Biology Revision


Biology Revision notes


Homeostasis is maintaining a stable and internal environment

  • The conditions inside your body are to be kept steady, even when the external environment changes.

Negative feedback counteracts changes

Your automatic control systems keep your internal environment stable using a mechanism called negative feedback. When the level of something gets too high or too low, your body uses negative feedback to bring it back to normal.

The Nervous System:

CNS- In vertabrates (animals with backbones) this consists of the brain and the spinal cord only.  In mammals, the CNS is connected to the body by sensory neurones and motor neurones.

Sensory neurones - They carry information as electrical impulses from the receptors to the CNS.

Motor neurones - The neurones that carry electrical impulses from the CNS to the effectors

Effectors - All your muscles and glands, which respond to nervous impulses.

The Endocrine System:

Hormones and nerves have differences

NERVES: A Very Fast action, Act for a short time, Act on a very precise area

HORMONES: A Slower action, Act…


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