Thermoregulation

Question 1

Endotherms:

Answer 1

Use internally generated heat to maintain a steady internal body temperature, regardless of environment.

Question 2

Ectotherms:

Answer 2

Dependent on external heart sources and sinks to manage body temperature. Their body temperature will fluctuate dependent of the environment.

Question 3

What is the primary type of method ectotherms use to manage their body temperature:

Answer 3

Behavioural strategies:

Question 4

What are the different processes in which an organism gains heat:

Answer 4

Waste heat from respiration, Conduction from surroundings, Convection from surroundings, radiation from surrounding.

Question 5

What are the different processes in which an organism loses heat:

Answer 5

Evaporation of water, conduction to surroundings, convection to surroundings, radiation to surroundings.

Question 6

Example of an ectotherm using a behavioural strategy to increase their body temperature via conduction:

Answer 6

Pressing their body against hot stones to increase body temperature by conduction.

Question 7

Example of an ectotherm using a behavioural strategy to increase their body temperature via radiation:

Answer 7

Basking in the sun to orient their body to maximise the surface area exposed to the sun.

Question 8

Example of an ectotherm using a behavioural strategy to decrease their body temperature:

Answer 8

Minimising movement to reduce the generation of metabolic heat.

Question 9

Example of an ectotherm using a physiological strategy to increases their body temperature via radiation:

Answer 9

Colour of reptiles. Reptiles with darker colours absorb more heat. However this adaptation might not be too prominent due to the selective advantage of camouflage.

Question 10

Thermoregulation is an example of what kind of response?

Answer 10

a negative feedback response.

Question 11

Heat Loss Centre

Answer 11

• Activated when the temperature of blood flowing through the hypothalamus increases.
• Sends impulses to autonomic motor neurones to effectors in the skin/muscles to lower the core temperature.

Question 12

Heat Gain Centre

Answer 12

• Activate when the temperature of the blood flowing through the hypothalamus decreases.
• Sends impulses via autonomic motor neurones in skin/muscles to increase the core temperature.

Question 13

Active Techniques of thermal regulation:

Answer 13

Internal exohermic metabolic activities to keep warm - e.g respiration. Physiological responces to keep cool.

Question 14

Passive techniques of thermal regulation:

Answer 14

Behavioural:

• basking
• wallowing
• huddling
• digging burrows
• hibernation
• Aestivation
• Adding clothes.

Question 15

Increasing Heat Prodution (thermogenesis)

Answer 15

Endotherms - various ways of incresing metabolic heat production.
Deliberate movements- shivering and rubbing hands.

Question 16

What is brown fat?

Answer 16

Fat tissue containing more capillaries, mitochondria and special proteins that directly release energy as heat, smaller fat droplets -> with less channeled into the formation of ATP.

Question 17

Why does brown tissue have more mitochondria?

Answer 17

To have a greater ability to release energy through metabolism.

Question 18

Explain how white fur is a good adaptation for endotherms in artic environments:

Answer 18

White fur reflects infrared radiation produced by the body back to the body. The white fur also provides camouflage.

Question 19

Vasodilation:

Answer 19

Arterioles near the skin surface dilate and the arteriovenous shunt constricts, forcing blood through the capillaries closer to the skin surface to increase heat loss by radiation or conduction (when pressed against a cold object.)

Question 20

Vasoconstriction:

Answer 20

Arterioles near the skin surface constrict and the shunt vessels dilates, diverting blood flow away from the skin surface, to reduce heat loss by radiation.

Question 21

Insulation - skin hairs/ feathers:

Answer 21

Contraction of erector pili at the base of hairs, causes hairs to erect. This traps a layer of air, by reducing air movement which provides a layer of insulation, reducing heat loss.

Question 22

Why is the high sensitivity of thermoreceptors important?

Answer 22

It allows for the hypothalamus to pre-empt changes and more effectively manage the core temperature.

Question 23

Where are thermal receptors located?

Answer 23

They’re located in the hypothalamus and in peripheral epithelial tissue (skin).

Question 24

Why is maintaining a stable temperature important?

Answer 24

To maximise the rate of metabolic reactions by providing them with kinetic energy and providing the optimum temperatures for enzymes.