Palaniappan
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Is it D?
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| klimt
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A?
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| fox
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D sounds good to me. I dont understand what E means....2.2 Micro metres?
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| klimt
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E reffers to the optimal length of sarcomere (2.2 micrometers) which corresponds to optimal contractility - it's the Frank Starling mechanism
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| dreamer
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d
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| ManuNastai
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I don't think it's D because it's the same answer as C till one point -> increasing the activity of ACE will produce a shortened activity of Ach. Now, if you decrease the time between contractions you end up with a tetanus which in my understanding will increase the length (in time) of the contraction and just secondary the force.
I think, I'll do an elimination and end up with A which doesn't sound good eather 
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| laura81
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its E
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| ssrpk
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well the max force any muscle can generate is dependent on the no. of actin-myosin sites tht are in cycling which in turn depends on the conc. of Ca++ intracellularly! which in turn depends on no. of action potentials each and every muscle fibers gets in the whole bulk, thus if one decrease the interval b/w action potentials, the major effect wud be, tht Ca++ will get more and more concentrated in the cytoplasm as the mitochondria and ER won't hv enuff time to clear up all the Ca++. This high Ca++ wud then be responsible for the saturation of all the available actin-myosin sites and keep them in cycling! [this last part i.e inc. contractility due to high Ca++ is analagous to how digitalis acts on cardiac muscle fiber]
secondly, the strength tht a muscle fiber can generate depends on the no. of actin/myosin sites that are in cycling, therefore increasing the pre-load beyond Lo will reduce the interaction between the two and thus reduce the max.force that can be generated!
answer is D
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