INTEGRATED SCIENCE

Subject: Integrated Science

Grade: 9 (1&2)

Topic: Sensitivity and Coordination

Sub-Topic: The Nervous System

Objectives: At the end of the lesson students should be able to:

1. Explain the purpose of the nervous system.2. List and explain the three main structures of the nervous system. 3. State the three main regions of the brain and their function.4. Explain how the nervous system works

Grade 9 (1&2)

INTEGRATED SCIENCE

THE NERVOUS SYSTEM

The nervous system enables us to respond quickly and immediately to stimuli (changes) in our environment. When a stimulus is received, it is transmitted very quickly from the point of detection to the point where the body can make sense of the information and respond appropriately. The messages are transmitted through the body along nerve fibres as electrical impulses. The nervous system consist of three main structures the brain, spinal cord and peripheral nerves.

The peripheral nerves carry messages (impulses) between the central nervous system (CNS) and the rest of the body.

Figure showing the structures of the nervous system.

Grade 9 (1&2)

INTEGRATED SCIENCE

THE CENTRAL NERVOUS SYSTEM

The central nervous system (CNS) is made up of the brain and the spinal cord.

THE BRAIN

The brain is located in the head and it is protected by the skull. It is made up of millions of nerves cells or neurones. The brain consist of three main regions, the cerebrum or cerebral hemispheres, the cerebellum and the medulla oblongata.

Figure showing the vertical section though the human brain

1. CEREBRUM OR CEREBRAL HEMISPHERE

The cerebrum receives and analyses all the impulses from the sense organs and it sends out the responses so that we react to the sensory input. The cerebrum is also where all the higher mental activities such as memory and abstract thought take place. It is this part of the brain that allows us to modify our behaviour so that we can do the right things in response to whatever out sense organ tell us about our surroundings.

2. CEREBELLUM

The cerebellum lies beneath the cerebral hemispheres. This part of the brain is concerned with our muscular coordination and with balance. We use the cerebellum when we are involved in any form of movement, such as riding a bicycle, running and walking, playing a musical instrument, writing, sewing etc.

Grade 9 (1&2)

INTEGRATED SCIENCE

Figure showing sensory and motor areas in the cerebrum

3. MEDULLA OBLONGATA

The medulla oblongata is the hindmost part of the brain. It is concerned with activities that control our internal systems, such as regulation of heartbeat and breathing, movement of food through the digestive system and regulation of body temperature. These activities carried out unconsciously, without our control.

THE SPINAL CORD

The spinal cord is an extension from the hind end of the brain. It goes all the way down the back of the body to a point just above the hips. The bones of the vertebral column enclose and protect the spinal cord. Nerves arise from the spinal cord and go from it to all parts of the body.

NEURONS AND NERVES

Grade 9 (1&2)

INTEGRATED SCIENCE

Figure showing a bundle of neurones which makes up the nerve

Nerves are made up of bundles of nerve cells called neurons.

Sensory neurone which takes information from the receptors cells found in the sense organs to the spinal cord and the brain.

Relay neurone which carries messages between the sensory and the motor neurones. Motor neurone takes messages out from the brain and spinal cord to the muscles and

glands in the body. The muscles and glands are called effectors.

Figure showing three types of neurones

Grade 9 (1&2)

INTEGRATED SCIENCE

HOW THE NERVOUS SYSTEM WORKS

Click the link below to watch video on how the nervous system works.

https://www.youtube.com/watch?v=1uG0AEnoLDU

Grade 9 (1&2)

INTEGRATED SCIENCEACTIVITY

Grade 9 (1&2)

INTEGRATED SCIENCE

Grade 9 (1&2)