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Striated muscle

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There are different types of muscle tissue in the human body , one of them is striated muscle , which corresponds to 90% of the total muscle mass that all human beings have. This type of muscle is made up of a series of long fibers which are also surrounded by a cell membrane.

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What is a striated muscle?

Striated muscle is a type of compound muscle cells form cylindrical and longer known by the name of fibers muscle which overlap in fascicles that are separated by means of the connective tissue .

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  • Characteristics of skeletal muscle
  • Types
  • Striated muscle function
  • Structure
  • Contraction
  • Striated muscle location
  • Examples

Characteristics of skeletal muscle

Among the main characteristics that can be observed in striated muscle we mention the following:

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  • The length of the striated muscles can vary, reaching the total length of the muscle where they are.
  • The fascicles of striated muscles are composed of a large number of fibers muscle .
  • It has a dark red color which it obtains thanks to its vascularity.
  • It is found throughout the entire human body.
  • They have excellent tonicity , elasticity , excitability and also can be easily contracted .
  • They can, after relaxing, return to their natural form.
  • Its muscle fibers are elongated in shape and have several cell nuclei.
  • They have myofibrils in large numbers.
  • The diameter of the muscle fibers of the skeletal muscle can vary between 10 and 100 micrometers.
  • Its fundamental unit is known as the sarcomere .

Types

There are two main types of striated muscles. The first group corresponds to the striated cardiac muscle, which is generally known as the myocardium . It forms the muscles of the heart and is characterized by being elongated, having a single nucleus and by working involuntarily with the heartbeat. It is fully regulated by the autonomic nervous system and, depending on the state of activity that a person has, this is how their frequency will behave.

A second group corresponds to skeletal skeletal muscle whose main function is to allow the human skeleton to move and join other structures through connective tissue and collagen , which when contracted make it possible for the body to move. This group functions voluntarily and for this reason, it is completely regulated by the central nervous system .

Striated muscle function

Striated muscles have several functions, but the main one is to allow the body to be mobilized because, when inserted into the bones through the connective tissue, tendons are formed which in turn function as a type of lever that makes it possible the contraction and muscle relaxation achieving the bones and joints can move properly.

They are responsible for, in addition to shaping the human body , they also help to maintain stability , produce heat and provide information to the brain about the different positions that the body acquires. They help pump the blood so that it does not stay in the lower part of the body, they also regulate and generate energy . It mobilizes the bones, tendons and joints in a synchronized way.

Structure

Striated muscles are composed of a superficial fascia that is located between the skin and the dermis, which is also made up of adipose and connective tissue , nerves and blood vessels . It also has an internal fascia which is made up of connective tissue , is irregular and is made up of a series of collagen fibers. Its cells have several nuclei and also little amount of cytoplasm, instead, it contains a greater amount of myofibrils . Sarcomeres , thick and thin filaments , are also found in its structure.

Contraction

The contraction of a muscle refers to a process by means of which a muscle is tensed causing it to contract or relax thanks to a previous stimulus. Striated muscles have in their structure a series of nerves , motor neurons , fibers and vessels that also have a series of striations that contain myofibrils that allow them to contract properly. This contraction makes possible the movements of the bones, tendons and cartilage that make up the skeleton.

When the muscle is in a relaxed state , protein fibers known as myosins and actins overlap each other. This type of contraction occurs by the union of cytoplasmic calcium ions with troponin , a substance that covers actin. At the moment in which a motor neuron exerts pressure on the muscle, the release of acetylcholine occurs in the muscle cells, thereby causing a depolarization of the membrane.

Striated muscle location

The striated muscle can be located in the heart and, being part of all the voluntary muscles, it can be found in practically the entire human body , in the arms, legs, neck, back, abdominal wall, buttocks, etc. They can be located in groups: the muscles that are responsible for maintaining good posture , the muscles that have the function of applying force and the muscles that have to produce force for long periods of time.

Examples

Some examples of striated muscles are as follows:

  • Twins
  • Biceps
  • Triceps
  • Pectorals
  • Deltoid

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