Junior Class 5 Answered

Muscles can contract and relax. Thus, they help in the movements of the body.

Two kinds of muscles are: - 

(a) Voluntary muscles: These are under the control of the will of an individual.
(b) Involuntary muscles: These are not under the direct control of an individual. They work on their own. These mucles control heart, kidney, stomach. 

Further muscles can also be classified as:  -

i)Skeletal muscles - These muscles helps in movements and usually attached to the bones. 

ii) Smooth muscles - Smooth muscles are involuntary muscles. These muscles are present in stomach, eyes, digestive system. 
iii) Cardiac muscles: They are involuntary and found only in the heart.