In: Anatomy and Physiology
With a reduced number of acetylcholine receptors, can acetylcholine stimulate a muscle fiber?
In the process of skeletal muscle contraction, neurotransmitter (acetyl choline) released from pre synaptic membrane binds to acetyl choline receptors on the post synaptic membrane of the motor unit.
This Binding helps entry of some positive ions which eventually leads to depolarization of post synaptic membrane and release of ca2+, which binds to troponin, which exposes myosin binding site on actin molecule, so that myosin binds to actin molecule--cross bridge formation and breakdown occur which cause muscle contraction.
If acetyl choline receptors are reduced-Initially during mild stimulus, acetyl choline will binds to available receptors that can cause muscle contraction.
But as the stimulus continues or during continuous motion, acetyl choline receptors become unavailable, so that acetyl choline cannot bind to receptors, hence muscle contraction will not occur.
So as the action progress--contraction becomes difficult and finally muscle become weak, unavle to contracy