Question

use the following information to answer question 21. a schematic diagram of the dorsal view cns (brain & spinal cord). 21. if the region labelled x in the diagram were damaged, one could infer reasonably that no information from x will move along the neuron labelled a. i b. ii c. iii d. iv hint: where do the nerves from the left side of the body cross over to the right side of the brain? this question also addresses the fact that if an individual has a stroke on the right side of the cerebral cortex, then motor skills on the left side of the body are affected. answer: in the region of the pons/medulla oblongata 22. the initiation of a sensory impulse varies among individuals as a result of difference in the a. interneurons b. reflex arcs c. effector neurons d. thresholds of stimulation hint: people vary in taste abilities (for salt, sugar, spices) because they come from various cultures and possess different genes. for example, even in a group of 20 individuals, variation exists in tasting various concentrations of salt.

Explanation:

For question 21, region X is part of the brain. Sensory neurons I and II carry information to the brain. If region X is damaged, information from sensory neurons (which bring information to the brain) won't be processed. Motor neurons III and IV carry information from the brain to muscles, so damage to X won't directly stop information flow in them.
For question 22, the initiation of a sensory impulse depends on whether a stimulus reaches the threshold required to trigger a nerve - impulse. Interneurons are involved in processing within the CNS, reflex arcs are a neural pathway for reflexes, and effector neurons carry impulses to effectors. Variation in sensory - impulse initiation is due to differences in stimulation thresholds among individuals.

Answer:

1. A. I
2. D. thresholds of stimulation