The Bio Brief

What provides control and coordination in animals?

In animals, control and coordination are carried out by:

• Nervous tissue (fast response)
• Muscular tissue (action like movement)

These systems help us detect changes and respond quickly, especially in dangerous situations.

Example: Touching a Hot Object

Touching something hot is dangerous, so our body must:

1. Detect the heat
2. Send the message to the brain/spinal cord
3. Respond quickly by pulling the hand away

How do we detect information from our surroundings?

Receptors

• Receptors are specialised tips of nerve cells.
• They are present in sense organs.

Types of receptors:

• Gustatory receptors → detect taste (tongue)
• Olfactory receptors → detect smell (nose)
• Auditory receptors → detect sound (ear)
• Photoreceptors → detect light (eyes)
• Touch receptors → detect heat, cold, pain (skin)

How does a nerve impulse travel?

Step-by-step flow chart:

Stimulus(hot object)→Receptor in skin→ Electrical impulse is created → Dendrite → Cell body → Axon → Synapse(gap) → Chemical signal → Next neuron/muscle cell → Response (hand pulled back)

Structure of a Neuron

Dendrite → Cell Body → Axon → Synapse

   |          |          |        |

Receives   Processes   Carries   Converts

message    message     impulse   to chemical

Answers to the questions:

1. Where information is acquired:  Dendrite
2. Where information travels as electrical impulse: Axon
3. Where impulse becomes a chemical signal: Synapse (axon end)

What is a Synapse?

• A synapse is the small gap between two neurons.
• Electrical impulse cannot jump the gap.
• It is converted into a chemical signal to cross the synapse.

Why does food taste different when the nose is blocked?

Yes, there is a difference.

Reason:

• Taste and smell work together.
• When your nose is blocked:
  • Olfactory receptors cannot detect smell.
  • Only taste receptors work → food tastes bland.

Example:

• Sugar tastes sweet, but its full flavour is missing.

 This also happens when you have a cold, because mucus blocks smell receptors.

Key Points to Remember

• Nervous system works using electrical impulses.
• Receptors detect stimuli.
• Neurons transmit information.
• Synapse uses chemicals for message transfer.
• Taste is closely linked to smell.