5.1.4 Thermoregulation Flashcards
1
Q
A
2
Q
How do endotherms regulate body temperature?
A
- Hypothalamus initiates homeostatic responses
- Vasodilation
- Sweating
- Flattening / erection of hairs
- Boosting metabolic rate
- Shivering
3
Q
How does vasodilation work?
A
- Increasing heat loss
- Arterioles relax causing arterioles near skin to dilate
- More blood flows through capillaries
- More heat lost via radiation to environment
4
Q
How does sweating work?
A
- Sweat glands secrete sweat
- Cools skin by evaporation because energy is used from body to evaporate the liquid water into gas
- Which is a cooling mechanism
5
Q
How does flattening of hairs work?
A
- Hair erector muscles relax
- Hairs lie flat
- Stops insulating layer of air forming at skin
- Allows air to circulate over skin and heat to leave by radiation
6
Q
What is vasoconstriction?
A
- Arteriole walls contract
- Arterioles near skin constrict allowing less blood to flow through capillaries
- So less heat lost via radiation
7
Q
How does boosting metabolic rate increase temperature of body?
A
- Metabolic reactions are exothermic so produce heat that warms body
- Thyroxine increases basal metabolic rate
8
Q
How do ectotherms regulate temperature?
A
- Seek sun, bask in these warm locations
- To cool down they seek water and shade
- Endotherms need more energy because their metabolic rate is greater to keep warm
- Ectotherms survive better in food limited environments, although cannot easily colonise habitats that are too warm or cold
- Aquatic ectotherms don’t need to worry because specific heat capacity of water is very high so environment remains at a fairly constant temperature
