FOr control of skeletal muscle contraction....
innervation is from.....
receptor on muscle is.....
innervation from motor neurons
acetylcholine is the NT
acts on nicotinic receptors
Describe the steps of the signal transduction in muscle.
1. acetylcholin acts on nicotinic receptors
2. nicotinic receptors are Na+ channels that causes the membrane to depolarize
3. depolarization opens VG calcium channels
4. calcium enters the muscle cell
5. the VG channels are physically connected to ryanodine receptors on the sarcolasmis reticulum, which opens and releases intracellular Ca++
6. the elevated intracellular Ca++ initiates contraction
what is the average ratio of nerve to muscle fibers?
Again, the acetylcholin nicotinic receptor is a ____ channel.
What are the voltage gated calcium channels called?
THe L channels are physically coupled to the ___ receptors on the _____.
the ryanodine receptors on the sarcoplasmic reticulum
Intracellular calcium concentration must reach ___ to trigger contraction.
1 micomolar (or 10-6 M)
How does calcium cause contraction?
It binds to TnC in the troponin complex to cause a conformational change in tropomyosin, revealing the actin binding sites for myosin to bind to.
the A band has ___ fibers
the I band has ____ fibers
A = myosin
I = actin
Which are the dihydropyridine receptors?
the L calcium channels
What molecule needs to be present in order for contraction to occur besides Ca++?
ATP - that's where the energy comes from