homeostasis and thermoregulation

Question 1

Homeostasis is…

Answer 1

The ability to maintain a constant internal environment

Question 2

Negative feedback is…

Answer 2

A type of control in which the conditions being regulated are brought back to a set value as soon as it is detected that they have deviated from it

Question 3

Human skin comprises of:

Answer 3

• Epidermis, dermis, subcutaneous layer

- Hair, sweat gland, temperature receptors, blood vessels and fatty tissues

Question 4

What are the effectors in thermoregulation?

Answer 4

Capillary networks, hair erector muscles, sweat glands, (shivering)

Question 5

Capillary networks: Describe the vasodilation of skin arterioles under warm conditions.

Answer 5

Skin arterioles are dilated, by-pass arterioles are constricted, more blood flows to the skin surface, resulting in more loss of heat energy.

Question 6

Capillary networks: Describe the vasoconstriction of skin arterioles under cold conditions.

Answer 6

Skin arterioles are constricted, by-pass arterioles are dilated, less blood flows to the skin surface resulting in a reduced loss of heat energy.

Question 7

Hair erector muscles: Describe under warm conditions.

Answer 7

Hair erector muscles relax under warm conditions, hair lays flat, heat loss is increased.

Question 8

Hair erector muscles: Describe under cold conditions.

Answer 8

Hair erector muscles contract under cold conditions, hair stands erect, heat loss is reduced.

Question 9

Sweat glands: Describe under warm conditions.

Answer 9

Sweat glands produce more sweat under warm conditions. More evaporation of sweat from skin surface results in increased heat loss through the latent heat of vaporisation.

Question 10

Sweat glands: Describe under cold conditions.

Answer 10

Sweat glands produce less sweat under cold conditions. Less evaporation of sweat from skin surface results in reduced heat loss through the latent heat of vaporisation.

Question 11

How does shivering help under cold conditions?

Answer 11

1. Body experiences a sudden loss of heat.
2. Shivering occurs, defined as the non-coordinated contraction of skeletal muscles
3. This raises muscle heat production about 5 times above the basal rate

Question 12

What is the hypothalamus?

Answer 12

The hypothalamus acts as the thermoregulation centre

- Consists of a heat loss/heat gain centre

Question 13

How does the hypothalamus receive information and how does it communicate with the rest of the body?

Answer 13

• Neurons detect changes in the temperature of the blood flowing through the brain (internal stimuli)
• It receives information via sensory nerves from temperature-sensitive receptors located in the skin (external stimuli)
• It communicates with the rest of the body via the nervous system.