What is smooth muscle depolarization?
What is smooth muscle depolarization?
Many SMCs are activated by membrane depolarization (ΔV) that opens L-type voltage-operated channels (VOCs) allowing external Ca2+ to flood into the cell to trigger contraction. This depolarization is induced either by ionotropic receptors (vas deferens) or a membrane oscillator (bladder and uterus).
What causes depolarization of smooth muscle?
Depolarization of smooth muscle cells induced by the change in intraluminal pressure and/or tissue-stretch produces an increase in the intracellular [Ca2+], consequent myosin light chain phosphorylation and contraction (for review, see [14]).
What is depolarization in muscle contraction?
muscle contraction The channels are opened by depolarization (an increase in membrane potential) of the nerve terminal membrane and selectively allow the passage of calcium ions. In muscle: The frequency of contraction.
What causes action potential in smooth muscle?
Smooth muscle action potentials are unique in that membrane potential acts to initiate or modulate contraction. As such, graded membrane response can become stimulated by multiple factors, including local humoral factors, circulating hormones, or mechanical stimulation like stretching of the cells.
What happens depolarization?
Depolarization occurs when a stimulus reaches a resting neuron. During the depolarization phase, the gated sodium ion channels on the neuron’s membrane suddenly open and allow sodium ions (Na+) present outside the membrane to rush into the cell.
What causes the depolarization of the contractile cells?
Voltage gated sodium channels in the membrane of the contractile cells open allowing sodium to move into the cell. This results in a reversal of charge (depolarization) (to about +25 mV) as sodium moves into the cell.
Where does depolarization happen in the muscle tissue?
Skeletal Muscles The opening of sodium channels causes depolarization of the skeletal muscle. The action potential from the motor neuron also travels through the T-tubules. It causes the release of Ca2+ ions from the sarcoplasmic reticulum. Thus, contraction of skeletal muscle occurs.