13. The amount of force produced by a skeletal muscle can be increased by which of the following? A. Decreasing the activity of nicotinic ACh receptor B. Decreasing extracellular Ca2+ C. Increasing the activity of acetylcholinesterase D. Decreasing the interval between contractions E. Greatly increasing the starting muscle length I understand why D is the right answer. However. Why wouldn't E be correct also. Because if you greatly increase the starting of muscle fiber..u increase its passive tension, and therefore increase its potential energy..wouldn't that mean you increase its tension to do work also?.. Thank you
Tetanic contractions differ from twitches because of the interval between contractions. Increasing the intracellular Ca2+ concentration will increase muscle force.
The way answer E is worded I agree with you that you could argue that it is also a correct answer. To make the question more clear and only have D be the correct answer you could add something distinctive regarding the force, like 'physiologically controlled force' or 'active force' or something similar.
I'm not entirely sure its necessary and here's why: the physiology of that relationship is the same as that in skeletal. The differences are this: 1. The passive tension starts at a shorter length in smooth muscle cells. This is due to the shape of the muscles and therefore there is pull on the connective proteins at the dense bodies already at rest. 2. The active length-tension curve is more broad than in skeletal muscles because the shape of the myosin head groups is different in that ll of the myosin head groups are facing the same direction and therefore there is a broader range of lengths where maximal active tension can be created.
13. The amount of force produced by a skeletal muscle can be increased by which of the following?
ReplyDeleteA. Decreasing the activity of nicotinic ACh receptor
B. Decreasing extracellular Ca2+
C. Increasing the activity of acetylcholinesterase
D. Decreasing the interval between contractions
E. Greatly increasing the starting muscle length
I understand why D is the right answer. However. Why wouldn't E be correct also. Because if you greatly increase the starting of muscle fiber..u increase its passive tension, and therefore increase its potential energy..wouldn't that mean you increase its tension to do work also?..
Thank you
Tetanic contractions differ from twitches because of the interval between contractions. Increasing the intracellular Ca2+ concentration will increase muscle force.
DeleteThe way answer E is worded I agree with you that you could argue that it is also a correct answer. To make the question more clear and only have D be the correct answer you could add something distinctive regarding the force, like 'physiologically controlled force' or 'active force' or something similar.
Dear Professor Johannessen,
ReplyDeleteIf you get the time, could you please make a video explaining length-tension relationship in the smooth muscle? Thank you very much.
Sincerely,
Haran Ratna
I'm not entirely sure its necessary and here's why: the physiology of that relationship is the same as that in skeletal. The differences are this:
Delete1. The passive tension starts at a shorter length in smooth muscle cells. This is due to the shape of the muscles and therefore there is pull on the connective proteins at the dense bodies already at rest.
2. The active length-tension curve is more broad than in skeletal muscles because the shape of the myosin head groups is different in that ll of the myosin head groups are facing the same direction and therefore there is a broader range of lengths where maximal active tension can be created.