Muscular system / What is a muscular system?

A muscular system is a system of the body consisting of muscle cells having contractile elements.
Muscles
Qn. What are muscles?
Muscles are bundles of elastic substances found in the body of an animal.
Types of muscles
Qn. Name the two types of muscles.
Voluntary muscles / skeletal muscles / striped muscles.
Involuntary muscles / smooth muscles.
a) Voluntary muscles
Qn. What are voluntary muscles?
Voluntary muscles are muscles whose movement can be controlled.
Or
Voluntary muscles are muscles whose movement is under one’s will.
Qn. State the characteristics of voluntary muscles.
Voluntary muscles are fibrous.
Voluntary muscles get tired quickly.
Movement of voluntary muscles is under one’s will.
Qn. Identify the examples of voluntary muscles.
Biceps muscles (flexor muscles)
Triceps muscles (Extensor muscles)
Thigh muscles
Quadriceps
Note:
The biceps and triceps muscles are regarded as antagonistic muscles.
Qn.What are antagonistic muscles?
Antagonistic muscles are muscles that work in pairs and have opposite effect on each other.
Qn. Why are the triceps and biceps regarded as antagonistic muscles?
Biceps and triceps muscles work in pairs and have opposite effect on each other.

Qn. State what happens to the following muscles when the arm is straight.
a) Biceps

The biceps relaxes.
b) Triceps
The triceps contacts.
Qn. State what happens to the following muscles when the arm is bent.
a) The biceps
The biceps contracts.
b) Triceps
The triceps relaxes.
Note:
Biceps muscles are called flexor muscles because they bend the arm / leg.
Triceps are called extensor muscles because they extend /stretch the arm / leg.