Muscle tissue:

Muscle tissue allows movement. Muscles tissue consists of muscle cells which respond to stimulus. The can contractile i.e. they can be shorten and generate the pulling force.

Types of muscle movements:

There are two types of muscle movement.

ü  Voluntary:

The movements which are in our control are called voluntary movements. For example a person decision to read a book.

ü  Involuntary:

The movements which are not in our hand are called involuntary movements. For example you pull your hand when it touches to a hot thing.

According to structure and function, skeletal muscles are classified into three types.

ü  Cardiac muscle

ü  Smooth muscle

ü  Skeletal muscle

Cardiac muscle:

The muscle which forms the contractile walls of heart is cardiac muscle. The cells of cardiac muscle are known as cardiomyocytes. These cells appear striated under microscope. Cardiomyocytes are single cells with a single nucleus located in the center. The muscular tissue of the heart is called myocardium. Cardiomyocytes contract on their own intrinsic rhythm without any external stimulation.

Intercalated discs:

The specialized cell junctions through which cardiomyocytes attach to each other are called intercalated discs. Anchoring junctions and gap junctions are present in intercalated discs.

Function of cardiac muscle is pumping of blood through the body. They pump blood through arteries and veins to the heart. Cardiac muscles are involuntary in their action. They are not in our control.  Cardiac muscle tissues are only found in the heart.

Smooth muscle:

Smooth muscle consists of sheets of smooth muscle cells. Actin and myosin fibers supported by a framework of other proteins are present in the smooth muscle. The contraction in the smooth muscles is responsible for involuntary actions in the internal organs.  The contractile components of digestive system, urinary system and reproductive system are formed by smooth muscles. It also forms the airways and arteries. It consists of single nucleus and has no visible striations. The cell shape is spindle.

In circulatory system, smooth muscle plays a vital role in blood pressure control and maintenance. It also controls the flow of oxygen throughout the body.

Smooth muscle is also responsible for contracting the iris, small hair raise on your arm, sphincters contracting in our body.

Skeletal muscle:

It is oneof the major types of animal tissues. It is striated muscle tissue which is in voluntary control of somatic nervous system. Skeletal muscles are attached to bones by bundles of collagen fibers called tendons. Skeletal muscle contraction makes locomotion, facial expression, posture and other voluntary actions of body possible. The forty percent of our body consists of skeletal muscle. Heat is produced as by product in skeletal muscle contraction.  Shivering is an involuntary contraction of skeletal muscle in response of low body temperature.

The cells of muscle are called myocytes. The number of myocytes remains constant throughout the life. Skeletal muscle appears striated having many nuclei. The striations are due to regular alternations of actin and myosin proteins.

Function of skeletal muscle is to move the body. It also protects the internal organs. It provides support and helps in blood cell formation.