Temperature Control in Endotherms Flashcards
What is the hypothalamus?
The part of the brain that coordinates homeostatic responses.
What do endotherms use to control their body temperature?
They can use physiological adaptations and behavioural means to control their body temperature.
What does temperature regulation rely on?
Effectors in the skin and muscles.
What does the skin do if the body is too hot?
Sweat glands secrete fluid onto the skin surface; as this evaporates it uses heat from the blood as the latent heat of vaporisation.
What happens to the body hairs/feathers of an endotherm that is too hot?
They lie flat to reduce insulation and allow greater heat loss.
What happens to the arterioles of an endotherm when it is too hot?
The arterioles vasodilate and precapillary sphincters direct blood to the skin surface so more heat can be radiated away from the body.
Why do some animals pant when they are too hot?
Panting increases the evaporation of water from the surface of the lungs and airways. Evaporation uses heat from the blood as the latent heat of vaporisation.
What does the liver do as a response to the body being too hot?
Less respiration takes place, so less heat is released.
What do the skeletal muscles do as a result of the body being too hot?
Fewer contractions mean that less heat is released.
What do the blood vessels do in response to the body being too hot?
Dilation to direct the blood to the extremities so that more heat can be lost.
What do endotherms do if they are too cold? (behavioural)
Lie in the sun
Orientate body towards sun to increase surface area exposed
Move about to generate heat in the muscles or, in extreme conditions, roll into a ball shape to reduce surface area and heat loss.
Remain dry
What are the advantages of endothermy?
Maintain a fairly constant body temperature whatever the temperature externally.
Remain active even when the external temperatures are low, can take advantage of prey that may be available or escape from potential predators.
Inhabit colder parts of the planet.
What are the disadvantages of endothermy?
Use a significant amount of their energy intake to maintain body temperature in the cold
Need more food
Use for growth a lower proportion of the energy and nutrients gained from food
May overheat in hot weather
What detects changes in temperature?
The hypothalamus.
If the core temperature is too low what will the hypothalamus cause?
Changes in the skin to reduce heat loss
Release of heat through extra muscular contraction (shivering)
Increased metabolism in order to release more heat from exergonic reactions
