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  • Muscles along with bones enable us to move and perform different activities
  • The cells are elongated and are called muscle fibres
  • The movement is possible due to special proteins called contractile proteins
  • The proteins contract and relax to cause movement

Based on the types of movement and where they are present, the muscles are of different types.


Striated muscles

  • Muscle cells are long, cylindrical, unbranched and multinucleate (having many nuclei).
  • Such muscles which we can move if we like to and control the movement is called voluntary muscle.
  • Since these are  mostly attached to bones and help in movement (for example movement of limbs), they are also called skeletal muscles.
  • When stained appropriately and observed under the microscope, they have alternate dark and light bands or striations . Thus they are called striated muscles.


Smooth muscles

Can you control the movement of muscles in our digestive system or the movement of your lungs ?

The movement of some muscle groups cannot be controlled by us and they are called involuntary muscles .

A few more example include:

  • Contraction and relaxation of blood vessels 
  • Muscles in iris of the eye
  • Muscles in ureters 
  • Muscles in the bronchi of the lungs

The cells are spindle-shaped (long with pointed ends) and uninucleate (having a single nucleus).

They have a rather smooth appearance and do not have dark and light striations when observed under the microscope.

Hence they are also called Smooth muscles or Unstriated muscles .


Cardiac muscles

  • The muscles in the heart are also involuntary, we cannot control the movement
  • However, the muscle tissue in the heart is different from other involuntary muscles
  • Heart muscle cells are cylindrical, branched and uninucleate. They have striations .
  • These involuntary muscles are called cardiac muscles and bring about contraction and relaxation of walls of the heart .

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Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 13 years and a teacher from the past 17 years. He teaches Science, Economics, Accounting and English at Teachoo