high importancemedium difficulty6 min

Synapse

A synapse is the small gap between two neurons, or between a neuron and an effector, where the message passes from one cell to another.

In one line: Synapse means signal bridge with a gap.

Practice This Concept

Understand it

Messages do not jump directly from one neuron to the next.
At the synapse, chemicals called neurotransmitters help carry the signal across the gap.
This makes the nervous system one-way and controlled.
The synapse is important because it allows orderly transfer of messages and prevents random movement of impulses in both directions.

Example

In a reflex action, a message from one neuron is passed across the synapse to the next neuron before the final response reaches the muscle.

Rule to remember

Rule: impulse passes across the synapse with the help of neurotransmitters.

See it worked out

Follow the example line by line, then use the same method on new questions.

Worked example

1A sensory neuron passes an impulse to a relay neuron.
2The impulse reaches the axon terminal, neurotransmitters cross the small gap, and the next neuron receives the message.

Method you can reuse

1Locate the end of the first neuron.
2Note the synaptic gap.
3Identify neurotransmitter release.
4Show transfer to the next neuron.
5State that the impulse continues in sequence.

Visual tip

A synapse diagram should show the axon terminal, synaptic gap, neurotransmitter release, and next neuron membrane.

Check yourself

Answer the question in your head before opening the answer.

Try it yourself

Why is the synapse important when one neuron passes a message to the next neuron?

Think first, then show answer

The synapse is important because it allows the message to move from one neuron to the next in a controlled way. Neurotransmitters help cross the gap, so the impulse continues without confusion.

Common wrong answer

The message passes directly through the gap like metal wire current.

Why it loses marks: Chemical transfer is needed at the synapse.

Don't mix this up

Many students think the impulse crosses the gap like electricity in a wire. In reality, the gap needs chemical transfer at the synapse.

Exam tip

If a question asks how impulses move from one neuron to another, mention neurotransmitters and the synaptic gap.

Write it in the exam

Each point is worth about one mark. Write point 1 for a 1-mark question and keep adding points as the marks go up.

How CBSE asks it

Exam questions often ask the definition of synapse, the role of neurotransmitters, or why messages do not flow in a straight continuous wire-like manner.

1
Enough for 1 mark
A synapse is the small gap between two neurons, or between a neuron and an effector, where the message passes from one cell to another.
2
Add for 2 marks
Example: In a reflex action, a message from one neuron is passed across the synapse to the next neuron before the final response reaches the muscle.
3
Add for 3 marks
Messages do not jump directly from one neuron to the next.

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