Chapter 4

Question 1

How contraction takes place within the sarcomere. Discuss the process of actin and myosin?

Answer 1

Actin and myosin are interlocking thin and thick filaments.Myosin the thicker filament has a pivoting head that cross bridges the with the actin. Two proteins are present in the actin troponin and tropomyosin. Calcium binds to these proteins which initiates boss bridge between myosin and actin which leads to contraction. In absence of calcium the two proteins bind to actin and prevent the cross bridge ensuring relaxation.

Question 2

Sarcoplasmic reticulum stores what?

Answer 2

calcium

Question 3

Once the heart contracts it will need to relax explain process of calcium moving back into the sarcolemma?

Answer 3

Calcium is moved back into the cell by the sarcoplasmic reticulum Ca pump and Na/Ca exchanger.

Question 4

Acetylcholine acts on what receptor?

Answer 4

Muscarinic receptors which reduces the action potential generated by the SA node.