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Smooth muscle is grouped into two types: single-unit smooth muscle, also known as visceral smooth muscle, and multiunit smooth muscle. Most smooth muscle is of the single-unit type, and is found in the walls of most internal organs (viscera); and lines blood vessels (except large elastic arteries), the urinary tract , and the digestive tract .
This action potential is transmitted to other smooth muscle cells via gap junctions, creating a peristaltic wave. The specific mechanism for the contraction of smooth muscle in the GI tract depends upon IP3R calcium release channels in the muscle. [4] Calcium release from IP3 sensitive calcium stores activates calcium dependent chloride ...
The spike potentials last 10 to 40 times as long in gastrointestinal muscle as the action potentials in large nerve fibers, each gastrointestinal spike lasting as long as 10 to 20 milliseconds. [1] Conduction of nerve impulse, depolarization is the first stage of conduction.
A depiction of a slow wave, contraction and electrical threshold in relation to smooth muscle tone and resting membrane potential.. Gastric slow waves occur at around 3 cycles-per-minute in humans and exhibit significance variances in both amplitudes and propagation velocities in the stomach [8] [9] [10] due to the existence of a gradient of resting membrane potential gradient, [11 ...
The action potential in a normal skeletal muscle cell is similar to the action potential in neurons. [61] Action potentials result from the depolarization of the cell membrane (the sarcolemma), which opens voltage-sensitive sodium channels; these become inactivated and the membrane is repolarized through the outward current of potassium ions ...
Skeletal muscle, smooth muscle, bone (osteoblasts), ventricular myocytes** (responsible for prolonged action potential in cardiac cell; also termed DHP receptors), dendrites and dendritic spines of cortical neurones P-type calcium channel ("Purkinje") /Q-type calcium channel: HVA (high voltage activated) Ca v 2.1 : α 2 δ, β, possibly γ
In cardiac and smooth muscle an electrical impulse (action potential) triggers calcium ions to enter the cell through an L-type calcium channel located in the cell membrane (smooth muscle) or T-tubule membrane (cardiac muscle). These calcium ions bind to and activate the RyR, producing a larger increase in intracellular calcium.
These slow wave potentials must reach a threshold level for the action potential to occur, whereupon Ca 2+ channels on the smooth muscle open and an action potential occurs. As the contraction is graded based upon how much Ca 2+ enters the cell, the longer the duration of slow wave, the more action potentials occur. This, in turn, results in ...