#133 Homeostasis
Homeostasis is the maintenance of a constant internal environment, which is vital for an organism to stay healthy. Fluctuations in temperature, water levels and nutrient concentrations … could lead to death.
Temperature regulation is one homeostatic function. Mammals and birds are warm-blooded – they maintain a constant body temperature despite external environment changes.
Human maintain a body temperature of 37 degrees C – we have mechanisms to lose heat when we get too hot, and ways of retaining heat when we get too cold.
Temperature regulation is one homeostatic function. Mammals and birds are warm-blooded – they maintain a constant body temperature despite external environment changes.
Human maintain a body temperature of 37 degrees C – we have mechanisms to lose heat when we get too hot, and ways of retaining heat when we get too cold.
The hypothalamus coordinates temperature control
The hypothalamus (part of brain) acts like a thermostat. It detects to of the blood running through it.
If temperature > or < 37 degrees C, it sends electrical impulses, along nerves, to parts of the body which function in regulating body to.
The hypothalamus (part of brain) acts like a thermostat. It detects to of the blood running through it.
If temperature > or < 37 degrees C, it sends electrical impulses, along nerves, to parts of the body which function in regulating body to.
When you are cold, body produces and saves heat
- shivering: muscles contract and relax spontaneously ---> produces heat ---> warms blood
- vasoconstriction: arterioles near skin become narrower so little blood can flow through them (the blood flows through the deep-lying capillaries instead)---> conserve heat
- metabolism may increase ---> release energy
- hair stands up. In human, it just produces ‘goose pimples’. But in hair animals (cat), it acts as an insulator: trap a thicker layer of warm air next to the skin, prevent skin from loosing more warmth.
- shivering: muscles contract and relax spontaneously ---> produces heat ---> warms blood
- vasoconstriction: arterioles near skin become narrower so little blood can flow through them (the blood flows through the deep-lying capillaries instead)---> conserve heat
- metabolism may increase ---> release energy
- hair stands up. In human, it just produces ‘goose pimples’. But in hair animals (cat), it acts as an insulator: trap a thicker layer of warm air next to the skin, prevent skin from loosing more warmth.
When you are hot, the body loses more heat:
- sweating: droplets of sweat evaporate, cooling the body
- vasodilation: more blood flows near skin surface ---> lose heat
- hair lies flat.
Common misconceptions
Remember that the process of vasodilatation and vasoconstriction happen only in arterioles – they do not happen in capillaries or veins. When writing about the process, make sure you refer to arterioles.
Remember that the process of vasodilatation and vasoconstriction happen only in arterioles – they do not happen in capillaries or veins. When writing about the process, make sure you refer to arterioles.