Muscle Phsyiology - Actin, myosin, Troponin and troponmysoin.

Question 1

What are thick filaments made up of ?

Answer 1

only myosin

Question 2

What are thin filaments made up of ?

Answer 2

Actin, troponin and tropomyosin are thin filaments.

Question 3

What are the three classes of protein in the muscle ?

Answer 3

• Contractile
• Regulatory
• Anchoring

Question 4

What are the contractile proteins?

Answer 4

Myosin and actin are the contractile proteins – these are the only ones which take place in the process of muscle contraction. And shortens the sarcromere.

Question 5

Explain whats happening here

Answer 5

In the first picture, all the actin sites are covered by tropomyosin, so myosin cannot bind to the actin, which is why it is RESTING.

Whenever calcium binds to troponin, the tropomyosin pulls away from the actin. This exposes the myosin-binding sites on the actin. Then, the myosin attaches to the actin, shortening the sarcomere and contracting the muscle.