Correct Option: B. Dendrite Explanation of the Correct Answer Neurons are specialized cells in the nervous system that transmit information throughout the body. They consist of several key parts, each with specific functions. The part of the neuron that is primarily responsible for receiving signals from other neurons is the dendrite.

1. Structure of Dendrites: Dendrites are tree-like extensions that branch out from the cell body (soma) of the neuron. They have numerous synaptic receptors on their surface, which are designed to receive neurotransmitters released by other neurons. This structure increases the surface area available for receiving signals, allowing a neuron to connect with many other neurons.
2. Function of Dendrites: When a neurotransmitter binds to a receptor on a dendrite, it can cause a change in the electrical state of the neuron. This change is known as a postsynaptic potential. If the signal is strong enough, it can lead to the generation of an action potential, which is an electrical impulse that travels down the axon to communicate with other neurons or muscles.
3. Signal Integration: Dendrites play a crucial role in integrating signals from multiple sources. A single neuron can receive inputs from thousands of other neurons through its dendrites. This integration is essential for processing information and making decisions in the nervous system.

Explanation of Why Other Options Are Incorrect

• A. Axon: The axon is the long, slender projection of a neuron that conducts electrical impulses away from the cell body. Its primary function is to transmit signals to other neurons, muscles, or glands, not to receive them. Therefore, the axon is not responsible for receiving signals.
• C. Synapse: A synapse is the junction between two neurons where communication occurs. It is the site where neurotransmitters are released from the axon terminal of one neuron and bind to the receptors on the dendrites of another neuron. While synapses are crucial for signal transmission, they are not a part of the neuron that receives signals; rather, they are the connection point for signal transfer.
• D. Myelin sheath: The myelin sheath is a fatty layer that surrounds the axon of some neurons, acting as an insulator to speed up the transmission of electrical signals along the axon. It does not play a role in receiving signals from other neurons, so it is not the correct answer.

Summary of Key Points

• Dendrites are the parts of the neuron that receive signals from other neurons.
• They have a branched structure that increases the surface area for receiving neurotransmitters.
• Dendrites integrate signals from multiple sources, which is essential for neuronal communication.
• Other parts of the neuron, such as the axon, synapse, and myelin sheath, have different functions related to signal transmission and insulation, not reception.

Revision Summary

• Dendrites are responsible for receiving signals from other neurons.
• They contain receptors for neurotransmitters and integrate incoming signals.
• Axons transmit signals away from the neuron, while synapses are the connection points for communication.
• The myelin sheath insulates axons to speed up signal transmission but does not receive signals.