Homeostasis and the liver
Homeostasis
- Homeostasis means keeping the conditions inside the body steady, even when outside changes.
- Steady temperature, water and glucose let enzymes and cells work properly.
- Almost all homeostasis follows the same plan — and corrects itself.
Practice
Homeostasis is:
Homeostasis keeps internal conditions (temperature, water, glucose) steady so cells work well.
The principle
- A change (a stimulus) is detected by a receptor.
- A coordination system carries the message — the nervous system (nerve signals) or the endocrine system (hormones).
- An effector (a muscle or gland) makes a response that corrects the change.
- This is negative feedback: a change away from normal triggers a response that pushes it back to normal.
Practice
Put the homeostatic control steps in order.
A stimulus is detected by a receptor, the message is coordinated, and an effector responds to correct it.
Practice
Negative feedback works by:
Negative feedback opposes the change, returning the condition toward its normal level.
The liver and urea
- The body cannot store extra amino acids.
- In the liver, deamination removes the amino group from excess amino acids.
- This is turned into urea, carried in the blood to the kidneys to be removed.
Practice
Excess amino acids are dealt with in the liver by:
Deamination removes the amino group from surplus amino acids; the product is converted to urea for excretion.
You've got it
Key idea
- homeostasis = keeping internal conditions steady so enzymes/cells work
- the loop: stimulus → receptor → coordination (nerve/hormone) → effector → response
- negative feedback pushes any change back towards normal
- the liver removes excess amino acids by deamination → urea → kidneys