AQA GCSE Biology Homeostasis

Some quick key points for homeostasis. Made when I had a test the next day, so the notes are very concise and memorable - for me.

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  • Created by: fmPerkins
  • Created on: 29-04-10 14:59
Preview of AQA GCSE Biology Homeostasis

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HOMEOSTASIS REVISION
What does homeostasis mean?
Homeostasis means the maintenance of constant internal environment.
Why is this important?
It is important because our external environment is constantly changing.
When we refer to 'internal' environment we mean the conditions surrounding the
millions of cells that make up our bodies.
When we are too hot, we end up fanning ourselves, sweating, and turning red.
Dogs loll their tongues out; we pant. {We also lose energy and our enzymes
denature}
When we are too cold, we end up trying to keep ourselves warm (by curling up,
putting on more layers of clothing etc.), shivering, and producing goose bumps.
We also turn paler or our skin turn bluer. {Our reactions also slow down.}
The hypothalamus is a part of the brain that detects the temperature of the
blood. If the blood is too hot, it sends nervous messages to different parts of
the body switching on cooling mechanisms. If the blood is too cold, the
opposite occurs.
Give definitions of:
-sweating: evaporation of water from the skin removes heat energy from the body.
-vasodilatation: more blood flows through capillaries close to the surface of the skin.
This means that more heat energy is lost through radiation.
-panting: evaporation of water from the tongue and respiratory system takes heat
energy away from the body
-hair standing on end: hair erector muscles contract causing hairs to stand on end.
This traps a layer of air. Air is a good insulator so less heat is lost from the body.
-shivering: random contraction and relaxation of muscles increases the rate of
respiration. Respiration releases heat energy which warms the body up.
-vasoconstriction: less blood flows through capillaries near the surface of the skin.
This reduces the amount of heat lost by radiation.
-thermoregulation: maintaining a constant body temperature.

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