1. Temperature control

2. Metabolic reactions
Inside the bodies of living organisms chemical reactions occur
Most of these chemical reactions happen at slightly higher temperatures and some are sensitive to heat…the right temperature is important

3. Poikilothermic animals and plants
Control/regulate body temperature based on their activity

5. Dealing with heat loss Burrow into ground Hibernation
Snails seal off the shell with them inside
Aestivation …state of dormancy/inactive eg lung fish, water bear

7. Plants Desert plants have long roots to get water
Remain as seeds until rain comes

8. Homeothermic animals Control body temperature to it constant
Enzymes that assist in chemical reactions work efficiently
Organism can continue to function in hot or cold temperatures
The energy to keep warm though comes from respiration…organisms must eat more than Poikilothermic animals

9. The human skin Two layers:
Top – epidemis… protects the the deeper layers. It is made as new cells are formed in the Malpighian layer (mitosis) and they die as they move towards the surface of the skin (cornified layer – hard and waterproof). The cells fill with Keratin ( a protein) as they move up
Some cells here may also contain Melanin – absorbs harmful rays from the sun
Epidermis may fold inward at points – form hair follicles ( hair made of keratin) which have a sebaceous gland on the side (makes an oily liquid called sebum to keep hair soft and supple)
Lower – dermis, made of connective tissue that contains elastic fibres
it contains sweat glands, blood vessels, nerve endings
layer of fat to provide insulation and food reserve

11. Hypothalamus
Part of the brain that sends messages to body regulate temperature

12. Temperature too low Message sent by Hypothalamus
For fat respiration to increase
Heat warms up the blood to transfer it around the body
(Brown fat produces more heat…temperature increases after eating)
Muscles contract and relax….shivering
Hair stands up – erector muscles contract to pull hairs up to trap heat
Blood system conserves heat – blood capillaries near skin become narrower/constricted …skin looks pale

14. When too hot Respirations slows down Hair lies flat
Blood loses heat – blood vessel becomes dilated …skin looks flushed
Sweating – sweat secreted by sweat glands onto skin, water evaporates taking heat with it

17. Negative feedback
Recall Homeostasis is the body’s way of maintaining normal/stable environment and conditions
Response to stimulus leads to change (in response to the receptor) the negative feedback is when the system cancels out the effect of the original stimulus