Maintaining Body Temperature Flashcards
What is an endotherm?
can use internal sources of heat (e.g. from metabolism) to maintain body temp
What are exergonic reactions?
release energy in form of heat
What are the advantages to endothermy?
fairly constant body temp regardless of external, activity possible when external cool, ability to inhibit colder parts of planet
What are the disadvantages to endothermy?
significant part of energy intake used to maintain body temp in cold, more food required (shrew has to eat its mass in food each day), less energy from food for growth
What are the 6 physiological mechanisms used by endotherms to maintain temperature?
Sweat glands in skin. Lungs, mouth and nose. Hairs on skin. Arterioles leading to capillaries in skin. Liver cells. Skeletal muscles.
What is the response of the sweat glands in skin when body temperature is too high or too low?
High: secrete more sweat: water in sweat evaporates, using heat from blood to supply latent heat of evaporation. Low: less sweat secreted
What is the response of the lungs, mouth and nose when body temperature is too high or too low?
High: panting increases evaporation of water from lungs, tongue, other moist surfaces, uses latent heat. Low: no panting
What is the response of the hairs on skin when body temperature is too high or too low?
High: hairs lie flat, little insulation, more heat lost by convection and radiation. Low: hair raised to trap layer of insulating air, heat loss reduced
What is the response of the arterioles leading to capillaries in skin when body temperature is too high or too low?
High: vasodilation = more blood into capillaries at surface, more heat radiated (may look red). Low: vasoconstriction = less heat radiated
What is the response of the liver cells when body temperature is too high or too low?
High: rate of metabolism is reduced, less heat from exergonic reactions like respiration. Low: high metabolism rate, more respiration heat into blood
What is the response of the skeletal muscles when body temperature is too high or too low?
High: no spontaneous contractions. Low: spontaneous contractions (shivering) generates heat as muscle cells respire more
What is the behaviour of endotherms if too hot?
move into shade/burrow, orientate body to decrease SA exposed to sun, remain inactive and spread limbs to increase SA
What is the behaviour of endotherms if too cold?
move into sunlight, orientate towards sunlight, move about to generate heat in muscles (except in extreme cold when need to be in ball to reduce SA)
If core temperature too low, what changes will be caused by the hypothalamus signals?
increased metabolism rate = more heat from exergonic reactions, release heat via more muscular contractions, decrease loss of heat to environment
What centre in the hypothalamus monitors blood temperature and detects changes in core body temperature?
thermoregulatory centre
