1. Nervous System Physiology

3. 3 functions of the nervous system 1) Sensory Input 2) Integration- decisions 3) Motor Output

5. Two types of Cells 1) Neuroglial Cells- “glial” cells 2) Neurons-stimulus conducting cells

6. Glial cells: Astrocytes

7. Glial Cell: Microglial

8. Glial Cell: Ependymal Cells

9. Glial Cells: Oligodendrocytes

10. Glial Cells: Schwann Cells

12. Neurons- transmit impulses Characteristics: 1) High longevity (  100 years) 2) amitotic-cell division 3) high metabolism / needs a lot of oxygen

13. Parts of a neuron

14. Parts of a Neuron 1) Dendrites  impulses to cell body 2) Cell Body – located in the CNS 3) Axon  impulses away from the cell body Direction of impulse-impulse travels from dendrite to cell body to axon

15. Types of Neurons Sensory (afferent) neuron – brings impulse from a receptor to CNS Motor (efferent) neuron- brings impulse from CNS to an effector Intergration (interneuron or association neuron) between sensory and motor in the CNS

16. Reflex Arc

17. Receptor- monitors stimuli Sensory neuron- transmits message to CNS Integration Neuron- makes a decision in the CNS Motor neuron- takes the message from the CNS to an effector Effector- a muscle or gland that responds

18. The impulse is Electochemical because of ion distribution A neuron that can conduct an impulse must be irritable Irritability is set up by the Na + / K+ pump A neuron that is not conducting is resting In a resting state there is a potential difference in charge between the inside of the membrane and the outside of the membrane The difference is negative ( about – 70 mV)

20. Na + (Sodium) ions are greater on the outside of the membrane K + (Potassium) ions are greater on the inside of the membrane The difference is maintained by the sodium/ potassium pump

21. Stimulation of the neuron: 1) Na gates open 2) Na rushes in 3) potential difference of the membrane changes from -70 mV to + 30 mV = depolarization

22. The K gates open and potassium leaves The potential difference goes from +30 mV back down to -70mV = repolarization

23. Depolarization + Repolarization = Action Potential

24. Before the Sodium/ Potassium Pump starts again to restore the resting potential hyperpolarization occurs

28. Conductivity- how an impulse leaves a neuron and stimulates another neuron, or a muscle, or a gland

29. Chemicals are released into the synapse and react with the post synaptic muscle, gland, or another neuron

30. Step 1 Calcium gates open in the synaptic axon terminal membrane and Calcium rushes in

31. Step 2 Calcium ions act as a messenger signaling the synaptic vesicles to fuse with the pre- synaptic membrane

32. Step 3 The vesicles empty the neurotransmitter into the synaptic cleft by exocytosis

33. Step 4 Neurotransmitter binds to post synaptic receptors

34. Step 5 Ion channels open and produce a change in the membrane potential

35. Step 6 Depending on the receptor protein to which the neurotransmitter binds – the post synaptic neuron may be excited or inhibited

36. Step 7 The neurotransmitter will degrade, diffuse away, or be removed by enzyme activity