1. Neurophysiology

2. Regions of the Brain and Spinal Cord
White matter – dense collections of myelinated fibers
Gray matter – mostly soma and unmyelinated fibers

3. Resting Membrane Potential (Vr)
potential difference (–70 mV) across the membrane of a resting neuron
generated by different concentrations of Na+, K+, Cl, and protein anions (A)
Ionic differences are the consequence of:
Differential permeability of the neurilemma to Na+ and K+
Operation of the sodium-potassium pump

4. Resting Membrane Potential
Figure 11.7

5. Resting Membrane Potential (Vr)
Figure 11.8

6. Changes in Membrane Potential
Depolarization – the inside of the membrane becomes less negative
Repolarization – the membrane returns to its resting membrane potential
Hyperpolarization – the inside of the membrane becomes more negative than the resting potential

7. Action Potentials (APs)
brief reversal of membrane potential with a total amplitude of 100 mV
only generated by muscle cells and neurons
Do not decrease in strength over distance
principal means of neural communication
action potential in the axon of a neuron is a nerve impulse

8. Absolute Refractory Period
The absolute refractory period:
Prevents the neuron from generating an action potential
Ensures that each action potential is separate
Enforces one-way transmission of nerve impulses

9. Synapse – a junction between nerves
Electrical synapse – connect cytoplasms of adjacent neurons – allows for ionic movement
Chemical synapse – utilizes a neurotransmitter

10. Saltatory Conduction only at the nodes of Ranvier
Voltage-gated Na+ channels are concentrated at these nodes
Action potentials jump from one node to the next
Much faster than conduction along unmyelinated axons

11. Saltatory Conduction
Figure 11.16

12. Neurotransmitter Classification
Ach
Biogenic amines – NDSH – norepinephrine; dopamine, serotinin, histamine
Purines – ATP and Adenosine
Amino acids – GABA, glutamate, glycine
Peptides – CETS (cholecystokinin, endorphins,tachykinins, somatostatin
Gases