The Structure of the Nervous System

1. The Structure of the Nervous System Chapter 23A

2. Nervous System • Brain • Spinal cord • Nerves • Sensory organs CNS PNS

3. nerves Neurons • neuron: nerve cell

4. Parts of a Neuron • Cell body • Dendrites • Axon • myelin sheath • Schwann cells • axon terminal

5. Synapse • The junction between two neurons • Synaptic cleft

6. Nerve Impulse • Electrochemical pulse that moves along the membrane of a neuron • Based on movement of sodium and potassium ions • Must cross synaptic cleft by using neurotransmitters

7. Three Types of Neurons • Sensory neurons • Interneurons • Motor neurons

8. Reflex

9. The Reflex Arc • Shortcut approach to nerve impulses • The impulse will be reflected back to the muscles or glands involved at the same time the impulse is sent to the brain.

10. The Reflex Arc sensory receptor sensory neuron interneuron motor neuron muscle brain

11. The CNS

12. Coverings of CNS • Meninges • dura mater • arachnoid membrane • pia mater

13. Cerebrospinal Fluid • Fluid between the pia mater and arachnoid membrane • Fills spaces around brain and spinal cord • Nourishes and cushions

14. The Brain

15. The Brain • 3 pounds • Receives 20% of the blood pumped by the heart • Pinkish-gray

16. The Brain • Gray matter • cell bodies and dendrites • White matter • axons and myelin sheaths

17. Divisions of the Brain • cerebrum • thalamus • hypothalamus • midbrain • pons • medulla oblongata • cerebellum

18. Cerebrum • Two hemispheres • Gyri (gyrus) • Fissures • Cerebral cortex (gray matter) • Lobes • frontal, parietal, occipital, temporal

19. Medulla Oblongata • Continuous with the spinal cord • Relay center between the spinal cord and the brain • Contains respiratory and cardiac control centers • Controls some reflexes

20. Cerebellum • Second largest part of brain • Two hemispheres • Regulates activities stimulated by the rest of the brain • Coordinates movement • Works on unconscious level

21. Thalamus • Two oval gray masses near center of brain • Receives sensations and decides which are important enough to be sent on • Alertness and wakefulness

22. Philippians 4:8 Finally, brethren, whatsoever things are true. . . honest. . . just. . . pure. . . lovely. . . of good report; if there be any virtue, and if there be any praise, think on these things.

23. Hypothalamus • Controls involuntary activities • body temperature • blood volume • fluid balance • appetite • emotional control (hormones)

24. Midbrain • Between thalamus and pons • Controls • body movements • space relationships • vision reflexes • hearing reflexes

25. Pons • Between medulla and midbrain • Carries information from one side of the brain to the other • Contains reflex centers that control facial expressions, chewing, sound responses, eyeball movement

26. The Spinal Cord

27. Spinal Cord Facts • 31 pairs of spinal nerves • Butterfly-shaped gray matter • interneurons and cell bodies of sensory and motor neurons • White matter • myelinated axons arranged vertically

28. The PNS

29. PNS • Sensory division • info from the body to the CNS

30. PNS • Motor division • info from the CNS to the body • somatic system (voluntary) • autonomic system (involuntary)