h omeostasis noadswood science, 2012. h omeostasis to know how the body controls internal conditions...
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HOMEOSTASIS
Noadswood Science, 2012
HOMEOSTASIS To know how the body controls internal conditions
Wednesday, April 19, 2023
WASTE What waste products does the human body produce?
Faeces
Urea
Carbon dioxide
It is vital that all of these materials are removed from the body to maintain its healthy functioning…
HOMEOSTASIS Homeostasis is the maintenance of a constant internal
environment
There are six different bodily levels which must all be controlled: -
Removal of CO2 (waste product)
Removal of urea (waste product)
Ion content (must remain at correct level)
Water content (must remain at correct level)
Sugar content (must remain at correct level)
Temperature (must remain at correct level)
ENZYMES Enzymes work best at 37°C, so the body’s
temperature needs to be controlled
The thermoregulatory centre within the brain monitors and controls body temperature, gathering information as nerve impulses from temperature receptors in both the brain and the skin
The brain - sensitive to the temperature of the blood flowing there
The skin - sensitive to skin temperature
CONTROL How does your body control is temperature?
TEMPERATURE If you become too hot or too cold, there are several ways in
which your temperature can be controlled
They involve sweating, shivering, skin capillaries and hairs…
SWEATING Sweating is one way to help cool the body – we sweat
more in hot conditions, so more water is lost from the body
Water must be replaced through food or drink to maintain the balance of water in the body
Ions such as sodium and chloride ions are also lost when we sweat which must be replaced through food and drink
If the body’s ion content is wrong, cells can be damaged
TEMPERATURE Too hot: -
Sweat glands in the skin release more sweat which evaporates, removing heat energy from the skin
Blood vessels leading to the skin capillaries dilate and become wider allowing more blood to flow through the skin, and more heat to be lost
Too cold: - Muscles contract rapidly (shiver), which require energy
(from respiration) with some of this energy released as heat
Blood vessels leading to the skin capillaries constrict and become narrower letting less blood flow through the skin and conserving heat in the body
TEMPERATURE Skin capillaries and hairs help regulate temperature…
The hairs on the skin also help to control body temperature – they lie flat when we are warm, and rise when we are cold
The hairs trap a layer of air above the skin, which helps to insulate the skin against heat loss
TEST Place your hands in cold water and then in warm water –
notice what happens to your blood vessels: - In warm water they dilate and become wider In cold water they constrict and become narrower
WATER Water enters the body
through food and drink as well as being a product of aerobic respiration in cells
If the amount of water in the body is wrong, cells can be damaged because too much water enters or leaves them
WATER Water and ions enter the body when you eat / drink
The water and ion content of the body must be carefully controlled to prevent damage to the cells
Water is lost through breathing, sweating and in the urine
Ions are lost through sweating and urine
If the water or ion content of the body is wrong too much water may move in / out of the cells, as well as the importance of water to help control core temperature and the sugar levels within the blood
LEAH BETTS Leah Betts died a few days after her 18th birthday after
taking an ecstasy tablet – 4 hours after taking it she collapsed into a coma from which she did not recover
Her death was caused by water intoxication - a potentially fatal disturbance in brain functions that results when the normal balance of electrolytes in the body is pushed outside of safe limits by over-consumption of water
LEAH BETTS
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