Nervous system
Nervous systemNervous System
The two major subdivisions of the nervous system are the
central nervous system and the peripheral nervous system.
The CNS consists of the brain and the spinal cord, it's
responsible for integrating, processing, and coordinating
sensory data and motor commands. The CNS integrates balance
and limb position and coordinates your recovery by
commanding the appropriate skeletal muscles. The CNS is
also the seat of higher learning, performing functions as
intelligence, memory, learning, and emotion.
The PNS includes all the neural tissue outside the CNS. The
PNS carries motor commands to the peripheral tissues and
systems. Nerve fibers called axons carry sensory
information and motor commands in the PNS.
Sketch and label the structure of a typical neuron and
describe the function of each.
* The soma, consists of the cell body of a neuron
which further contains the nucleus.
* Glial cells interact with neurons and regulate the
extracellular environment, protect against
pathogens and repair damaged neural tissue.
* Axons are-capable of propagating nerve impulses.
* Dendrites respond to specific stimuli in the
extracellular environment.
* Synapse terminals communicate information from the
presynaptic cell to the posisynaptic cell.
Structural Classification
*Anaxonic neurons- have multiple processes and the axon is
indistinguishable from the
from the dendrites. They're fairly small.
*Bipolar neurons- have two processes in which one is a
dendrite, and the other an axon.
The dendrite is distinguishable from it's extensive
branching at it's distal end. it's less than 3Omm from tip
to tip.
*Unipolar neurons- have a continuous dendritic and axonal
process, in which case the cell body lies off to the side.
The dendritic end of the process has extensive branching,
the anoxic part of the process may extend to be a meter or
more.
*Multipolar neurons- have dendrites around the soma and the
axon is distinguishable from it's long length.
Functional Classification
*Sensory neurons- deliver information from the sensory
receptors to the CNS. Consists of somatic sensory neurons
that monitor the outside world and our position in it, and
visceral sensory neurons that monitor internal conditions
and the status of other organs. Sensory receptors may be
the processes of specialized sensory neurons or cells
monitored by sensory neurons, among the are
exteroreceptors, proprioceptors, and interoceptors.
*Motor neurons- carries information from the CNS to the
peripheral effectors by stimulating a peripheral tissue,
organ, or organ system.
*Interneurons~ are responsible for the distribution of
sensory information and the coordination of motor activity.
There are four types of neuralgia of the CNS. They are:
(1) Ependyrnal cells- which line the ventricles of the
central canal and the central canal itself They assist in
production, circulation, and monitoring of cerebrospinal
fluid.
(2) Astrocytes- maintain blood-brain barrier, produce
structural support; regulate ion, nutrient, and dissolved
gas concentrations; absorb and recycle neurotransmitters;
assists in tissue repair after injury.
(3) Oligodendrocytes- myelnate CNS axons; provide
structural framework.
(4) Microglia- remove cell debris, waste, and pathogens
by phagocytes.
There are two types of neuralgia of the PNS. They are:
(1) Satellite cells- surround neuron cell bodies in
ganglia.
(2) Schwann cells- cover all axons in the PNS;
responsible for myclination of some peripheral axons;
participate in repair process after injury.