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10. Review the two figures below and compare the condition of the sarcomere afte

ID: 3521212 • Letter: 1

Question

10. Review the two figures below and compare the condition of the sarcomere after contraction at rest and (a) Sarcomere at rest (b) Sarcomere after contraction A band l band A band I band Z line H band Z line H band Z line Z line a. Which band(s) change in length during contraction? b. Which band(s) do not change in length during contraction? the terms in the list below. Excitation-contraction coupling T tubules Acetylcholine Cisternae . Sodium ions Sarcoplasm At a neuromuscular junction, synaptic vesicles release which binds to receptors on the motor end plate and initiates an influx of 12. Describe the role that each of the following has in the contraction of a muscle fiber according to the sliding filament theory. a. The power stroke: An action potential spreads along the sarcolemma and b. Calcium ions: causing the release of calcium ions from the reticulum and c. Troponin-tropomyosin complex: Photo Credits: 10-01-01 Steve Downing/Pearson Education, Inci 10-02-02 Wood/Science Source: 10-03-01 Biophoto Associates/Science Source Pre-lab Quiz Answers 1. d: 2. False: 3. model of a neuromuscular skeletal muscle fiber: 4.True: S. False: 6. sarcomere: 7, synaptic e neuromuscular junction; 9. False: 10. True junction, model of a Introduction to Skeletal Muscie 142

Explanation / Answer

Answer 10.

A) Bands that change length

B. Bands thst do not change length

ANSWER 11.

A. Acetylcholine

B. Sodium

C. T tubule

D. Cisternae

ANSWER 12

A. The power stroke describe pulling of actin towards the midline ot M-line. In relaxed state Myosin head is bound to ATP but when it is activated by binding with actin then ATP is hydrolyzed and Pi is released which pulls actin towards M line and cause muscle contraction.

B. Calcium is important for activation of Actin. There is increase in intracellular calcium during action potential in muscle. This calcium binds to troponin which cause conformational change in Tropomyosin which is then released from active site of actin. Now Myosin can bind to actin and cause muscle contraction.

C. Troponin - Tropomyosin complex are regulatory protein. They regulate binding of Actin to Myosin. In relaxed state Tropomyosin is bound at active site of Actin which prevent binding of Myosin to actin. Troponin is bound to Tropomyosin and regulate it's function. When intracellular calcium ion increase, the calcium ion bind to troponin which cause Tropomyosin to be released from actin. Now Myosin can bind to actin.

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