Acetylcholine binds to the muscle cell membrane, causing a temporary rush of calcium ions into the muscle cell. This influx of calcium triggers muscle contraction.
If enough ACh is released, the sarcolemma at that point becomes temorarily more permeable to sodium ions, which rush into the muscle cell and to potassium ions which diffuse out of the cell. Although more sodium ions enter than posassium ions leave.
Sodium ions (Na+) enter the muscle cell during the depolarization phase of an action potential, causing the cell membrane to become more positively charged. This influx of sodium ions is responsible for the rapid rise in membrane potential.
Calcium ions are stored in the sarcoplasmic reticulum of muscle cells. These ions play a crucial role in muscle contraction by triggering the release of more calcium ions into the muscle cell, leading to the contraction of the muscle fibers.
Transmitting a muscle impulse into the interior of the cell involves depolarization of the cell membrane through the opening of voltage-gated sodium channels, allowing sodium ions to rush into the cell. This depolarization then triggers the release of calcium ions from the sarcoplasmic reticulum, leading to muscle contraction.
sodium and potassium
The binding of neurotransmitters to receptors on the muscle membrane triggers the opening of ion channels, allowing sodium ions to enter the muscle cell. This influx of sodium ions initiates an action potential, leading to muscle contraction.
It is the Terminal Cisternae- Sac like regions of the sarcoplasmic reticulum that serve as specialized resevoirs of calcium ions
Excitation coupling is the process by which an action potential in a muscle cell triggers the release of calcium ions from the sarcoplasmic reticulum, leading to muscle contraction. The steps of excitation coupling in muscle cells involve depolarization of the cell membrane, activation of voltage-gated calcium channels, release of calcium ions from the sarcoplasmic reticulum, and activation of the contractile proteins within the muscle cell.
sarcoplasmic reticulum (SR)
The graded potential generated along the muscle cell membrane is known as an action potential. This is an electrical signal that travels along the membrane of the muscle cell, leading to muscle contraction. It is initiated by the movement of ions across the membrane in response to a stimulus.
The chemical that triggers the sliding of muscle filaments is calcium ions. When muscle cells receive a signal to contract, calcium ions are released into the muscle cell, binding to specific proteins and initiating the sliding mechanism between actin and myosin filaments in the muscle cells.