1. Neuron Structure & Function

2. I. Functions of the Nervous System A
I. Functions of the Nervous System A. Sensory – gather info from inside and outside the body B. Integrative – receive the info and decide what to do about it C. Motor – respond to the info

4. II. Cellular Structure A. Neurons – structural and functional unit 1
II. Cellular Structure A. Neurons – structural and functional unit 1. Cell Body – cytoplasm and most organelles 2. Dendrites – short, highly branched, bring in info 3. Axons – long, sends impulse away from cell body a. Axon Terminal – releases neurotransmitters (chemical signals for the next cell)

5. B. Neuroglial cells (support cells) 1
B. Neuroglial cells (support cells) 1. Schwann cells – around axons (PNS) a. Produce myelin - a lipoprotein that insulates axon to keep impulses in b. Nodes of Ranvier – narrow gaps in the myelin sheath

6. 2. Astrocytes – star shaped, structural support, scar tissue 3
2. Astrocytes – star shaped, structural support, scar tissue 3. Oligodendrocytes – form myelin in brain and spinal cord

7. 4. Microglial cells – CNS, support, phagocytize bacteria and cell debris 5. Ependymal cells – covers and lines CNS

8. III. Functional Classifications of Neurons A
III. Functional Classifications of Neurons A. Sensory (afferent) neurons – carry information to the CNS B. Interneurons – in the CNS, connect sensory neurons to motor neurons C. Motor (efferent) neurons – carry impulses from the CNS

9. IV. Nerve Impulses A. Resting potential – at rest, the neuron cell membrane is polarized (more positive outside than inside) to -70mV

10. Depolarization – a stimulus depolarizes the membrane allowing Na+ into the cell.
1. If the impulse is strong enough (reaches the threshold) an Action Potential is generated (goes down the length of the axon)

11. Repolarization – K+ ions rush out of the cell in response to the Na+ coming in
Hyperpolarization – prevents another action potential from starting before one is finished

13. V. Communication between neurons
Action potential reaches axon terminals of pre- synaptic cell, signals for the release of neurotransmitter into the synapse by exocytosis
Neurotransmitter diffuses across synapse, binds to receptors on post-synaptic cell, opening sodium gates to start an action potential