Biology Homeostasis - 21st century science

Homeostasis - means keeping things constant in the body

The body tries to keep internal conditions constant. Things the body keeps constant:

• Temperature
• Water level
• Salt Level
• Glucose level

If theres a fall in temp this process occurs:

1. Ideal body temp of 37'C

2. Fall in temp detected by a receptor in the body

3. A co-ordinator in the body (ie. the brain) coordinates

4. part of the body called an effector produces a response

5. body temp is brought back to normal

And if there is a rise in the body temperature then the opposite occurs.

What are enzymes made from?

- Large protein molecules, which are made up of long chains of amino acids

Why are enzymes important in the Human body?

- At 37'C chemical reactions would happen too slowly to keep us alive

- Enzymes give us the rate of reaction we need

- Its not possible to live without enzymes

Why does the shape of an enzyme important to the way it works?

The molecules must fit exactly into a part of the enzyme...called an Active Site:

- An enzyme has anActive Site

- The reaction takes place in the Active Site

- Only the correct molecule fits into the Active Site

- The product leaces the Active Site. The enzyme can be used again.

How temperature and PH effects enzymes?

At low temperatures, the enzyme reactions get faster if the temp is increased. Abovea certain temp the reaction stops; due to the enzymes being proteins. Highertempschange the enzymes shape so it no longer works - it gets denatured

The shape of an enzyme's active site is also affected by PH. Every enzyme has an optimum PH at which it works best.

This is how the skin controls the rate of temp loss:

• Your skin hair stands up
• Elevator muscles contract to raise hairs
• Blood vessels in the skin narrow
• Skin looks pale
• Shivering occurs
• Sweat glands not active

This is how the skin controls the rate of temp gain:

• Your skin hair lies flat
• Elevator muscles relax to lowerhairs
• Blood vessels in the skin widen
• Skin looks red
• No shivering occurs
• Sweat glandsactive, and sweat is produced

If you've run a marathon on a hot day, your body temp at the end of the race is going to be above 37'C. So you need to loose heat quickly to get your body temp back to 37'C.

Your blood vessels in your skin become WIDER, so that MORE blood flows near to your skin surface. This meansyour skin looks RED in colour. This helps you toloose heat FASTER by convection and radiation.The hairs on your skin are LYING FLAT to INCREASE heat loss. Your sweat glands have released sweat onto the skin surface. As sweat evaporates it TAKES heat from your body and so cools you down.

If your body temp is below 37'C then you need to gain heat quickly to get your body temp back to 37'C so the opposite occurs.