Cooling down and warming up

Question 1

What is vasodilation?

Answer 1

• arterioles near the surface of the skin dilate when temp rises
• the vessels that provide a direct connection between the arterioles and the venules (the arteriovenous shunt vessels) constrict
• this forces blood through the capillary networks close to the surface of the skin

Question 2

How does vasodilation cool down the body?

Answer 2

• the skin flushes
• and cools as a result of increases radiation
• if the skin is pressed against cool surfaces, then the cooling results from conduction

Question 3

How does sweatt cause cooling down?

Answer 3

• sweat glands across the body
• as the sweat evaporates, heat is lost, cooling the blood below the surface

Question 4

What do some animals do that can’t sweat?

Answer 4

• pant - losing heat as the water evaporates
• cats and kangaroos lick legs

Question 5

Whats is vasoconstriction? what effect does it have?

Answer 5

• the arterioles near the surface of the skin constrict
• the arteriovenous shunt vessels dilate
• very little blood flow through the capillary networks close to the surface of the skin
• the skin looks pale. very little radiation takes place
• the warm blood is kept below the surface

Question 6

How are hairs changed in cold condition?

Answer 6

• raising the body hair or feather
• erector pili in the muscles in the skin contract, pulling the hair or feather of the animal erect
• this traps an insulationg layer of air and so reduced cooling through the skin

Question 7

What is shivering?

Answer 7

• rapid, involuntary contracting and relaxing of the large voluntary muscles in the body

Question 8

How does shivering work?

Answer 8

• the metabolic heat from the exothermic reactions warm up the body instead of moving and is an effective way of raising core temperauter