Anatomy and Physiology Answer Key

B ach causes depolarization of the postsynaptic

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Unformatted text preview: neurotransmitter. Drugs at Synapses (page 81) 1. (a) and (b) any of in any order: • Drug can act as a direct agonist, binding to and activating Ach receptors on the postsynaptic Biozone International 2009 Photocopying Prohibited 3. Atropine and curare are direct antagonists because they compete for the same binding sites (as Ach) on the postsynaptic membrane (hence direct) and they block sodium influx so that impulses are not generated (hence antagonist = against the usual action). 4. Curare is used to cause flaccid paralysis (relaxed or without tone) to the isolated abdominal region in order to facilitate operative procedure (of course, the drug is administered as a carefully produced formulation). Aging and the Brain (page 82) 1. Alzheimer's results when neurons, and their connections, are lost at an accelerated rate in the brain. Loss of processing ability affects a number of functions including memory, reasoning and language. 2. A mutation for the APP gene has been discovered within families who demonstrate a history of Alzheimer's. The protein is thought to be involved in synapse formation and neural plasticity. 3. Alzheimer's sufferers suffer an accelerated loss of neurons and show reduced brain activity, particularly in regions that are important for memory and intellectual processing, such as the cerebral cortex and hippocampus. Note: The most recent evidence indicates that, during normal aging, there is a loss of synaptic function in the brain, but the neurons themselves are not lost. In Alzheimer's, there is a pathological loss of the neurons themselves. Detecting Changing States (page 83) 1. Stimulus: Any physical or chemical change in the environment, capable of provoking a response in an organism. 2. Communication systems (here referring to the means by which changes in the environment are communicated to effectors) are necessary in order to respond appropriately to environmental stimuli. Appropriate responses aid survival and enable effective interpretation about the ch...
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This document was uploaded on 01/28/2014.

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