Nervous system (Click to select text)

Nervous 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.