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๐ฌ Think about it
You decide to lift a bag, and your arm obeys. But your heart beats and your food moves through your gut without you thinking about it. Different muscles do these jobs. Let us meet the three kinds.
What are skeletal muscles?
- They carry out voluntary movements, under our control.
- They are attached to the skeleton.
- Their cells are long, cylindrical muscle fibres.
- These fibres are unbranched, multinucleate and striated.
What are smooth muscles?
- They carry out involuntary movements, without our control.
- They are found in organs like the stomach and intestines.
- Their cells are spindle-shaped with a single nucleus.
- They lack striations and help in slow movements like digestion.
Example:
Smooth muscles push food slowly along the intestine without you thinking about it.
What are cardiac muscles?
- They are found only in the heart.
- Their fibres are cylindrical and branched with a single nucleus.
- They have faint striations.
- They work tirelessly and rhythmically, so the heart never stops.
Important Points
- Skeletal muscle does voluntary movement and is striated.
- Smooth muscle does involuntary movement and lacks striations.
- Cardiac muscle is found only in the heart and never tires.
โ Test Yourself
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Which muscle carries out voluntary movement?
View Answer
Skeletal muscle. -
Where are smooth muscles found?
View Answer
In organs like the stomach and intestines. -
Which muscle is found only in the heart?
View Answer
Cardiac muscle. -
Which muscles are striated?
View Answer
Skeletal muscle (strongly) and cardiac muscle (faintly).
Important Definitions
- Voluntary movement — movement under our conscious control, done by skeletal muscle.
- Involuntary movement — movement without conscious control, done by smooth and cardiac muscle.
- Cardiac muscle — branched muscle found only in the heart that beats without fatigue.
