Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
The human body has more than muscles that help in movement, maintain posture, and circulate blood.
Muscles are attached to the bones by strong, thread-like structures called tendons.
Muscles work by contracting (becoming shorter and tighter) and relaxing (returning to their original size).
Muscles always work in pairs; when one muscle contracts, the other relaxes to produce movement.
Voluntary Muscles: These are muscles we can control at our will, such as those in our arms and legs ( lifting a bag).
Involuntary Muscles: These work automatically without our conscious control, such as the muscles in the heart and stomach.
The heart is made of a special type of involuntary muscle called the cardiac muscle.
To keep our muscular system healthy, we need regular exercise and a diet rich in proteins ( milk, eggs, pulses).
📐Formulae
💡Examples
Problem 1:
If you want to bend your arm at the elbow to touch your shoulder, what happens to the biceps muscle?
Solution:
The biceps muscle contracts.
Explanation:
To pull the lower arm bone upward, the biceps muscle on the front of the upper arm must shorten or contract, while the triceps muscle at the back relaxes.
Problem 2:
Classify the following as Voluntary or Involuntary: (a) Heart beating (b) Kicking a football.
Solution:
(a) Involuntary, (b) Voluntary
Explanation:
The heart beats on its own without us thinking about it (Involuntary), whereas kicking a ball is an action we choose to perform (Voluntary).
Problem 3:
Why do muscles work in pairs to move a bone?
Solution:
Muscles can only pull, they cannot push.
Explanation:
Since a muscle can only pull a bone by contracting, another muscle is needed on the opposite side to pull the bone back to its original position.