Question

Receptor sites for neurotransmitters are present on :

• A. Pre-synaptic membrane
• B. Tips of axons
• C. Post-synaptic membrane
• D. Membrane of synaptic vesicles

Answer 1

The Correct Option is C

The question asks about the location of receptor sites for neurotransmitters in the context of a synapse in the nervous system. To answer this, it is important to understand how synaptic transmission works.

In synaptic transmission:

1. Pre-synaptic Neuron: This neuron sends the signal. Neurotransmitters are stored in synaptic vesicles within the axon terminal of this neuron.
2. Synaptic Cleft: This is the gap between the pre-synaptic neuron and the post-synaptic neuron.
3. Post-synaptic Neuron: This neuron receives the signal. It contains specific receptor sites that bind to neurotransmitters.
4. Transmission Process: When an action potential reaches the axon terminal of the pre-synaptic neuron, it triggers the release of neurotransmitters into the synaptic cleft. These neurotransmitters diffuse across the synaptic cleft and bind to the receptor sites on the post-synaptic membrane.

Now, based on the roles above:

• Pre-synaptic membrane: Contains neurotransmitters in vesicles but does not have receptor sites for them.
• Tips of axons: Release neurotransmitters, but do not contain the receptor sites for neurotransmitters.
• Post-synaptic membrane: Contains the receptor sites that neurotransmitters bind to, which then trigger a response in the post-synaptic neuron.
• Membrane of synaptic vesicles: Involved in storing and releasing neurotransmitters, but not in receiving them.

Therefore, the receptor sites for neurotransmitters are present on the Post-synaptic membrane. This allows the post-synaptic neuron to receive and process the chemical signals sent from the pre-synaptic neuron.