Homeostasis - Module 5

Question 1

Define homeostasis

Answer 1

The maintenance of a stable equilibrium of conditions inside the body

Question 2

What is a negative feedback system? give an example

Answer 2

When a system acts to reverse a change back to ideal conditions
E.g blood glucose levels

Question 3

What is a positive feedback system? Give an example

Answer 3

When a system acts to reinforce a change and increase a response
E.g blood clotting

Question 4

What is thermoregulation?

Answer 4

Maintenance of stable core body temperature to maintain optimum enzyme activity

Question 5

What 5 factors control thermoregulation?

Answer 5

1. Exothermic chemical reactions
2. Convection
3. Radiation
4. Latent heat of evaporation
5. Conduction

Question 6

How do ectotherms control internal temperature?

Answer 6

Using their environment

Question 7

Why don’t ectotherms living in water need to thermoregulate?

Answer 7

High specific heat capacity of water means temperature remains constant

Question 8

Name 3 behavioural responses of ectotherms to increase body temperature, how do these change to decrease body temperature?

Answer 8

1. Basking in sun
2. Orientation to maximise surface area in the sun
3. Pressing bodies against the ground

To decrease body temperature, reverse!

Question 9

Describe 2 physiological responses of ectotherms to regulate body temeprature

Answer 9

1. Colour - in colder environments dark colours to absorb heat vice versa with light colours in warm environments
2. Alter heart rate to change metabolism

Question 10

Who has the higher metabolism; endotherms or ectotherms?

Answer 10

Endotherms

Question 11

How do endotherms detect a change in temperature?

Answer 11

1. Peripheral receptors in skin detect surface temperature
2. Hypothalamus detects changing blood temperature

Question 12

Describe 5 behavioural responses from endotherms to maintain temeprature

Answer 12

1. Burrowing
2. Basking in sun
3. Pressing against surfaces
4. Hibernation
5. Wallowing in water

Question 13

Describe behavioural responses specifically of humans to maintain body temeprature

Answer 13

1. Clothing
2. Houses
3. Heating sources

Question 14

Describe the physiological mechanisms endotherms use to cool down

Answer 14

1. Vasodilation
2. Sweating/ dogs panting, this is evaporation
3. Hairs lie flat, this reduces the insulation effect of body hair

Question 15

What is vasodilation?

Answer 15

When arterioles dilate forcing blood into capillaries close to the surface of the skin to release heat by radiation
Opposite occurs for vasoconstriction

Question 16

Describe the physiological responses of endotherms to warm up

Answer 16

1. Vasoconstriction
2. Decreased sweating
3. Hairs raise - to induce insulating effect
4. Shivering

Question 17

What are 3 anatomical adaptations endotherms in cold environments have?

Answer 17

1. Blubber
2. Minimal SA:V ration
3. Hibernation and making fat stores

Question 18

How is thermoregulation controlled in endotherms?

Answer 18

Using negative feedback systems in the hypothalamus
- heat loss centre
- heat gain centre