What is the function and location of smooth muscles?

Answer 1

Smooth muscle can be found in multiple places, like the eyes and skin. In the eyes it makes pupils dialate in reaction to light. In the skin it contracts in reaction to cold; pulling hair on the body up to trap a layer of warm air above the skin. (this also causes goose bumps)

Answer 2

smooth muscle

The cardiovascular, gastrointestinal, genitourinary, and respiratory systems are composed mostly of hollow organs (tubular or sacular), which transport and/or store fluids (either liquids or gases) within the body. The walls of these organs contain smooth muscle, a type of tissue which enables them to constrict or dilate, in this way retarding or facilitating fluid movement as required. This is accomplished by the shortening or lengthening of the individual smooth muscle cells, which occurs in a co-ordinated fashion because the cells are electrically coupled by intercellular connections, known as gap junctions. Other structures in the body that contain smooth muscle include the myometrium - the muscular wall of the uterus - which is responsible for the rhythmic contractions of labour; the piloerector muscles, which cause skin hair to stand up; and the irises, which control the diameter of the pupils.

Function

Smooth muscle thus subserves all internal, involuntary functions, except the movements of breathing and the beating of the heart. Many directly acting chemical agents affect its contraction, but most smooth muscle is also under the control of the autonomic nervous system; in some sites (notably most blood vessels) it is influenced only by the sympathetic component, and at others (for example in the gut and the iris) by dual, and sometimes opposite, effects of sympathetic and parasympathetic nerves.

As befits its many functions, smooth muscle at different sites is much more heterogeneous than skeletal or cardiac muscle. By creating diverse structural arrangements of smooth muscle and other associated cells, and at the same time varying the mechanisms that control contraction, evolution has achieved a remarkable diversity of smooth muscle-containing organs, each of which is designed to fill a unique functional niche.

Location

Found within the "walls" of hollow organs and elsewhere like the bladder and abdominal cavity, the uterus, male and female reproductive tracts, the gastrointestinal tract, the respiratory tract, the vasculature, the skin and the ciliary muscle and iris of the eye. The glomeruli of the kidneys contain a smooth muscle like cell called the mesangial cell. Smooth muscle is fundamentally different from skeletal muscle and cardiac muscle in terms of structure and function.

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