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Advanced Physiology Sample Questions

For 1) - 2) Responses should be 1 or 2 paragraph clear explanations?
1) Is there a correlation between the frequency of action potentials in a single muscle fiber and the tension it can develop?

2) Describe the 4 types of chromophores in the retina?

3) For 3a - 3j answer True/False; and offer brief eplanation to support your answer:
3a. A control system in which the response increases the strength of the original stimulus is known as negative feedback?
3b. Competition for receptors is strictly a pharmacological phenenomenon since naturally occurring chemical messengers do not compete with each other for the same receptor site?
3c. Information about the location of a given stimulus on or in the body is conveyed by the same mechanisms that convey information about stimulus intensity?
3d. The function of the tympanic membrane is to amplify sound waves on their way to the inner ear?
3e. The phenomenon of referred pain may occur because the ascending pathways for pain are not completely specific with respect to localization of the pain receptor?
3f. A skeletal muscle generates its greatest twitch tension when it is stretched to twice its resting length?
3g. Endurance exercises such as long-distance swimming causes a preferential increase in glycolytic enzymes and increasesd mass of the exercising muscles?
3h. The myosin in smooth muscle cells differs from that in skeletal muscle in that smooth-muscle myosin requires phosphorylation before it can bind to actin?
3i. The shortening velocity of a skeletal muscle fiber increases with decreasing load because the rate at which the cross-bridge cycle can occur increases with decreasing load?
3j. The term "twitch" refers to the mechanical response of a muscle fiber during one cross-bridge cycle?

Solution Preview

1) Is there a correlation between the frequency of action potentials in a single muscle fiber and the tension it can develop?
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<br>Answer: I am answering your question based on smooth muscle, a vitally important muscle class in organ function. Smooth muscle strips, for example in the bladder, develop spontaneous phasic contractions. Underlying these contractions are thought to be spontaneous action potentials and corresponding calcium transients. Spontaneous action potentials result from the opening of L-type calcium channels and Ca2+ entry through these channels would be amplified by calcium-induced calcium release (CICR) from intracellular stores, to contract bladder smooth muscles. The spontaneity of action potential is directly associated with the tension developed in a muscle fibre. Thus action potential generation and tension development are ionically controlled.
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<br>2) Describe the 4 types of chromophores in the retina?
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<br>Answer: The retina contains chromophores of 11-cis-retinal-protein complexes which collectively absorb across the whole of the visible spectrum. Some chromophores readily absorb visible light. These include:
<br>a) The broad band absorbers melanin and lipofuscin -- absorption increases with decreasing wavelength. These chromophores have been implicated in blue light damage to ...

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