Question 34

Motor neurons carry signals from the central nervous system to muscles or glands causing them to act.

Motor neurons are specialized nerve cells that transmit impulses from the central nervous system to effectors such as muscles and glands, facilitating movement and bodily responses.

A) They carry signals from the central nervous system to muscles or glands causing them to act.

This option accurately describes the primary function of motor neurons. They play a crucial role in the nervous system by sending signals that lead to muscle contraction and glandular secretion, thereby enabling voluntary and involuntary movements.

B) They are involved in the digestion and absorption of nutrients in the gastrointestinal tract.

This option is incorrect as it pertains to the functions of other types of neurons or cells, such as enteric neurons or specialized cells within the gastrointestinal system, which are responsible for digestion and nutrient absorption rather than motor control.

C) They form the blood-brain barrier and regulate the passage of substances.

This choice is incorrect because the blood-brain barrier is primarily formed by endothelial cells and astrocytes, not motor neurons. Motor neurons do not have a role in regulating the blood-brain barrier or the passage of substances across it.

D) They transmit sensory information from the sensory organs to the brain.

This option is incorrect as it describes the function of sensory neurons, which carry information from sensory receptors to the central nervous system. Motor neurons, in contrast, are responsible for conveying signals away from the central nervous system to effectors.

Conclusion

The correct answer is A, as it directly addresses the fundamental role of motor neurons in the nervous system. Options B, C, and D misrepresent the functions of motor neurons, either attributing their roles to other cell types or mischaracterizing their primary purpose. Thus, option A stands out as the only accurate description.