1. Nervous System Physiology

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

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

6. Glial cells: Astrocytes

7. Astrocyte Functions Axon guidance Synaptic support between neurons
Support in controlling the blood- brain barrier

8. Glial Cell: Microglial
Act as the first and main form of active immune cells in the CNS

9. Glial Cell: Ependymal Cells

10. Glial Cells: Oligodendrocytes

11. Glial Cells: Schwann Cells

13. Neurons- transmit impulses
Characteristics:
1) High longevity ( 100 years)
2) amitotic-cell division-cell division by simple cleavage of the nucleus and division of the cytoplasm without spindle formation or appearance of chromosomes)
3) high metabolism; needs a lot of oxygen

14. Parts of a neuron

15. Parts of a Neuron 1) Dendrites receive impulses and send to cell body
2) Cell Body – located in the CNS
3) Axon  moves impulses away from the cell body
Direction of impulse-impulse travels from dendrite to cell body to axon-ends at the axon terminal

16. 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 (support)

17. Reflex Arc

18. Reflex Arc 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

19. The impulse is Electrochemical 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)

21. At Resting:
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

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

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

24. Depolarization + Repolarization =
Action Potential

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

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

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

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

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

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

34. Neurotransmitter binds to post synaptic receptors
Step 4
Neurotransmitter binds to post synaptic receptors

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

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

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