Question

The specific receptors for neurotransmitters in a synapse are present on ________.

• A. Post-synaptic membrane
• B. Pre-synaptic membrane
• C. Myelin sheath
• D. Schwann cell

Hint:

Logic Tip: Communication is a one-way street at a chemical synapse. The "Pre-" side speaks (releases neurotransmitters), and the "Post-" side listens (has the receptors).

Answer 1

The Correct Option is A

Step 1 : Understanding the Question:
The question asks us to identify the location of the receptor proteins that detect and bind neurotransmitters during the transmission of a nerve impulse across a chemical synapse.
Step 2 : Key Formulas and Approach:
Synaptic transmission involves:
1. Arrival of an impulse at the pre-synaptic terminal.
2. Release of neurotransmitters into the synaptic cleft.
3. Diffusion of neurotransmitters across the gap.
4. Binding to receptors on the receiving membrane to generate a new potential.
Step 3 : Detailed Explanation:

The Synapse: A chemical synapse consists of a pre-synaptic neuron, a synaptic cleft, and a post-synaptic neuron.

Role of the Pre-synaptic Membrane (B): This membrane belongs to the axon terminal of the sending neuron. It contains voltage-gated calcium channels and is responsible for releasing neurotransmitters from vesicles into the cleft. It does not contain the primary receptors for these transmitters.

Role of the Post-synaptic Membrane (A): This is the membrane of the dendrite or cell body of the receiving neuron. It is embedded with specific receptors for neurotransmitters. Binding of the transmitter to these receptors opens ligand-gated ion channels, causing depolarization or hyperpolarization of the receiving cell.

Myelin and Schwann Cells (C/D): Myelin sheaths and Schwann cells provide electrical insulation for the axon to facilitate saltatory conduction; they are not involved in the chemical reception of signals at the synapse.

Step 4 : Final Answer:
The reception of the chemical signal occurs on the receiving side of the junction, which is the post-synaptic membrane. This corresponds to option (A).