(Left) Comparison of a motor nerve and a nerve diagram. Signals often move from dendrite to soma to axon.
(Right) A tracing of a pyramidal cell showing the extensive branching of the dendrites (bottom) and long, branched axon (top).
Introduction to Nerves
(Left) Comparison of a motor nerve and a nerve diagram. Signals often move from
dendrite to soma to axon.
(Right) A tracing of a pyramidal cell showing the extensive branching of the
dendrites (bottom) and long, branched axon (top).
Various forms of nerve cells. A. Pyramidal cell. B. Small multipolar cell, in which the axon quickly divides into numerous branches. C. Small fusiform cell. D and E. Ganglion cells (E shows T-shaped division of axon). ax. Axon. c. Capsule. (From Grey's Anatomy)
Purkinje fiber (cerebellum)
Cross section through the spinal cord showing the location of
grey and white matter. White matter has a myelin sheath around the axons while
grey matter lacks the myelin. Generally, grey matter is used to make decisions
while white matter is used for communicating among various parts of the nervous
system.
Presynaptic vs. Postsynaptic cells and a micrograph of a synapse
A stimulated presynaptic cell (left) releases neurotransmitters from vesicles (
).
The transmitters(
)
float across the synaptic cleft (gap) and join with receptors on the
postsynaptic cell (
).
This excites the postsynaptic cell (
)
and the postsynaptic cell produces an action potential (Nerve Impulse)
After the postsynaptic cell releases the neurotransmitters, they are reabsorbed by the presynaptic cell. Many antidepressants, such as Prozac, work at this level. Serotonin uptake inhibitors raise serotonin (a neurotransmitter) levels in the brain by interfering with the
Cartoon depicting the movement of an action potential down an axion, release of
neurotransmitters from vesicles, neurotransmitters hitching up to receptors on
the postsynaptic cell, then depolarization of the postsynaptic cell and
recycling of neuroptransmitter by the presynaptic cell.
Review of Synaptic Function
Acetylcholine and Spider Behavior
Digital coding of analog signals
Sodium flow and
the action potential
Detailed action potential
Action Potential Details
then Run the
Nerve Simulation
Generalized structure of the nervous system