A. THE NERVOUS SYSTEM

1. What are the two main parts of the nervous system?

- The two main parts of the central nervous system are the nervous system and the nerves.

2. What are nerves? How do they work?

- Nerves are long fibres of nervous tissue. They are connected to the central nervous system and extend to all parts of the body to contact sense organs and muscles.

B. NEURONS AND NERVOUS ACTIONS

1. What are the two types of nerve extensions in a neuron?
- The two types of nerve extensions in a neuron are called:
*Dendrites: short nerve extensions
*Axon: a longer nerve extension

2. How do the nerve signals enter a neuron? How do they leave it?

- Nerve signals enter a neuron throgh the dendrites and leave it through the axon.

3. Name the three types of neurons?

- Sensory neurons: which conect the sense organs to the nervous centres.

- Interneurons: which form very complex circuits in the nervous centres.

- Motor neurons: which connect the nervous centres to the muscles.

4. What are the two main kins of nervous actions?
- The two main kind of nervous actions are voluntary actionns and involuntary actions:
* We produce voluntary actions because we want to. The actions are complicated and many interneurons are involved.
* We produce involuntary actions without consciously wanting to. They are simpler than voluntary actions and fewer interneurons are involved.

C. THE FUNCTIONS OF THE NERVOUS CENTRES

1. Describe the cerebrum.
- The cerebrum is the most important nervous centre. It contains over 10 billion neurons and represents 80% of the volume of the brain.

Higher functions like the senses, language and mobility are located in the outer surface of the cerebrum, called the cerebral cortex.

Inside the cerebrum there are areas responsible for memory, emotions and instincts like the maternal instinct and sexuality. 

Intelligence does not have a specific area in the cerebrum.

2. What is the importance of the cerebellum?

- The cerebellum helps us to mantain our balance and produce precise and coordinated movements.

3. How does the cerebrum transmit information?
- The cerebrum receives information from the sensory nerves via the brain stem and the spinal cord. It sends instructions to the motor nerves via the same organs.