Respuesta :
Answer:
1.An action potential is conducted deep into the muscle fiber by the T tubule.
3.The membranes of the sarcoplasmic reticulum become more permeable to calcium ions.
4.Calcium ions diffuse into the sarcoplasm around the myofibril.
2.Calcium ions bind to troponin.
5.The troponin-tropomyosin complex moves exposing active sites.
Explanation:
The arrival of a nerve impulse at synaptic end bulbs stimulates the release of acetylcholine into the synaptic cleft. The acetylcholine binds to its receptors located on the motor end-plate followed by the opening of ion channels to allow the small cations such as Na+ to enter the muscle fiber and make it positive.
The change in the membrane potential triggers the action potential that propagates along the sarcolemma into the T tubules. The action potential stimulates the release of calcium ions from the sarcoplasmic reticulum into the sarcoplasm.
The released calcium ions combine with troponin. Binding of calcium ions to troponin stimulates conformational change in troponin that makes the tropomyosin to shift away from the myosin-binding sites of actin.
The myosin heads join the free binding sites to form cross-bridges leading to contraction of muscle fiber.
Answer:
Action potential is defined as the rapid change in the electric potential of the muscle or nerve cell. The correct sequence of action potential is:
1.An action potential is conducted deep into the muscle fiber by the T tubule.
3.The membranes of the sarcoplasmic reticulum become more permeable to calcium ions.
4.Calcium ions diffuse into the sarcoplasm around the myofibril.
2.Calcium ions bind to troponin.
5.The troponin-tropomyosin complex moves exposing active sites.
Explanation:
Action potential commonly referred to as an impulse is a change in the electric potential of a cell during the transmission of an impulse. The action potential starts with the release of acetylcholine into the synaptic cleft. The receptors bind to the acetylcholine, which initiates the opening of ion channels. These channels allow molecules such as sodium to enter the muscles fibers and adding the positive charge.
The action potential is triggered due to the change in electric potential that occurred at sarcolemma's T tubules. This stimulates the permeability of the calcium ions from the sarcoplasmic reticulum into the sarcoplasm. The calcium ions combine with troponin, which undergoes conformational changes and making it into tropomyosin. tropomyosin shifts away from the myosin-binding sites. Thus, myosin forms the cross-bridges by binding to the free sites, which eventually leads to the contraction of muscle fiber.
Thus the correct sequence of action potential in muscles fiber is 1, 3, 4, 2, and 5.
For Further Reference:
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