Muscle Fibres – Class 11 | Chapter – 20 | Biology Short Notes Series PDF

Muscle fibres consist of a single muscle cell. They help to control the physical forces within the body. The Function of muscle fibre is to control the physical forces which are moving through the human body. A muscle fibre is composed of many long cylindrical-shaped fibres which are nearly 0.02 to 0.08 mm in diameter.

Types of Muscle Fibres

Now let’s discuss the various types of skeletal muscle fibre. 

There are mainly three types of muscle fibre namely:

1. Slow Oxidative (SO) Fibre:

These are the types of muscle fibre that contract slowly, they show slow contractions and use aerobic glucose and oxygen for producing ATP.

2. Fast Oxidative(FO) Fibre:

These are the type of muscle fibre that contract fastly and use aerobic respiration as well as anaerobic respiration. That is why they can get tired more quickly than the Slow oxidative fibres.

3. Fast Glycolytic (FG) Fibre:

These types of fibre have fast contractions and These fibres are slightly larger in diameter, they help in times of fatigue and help the body to be resistant towards fatigue.

 Structure of a Muscle Fibre

 Structure of a Muscle Fibre

  • Each muscle fibre is a single cylindrical muscle cell. A single skeletal muscle can be made up of hundreds or even thousands of muscle fibres bundled together which are wrapped in a connective tissue covering. 

  • Every muscle has a connective tissue sheath, which is called the epimysium. 

  • Outside the epimysium, a connective tissue known as fascia is present which further separates the muscles. 

  • Every bundle of muscle fibre known as a fasciculus has a layer of connective tissue known as the perimysium.

Location of a Muscle Fibre

Different types of muscle fibres are located in different parts of the human body.

  • The cardiac muscle fibres are located in the walls of the heart and are under involuntary control. 

  • The smooth muscle fibres are located in organs like the intestines, pancreas, and liver and are also under involuntary control. 

  • Skeletal muscle fibres are there in the muscles which are attached to the skeleton.

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By Team Learning Mantras