Question

Please answer all questions.

6. If tropomyosin is never moved off actin, what would be the result?

7. If you died, why would you develop rigor mortis?

8. All of the motor units in the fingers were very large (many muscle fibers per motor unit. How would this affect function?

9. If the calcium (Ca++) pumps did not function how would this affect muscles?

Answer 1

6. Increased calcium concentration in the cytosol causes muscle contraction by the action of two proteins called 'tropomyosin' and 'troponin'. These proteins binds to actin filaments. Tropomyosin is bound to actin filaments along their groove. But, in a striated muscle, tropomyosin binds to troponin and when the calcium concentration is low, the complex of tropomyosin and troponin blocks the interaction of actin and myosin and the muscles does not contract. At high concentrations, calcium binds to troponin and shifts the position of the complex, by relieving its inhibition and allowing it to contract. So, if the tropomyosin is never moved off actin, the muscle does not contract.

7. Rigor mortis is a condition of stiffening of bone and muscles of body after death. If we died, rigor mortis occurs just after three to four hours of our death and it lasts for about one to four days after our death. Rigor mortis occurs after our death because when the pumping system of our body stops working after our death, calcium starts to flood our cells, causing our muscles to contract and gets stiffened. This stiffening is called rigor mortis and this occurs after our death.

8. The large motor units in the fingers contracts along with the small motor units and all the muscle fibers the single muscle gets activated. This activation produces maximal muscle force. Large motor units are composed of faster muscle fibers and they generate higher forces. In this way, large motor units in fingers affects the muscle.

9. Calcium pumps plays a crucial role in our body for the active transport of calcium and it also helps in proper signaling and intracellular calcium lower than extracellular concentration in our body. If these calcium pumps stops working, muscle cramps occurs. When the calcium pumps stop working, calcium cannot be circulated and the blood clot will not occur in our body.

Thank you!