Central Nervous System

1. Central Nervous System

2. CNS • Communication and control centre of body • Brain and spinal cord

3. Nerve Cells • Neuron- basic structural and functional unit of nervous system • Vary in size and shape • All consist of dendrite, cell body and axon

4. CNS- Cell Body • Contains nucleus and cytoplasm • Cytoplasm similar to other cells

5. CNS- Dendrites • Short extensions of cytoplasm • Carry nerve impulse INTO cell body

6. CNS- Axon • Long extension from cell body • Usually carry impulse away from cell body • Length highly varied • Most myelinated- covered by fatty material called myelin

7. CNS • Interneurons- brain and spinal cord • Many branches able to send and receive messages from adjacent neurons • Grey Matter- nerve cell bodies and unmyelinatedfibres • White matter- myelinatedfibres

8. Generalised Neuron

9. Protecting the CNS • Bone • Meninges • CSF- protection, support and trasnport

10. Brain- Cerebrum • Biggest part of brain • Cerebral cortex- Outer surface of grey matter, 2- 4 mm thick • Below cortex is basal ganglia • Right and left hemisphere • Highly convoluted

11. Brain- Cerebrum

12. Brain- Cerebrum • 4 lobes- frontal, temporal, occipital and parietal

13. Brain- Cerebrum • Tract- bundles of nerve fibers • Connect various areas of cortex within the same hemisphere • Carry impulses between the left and right hemisphere • Connect cortex to other parts of brain or spinal cord

14. Brain- Cerebrum: Function • Cortex- thinking, reasoning, learning, memory, intelligence, sense of responsible, perception of senses, initiation and control of voluntary muscle contractions.

15. Brain- Cerebrum: Function • Sensory- interpret impulses from receptors • Motor- control muscular movement • Association- intellectual and emotional areas

16. Brain- Cerebellum • Under rear part of cerebrum • 2nd largest part of brain • Folded into parallel ridges • Outer- grey • Inner- white- branches to all parts of cerebellum

18. Brain- Cerebellum: Function • Posture, balance, coordination • Receives info from inner ear and stretch receptors in skeletal muscles • Unconsciously controls us- jerky without it

19. Hypothalamus • Middle of brain • Mostly concerned with homoestasis

20. Brain- Hypothalamus: Function • Regulation of • ANS- HR, BP, secretion of digestive juices, alimentary canal, pupil dialation • Body temp • Food and water intake • Patterns of walking and sleeping • Conc urinary bladder • Emotional responses • HORMONES!!

21. Brain- Medulla Oblongata • Continuation of spinal cord • 3cm long • Extends just above point where spinal cord enters scull • ‘Highway for nerves’

22. Brain- Medulla Oblongata: function • Cardiac centre • Respiratory centre • Vasomotor center • Swallowing, sneezing, coughing and vomiting • Controlled by higher centers in brain

23. Spinal Cord • Roughly cylindrical • Foramen magnum to L2 • Heavily protected • Vertebral canal • Meningies • Outer layer not connected to bone rather space filled with fat, connective tissue and blood serving as padding for when spine is bent

24. Spinal Cord • Grey and white matter opposite configuration to brain

25. Spinal Cord • Central Canal- CSF • Ascending and Descending Tracts • Bundles of myelinated nerve fibre

27. Control of Movement • Cerebral Cortex • Motor Association Area of Brain initiates intention to move • Neurons make up program for sequence and intensity of contractions • Program then sent to Primary motor area (primary motor cortex) • Impulses then sent to lower centres in brain and spinal cord- result being contraction

29. Motor Homunculus

30. Homunculus “A diagram of the body that shows the relative size of parts of the cortex devoted to control of different muscles.”

31. Cross overs

32. Cerebellum • Receive nerve impulses from cerebrum through upper motor neurons • Also receives information from eyes, ears and stretch receptors • Smoothes contractions • Learning of motor skills • Maintain Balance