Explanations to Discrete Practice Questions

1. D
   Sensory neurons are also referred to as afferent neurons, while motor neurons are also referred to as efferent neurons, eliminating (A) and (B). Motor neurons transmit motor information from the brain to the body, contrary to (C), and sensory neurons transmit sensory information from receptors to the brain.
2. B
   The cerebral cortex is not involved in the initial reflexive response to pain. Instead, the sensory receptors send information to the interneurons in the spinal cord, which stimulate a motor neuron to allow quick withdrawal. While the brain does ultimately get the signal, the reflexive withdrawal has already occurred by that time.
3. C
   The hindbrain is responsible for balance and motor coordination, which would be necessary for dribbling a basketball. The midbrain, (B), manages sensorimotor reflexes that also promote survival. The forebrain, (A), is associated with emotion, memory, and higher-order cognition. The spinal cord, (D), is likely not damaged as the child can still walk.
4. D
   The temporal lobes have many functions, but motor skills are not associated with this area. The temporal lobes contain Wernicke’s area, which is responsible for language comprehension, (A). The temporal lobes also function in emotion and memory, (B) and (C), because they contain the amygdala and hippocampus. Motor skills are associated with the frontal lobe (primary motor cortex), basal ganglia (smooth movements), and cerebellum (coordination).
5. C
   The hypothalamus is responsible for homeostatic and emotional functions. The cerebellum, (A), is responsible for maintaining posture and balance while the pons, (B), is above the medulla and contains sensory and motor tracts between the cortex and the medulla. The thalamus, choice (D), acts as a relay station for sensory information.
6. A
   The right hemisphere is usually the nondominant hemisphere, even in left-handed individuals. Sense of direction is an ability of the nondominant hemisphere. The other answer choices are all abilities attributed to the dominant hemisphere.
7. B
   Neurulation occurs when the notochord causes differentiation of overlying ectoderm into the neural tube and neural crest cells. The neural tube ultimately becomes the central nervous system (brain and spinal cord), and neural crest cells migrate to other sites in the body to differentiate into a number of different tissues. Thus, only statement III is true.
8. D
   Acetylcholine is not a catecholamine; however epinephrine, norepinephrine, and dopamine are.
9. A
   If there were increased amounts of acetylcholinesterase, more acetylcholine would be degraded, lowering acetylcholine levels in the body. Low levels of acetylcholine would result in weakness or paralysis of muscles. Pain, (B), could result if one were injured and endorphins were found in low levels. Mood swings, (C), could be a result of varying levels of serotonin. Hallucinations, (D), have been seen to result from high levels of dopamine.
10. A
    The adrenal glands do promote the fight-or-flight response, but through epinephrine and norepinephrine, not estrogen. The adrenal cortex produces both estrogen and testosterone in both sexes, as mentioned in (D), thus serving as a source of estrogen in males and testosterone in females.
11. C
    The pineal gland is responsible for producing melatonin, which controls the body’s circadian rhythm. Insomnia would be a disturbance of this circadian rhythm, and may be attributable to a pineal gland disorder in some cases. Hypertension, diabetes, and hyperthyroidism would be unrelated to issues with the pineal gland.
12. C
    Schizophrenia is associated with high levels of dopamine or high sensitivity to dopamine. Parkinson’s disease is associated with destruction of the dopaminergic neurons in the basal ganglia.
13. C
    Personality is seen to be somewhat hereditary, as monozygotic, or identical, twins have been seen to express more of the same personality traits. However, environment is also a factor. Thus, identical twins raised in the same home would be expected to have the most similar personalities.
14. D
    The Babinski reflex is a primitive reflex that refers to an extension of the big toe accompanied by fanning of the other toes. It is normal in infants, but should disappear with time—certainly by the time a child begins to walk. In a fifty-year-old woman, the Babinski reflex would be abnormal. However, despite her neurological illness, this patient is exhibiting a normal response to the brushing of her foot; that is, she is not showing the Babinski reflex.
15. B
    Motor skills tend to develop from the core toward the periphery. Following objects with the eyes occurs around four weeks of age. The other actions all require movements of the hand, which do not occur in an organized fashion until later.