Download - Local Control
Local Control
The Control Systems of the Body
Long Distance Control
Autocrine -
Paracrine -
Endocrine System
Nervous System
Slower Response, Broad, Long Lasting
Faster Response, Specific, Brief
• Overview
• Neurophysiology
• Central Nervous System
• Peripheral Nervous System– Autonomic N.S.– Somatic N.S.
The Nervous System
Overview of the Nervous System
Sensory Pathway
Motor Pathway
Interneuron(Integration)
CNSPNS
Receptors
EffectorTissue
• Dentrites
• Cell Body
• Axon
• Axon Terminal
with End Bulb
A Typical Neuron
incoming info.
integration of info.
outgoing info.
release of neurotransmitter
Nodes ofRanvier
Graded Potentials
Action Potentials
Localized change in membrane potential that varies in magnitudeand is decremental.
Rapid reversal in membrane potential (due to changes in ionpermeability), with constant magnitude and is non-decremental.
• "All or none" event
• Signal does not diminish over distance
1. Threshold
2. Depolarization
3. Repolarization
4. Hyperpolarization
Action Potentials
There are 4 Phases in an Action Potential:
Refractory Periods
• Absolute Refractory Period:
• Relative Refractory Period:
Summation of Graded Potentials
• Temporal Summation:
• Spatial Summation:
As the frequency of a single stimuli increases, the changes in membrane potential can be added and its magnitude can increase.
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.
Graded vs. Action Potentials
2. Decremental (passive spread)
2. Non-decremental
(self-regenerating)
3. No Refractory Periods
in Graded Potentials
4. Summation is possible 4. No Summation possible
5. Trigger: NT's, hormones 5. Trigger: Threshold
1. Magnitude varies 1. No variation - All or None
6. Occurs at cell body
(direction can vary)
6. Occurs at axon hillock (one way direction)
3. Two Refractory periods:
Absolute and Relative
How fast can a signal travel down an axon?
Speed of Conduction of Signal
• Small Diameter • Large Diameter
Speed of Conduction of Signal
• Small Diameter • Large Diameter
• Temperature
• Axon Myelination
The Biochemistry of the Synapse
Stopping Signal Transmission
• Stop the Impulse (Pre-Synaptic AP)
• Clear Away the Synaptic Cleft
– 3. Re-uptake of NT by Pre-Synaptic cell.
– 1. Diffusion away from Receptors.
– 2. Enzymatic Degradation of NT.
• Ionotropic Effect
• Metabotropic Effect
Post-Synaptic Cell Responses
• Divergent:
Neuronal Pathways
• Convergent:
Neuronal Pathways
The Presynaptic terminalInhibitory neuron(s) – less NT releasedExcitatory neuron(s) – more NT released
The Postsynaptic membrane and receptors- Receptor numbers- Degradation rates- Permeability
Pre- and Postsynaptic Inhibition and Facilitation
The Different Glial Cells