1. Controlling Body Temperature
Homeostastis
Controlling Body Temperature

2. Homeostasis Waste products that need to be removed + how CO2
Homeostasis means “controlling internal conditions”:
Waste products that need to be removed + how
CO2
Urea
Internal conditions that need controlling + how
Temperature
Ion content
Water content
Blood glucose
Produced by respiration, removed via lungs
Produced by liver breaking down amino acids, removed by kidneys and transferred to bladder
Increased by shivering, lost by sweating
Increased by eating, lost by sweating + urine
Increased by drinking, lost by sweating + urine
Increased and decreased by hormones

3. Body Temperature
Body temperature must remain constant, therefore energy gain and energy loss need to be balanced
Body extremities tend to be cooler than core
Energy is transferred from the blood to the tissues when it reaches cooler parts

4. Receptors, processing centre and effectors
Stimulus – a change in the environment
Receptor – the part of the nervous system that detects a stimulus
Processing Centre – the part of the body, usually the brain or central nervous system, that controls the response
Effector – the part of the body, e.g. a muscle or a gland, that produces a response

5. Controlling Body Temperature
Temperature receptors in the skin detect a change in temperature
Temperature receptors in the brain measure blood temperature
The brain processes this information and triggers the appropriate response

6. Controlling Body Temperature
Too high!!!
Heat needs to be lost to the environment
Sweating: evaporation from the skin requires energy and therefore causes heat to be lost from the body
Too Low!!!
Heat needs to be generated or gained
Shivering: rapid contraction and release of muscles. This requires energy from increased respiration. The heat released as a by-product warms the surrounding tissues.

7. Controlling body temperature
Body temperature is controlled by the thermo-regulatory centre in the brain. It is kept at 370C as this is the best temperature for enzymes to work in. If the body becomes too hot then blood vessels dilate and sweat glands release sweat. If the body is too hot then blood vessels constrict and muscles start to shiver.

8. Heat Stroke Uncontrolled increase in body temperature
Leads to increased sweating which dehydrates the body
Dehydration stops sweat occurring so core temperature increases further
Can result in death if body is not cooled down

9. Causes of heat stroke Exercising in very warm conditions
Very high humidity
Very hot temperatures
Dehydration

10. Symptoms of heat stroke
Confusion
Red/dry skin
Low blood pressure
Convulsions
Fainting
Rapid heartbeat

11. Treatment of heatstroke
Removing clothing
Bathing in cool water
Using a fan
Ice packs on neck, head and groin area
Raising the legs

12. Hypothermia
Exposure to very low temperatures over a long period of time
Body can’t replace heat as fast as it is lost
If left untreated can lead to death
Common cause is when core body temperature falls below 35oC

13. Symptoms of hypothermia
Grey skin colour
Amnesia
Shivering
Slurred speech
Confusion
Loss of co-ordination
Cold skin

14. Treatment of hypothermia
Raise core body temperature
Insulate the body (in particular the armpits, head and groin
Drink warm drinks, but not alcohol
DO NOT rub or massage skin as this brings blood to the surface and causes further heat loss