GROSS ANATOMY

Detailed explanation-1: -Muscles contract in response to depolarization, activation of G-protein-coupled receptors and other stimuli.

Detailed explanation-2: -Under normal conditions, membrane depolarization triggers an influx of calcium and this calcium serves as an activator source for contraction. A number of studies have found that gastrointestinal smooth muscles do not show spontaneous contractile activity during exposure to calcium-free solution.

Detailed explanation-3: -Depolarization does not mean contraction. Depolarization is a process where a cell’s membrane potential becomes more positive. In certain types of contractile tissue, such as muscle or heart tissue, this can result in contraction.

Detailed explanation-4: -In the process of depolarization, the negative internal charge of the cell temporarily becomes more positive (less negative). This shift from a negative to a more positive membrane potential occurs during several processes, including an action potential.

Detailed explanation-5: -When the electrical signal of a depolarization reaches the contractile cells, they contract. When the repolarization signal reaches the myocardial cells, they relax.