Medical Physiology IV (CNS) | MCQ Quiz | OmpathStudy Kenya

Question 1

The following neurotransmitter is used by the substantia nigra neurons that project to the caudate and putamen:

Accepted Answer

Dopamine — The substantia nigra contains dopaminergic neurons that project to the caudate nucleus and putamen (collectively called the striatum) via the nigrostriatal pathway. This dopaminergic pathway is crucial for motor control and is affected in Parkinson's disease. The other neurotransmitters listed are not the primary neurotransmitters used by substantia nigra neurons in this pathway. ---

Question 2

Which of the following items correctly describes the relationship of cerebrospinal fluid pressure to the venous pressure in the superior sagittal sinus?

Accepted Answer

A few millimeters higher — CSF pressure is normally maintained at a few millimeters of mercury higher than venous pressure in the superior sagittal sinus. This pressure gradient is essential for CSF drainage through the arachnoid granulations into the venous system. If CSF pressure were lower or equal to venous pressure, proper drainage would not occur. ---

Question 3

Which statement best describes a characteristic functional difference between a Golgi tendon organ and a muscle spindle?

Accepted Answer

The output signals of a Golgi tendon organ lead to inactivation of the muscle associated with the active tendon organ — Golgi tendon organs detect muscle tension and when activated, they cause inhibition of the muscle they monitor (autogenic inhibition). This is opposite to muscle spindles, which detect muscle stretch and cause activation of the same muscle. The other options are incorrect as Golgi tendon organs do function during voluntary movements, do contribute to proprioception, are not directly linked to alpha motor neurons, and their signals are conducted at similar speeds to muscle spindles. ---

Question 4

Output signals from Golgi tendon organs are transmitted to which of the following higher centers?

Accepted Answer

Cerebellum — Golgi tendon organs send proprioceptive information about muscle tension to the cerebellum via spinocerebellar tracts. The cerebellum uses this information for motor coordination and balance. The other structures listed are not primary targets for Golgi tendon organ afferents. ---

Question 5

Which type of cholinergic receptor is found at synapses between preganglionic and postganglionic neurons of the sympathetic system?

Accepted Answer

Nicotinic — All autonomic ganglia (both sympathetic and parasympathetic) use nicotinic cholinergic receptors at the synapse between preganglionic and postganglionic neurons. Muscarinic receptors are found at parasympathetic postganglionic terminals, while alpha and beta receptors are adrenergic receptors found at sympathetic postganglionic terminals. ---

Question 6

The term limbic cortex includes the orbitofrontal cortex, subcallosal gyrus, cingulate gyrus, and which one of the following areas?

Accepted Answer

Parahippocampal gyrus — The limbic cortex includes the parahippocampal gyrus along with the orbitofrontal cortex, subcallosal gyrus, and cingulate gyrus. These areas are involved in emotion, memory, and behavior. The other options are not considered part of the limbic cortex. ---

Question 7

Occlusion of which of the following structures would lead to communicating hydrocephalus?

Accepted Answer

Arachnoid villi — Communicating hydrocephalus occurs when CSF can flow through the ventricular system but cannot be absorbed properly. Obstruction of arachnoid villi (granulations) prevents CSF absorption into the venous system, leading to communicating hydrocephalus. Obstruction of the other structures would cause non-communicating (obstructive) hydrocephalus. ---

Question 8

The withdrawal reflex is initiated by stimulation delivered to which of the following receptors?

Accepted Answer

Cutaneous free nerve ending — The withdrawal reflex is a protective reflex triggered by noxious stimuli detected by cutaneous free nerve endings (nociceptors). These receptors detect potentially harmful stimuli and initiate rapid withdrawal from the stimulus. The other receptors listed detect different types of stimuli but are not primarily involved in withdrawal reflexes. ---

Question 9

Which substance activates adrenergic alpha and beta receptors equally well?

Accepted Answer

Epinephrine — Epinephrine (adrenaline) has equal affinity for both alpha and beta adrenergic receptors. Norepinephrine has higher affinity for alpha receptors than beta receptors. Acetylcholine, serotonin, and dopamine are not adrenergic receptor agonists. ---

Question 10

The posterior and lateral hypothalamus, in combination with the preoptic area, are involved in the control of which of the following functions?

Accepted Answer

Regulation of thirst and water intake — The posterior and lateral hypothalamus, along with the preoptic area, are key regions involved in osmoregulation and thirst control. These areas contain osmoreceptors that detect changes in blood osmolality and initiate appropriate responses including thirst and ADH release. The other functions are controlled by different hypothalamic regions. ---

Question 11

Which statement concerning the reticulospinal system is correct?

Accepted Answer

Pontine reticulospinal fibers excite spinal cord motor neurons that activate limb extensor muscles — Pontine reticulospinal fibers facilitate extensor muscle tone and activity, while medullary reticulospinal fibers generally inhibit extensor muscles and facilitate flexor muscles. The other statements are incorrect: reticulospinal neurons do receive cortical input, medullary fibers inhibit rather than excite extensors, and pontine fibers course in the ventral funiculus, not posterior funiculus. ---

Question 12

The neurons located in the locus ceruleus release which of the following neurotransmitters at their synaptic terminals?

Accepted Answer

Norepinephrine — The locus ceruleus is the major noradrenergic nucleus in the brain, containing norepinephrine-producing neurons that project widely throughout the CNS. These neurons are involved in arousal, attention, and stress responses. The other neurotransmitters are produced by different neural populations. ---

Question 13

Which of the following items represents the structural basis of the blood-cerebrospinal fluid barrier?

Accepted Answer

Tight junctions between adjacent choroid plexus cells — The blood-CSF barrier is formed by tight junctions between choroid plexus epithelial cells. This barrier controls the movement of substances from blood into CSF. Option E describes the blood-brain barrier, while the other options are not correct structural bases for the blood-CSF barrier. ---

Question 14

Damage to which of the following brain areas leads to the inability to comprehend the written or the spoken word?

Accepted Answer

Junction of the parietal, temporal, and occipital lobes — Wernicke's area, located at the junction of the parietal, temporal, and occipital lobes in the dominant hemisphere, is responsible for language comprehension. Damage to this area results in Wernicke's aphasia, characterized by inability to comprehend written or spoken language. The other areas are not primarily involved in language comprehension. ---

Question 15

In an otherwise normal individual, dysfunction of which brain area will lead to behavior which is not appropriate for the given social occasion?

Accepted Answer

Amygdala — The amygdala is crucial for processing emotions and social behavior, including the ability to recognize social cues and respond appropriately to social situations. Dysfunction of the amygdala can lead to inappropriate social behavior and difficulty reading social situations. The other structures, while important for various functions, are not primarily responsible for social appropriateness. ---

Question 16

Which of the following reflexes best describes incoming pain signals that elicit movements performed by antagonistic muscle groups on either side of the body?

Accepted Answer

Crossed extensor reflex — The crossed extensor reflex occurs when a painful stimulus causes withdrawal of the affected limb (flexion) while simultaneously causing extension of the opposite limb to maintain balance and support. This involves antagonistic muscle groups on both sides of the body. The withdrawal reflex only involves the affected side, while reciprocal and autogenic inhibition are different mechanisms. ---

Question 17

Decerebrate rigidity results from which of the following situations?

Accepted Answer

An imbalance in the activity of medullary and pontine reticulospinal systems such that excitation of extensor motor neurons is the end result — Decerebrate rigidity results from damage above the level of the vestibular nuclei, leading to an imbalance where pontine reticulospinal activity (which facilitates extensors) predominates over medullary reticulospinal activity (which inhibits extensors). This results in excessive extensor muscle tone and rigidity. ---

Question 18

Which portion of the cerebellum functions in the planning of sequential movement?

Accepted Answer

Cerebrocerebellum and dentate nucleus — The cerebrocerebellum (lateral hemispheres) and dentate nucleus are involved in motor planning and coordination of complex, sequential movements. They receive input from cerebral cortex and are important for cognitive aspects of motor control. The other cerebellar regions have different functions related to balance, posture, and limb coordination. ---

Question 19

Bilateral lesions involving the ventromedial hypothalamus will lead to which of the following deficits?

Accepted Answer

Excessive eating, rage and aggression, hyperactivity — The ventromedial hypothalamus contains the satiety center. Bilateral lesions of this area result in hyperphagia (excessive eating), leading to obesity, along with increased aggression and hyperactivity. This is opposite to what would occur with lateral hypothalamic lesions, which would cause decreased eating. ---

Question 20

Which structure is an important pathway for communication between the limbic system and the brainstem?

Accepted Answer

Medial forebrain bundle — The medial forebrain bundle is a major pathway connecting limbic structures to the brainstem, particularly the hypothalamus. It carries both ascending and descending fibers and is important for emotional and motivational behaviors. The other structures have different functions and connections within the limbic system. ---

Question 21

The function of which of the following organs or systems is dominated by the sympathetic nervous system?

Accepted Answer

Systemic blood vessels — Systemic blood vessels receive predominantly sympathetic innervation and have minimal parasympathetic innervation. Sympathetic stimulation causes vasoconstriction of most systemic vessels. The other organs listed receive dual innervation from both sympathetic and parasympathetic systems, with varying degrees of dominance. ---

Question 22

Which of the following structures in the vestibular apparatus is responsible for the detection of angular acceleration?

Accepted Answer

Semicircular canals — The semicircular canals detect angular acceleration (rotational head movements). They contain the ampullae with hair cells that respond to endolymph movement during rotation. The macula, saccule, and statoconia are involved in detecting linear acceleration and gravity, not angular acceleration. ---

Question 23

A person who has had a traumatic brain injury seems to be able to understand the written and spoken word but cannot create the correct sounds to be able to speak a word that is recognizable. This person most likely has damage to which area of the brain?

Accepted Answer

Broca's area — Broca's area is responsible for speech production and motor aspects of language. Damage to this area results in Broca's aphasia, where comprehension is intact but speech production is severely impaired. Wernicke's area damage would affect comprehension, while the other areas are not primarily involved in speech production. ---

Question 24

Schizophrenia is thought to be caused in part by excessive production and release of which of the following neurotransmitter agents?

Accepted Answer

Dopamine — The dopamine hypothesis of schizophrenia suggests that excessive dopaminergic activity, particularly in the mesolimbic pathway, contributes to the positive symptoms of schizophrenia. Antipsychotic medications work by blocking dopamine receptors. The other neurotransmitters are not primarily implicated in schizophrenia pathophysiology. ---

Question 25

Which of the following structures is not considered to be part of the basal ganglia?

Accepted Answer

Dentate nucleus — The dentate nucleus is part of the cerebellum, not the basal ganglia. The basal ganglia includes the caudate nucleus, putamen, globus pallidus, substantia nigra, and subthalamic nucleus. The dentate nucleus is the largest of the deep cerebellar nuclei and is involved in motor planning and coordination. ---

Question 26

Stimulation of which of the following subcortical areas can lead to contraction of a single muscle or small groups of muscles?

Accepted Answer

Red nucleus — The red nucleus, particularly the magnocellular part, can produce discrete muscle contractions when stimulated. It has somatotopic organization and gives rise to the rubrospinal tract. The other structures listed do not have this capability for producing discrete muscle contractions upon stimulation. ---

Question 27

Which structures in the cerebellum have a topographical representation of the body?

Accepted Answer

The vermis and intermediate hemisphere — The vermis and intermediate hemisphere (spinocerebellum) have somatotopic organization with topographical representation of the body. The vermis represents axial muscles and the intermediate hemisphere represents limb muscles. The lateral hemispheres are involved in motor planning rather than direct body representation. ---

Question 28

Which statement concerning memory processing in the brain is correct?

Accepted Answer

Short-term memory is considered to be a list of 7–10 discrete facts that can be recalled within a period of several hours — Short-term memory has a limited capacity (about 7±2 items) and duration (seconds to hours). The other statements are incorrect: the brain can form negative memories, rehearsal is important for long-term memory formation, hippocampal lesions primarily affect long-term memory formation, and structural changes do occur in long-term memory formation. ---

Question 29

Which of the following structures is maximally sensitive to linear head movement in the vertical plane?

Accepted Answer

Macula of the saccule — The macula of the saccule is oriented vertically and is maximally sensitive to linear acceleration in the vertical plane (up-down movements). The macula of the utricle is oriented horizontally and detects horizontal linear movements. The cristae ampullaris detect angular acceleration, not linear acceleration. ---

Question 30

Retrograde amnesia is the inability to recall long-term memories from the past. When damaged, which of the following brain regions leads to retrograde amnesia?

Accepted Answer

Hippocampus — The hippocampus is crucial for memory consolidation and retrieval. Damage to the hippocampus can cause retrograde amnesia, affecting the ability to recall memories formed before the injury. The other structures, while involved in memory circuits, are not the primary cause of retrograde amnesia when damaged. ---

Question 31

Which structure connects the hippocampus to the limbic system?

Accepted Answer

Fornix — The fornix is the major output pathway from the hippocampus, connecting it to other limbic structures including the mammillary bodies, septal nuclei, and hypothalamus. It is crucial for hippocampal communication within the limbic system. The other tracts have different functions and connections. ---

Question 32

The condition of athetosis results when which area of the brain is dysfunctional?

Accepted Answer

Globus pallidus — Athetosis, characterized by slow, writhing movements, typically results from dysfunction of the globus pallidus. This structure is part of the basal ganglia and is important for controlling movement. Dysfunction of other basal ganglia structures causes different movement disorders. ---

Question 33

Which component of the basal ganglia plays the major role in the control of cognitive (memory-guided) motor activity?

Accepted Answer

Caudate nucleus — The caudate nucleus is part of the associative circuit of the basal ganglia and plays a major role in cognitive aspects of motor control, including memory-guided movements and executive motor functions. The putamen is more involved in automatic motor patterns, while the other structures have different roles in basal ganglia function. ---

Question 34

A wide variety of neurotransmitters have been identified in the cell bodies and afferent synaptic terminals in the basal ganglia. A deficiency of which of the following transmitters is typically associated with Parkinson disease?

Accepted Answer

Dopamine — Parkinson's disease is characterized by degeneration of dopaminergic neurons in the substantia nigra, leading to dopamine deficiency in the striatum. This dopamine deficiency is responsible for the motor symptoms of Parkinson's disease. Treatment often involves dopamine replacement therapy. ---

Question 35

Most excitatory neurotransmission in the brain is believed to be mediated by:

Accepted Answer

Glutamate — Glutamate is the major excitatory neurotransmitter in the central nervous system, mediating most excitatory synaptic transmission. GABA and glycine are inhibitory neurotransmitters, while GnRH is a hormone, not a neurotransmitter for general brain communication. ---

Question 36

The inhibitory amino acid neurotransmitters in the CNS are:

Accepted Answer

GABA and glycine — GABA (gamma-aminobutyric acid) and glycine are the two major inhibitory amino acid neurotransmitters in the CNS. GABA is the primary inhibitory neurotransmitter in the brain, while glycine is the primary inhibitory neurotransmitter in the spinal cord. Glutamate and aspartate are excitatory neurotransmitters. ---

Question 37

The concept of "autonomic tone" is quite advantageous because it allows the nervous system to have much finer control over the function of an organ or organ system. This is exemplified in the control of systemic arterioles. Which of the following actions would lead to vasodilation of systemic arterioles?

Accepted Answer

Decreased activity of postganglionic sympathetic neurons — Systemic arterioles are primarily controlled by sympathetic innervation, which maintains a baseline level of vasoconstriction (sympathetic tone). Decreased sympathetic activity leads to vasodilation. Most arterioles have minimal or no parasympathetic innervation, so parasympathetic activity changes would have little effect on most systemic vessels. ---

Question 38

Brain edema is a serious complication of altered fluid dynamics in the brain. Continued progression of brain edema may lead to which of the following situations?

Accepted Answer

Compression of blood vessels leading to ischemia and compensatory capillary dilation — Progressive brain edema increases intracranial pressure, which compresses blood vessels and reduces cerebral blood flow, leading to ischemia. The brain attempts to compensate by dilating capillaries to maintain blood flow. This can create a vicious cycle as increased blood flow can worsen edema. ---

Question 39

Which of the following reflexes is correctly paired with the sensory structure that mediates the reflex?

Accepted Answer

Stretch reflex-muscle spindle — The stretch reflex (myotatic reflex) is mediated by muscle spindles, which detect muscle stretch and initiate a reflex contraction of the same muscle. Autogenic inhibition is mediated by Golgi tendon organs, not muscle spindles. Reciprocal inhibition involves multiple sensory inputs, and the Golgi tendon reflex is mediated by Golgi tendon organs, not Meissner corpuscles. --- Medical Physiology IV (CNS) - Exam Answers ## ### Unit Code: BMP1205 --- ## SECTION B (30 MARKS) - Answer All Questions

Medical Physiology IV (CNS) | MCQ Quiz | OmpathStudy Kenya

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