AP4

Question 1

Birds dont have sweat glands so what are 2 ways they cool down?

Answer 1

1) Gular flutter- rapidly flap membrane in throat, increases evaporation
2) Urohichosis- defecate on legs for evaporative cooling

Question 2

How does perspiration cool you down?

Answer 2

• Increased heat loss by evaporation
• Water has greater capacity for absorbing heat than air
• Sweat increases convection rate

Question 3

How do countercurrent heat exchanges work to keep you warm?

Answer 3

Hot arteries flow by colder veins and exchange heat so cold blood doesnt return to heart

Question 4

How does insulation from brown adipose tissue help to keep you warm?

Answer 4

• Rich in mitochonria
• Rich in blood supply, warmed blood get quickly pumped round the body
• Found in newborns and necks of adults

Question 5

How does shivering work to keep you warm?

Answer 5

• Rapid muscle contractions
• Consumes ATP
• Regeneration of ATP increases heat production

Question 6

Describe vasoconstriction

Answer 6

• Diameter of superficial blood vessel decreases

- Less heat loss through radiation, conduction and convection

Question 7

What is the thermoneutral zone?

Answer 7

• A temp range with boundaries set by the hypothalamus

- Where no energy is expended to maintain its body temp, metabolic rate is stable

Question 8

What are 4 costs and benefits of being an endotherm?

Answer 8

Benefits:

1) High activity bursts
2) Nocturnal activity
3) Can exploit colder environments
4) Can migrate over long distances

Costs:

1) Require large body size= small SA:V ratios
2) Very fast metabolic rate so require more food
3) Less energy devoted to reproduction
4) Poor colonisers of poor environments

Question 9

What are 4 costs and benefits of being an ectotherm?

Answer 9

Benefits:

1) Slow metabolic rate
2) Less energy= less food= less 02
3) Large proportion of energy put into reproduction
4) Can colonise poor environments

Costs:

1) Cant be nocturnal
2) Cant sustain high activity
3) Anaerobic- fatigue
4) Not very good predators

Question 10

What are 3 things that can affect heat storage?

Answer 10

1) SA: V ratio
2) Temp gradient
3) Specific heat conductance

Question 11

What are the 4 types of heat exchange?

Answer 11

1) Radiation- without contact- 60%
2) Conduction- with contact- 3%
3) Convection- air/fluid across body surface- 15%
4) Evaporation- water from body surface- 22%

Question 12

3 problems in the body that occur if the temperature is either too hot or too cold

Answer 12

Too Hot;

1) Proteins denature
2) Inadequate oxygen supply
3) Membrane structure alterations

Too Cold:

1) Slow metabolism
2) Inadequate oxygen supply
3) Freezing of cells