The Nervous System

good revision notes

HideShow resource information
Preview of The Nervous System

First 128 words of the document:

Science Revision notes
The nervous system
The nervous system allows the body to respond to changes in the environment. This is a
process usually coordinated by the brain. Reflex actions are extra-rapid responses to
stimuli, and this process also involves the nervous system, but bypasses the brain.
Receptors and effectors
Receptors
Receptors are groups of specialised cells. They can detect changes in the environment,
which are called stimuli, and turn them into electrical impulses. Receptors are often
located in the sense organs, such as the ear, eye and skin. Each organ has receptors
sensitive to particular kinds of stimulus.
Receptors
sense organs receptors sensitive to
touch, pressure, pain and
temperature
Skin

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

Tongue
chemicals in the air
Nose
light
Eyes…read more

Page 3

Preview of page 3

Here's a taster:

Ears
The central nervous system - CNS - in humans consists of the brain and spinal cord. When a
receptor is stimulated, it sends a signal along the nerve cells - neurones - to the brain. The
brain then co-ordinates the response.
Effectors
An effector is any part of the body that produces the response.…read more

Page 4

Preview of page 4

Here's a taster:

A motor neurone
Synapses
Where two neurones meet, there is a tiny gap called a synapse. Signals cross this gap
using chemicals. One neurone releases the chemical into the gap. The chemical diffuses
across the gap and makes the next neurone transmit an electrical signal.
Reflex actions
When a receptor is stimulated, it sends a signal to the central nervous system, where the
brain co-ordinates the response. But sometimes a very quick response is needed, one that
does not need the involvement of the brain.…read more

Page 5

Preview of page 5

Here's a taster:

In dim light:
Radial muscles of the iris contract.
Circular muscles of the iris relax.
More light enters the eye through the dilated pupil.…read more

Comments

No comments have yet been made

Similar Biology resources:

See all Biology resources »See all resources »