Module 5: Thermoregulation in endotherms Flashcards
Make 2 initial points about endotherms
-they rely on their metabolic processes to warm up
-they usually maintain a very stable core temperature regardless of the environmental temp
Give 2 detection methods that are used in endotherms to detect changes in temperature
(one for surface temperature and one for blood temperature)
peripheral temp receptors-found in the skin and detect changes in surface temp
temp receptors in the hypothalamus-detect temperature of blood deep in the body
Do endotherms carry out some of the same behavioural responses that ectotherms do?
Give 2 additional behavioural adaptations that humans use to thermoregulate
yes they do
wearing clothes , building houses that can be heated or cooled by human control
What does the combination of the 2 detection methods allow in terms of responding to temp changes?
2 things
-allows organisms to respond quickly to actual changes in blood temp
-allows organisms to pre-empt possible problems that may result from environmental changes
State the 3 ways that endotherms can reduce their core body temperature
-vasodilation
-increased sweating
-reducing insulating effect of hair/feathers
Describe how vasodilation reduces core body temperature
3 points
-arterioles near skin surface dilate when temp rises and vessels that provide a direct connection between arterioles and venules constrict
-this forces blood through capillary networks close to the surface of the skin
-causes skin to flush and cool as a result of increased radiation
Describe how increased sweating reduces core body temperature
2 points
-sweat spreads across the skin and as it evaporates heat is lost
-this cools the blood below the skins surface
How do animals whos sweat glands are restricted to less hairy areas of the body only thermoregulate?
1 point
-they pant through their mouths which loses heat energy as water evaporates from the mouth
Describe how reducing the insulating effect of hair/feathers reduces core body temp
3 points
-as body temp increases , the ERECTOR PILLI MUSCLES in the skin relax
-this results in hairs/feathers lying flat to the skin
-this avoids trapping of an insulating layer of air
State the 4 ways in which endotherms warm up
-vasoconstriction
-decreased sweating
-raising hairs/feathers
-shivering
Describe how vasoconstriction helps to increase core body temperature
3 points
-arterioles near surface of skin constrict and arteriovenous shunt vessels dilate
-results in very little blood flow through capillaries close to the skin surface
-therefore little radiation takes place , keeping warm blood far from the surface
How does decreased sweating help to increase core body temp
1 point
-this greatly reduces the rate of evaporation of water from the surface of the skin (reduces cooling)
Describe how raising hairs/feathers helps to increase core body temp
3 points
-as body temp decreases , erector pilli muscles contract
-this pulls hairs and feathers erect
-this traps an insulating layer of air and hence decreases cooling through the skin
Describe how shivering helps to increase core body temp
2 points
-this is the rapid involuntary contracting/relaxing of large voluntary muscles
-the metabolic heat from these exothermic reactions warms the body
Thermoregulation involves complex homeostatic mechanisms , what do these mechanisms involve?
(hint: type of feedback , part of the brain)
negative feedback control from the hypothalamus
What are the 2 control centres within the hypothalamus?
the heat loss centre
the heat gain centre
Heat Loss Centre:
-when is it activated?
-what does it do in response to this detection(2)
-activated when temp of blood flowing through the hypothalamus increases
-it sends impulses through autonomic motor neurons to effectors in the skin/muscles
-this triggers responses to lower core temp
Heat Gain Centre:
-when is it activated?
-what does it do in response to this detection?
-activated when temp of blood flowing through the hypothalamus decreases
-sends impulses through the ANS to effectors
-this triggers responses to increase core temp
