Activity 1

Questions
1. Name the heat regulation centre in the brain. (1)
2. What happens to the blood vessels of the skin on a cold day? (1)
3. Describe how the state of the blood vessels mentioned in question 2 decreases heat loss. (4)
4. What happens to blood vessels of the skin on a hot day? (1)
5. Describe how the state of the blood vessels mentioned in question 4 increases heat loss. (4) [11]

Answers to activity 1
1. Hypothalamus✔ (1)
2. Blood vessels constrict✔/vasoconstriction (1)
3.

• Less blood flows to the surface of the skin.✔
• Less heat is lost from the surface of the skin.✔
• Less blood flows to the sweat glands.✔
• Sweat glands release less sweat.✔
• Less evaporation of sweat.✔
• Less cooling of the skin on a cold day.✔ (any 4)(4)

4. Blood vessels dilate✔/vasodilation (1)
5.

• More blood flows to the surface of the skin.✔
• More heat is lost from the surface of the skin.✔
• More blood flows to the sweat glands.✔
• Sweat glands release more sweat.✔
• Evaporation of sweat✔
• cools the skin on a hot day.✔ (any 4)(4) [11]