The Bio Brief

Is spinal cord only for reflex actions?

 No.
We are thinking beings, so control and coordination cannot depend only on reflex actions.

• The spinal cord carries messages to and from the brain.
• Thinking, decision-making, and memory are done by the brain.

Central Nervous System (CNS)

The brain and spinal cord together form the Central Nervous System.

Functions of CNS:

• Receives information from all parts of the body
• Thinks and makes decisions
• Sends messages to muscles and glands
• Coordinates body activities

Peripheral Nervous System (PNS)

• Connects CNS to the rest of the body
• Made up of:
  • Cranial nerves (from brain)
  • Spinal nerves (from spinal cord)

Types of Actions

1. Voluntary actions (under our control)

Examples:

• Writing
• Talking
• Moving a chair
• Clapping

 Controlled by the brain

2. Involuntary actions (not under our control)

Examples:

• Breathing
• Heartbeat
• Digestion
• Salivation

 Controlled by mid-brain and hind-brain

Main Parts of the Human Brain

The brain has three major regions:

1. Fore-brain
2. Mid-brain
3. Hind-brain

1. Fore-Brain (Thinking Brain)

Functions:

• Main thinking and decision-making centre
• Receives sensory information:
  • Sight
  • Hearing
  • Smell
  • Taste
• Interprets information
• Controls voluntary muscles
• Contains centres for hunger and emotions

Example Flow:

Seeing food
⬇
Fore-brain interprets
⬇
Feeling hungry or full
⬇
Decision to eat or stop eating

2. Mid-Brain (Involuntary Actions)

• Controls some involuntary movements
• Helps in:
  • Eye movements
  • Reflexes related to sight and sound

3. Hind-Brain

Parts of Hind-Brain:

• Medulla
• Cerebellum

(a) Medulla

Controls vital involuntary actions such as:

• Breathing
• Heartbeat
• Blood pressure
• Salivation
• Vomiting

 We do not think to perform these actions.

(b) Cerebellum

Controls:

• Balance
• Posture
• Precision of movements

Examples:

• Walking straight
• Riding a bicycle
• Picking up a pencil

Simple Diagram of Human Brain (Text Form)

Fore-brain  → Thinking, voluntary actions

Mid-brain   → Involuntary actions

Hind-brain  → Balance, breathing, heartbeat

   |____ Cerebellum – balance

   |____ Medulla – vital functions

Why Is the Brain Important?

• Allows us to think
• Helps us decide and act
• Controls both voluntary and involuntary actions
• Keeps the body balanced and alive

Key Points to Remember

• Brain + spinal cord = Central Nervous System
• Fore-brain → thinking and voluntary actions
• Mid-brain & hind-brain → involuntary actions
• Cerebellum → balance and posture
• Medulla → heartbeat, breathing, digestion