Site author Richard Steane

The BioTopics website gives access to interactive resource material, developed to support the learning and teaching of Biology at a variety of levels.

THE BRAIN and NERVOUS SYSTEM

Many more brains /heads and
other anatomical models
available online
via this link

The brain acts as a command and control centre for the body's voluntary actions, as well as the main co-ordinating centre for automatic actions, but some of these functions are also carried out by other parts of the body.

The brain, which is protected by the skull , is connected to the spinal cord, which is protected by the backbone. The brain and spinal cord together make up the central nervous system (C.N.S.).

From this, a number of nerves branch out, which are connected to the rest of the body. These are bundles of nerve fibres .

The nervous system is composed of special cells which carry information in the form of impulses . In shape, nerve cells (also called neurons) are different from other body cells because they can be long and thin .

Because these impulses pass in one direction only, there are different types of nerve cells carrying information in from sense organs (sensory nerve cells), and relaying commands out from the central nervous system (motor nerve cells).

Name some sense organs which may provide an input to the central nervous system.

> eye > ear > nose

> tongue > skin

Name some types of organ which may be used to produce an output from the central nervous system.

> muscle > gland

Stimulus and Response

As in other animals, the nervous system of Man is used in order to produce a response, i.e. an appropriate action in certain situations, signalled by a stimulus received by a sense organ. If the response is done without the need for thinking (sometimes to protect the body in an emergency), it is called a reflex action, but if it requires thought, it is called a voluntary action.

Parts of the brain

The brain is composed of 3 main parts.

Colour-code the diagram below to show them as follows:
Use the mouse to label the three main areas of the brain.

1) The largest part of the brain is called the cerebrum, and it is divided into 2 halves called cerebral hemispheres.

In the sensory areas, impulses pass in from the sense organs, and are registered as sensations or feelings .

Most of the cerebrum is made up of association areas which are responsible for memory and thought . The inputs from the sense organs are processed and as a result an action may, or may not, be initiated.

From the motor areas, impulses pass out, mostly to the muscles.

2) The cerebellum controls muscles and balance, during activities such as:
>walking, running,

> cycling, etc.

3) The medulla (oblongata) controls many bodily functions that go on "automatically", such as:
>heart beat

>breathing

>blood pressure

Brain and head models available online

Many other anatomical models and charts available by following this link.

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