The Bio Brief

Basic Idea

• Nervous tissue carries messages (nerve impulses).
• Muscle tissue does the actual work (movement).
• When a nerve message reaches a muscle, the muscle contracts and causes movement.

 Nervous tissue controls, muscle tissue acts.

How Does a Muscle Move?

Step-by-step Explanation

• A nerve impulse reaches the muscle fibre.
• The muscle fibre responds by changing its shape.
• It becomes shorter and thicker.
• This shortening is called muscle contraction.
• Contraction causes movement of body parts.

What Happens Inside a Muscle Cell?

At the cellular level:

• Muscle cells contain special proteins.
• These proteins:
  • Change their shape
  • Change their arrangement
• This happens in response to electrical nerve impulses.
• The rearrangement makes the muscle cell shorter.

Flow Chart: Nervous Tissue Causing Action

Stimulus
⬇
Nerve impulse generated
⬇
Impulse travels through neuron
⬇
Impulse reaches muscle cell
⬇
Muscle proteins rearrange
⬇
Muscle shortens (contracts)
⬇
Movement occurs

Simple Diagram (Text Form)

Nerve Impulse

      ↓

Muscle Cell

      ↓

Protein rearrangement

      ↓

Muscle contraction

      ↓

Movement

Types of Muscles

1. Voluntary Muscles

• Under our control
• Work according to nerve signals from the brain
• Found in arms, legs, face

Examples:
Walking, writing, lifting a bag

2. Involuntary Muscles

• Not under our control
• Work automatically
• Controlled by nervous system without thinking

Examples:
Heartbeat, movement of food in stomach, breathing

Differences Between Voluntary and Involuntary Muscles

Voluntary Muscles	Involuntary Muscles
Under conscious control	Not under conscious control
Controlled by brain	Controlled automatically
Found in limbs	Found in internal organs
Act slowly and carefully	Act continuously

Key Points to Remember

• Nervous tissue sends electrical impulses
• Muscles respond by contracting
• Muscle contraction is due to protein changes
• Nervous system decides → muscles perform
• Movement is a result of coordination between nerves and muscles