Anatomy And Physiology: The Human Nervous System

1. The nervous system maintains homeostasis by sending electrochemical signs throughout the body, coordinating and executing both the voluntary and involuntary processes. The nervous system is the most complex system in the body and is comprised of the central nervous system, compromised of the brain and the spinal cord, and the peripheral nervous system, composed of the nerve extensions beyond those central pathways.
2. Central nervous system processes information and dictates actions
Peripheral nervous system gathers information form the environment and performs actions
A. The two main organs of the CNS are the brain and the spinal cord.
B. The peripheral nervous system is the part of the nervous system that is made up of the nerves and
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Neurons have the metabolic machinery characteristics to somatic cells of other types. They have a nucleus and all other organs that are needed for a normal cellular life. Neurons are characterized by specialization in intracellular communication. Neurons in the matured CNS involves a secretion of special chemical molecules called neurotransmitters.
Neuroglia provide a variety of functions for brain tissue and support the metabolic and signaling functions of the neurons. Certain types of neuroglia, myelin, serve as an insulation around axons.
4. Neuroglia function depends on the specific type of neuroglia, but they are not sensitive the stimuli and do not generate or conduct nerve impulses.
A. Astrocytes: is a star shaped cell that has many processes extending from its cell body into the surrounding network of nerve fibers. They are a supply of nutrients to neurons, removes excess neurotransmitters, maintain balance of calcium and potassium.
B. Oligodendrocytes: have fewer and thinner processes and no gap junctions, unlike astrocytes, that is in tissues of the brain and spinal cord. They support network around CNS neurons.
C. Microglia: are found in the CNS in the tissues of the brain and spinal cord. Microglia protects CNS neurons from diseases by clearing away debris and dead
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Axon hillock is the last site in the soma where membrane potentials propagated form synaptic inputs are summated before being transmitted to the axon. The structure of the initial segment is made up of three things: a dense layer of finely granular material undercoating the plasma membrane, scattered clusters of ribosomes, and fascicles of microtubules.
2. A collateral axon is a branch off the main axon that usually feeds back onto the soma. This function provides modulation of cell firing.
3. Axon terminals are distal terminations of the branch of an axon. These release electrical impulses of the presynaptic cells.
7. Name and describe the three different types of neurons and describe their functions:
A. Multipolar neurons have several dendrites; most neurons in the spinal cord and brain. Bipolar neurons have only two processes: a single dendrite and an axon. These are found in the sense organs and in the retina of eye and in olfactory cells. Unipolar neurons lack dendrites and have a single axon and are also sensory neurons.
B. Multipolar and Bipolar neurons have dendrites where Unipolar neurons do not.
C. The Purkinje cells and Pseudounipolar cells.
D. Multipolar and pseudounipolar cells.

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