Smooth Muscle | Definition, Structure & Functions

By | November 21, 2019

Smooth Muscle

Smooth Muscles Definition:

Smooth muscle is defined as a form of muscle tissue that is used by various systems in order to apply pressure to vessels and the organs. The smooth muscles are made up of sheets or strands of smooth muscle cells. These cells contain fibers of actin and myosin that run though cells and are supported by frameworks of other many proteins. The smooth muscles contract under specific stimuli as ATP is free for use by myosin. The amount of ATP release on the basis of the intensity of stimuli and allow the smooth muscles to have a graded contraction as opposed to ‘on-or-off’ contraction of the skeletal muscle.

Image result for smooth muscle definition

Smooth Muscle Structure:

Smooth muscle tissue does not contain clearly defined striations visible on the cells, because the smooth muscle cells are organized in different ways than other muscle cells. In smooth muscles, the actin and myosin filaments are arranged in stacked patterns with across cells. This staircase arrangement of the actin and the myosin is different than the skeletal structure and the cardiac muscle. The actin filaments in smooth muscles flow from one side of the cell to the other end that connects at dense bodies and at the cell membrane. In smooth muscles, the actin and the myosin fibers arrange an angle together as they run through the cell.

The functions of Smooth Muscle:

The smooth muscles perform the functions in the contrast of other types of muscles.

In skeletal muscle, a single type of somatic nervous system traverses to muscle, where it stimulates organelle in the muscle cells in order to release calcium. The calcium is the cause of protein to detach from the actin and myosin fastly binds with the opening of actin.

But this is not the same done in smooth muscles. In smooth muscles, the somatic nervous system does not control the contraction, but by the signals from the autonomous nervous system. The smooth muscles are specialized in contract persistently. Instead of calcium trigger that sets off a contraction, the smooth muscles contain more of a throttle such as in a car.

Related image

Smooth Muscle Location:

The smooth muscle present in many regions of the body. It lines many parts of the circulatory system, digestive system and also responsible for raising the hair of arms.

In the circulatory system, the smooth muscle used for maintaining and controlling blood pressure and the flow of oxygen in the body. Smooth muscle also lines every vein and artery because the majority of pressure is applied by heart. These small muscles may contract in order to apply pressure to the system or relax in order to allow more blood to flow. These muscles also stimulated by the presence or absence of oxygen and modify the veins to provide enough oxygen when it is low.

Smooth muscle also lined the majority of the digestive system. The cells in the digestive system contain different stimuli than the cells in the circulatory system. The phenomenon which is responsible for moving of food through many twists and turns of the gut is known as Peristalsis.

Smooth muscle has the ability to contract and hold, so it is used for many functions in many areas of the body. The smooth muscle is also responsible for the contraction of the irises, raising the small hairs of the arm, contraction of many sphincters in the human body and even movement of fluid through the organs by applying the pressure to them.

Image result for smooth muscle location