5.3 & 5.4 Homeostatic Mechanisms in Humans Flashcards
What is conduction? Give an example:
The transfer of heat energy from a hotter object to a cooler object with which it is in contact.
Eg. Touching ice
What is convection?
The transfer of heat by means of warmed air or water rising and being replaced by cooler air or water.
What is radiation?
The transfer of heat from a hot object to the atmosphere by means of infra-red waves.
What is evaporation?
When a liquid becomes a gas as a result of heat.
List the 2 sources of body heat?
- Ectotherms
- Endotherms
What do ectotherms rely on? Give an example:
Rely on the external environment for heat.
Eg. Smoke
What do endotherms produce? Give an example:
Produce heat through their metabolism.
Eg. Humans, other mammals
What is vasoconstriction?
The constriction of blood vessels in the skin which reduces heat loss from the skin as the amount of blood moving close to the exposed surface is reduced.
What is piloerection (goosebumps)?
The contraction of blood vessels and small muscles that pull the hairs on the skin upright, trapping a layer of air. In animals with thick fur, this reduces heat loss from the body.
What are 4 things we can do to stay warm?
- Seek shelter
- Decrease our surface area by curling up
- Putting on more clothes
- Moving around
What is shivering thermogenesis?
An involuntary movement of the muscles which generates large amounts of heat, stimulated by adrenaline.
What is non-shivering thermogenesis?
Increased cellular activity in brown fat which is a tissue specialised for heat production.
What is the Thyrotropin-releasing hormone?
Is secreted by the hypothalamus and acts on the anterior pituitary to secrete the Thyroid stimulating hormone.
What is the Thyrotropin-stimulating hormone?
Acts on the thyroid gland to release T3 and T4 hormones which increase cellular respiration
Describe the process of sweating:
- Sweat is produced by sweat glands
- Body heat is used to evaporate sweat from the skin
- Changing state from liquid gas uses heat energy and thus cools the surface of the skin