Grade 8 Science Assessment 3

Unit 2: Human Nervous System

KEY POINTS

1. Nervous system carries messages from one part of the body to another and coordinates body’s functions.

2. Central nervous system consists of brain and spinal cord.

3. Peripheral nervous system consists of a network of nerves which connects the central nervous system to all the body parts.

4. Sensory neurons carry messages from sense organs to central nervous system.

5. Motor neurons carry messages from central nervous system to muscles and glands.

6. Inter-neurons are present in brain and spinal cord. They form a link between sensory neurons and motor neurons.

7. The actions which are performed under conscious control are called voluntary actions.

8. The actions which are performed without involvement of thinking process are called involuntary actions.

9. An immediate and involuntary response to a stimulus is called reflex action.

QUESTIONS

1. Encircle the correct option
(i) The neurons which decide about the action for a certain stimulus:
(a) Sensory neuron (b) motor neuron
(c) Inter-neuron (d) all of above
(ii) The parts of a neuron which receive messages are:
(a) cell bodies (b) dendrites
(c) axons (d) nuclei
(iii) Heartbeat is controlled by:
(a) cerebrum (b) cerebellum
(c) medulla oblongata (d) hypothalamus
(iv) Many axons present side by side and enclosed in a common sheath form:
(a) nerve cell (b) nerve
(c) dendrite (d) spinal cord

(v) Sensory neurons carry messages towards:
(a) muscles (b) glands
(c) sense organs (d) brain and spinal cord

(vi) Which part of brain is involved in precise and accurate body movements?
(a) Cerebellum (b) Cerebrum
(c) Thalamus (d) Midbrain

(vii) When you have a toothache, you feel pain because:
(a) there is a cavity in your tooth
(b) tiny bits of food are left between your teeth
(c) bacteria digest the food left between your teeth and produce an acid
(d) the cavity reaches the nerves and the nerves send a message to the brain