Question

1. How is the contraction of a skeletal muscle cell different than the contraction of a smooth muscle cell? How does this aid in each muscle cell's function? 2. What is the purpose of myoglobin in slow-twitch muscle fibers? Why is there more myoglobin in slow-twitch muscle fibers than in fast-twitch fibers? 3. What is the purpose of gap junctions in cardiac muscle cells and some smooth muscle cells?

Answer 1

1. In the contraction big skeletal muscle there is the utilisation big more ATP. The calcium ions that enter the sarcoplasm binds to the troponin and remove troponin tropomyosin blockage and make the active sites of actin ready for the myosin head to bind. Along with that ATP in the myosin head turs to ADP utilising energy. In smooth muscle the calcium that enters the sarcoplasm combines with calmodulin and stimulate myosin light chain kinase which phosphorylate myosin and cause the contraction. There is no tropin blockade bin this

2. Slow twitch muscles need energy to contract. Along with that it need oxygen supply for the energy utilisation and contraction. So myoglobin is the protein that stores the oxygen in the slow twich muscle to make the constant supply big oxygen to the muscle. In fast twitch muscle they use anaerobic means to produce energy for the muscle contraction so they need less oxygen. So the myoglobin presence is less in the fast twitch muscle

3. Smooth muscles and cardiac muscles are involuntary muscles. They work for a long time. So they need the current to spread through them for a long time. As the cells depolarised they transfer the current from one cell to another through bthia gal junction. In heart the depolarised current is spread much faster to produce the contraction of heart chambers.