The Nervous Syste3

The Nervous Syste3 - neurons, an efferent neuron, and an...

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The Nervous System Propagation of Action Potentials Membrane Potentials and Action Potentials o A resting membrane potential results from the charge difference that exists across the membrane of cells. o An action potential occurs when the charge across the cell membrane is briefly reversed. The Synapse o The synapse is the point of contact between two neurons or between a neuron and some other cell, such as a muscle or gland cell. An action potential arriving at the synapse causes the release of a neurotransmitter from the presynaptic terminal, which diffuses across the synaptic cleft and binds to the receptors of the postsynaptic membrane. Reflexes o Reflexes are the functional units of the nervous system. o A reflex arc consists of a sensory receptor, an afferent neuron, association
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Unformatted text preview: neurons, an efferent neuron, and an effector organ. Neuronal Circuits o Neuronal circuits are either diverging or converging. Central Nervous System The CNS consists of the brain and spinal cord. The brain consists of the brainstem, diencephalon, cerebrum, and cerebellum. Brainstem o The brainstem contains several nuclei, as well as ascending and descending tracts. o The medulla oblongata contains nuclei that control such activities as heart rate, breathing, swallowing, and balance. o The pons contains relay nuclei between the cerebrum and cerebellum. o The midbrain is involved in hearing and in visual reflexes. o The reticular formation is scattered throughout the brainstem and is involved in maintaining consciousness and in the sleep-wake cycle....
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