The nervous system

1. The nervous system

2. What is the nervous system made up of? • The brain • The spinal cord • The nerves (neurones)

3. the brain and the spinal cord.

5. Response Stimulus Receptor Effector Motor neurone Sensory neurone Central Nervous system How does our nervous system work then?

6. Reacting without thinking • Sometimes a stimulus requires an immediate response. This is called a reflex action. It is an involuntary response and is done without thinking. They are very important in preventing injury to ourselves.

7. A reflex arcThe nerve pathway taken in a reflex action is called a reflex arc. The nervous message goes to the spinal cord, then a message passes from the spinal cord directly to an effector to give an immediate response.

8. Reflex arc Sensory neuron stimulus Motor neuron

9. A reflex arc

10. The knee jerk reflex action Sometimes called a relay or Connector neurone

11. Another reflex action

12. Summary: • 1. Grey matter is made up of nerve cell bodies, and white matter is made up of fibers. • 2. Grey matter occupies 40 percent of the brain, while white matter fills 60 percent of the brain. • 3. Processing is concluded in the grey matter, while white matter allows communication to and from grey matter areas, and between the grey matter and the other parts of the body. • 4. Grey matter has no myelin sheath, while white matter is myelinated. • 5.The real processing is concluded in the grey matter. It fills about 40 percent of the whole brain in humans, and consumes 94 percent of oxygen. • The absence of myelin makes it easier for the grey matter to direct transmission of impulse along a variety of interconnections

13. Quick check-Chapter 5&6 • Ch.5 review q-3,4,5,6 • Ch.6 reviewQ.-8,9