Where A stands for axon, D for dendrite, S for synapse, and CB for cell body, a typical sequence of structures between a receptor and an efferent is?

Options

A. D -CB -A -S -D -CB -A
B. A -D -CB -S -A -D -CB
C. D -CB -A -S -A -CB -D
D. D -A -S -CB -D-A -CB

Answer

To determine the typical sequence of structures between a receptor and an efferent neuron, we need to understand the flow of information in the nervous system. Here’s a step-by-step breakdown of the sequence:

### Step-by-Step Solution:

1. **Start with the Receptor**: The process begins when a receptor detects a stimulus. The receptor generates a nerve impulse.

2. **Dendrite (D)**: The nerve impulse is first received by the dendrites of the sensory neuron. Dendrites are the branched structures that receive signals from receptors.

3. **Cell Body (CB)**: After the dendrites receive the impulse, it is transmitted to the cell body (CB) of the neuron. The cell body processes the incoming signals.

4. **Axon (A)**: From the cell body, the impulse travels down the axon (A). The axon is a long, slender projection that conducts electrical impulses away from the cell body.

5. **Synapse (S)**: Once the impulse reaches the end of the axon, it triggers the release of neurotransmitters at the synapse (S). The synapse is the junction between two neurons where the signal is transmitted.

6. **Next Neuron's Dendrite**: The neurotransmitters cross the synaptic gap and bind to the dendrites of the next neuron, starting the process again in that neuron.

### Typical Sequence:
- Dendrite (D) → Cell Body (CB) → Axon (A) → Synapse (S) → Dendrite (D) of the next neuron → Cell Body (CB) of the next neuron → Axon (A) of the next neuron.

### Final Sequence:
D → CB → A → S → D → CB → A

### Answer:
The typical sequence of structures between a receptor and an efferent is: **D → CB → A → S**.

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