Chapte r 10 – Temperature change

1. Chapter 10 – Temperature change

4. Screen clipping taken: 20/03/2013, 9:13 AM

5. Screen clipping taken: 20/03/2013, 9:13 AM

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7. Screen clipping taken: 20/03/2013, 9:15 AM Hormones – chemical regulators • Endocrine system • Produces hormones • Endocrine glands • Transported via bloodstream, slower than nervous system signals

8. Screen clipping taken: 20/03/2013, 9:27 AM • Two receptors that detect temp change • Hot/Cold = detect-> increase rate of discharge of electrical info along ______ neurons. • Impulses -> hypothamalus • Temp receptors all over the body. Even in H.

9. Screen clipping taken: 20/03/2013, 9:28 AM • An example of homeostasis • Mammals need more energy – compare snake diet to human diet

10. How our bodies lose heat Water evaporates from the lung and skin surface. Heat is required for this to occur. Conduction into air occurs when the temperature of the air is less than that of the body. Heat loss this way stops if the temperature outside is greater. Heat in the form of infra-red heat rays that radiates from the body in all directions If the air around the body is moving then convection carries heat away from the body causing greater heat loss Conduction from direct contact

11. How we can heat / reduce heat loss

12. Metabolism

13. Piloerection The erection of hair or fur results in a layer of air being trapped that acts as an insulation layer between the skin and the external environment. Sympathetic motor neurons bring impulses from the hypothalamus to the muscle at the base of each hair causing them to contract and the hair to become erect

14. Constriction of blood flow Neurons in the hypothalamus send the impulses via the sympathetic nervous system to the peripheral blood vessels in the skin The impulses causes arterioles to constrict, reducing the surface area across which heat can be lost and reduces the amount of blood flow close to the skin.

15. Shivering The alternate contraction and relaxation of small muscle groups. The hypothalamus activates somatic motor neurons that controls muscles in the upper limbs and body trunk. All the energy of a muscle contraction is converted to heat energy. This can’t be kept up for long due to muscle tissue losing energy reserves.

16. Heat Sources

17. Surviving the Heat – structural, behavioural or physiological adaptations • Spinifex hopping mouse • Behavioural • Avoiding the sun, being noctural • Physiological • Specialized kidneys to absorb water • Concentrated urine • Structural • Being smaller – release more heat • Snake • Behavioural • Basking in the sun • Flattened body to increase surface area to volume • Physiological • Increase of blood flow to skin to warm blood faster

18. Surviving the Cold • Antifreeze – glycerol, amino acids, proteins • Keep their body liquids from freezing • Migration – birds • Burrowing – frogs and toads • Mammals – insulating layers • Bears?

19. Surviving in Water • Aquatic Mammals such as elephant seals, whales • Higher concentration of red blood cells to increase oxygen carrying capacity • Insulating layer of fat. Up to 50cm thick Counter-current exchange system • Fine network of vasular tissue within fins, tails, outer appendages • Outer vessels constrict when cold • Outgoing artery is paired with incoming vein. • Warmed blood from artery heats up cold blood from vein • Appendages are usually small, to reduce SA.V ratio.