1. The Nervous system

2. The Nervous System Brain Spinal cord Nerves Enables you to control your body Gives you feedback about the world What does it do? What are its component parts?

3. Look away if you’re squeamish… A dissected brain, spinal cord and sections of major nerves.

4. The Cells of the Nervous System - Neurones

5. The route impulses take

6. Effectors – Sensory neurone Motor neurone Relay neurones (in brain or spinal cord)

7. The Spine You don’t need to know any of these little details – just remember that the spinal cord carries messages to and from the brain.

8. The spine – the message motorway

9. Effects of a spinal cord injury on breathing With a spinal cord injury of C4 and higher, all the muscles which control breathing will be paralysed. These are the intracostal muscles, the diaphragm and the abdominal muscles. In order to breathe, the person will need a machine called a ventilator to breath for them. In order to cough, the person will need help by way of a carer performing an assisted cough procedure. Injuries between C4 and T6 will leave the person able to breathe on their own. However, because the intracostal muscles may be weakened or paralysed depending on the level of injury, breathing may be done solely or mainly by the diaphragm. Again, coughing may also be a problem. Injuries between T6 and T12 do not normally affect breathing. However the ability to cough will be impaired. It is only with injuries below T12 that normal breathing and cough reflexes are preserved.

10. Left: sensory neurone Right: motor neurone

11. Above: Sensory Neurone Below: Motor Neurone

12. Diagrams and Drawings in Biology

13. Nerves – bundles of neurones

14. Close-up of a nerve

15. Single neurones in cross-section

16. How Impulses Pass from Neurone to Neurone – the Synapse

17. Synapses

18. Reflex Reactions – bypassing the brain for extra speed

19. Reflex Reactions Can you think of any? Startle reflex – moving away, contraction of arm and leg muscles, blinking, breathing changes Withdrawal reflex – moving away from potentially harmful influences (e.g. high temperature) Iris reflex – pupil becomes smaller in bright light

20. Knee Jerk Reflex

21. Why the knee jerk reflex? This reflex is quite useful for walking. Every time you put weight on your foot, your muscles contract to support you. Without this reflex, we would all look silly staggering around, having to consciously think about working our muscles for each step, but with the muscles reacting too hopelessly late to be useful. Chewing gum at the same time would be out of the question.

23. Rod and Cone cells

24. Iris Reflex

25. Look at the difference between the two eyes

26. Accommodation of the eye