoregulation, although this is only a partial description.
Lizards, for example, will often shuttle between locations where they can absorb heat from the sun, or warm ground, and then venture into cooler spots to forage and do other things lizards do.
This is called shuttling thermoregulation. By shuttling between locations where they absorb heat and locations where they lose it, a lizard's body temperature will oscillate within a narrow range, which can be impressively warm. Read and download Log in through your school or library. Alternate access options. Get Started Already have an account? How does it work? Select the purchase option. Check out using a credit card or bank account with PayPal.
Read your article online and download the PDF from your email or your account. The hypothalamus controls thermoregulation. When the environment is not thermoneutral, the body uses four mechanisms of heat exchange to maintain homeostasis: conduction, convection, radiation, and evaporation. Each of these mechanisms relies on the property of heat to flow from a higher concentration to a lower concentration; therefore, each of the mechanisms of heat exchange varies in rate according to the temperature and conditions of the environment.
The metabolic rate is the amount of energy consumed minus the amount of energy expended by the body. The basal metabolic rate BMR describes the amount of daily energy expended by humans at rest, in a neutrally temperate environment, while in the postabsorptive state.
It measures how much energy the body needs for normal, basic, daily activity. About 70 percent of all daily energy expenditure comes from the basic functions of the organs in the body.
Another 20 percent comes from physical activity, and the remaining 10 percent is necessary for body thermoregulation or temperature control. This rate will be higher if a person is more active or has more lean body mass. As you age, the BMR generally decreases as the percentage of less lean muscle mass decreases. Some of the energy from the food that is ingested is used to maintain the core temperature of the body. Most of the energy derived from the food is released as heat.
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