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What you need to know
Reflections and Exam tips
Homeostasis is the maintanance of a constant internal environment. This environment includes tissue fluid, blood and cytoplasm.
Homeostasis comes from 2 words:
What things need to be kept constant?
Why should they be kept constant
- if enzymes are affected, they may be denatured, reactions will stop, that's a disaster.
Principles of Homeostasis
The skin and temperature control
The skin is the main organ which is involved in temperature control (Thermoregulation).
There are 2 locations for receptor which detect changes to body temperature:
1. Thermoregulatory centre: Located in the hypothalamus in the base of the brain, has receptors which detect changes in the temperature of the blood passing through.
They mainly detect changes in the core body temperature: This is the temperature of internal vital organs like the brain, heart, liver. The core body temperature is strictly controlled and cannot vary much.
2. Skin: Has receptors which detect skin surface temperature. This can vary a bit.
Skin structure diagram comes here
Some key terms
Hypothermia (hypo=below; thermia= temperature)- when the core body temperature goes below the Norm.
Hyperthermia (hyper= above; thermia= temperature)- when the core body temperature goes above the Norm.
What happens when the core body temperature goes up (Hyperthermia)?
-Usually this happens during exercise when respiring muscles are producing excess heat energy.
As sweating results in loss of water and salts, more water has to be taken in on a hot day to replace it.
The kidneys also respond by reducing the amount of urine produced i.e. water is conserved.= Small volumes of dark coloured urine on a hot day.
What happens when the core body temperature goes down (Hypothermia)?
When we are cold:
Since sweating (water loss) is reduced on a cold day, the kidneys respond by producing large volumes of watery urine.