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Neural Tissue and NeruophysiologyNeural Tissue and
Neruophysiology
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Summary of Nervous System Function
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Major Structual
and Functional
components ofthe Nervous
SystemCentral Nervous System
Peripheral Nervous System
Sensory
Somatic Visceral
Motor
Somatic
Visceral (Autonomic NS)
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Astrocyte Microglial cell
Ependymal cells
Oligodendrocyte
Schwann cells and Satellite cells
Neuroglia (Glial Cells)
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The structure of a neuron
Soma
Dendrites
Axon
Synapse
Myelin sheath(Schwann cells)
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Schwann Cells
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Multipolar Neuron:
Motor neurons and
interneurons
Types of Neurons
Unipolar Neuron:
Sensory neurons
Bipolar Neuron:
Special sensory (vision,
hearing, smelling
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Types of Synapses
Neuron-to-neuron
Neuromuscular
Neuroglandular
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Principles of Electricity
Voltage: A potential energy that exists due to aseparation of
charges
Current: Flow of electrical charge from one point to
anotherCurrent Voltage
Current 1/ Resistance
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Chemically (Ligand) Gated Channels
Changes in the Transmembrane Potential
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Voltage Gated Channels
Changes in the Transmembrane Potential
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Changes in the Transmembrane Potential
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Mechanically Gated Channels
Movement
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The Resting Transmembrane PotentialThe Transmembrane potential =
Sum of
chargesSum of
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The Transmembrane Potential:
Dynamic equilibrium
Na+
K+
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Na+
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Na+ Na+
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K+K+
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K+
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K+ K+
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K+
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Membrane potential is resting, but not static:
Leak channels permit ions (esp. K+) to escape Na+/K+ Exchange
pump
- Removes 3 Na+ and pulls in 3 K+ using ATP
K+K+
Na+ Na+
K+
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Signals: depolarization and hyperpolarization
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Graded Potentials
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1 resting state
2 depolarization phase
3 repolarization phase
4 hyperpolarization
Action
Potentials
1
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4
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Action Potentials:
Na+ and K+ voltage gated channels
70
55
0
+30
M
emb
ranep
ote
ntial
(m
V)
Relat ive
membrane
permeabili t
y
Action potential
PNa
PKThreshold
2
3
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Voltage gated Na+ channels open in response to
graded potentials at the trigger zone
Voltage gated Na+ channels open in response to
action potentials at the conduction zone
Conduction zone
Receptive zone
Action Potentials: Propagation
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Action Potentials: Propagation
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Action Potentials: Propagation
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Refractory Periods
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Coding for Stimulus Intensity
All action potentials are alike and areindependent of stimulus
intensity
The CNS determines stimulus intensity by thefrequency of impulse
transmission
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Conduction VelocityFactors:
Axon diameter
Degree of myelination
Saltatory Conduction
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Types of Synapses:
Electrical vs. Chemical Synapses
Chemical synapse
Electrical synapse
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The Cholinergic Synapse:From Action Potential to Graded
Potential
Ion channel (open)
Ion channel closed
Ion channel open
Neurotransmitter
Receptor
Postsynaptic
membrane
Degraded
neurotransmitter
Na+
Na+
Ca2+
Actio
nPoten
tial
1
2
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Termination of Neurotransmitter Effects
Degradation (AChE)
Reuptake
Diffusion from synapse
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Post-synaptic potentials
