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Local Control

The Control Systems of the Body. Local Control. Autocrine -. Paracrine -. Long Distance Control. Endocrine System. Slower Response, Broad, Long Lasting. Nervous System. Faster Response, Specific, Brief. The Nervous System. Overview Neurophysiology Central Nervous System

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Local Control

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  1. The Control Systems of the Body Local Control Autocrine - Paracrine - Long Distance Control Endocrine System Slower Response, Broad, Long Lasting Nervous System Faster Response, Specific, Brief

  2. The Nervous System • Overview • Neurophysiology • Central Nervous System • Peripheral Nervous System • Autonomic N.S. • Somatic N.S.

  3. Overview of the Nervous System

  4. PNS CNS Sensory Pathway Receptors Interneuron (Integration) Motor Pathway Effector Tissue

  5. A Typical Neuron • Dentrites • Cell Body • Axon • Axon Terminal with End Bulb incoming info. integration of info. Nodes of Ranvier outgoing info. release of neurotransmitter

  6. Graded Potentials Localized change in membrane potential that varies in magnitude and is decremental. Action Potentials Rapid reversal in membrane potential (due to changes in ion permeability), with constant magnitude and is non-decremental.

  7. Action Potentials • "All or none" event • Signal does not diminish over distance There are 4 Phases in an Action Potential: 1. Threshold 2. Depolarization 3. Repolarization 4. Hyperpolarization

  8. Refractory Periods • Absolute Refractory Period: • Relative Refractory Period:

  9. Summation of Graded Potentials • Temporal Summation: As the frequency of a single stimuli increases, the changes in membrane potential can be added and its magnitude can increase. • Spatial Summation: As multiple simultaneous stimuli occur at different places on the neuron, the changes in membrane potential can be added and its magnitude increased or decreased.

  10. 2. Decremental (passive spread) 2. Non-decremental (self-regenerating) Graded vs. Action Potentials 1. Magnitude varies 1. No variation - All or None 3. No Refractory Periods in Graded Potentials 3. Two Refractory periods: Absolute and Relative 4. Summation is possible 4. No Summation possible 5. Trigger: NT's, hormones 5. Trigger: Threshold 6. Occurs at cell body (direction can vary) 6. Occurs at axon hillock (one way direction)

  11. How fast can a signal travel down an axon?

  12. Small Diameter Large Diameter Speed of Conduction of Signal

  13. Small Diameter Large Diameter Speed of Conduction of Signal • Temperature • Axon Myelination

  14. The Biochemistry of the Synapse

  15. Stopping Signal Transmission • Stop the Impulse (Pre-Synaptic AP) • Clear Away the Synaptic Cleft • 1. Diffusion away from Receptors. • 2. Enzymatic Degradation of NT. • 3. Re-uptake of NT by Pre-Synaptic cell.

  16. Post-Synaptic Cell Responses • Ionotropic Effect • Metabotropic Effect

  17. Neuronal Pathways • Divergent:

  18. Neuronal Pathways • Convergent:

  19. Pre- and Postsynaptic Inhibition and Facilitation • The Presynaptic terminal • Inhibitory neuron(s) – less NT released • Excitatory neuron(s) – more NT released • The Postsynaptic membrane and receptors • - Receptor numbers • - Degradation rates • - Permeability

  20. The Different Glial Cells

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