Homeostasis in Humans Life Sciences Grade 12 Questions and Answers. The tendency to maintain a stable, relatively constant internal environment is called homeostasis. The body maintains homeostasis for many factors in addition to temperature. For instance, the concentration of various ions in your blood must be kept steady, along with pH and the concentration of glucose.
HOMEOSTASIS IN HUMANS – LIFE SCIENCES QUESTIONS AND ANSWERS
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]