Chapter 39, Problem 1TYK

Summary Introduction

Introduction:

Neurons or nerve cells are specialized cells that are capable of carrying the stimulus as well as the response to the stimulus from one part of the body to another. These cells carry information in the form of an action potential. The neuron has an axon, dendrites, and an enlarged cell body. The dendrites and axons conduct electrical signals, which are produced due to the flowing of ions down the concentration gradient.

Answer to Problem 1TYK

Correct answer:

A dendrite of a sensory neuron receives the signal, the axon of the cell transmits the signal to an interneuron, and the signal is transmitted by the efferent neurons to the effectors.

Explanation of Solution

Explanation/Justification for the correct answer:

Option (d) states that the dendrite of a sensory neuron receives the signal, the cell's axon transmits the signal to an interneuron, and the signal is transmitted by the efferent neurons to the effectors. This statement is true because the sensory or afferent neurons receive information and pass it to interneurons. The interneurons integrate the neural messages, and the neural message produced is transmitted by the efferent neurons to the effector or the target site to act as per the stimulus. Hence, option (d) is correct.

Explanation for the incorrect answers:

Option (a) states that the dendrite of sensory neurons receives the signal, its cell body transmits the signal to the axon of a motor neuron and the signal is sent to the target. This statement is false because the dendrites of the sensory neurons receive the signal and the axons transmit the signals to the interneurons, which then produce neural messages that are transmitted to the target site. So, it is an incorrect option.

Option (b) states that the axon of a motor neuron receives the signal, its cell body transmits the signal to the dendrite of a sensory neuron and the signal is then sent to the target site. This statement is false because the dendrite of a sensory neuron receives the signal and the axon conducts the signal to another neuron. So, it is an incorrect option.

Option (c) states that the efferent neurons conduct the electrical signal to the sensory neurons, which sends the impulse to the interneurons and finally to the afferent motor neurons. This statement is false because the afferent neurons conduct the nerve impulse and send it to the interneurons, which then send the neural message to the efferent neurons, thus taking the message to the target site. So, it is an incorrect option.

Option (e) states that the axons of oligodendrocytes transmit the nerve impulses to the dendrites of astrocytes. This statement is false because astrocytes and oligodendrocytes are glial cells, which means that they support and provide nutrition to the neurons. So, it is an incorrect option.

Hence, options, (a), (b), (c), and (e) are incorrect.

Conclusion

Thus, it can be concluded that the dendrites of sensory neurons receive the signal and the axons transmit the signal to interneurons, which integrate the neural message and transmit the message to the efferent neurons, and then to the effector or the target site.