4.5.2.4 Control of Body Temperature Flashcards
1
Q
What is the optimum temperature for enzymes in the body?
A
- 37°C
2
Q
How is body temperature controlled (thermoregulation)
A
- thermoregulatory centre
- in the hypothalamus
3
Q
What does the thermoregulatory centre contain?
A
- receptors sensitive to temperature of blood (so does skin, which send impulses back to centre)
4
Q
What happens in the body when it is too cold?
A
- skeletal muscles contract rapidly and we shiver (contractions need energy from respiration and some is released as heat)
- blood vessels become narrower (constrict) which allows less blood to flow (called vasoconstriction)
5
Q
What happens in the body when it is too hot?
A
- sweat glands release more sweat which evaporates, transfers heat energy to environment
- blood vessels become wider (dilate) which allows more blood to flow (called vasodilation)
6
Q
What else helps the body control temperature?
A
- hairs on skin
7
Q
What do the hairs on the skin do when it is too cold?
A
- rise due to nerve impulses being sent to hair erector muscles which contract
- trap a layer of insulating air next to skin
8
Q
What is the control of body temperature an example of?
A
- negative feedback mechanism
9
Q
What does the negative feedback mechanism regulate?
A
- shivering (rapid muscle contractions release heat)
- sweating (evaporation of water in sweat causing cooling)
- blood flowing in skin capillaries
10
Q
What happens in vasoconstriction?
A
- arteriole becomes constricted
- shunt vessel dilates
- little heat lost
11
Q
What happens in vasodilation?
A
- arteriole becomes dilated
- shunt vessel constricts
- much heat lost by radiation
