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Section 11 : The Nervous System

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Section 11: The Nervous System
Structure and Function
Neurons
I. Neurons: cells of the nervous system, specialized to conduct electric like impulses
II. Axons and dendrites: impulses enter the neuron only through the dendrites and leave only through the axon
III. Synapse: space between the axon of one cell and the dendrites of others
IV. Axons and dendrites in the periphery are covered with myelin, which acts as insulation
Neurotransmitters
I. Neurotransmitters: chemicals that enable messages (nerve impulses) to pass from one cell to another, if chemicals are not produced in the right amounts, the message pathway becomes confused or blocked
Nerves
I. Some axons and dendrites are long and others short. Axons and dendrites of many …show more content…

Certain activities are centered in each lobe.
 In general the right side of the cerebrum interprets for and controls the left side of the body and vice versa.
II. Cerebellum: found beneath the occipital lobe of the cerebrum. It too has an outer layer of gray cell bodies; this portion of the brain coordinates muscular activities and balance.
III. Brain stem: the midbrain, pons, and medulla are located in the brain stem. They are composed mainly of axons and dendrites. These fibers serve as connecting pathways between the control centers in the cerebrum and cerebellum and the spinal cord. Control centers are found within the brain stem for involuntary movements of such vital organs as the:
 Heart
 Blood vessels
 Lungs
 Stomach
 Intestines
The Spinal Cord
I. The spinal cord extends from the medulla to the second lumbar vertebra in the spinal canal, which is above the small of the back, a distance of about 17 inches. Nerves entering and leaving the spinal cord carry impulses to and from the control centers.
The Meninges
I. There are three membranes called meninges, they surround both the brain and the spinal cord, they are the dura mater, the arachnoid mate, and the pia mater
 The dura mater is the tough outer covering
 The arachnoid mater is the middle, loosely structured layer
Cerebrospinal Fluid
I. Ventricles are cavities within the cerebrum that are lined with highly vascular tissue.
II.

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