Anatomy and Physiology Answer Key

G blockers used to treat hypertension delay at the

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Unformatted text preview: y on the membrane of the receiving neuron (in this case, acetylcholinesterase acts on Ach to produce acetyl and choline). This reference is to the cholinergic synapse pictured. Continued action of the NT at adrenergic synapses is prevented by reuptake of the NT (norepinephrine) by the presynaptic neuron. (b) The neurotransmitter must be deactivated so that it does not continue to stimulate the receiving neuron (continued stimulation would lead to depletion of neurotransmitter and fatigue of the nerve). Deactivation allows recovery of the neuron so that it can respond to further impulses. (c) Transmission is unidirectional because the synapses is asymmetric in structure and function. The presynaptic membrane does not possess the receptors for the NT and the postsynaptic neuron does not have the stores of NT within vesicles. 5. Note numbering error The amount of neurotransmitter released influences the response of the receiving cell (response strength is proportional to amount of neurotransmitter released). Integration at Synapses (page 80) 1. Integration refers to the interpretation and coordination (by the central nervous system) of inputs from many sources (inputs may be inhibitory or excitatory). 2. (a) Summation: The additive effect of presynaptic inputs (impulses) in the postsynaptic cell (neuron or muscle fiber). (b) Spatial summation refers to the summation of impulses from separate axon terminals arriving simultaneously at the postsynaptic cell. Temporal summation refers to the arrival of several impulses from a single axon terminal in rapid succession (the postsynaptic potentials are so close together in time that they can sum to generate an action potential). 3. (a) Acetylcholine is the NT involved; arrival of an action potential at the neuromuscular junction causes the release of Ach from the synaptic knobs. (b) Ach causes depolarization of the postsynaptic membrane (in this case,the sarcolemma). Note: The depolarization in response to the arrival of an action potential at the postsynaptic cell is essentially the same as that occurring at any excitatory synapse involving Ach...
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This document was uploaded on 01/28/2014.

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