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Muscle Tissue: – Characteristics, Structure, Types and Function

In this article we will discuss about the Muscle tissue: – Definition, Characteristics, Structure, Types and Function

Definition of Muscle Tissue

Muscle tissue is composed of cells that have the ability to shorten or contract in order to produce movement of the body parts.
Muscle fibres contract (shorten) in response to stimulation, then relax (lengthen) and return to their uncontracted state in a coordinated fashion. Their action moves the body to adjust to the changes in the environment and to maintain the positions of the various parts of the body.
In general, muscles play an active role in all the movements of the body

Properties of Muscular Tissue

Contractibility – Ability of muscle cells to shorten
Excitability – Muscle tissue responds to a stimulus delivered from neuron or hormone
Extensibility – Ability to be stretched
Elasticity – Ability to recoil back to its original length after being stretched

Structure of Muscular tissue

Muscular tissues are bundled together and surrounded by tough connective tissue known as epimysium
The tissue made of many muscle fibres (myocytes)
Fascicles are surrounded by a protective layer known as perimysium
Muscle fibres are composed of numerous fine myofibrils
Muscle fibres can contract and relax
Muscles take part in locomotion and movements

Types of Muscle Tissue

There are three types of muscle tissues in animal
1. Skeletal muscle
2. Cardiac muscle
3. Smooth muscle

1. Skeletal muscle

Skeletal muscles are attached to the skeleton
They are also known as striated muscles because of the presence of alternate patterns of light and dark bands
These light and dark bands are highly organized structures of actin, myosin, and proteins.
These add to the contractility and extensibility of the muscles
Skeletal muscles are also known as voluntary muscles
Skeletal muscle tissue is composed of long cells called muscle fibers that have multinucleated
They play a vital role in everyday activities

2. Smooth muscle

These muscle cells are spindle-shaped with a single nucleus
Smooth muscle is found in the walls of hollow organs throughout the body
These are non-striated, involuntary muscles controlled by nervous system
The actin and myosin filaments are very thin and arranged randomly, hence no striations
It stimulates the contractility of the digestive, urinary, reproductive systems and blood vessels

3. Cardiac Muscle Tissue

Cardiac muscle tissue is present only in the heart
They are single celled and uninucleate
The cells of the cardiac muscles known as the cardiomyocytes are striated
These are involuntary muscles and the heart pumps the blood through cardiac contractions
Muscle cells, unique junctions called intercalated discs (gap junctions)
Intercalated discs are the major portal for cardiac cell to cell communication

Function of Muscle Tissue

Functions of Skeletal Muscle

It maintains body posture nad regulates the body temperature
Skeletal muscles connects, controls the motions of the skeleton
It is responsible for performing muscular involuntary movements
It is responsible for the erect posture of the body. The sartorius muscles in thighs are responsible for body movement
The skeletal muscles protect the internal organs and tissues from any injury and also provide support to these delicate organs and tissues
These also support the entry and exit points of the body

Functions of a Cardiac Muscle

Cardiac muscle regulate the functioning of the heart by the relaxation and contraction of the heart muscles
The cardiac muscles function as involuntary muscle.
The cardiac muscles are also involved in the movement or locomotion.
The cardiac muscles work without stopping, day and night. They work automatically and make the heart contract so that the heart can squeeze the blood vessels and release them so that the heart can fill up with blood again.
The heart comprises a specialized type of cardiac tissue, which consists of “pacemaker” cells. These contract and expand in response to electrical impulses from the nervous system.

Functions of a Smooth Muscle

Like all other types of muscles, smooth muscles are also involved in contraction and relaxation. Other functions of smooth muscles include:
It is involved in the sealing of orifices.
It produces connective tissue proteins such as collagen and elastin.
Transports chyme (a pulpy acidic fluid) for the contractions of the intestinal tube.
Smooth muscle plays a vital role in the circulatory system by maintaining and controlling the blood pressure and flow of oxygen throughout the body.

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