Page 28 - Future Stars Science Explorer-5

Our heart, stomach, and intestines are also made up of muscles. Muscles are
attached to bones by strong bands of tissues called tendons.

How do Muscles Work?

Muscles of the body can only pull, they cannot push. Therefore, Two

muscles are required to move a bone at a joint. Muscles work in pairs by
contracting and stretching (relaxing).

For example, to move the lower arm up
and down, two muscles called the Humerus

biceps and triceps are required. When Origin
we raise our lower hand, the biceps in Radius Biceps
the front become shorter by contraction

and the triceps at the back stretch to
pull up the arm. When we lower our Ulna

arm, the triceps at the back contract and
the biceps stretch to pull the arm down. Triceps
muscle

Types of Muscles Muscles

Our muscular system consists of three different types of muscles.

1. Voluntary muscles : These muscles are under our control. We can use
them as we like. These muscles have stripes on them, just like the stripes on

the body of a zebra. That is why they are also called striated muscles. These
muscles are present in our arms, legs, hands, and feet.

2. Involuntary muscles : Some muscles in our body are not under our
control. For example, we cannot control our stomach muscles. They work

on their own. They are controlled by the brain and the spinal cord.
Involuntary muscles are also called smooth muscles.

Voluntary muscles Involuntary muscles Cardiac muscle cell
(Striated muscle cell) (Smooth muscle cell) (Heart muscle)

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