Describe the process of muscle excitation from neural signal at the synapse junc
ID: 3509492 • Letter: D
Question
Describe the process of muscle excitation from neural signal at the synapse junction of the motor neuron to the activation of the myosin/actin crossbridge. Include the following terms in your description: sarcoplasmic reticulum, t-tubule, troponin, tropomyosin, Ca2*, ATP, actin, myosin, ACb, Acetylcholinesterase, mitochondria, binding site, power-stroke. 2. 3. What are the z-discs? What is their role in muscle contraction? 4. What is titin? What role does it play? How is the force-length curve affected by titan?Explanation / Answer
When action potential reaches Dihydropyridine receptor located at the t-tubule,it caused confirmational change which opens Ryanodine receptor of sarcoplasmic reticulum.As a result,Ca ions comes out of SR into sarcoplasm.As soon as Ca is available,it binds to Troponin C causing confirmational change causing Tropomyosin C to slide exposing the Active site. Then occurs Power stroke in which ATP attaches to myosin head.Confirmational change in it causes hydrolysis of ATP by ATPase and again the myosin head reaches to high energy state which is called recocking of myosin head.the neurotransmitter Ach at the NMJ is later degraded by acetylcholinesterase.
3:z line is the border that separates and links sarcomere with skeletal muscle.1 sarcomere lies between 2 z lines.
Actin molecules which are involved in muscle contraction are bound to z lines
4:Titin binds z lines to M lined.
It is the largest known protein.it is responsible for elasticity.
There is enhanced Titin based force in a myofibril which actively stretches
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