15.3 Thermoregulation in endotherms

Question 1

What happens if temperature changes from set point?

Answer 1

Thermoreceptors in the hypothalamus can detect changes in blood temperature
Peripheral temperature receptors in the skin can detect changes in the surface temperature
Hypothalamus acts to return temperature to 37oC

Question 2

How do endotherms cool down?

Answer 2

Vasodilation
Increased sweating
Hairs on skin lie flat

Question 3

How does vasodilation cool down endotherms?

Answer 3

Arterioles near skin surface dilate
Arteriovenous shunt vessels constrict
Forces blood through capillary networks close to surface of skin
Increased radiation, skin flushes, heat lost from the body

Question 4

How does sweating cool down endotherms?

Answer 4

Sweat is released by sweat glands onto the skin surface
As sweat evaporates from the skin surface, heat is lost
This cools down the skin surface

Question 5

How are hairs used to cool down endotherms?

Answer 5

Hair erector muscles relax
Hairs lie flat to the skin
Prevents insulating layer of air being trapped

Question 6

How do endotherms increase body temperature?

Answer 6

Vasoconstriction
Decreased sweating
Raising body hairs
Shivering

Question 7

How does vasoconstriction warm up endotherms?

Answer 7

Arterioles near surface of skin constrict
Arteriovenous shunt vessels dilate
Less blood flows through capillary networks near the surface of the skin, less radiation of heat

Question 8

How does shivering warm up endotherms?

Answer 8

Rapid involuntary contracting and relaxing of the large voluntary muscles in the body
Metabolic heat from exothermic reactions warm up the body

Question 9

2 types of cell signalling

Answer 9

Paracrine signalling
Endocrine signalling

Question 10

Paracrine signalling

Answer 10

Between cells that are close together

Question 11

Endocrine signalling

Answer 11

Hormonal communication - transported in circulatory system
Between cells that are far apart

Question 12

How does cell signalling work?

Answer 12

Stimulus received by a receptor cell
Stimulus converted to a signal (transduction)
Signal transmitted to a target cell (effector) that detect through receptors in cell membrane
Response occurs

Question 13

Cell surface membranes

Answer 13

Important in cell signalling
Signalling molecules are small for easy transport across cell membranes
Receptor molecules - proteins or glycoproteins (on/in membrane) some in the cytoplasm
Signalling molecule binds to the receptor molecule, causing specific changes in the receiving cell