Deck 2: Neurophysiology

Question 1

Which autonomic receptor is blocked by hexamethonium at the ganglia, but not at the neuromuscular junction?

A) Adrenergic $\alpha$ receptors
B) Adrenergic $\beta_{1}$ receptors
C) Adrenergic $\beta_{2}$ receptors
D) Cholinergic muscarinic receptors
E) Cholinergic nicotinic receptors

Answer 1

Cholinergic nicotinic receptors

Question 2

A 66-year-old man with chronic hypertension is treated with prazosin by his physician. The treatment successfully decreases his blood pressure to within the normal range. What is the mechanism of the drug's action?

A) Inhibition of $\beta_{1}$ receptors in the sinoatrial (SA) node
B) Inhibition of $\beta_{2}$ receptors in the SA node
C) Stimulation of muscarinic receptors in the SA node
D) Stimulation of nicotinic receptors in the SA node
E) Inhibition of $\beta_{1}$ receptors in ventricular muscle
F) Stimulation of $\beta_{1}$ receptors in ventricular muscle
G) Inhibition of $\alpha_{1}$ receptors in ventricular muscle
H) Stimulation of $\alpha_{1}$ receptors in the SA node
I) Inhibition of $\alpha_{1}$ receptors in the SA node
J) Inhibition of $\alpha_{1}$ receptors on vascular smooth muscle
K) Stimulation of $\alpha_{1}$ receptors on vascular smooth muscle
L) Stimulation of $\alpha_{2}$ receptors on vascular smooth muscle

Answer 2

Inhibition of $\alpha_{1}$ receptors on vascular smooth muscle

Question 3

Which of the following responses is mediated by parasympathetic muscarinic receptors?

A) Dilation of bronchiolar smooth muscle
B) Erection
C) Ejaculation
D) Constriction of gastrointestinal (GI) sphincters
E) Increased cardiac contractility

Answer 3

Erection

Question 4

Which of the following is a property of C fibers?

A) Have the slowest conduction velocity of any nerve fiber type
B) Have the largest diameter of any nerve fiber type
C) Are afferent nerves from muscle spindles
D) Are afferent nerves from Golgi tendon organs
E) Are preganglionic autonomic fibers

Question 5

When compared with the cones of the retina, the rods

A) are more sensitive to low-intensity light
B) adapt to darkness before the cones
C) are most highly concentrated on the fovea
D) are primarily involved in color vision

Question 6

Which of the following statements best describes the basilar membrane of the organ of Corti?

A) The apex responds better to low frequencies than the base does
B) The base is wider than the apex
C) The base is more compliant than the apex
D) High frequencies produce maximal displacement of the basilar membrane near the helicotrema
E) The apex is relatively stiff compared to the base

Question 7

Which of the following is a feature of the sympathetic, but not the parasympathetic nervous system?

A) Ganglia located in the effector organs
B) Long preganglionic neurons
C) Preganglionic neurons release norepinephrine
D) Preganglionic neurons release acetylcholine (ACh)
E) Preganglionic neurons originate in the thoracolumbar spinal cord
F) Postganglionic neurons synapse on effector organs
G) Postganglionic neurons release epinephrine
H) Postganglionic neurons release ACh

Question 8

Which autonomic receptor mediates an increase in heart rate?

A) Adrenergic $\alpha$ receptors
B) Adrenergic $\beta_{1}$ receptors
C) Adrenergic $\beta_{2}$ receptors
D) Cholinergic muscarinic receptors
E) Cholinergic nicotinic receptors

Question 9

Cutting which structure on the left side causes total blindness in the left eye?

A) Optic nerve
B) Optic chiasm
C) Optic tract
D) Geniculocalcarine tract

Question 10

Which reflex is responsible for monosynaptic excitation of ipsilateral homonymous muscle?

A) Stretch reflex (myotatic)
B) Golgi tendon reflex (inverse myotatic)
C) Flexor withdrawal reflex
D) Subliminal occlusion reflex

Question 11

Which type of cell in the visual cortex responds best to a moving bar of light?

A) Simple
B) Complex
C) Hypercomplex
D) Bipolar
E) Ganglion

Question 12

Administration of which of the following drugs is contraindicated in a 10 -year-old child with a history of asthma?

A) Albuterol
B) Epinephrine
C) Isoproterenol
D) Norepinephrine
E) Propranolol

Question 13

Which adrenergic receptor produces its stimulatory effects by the formation of inositol 1,4,5-triphosphate ( $\left.\mathrm{IP}_{3}\right)$ and an increase in intracellular $\left[\mathrm{Ca}^{2+}\right]$ ?

A) $\alpha_{1}$ Receptors
B) $\alpha_{2}$ Receptors
C) $\beta_{1}$ Receptors
D) $\beta_{2}$ Receptors
E) Muscarinic receptors
F) Nicotinic receptors

Question 14

The excessive muscle tone produced in decerebrate rigidity can be reversed by

A) stimulation of group la afferents
B) cutting the dorsal roots
C) transection of cerebellar connections to the lateral vestibular nucleus
D) stimulation of $\alpha$ -motoneurons
E) stimulation of $\gamma$ -motoneurons

Question 15

Which of the following parts of the body has cortical motoneurons with the largest representation on the primary motor cortex (area 4)?

A) Shoulder
B) Ankle
C) Fingers
D) Elbow
E) Knee

Question 16

Which autonomic receptor mediates secretion of epinephrine by the adrenal medulla?

A) Adrenergic $\alpha$ receptors
B) Adrenergic $\beta_{1}$ receptors
C) Adrenergic $\beta_{2}$ receptors
D) Cholinergic muscarinic receptors
E) Cholinergic nicotinic receptors

Question 17

Cutting which structure on the right side causes blindness in the temporal field of the left eye and the nasal field of the right eye?

A) Optic nerve
B) Optic chiasm
C) Optic tract
D) Geniculocalcarine tract

Question 18

A ballet dancer spins to the left. During the spin, her eyes snap quickly to the left. This fast eye movement is

A) nystagmus
B) postrotatory nystagmus
C) ataxia
D) aphasia

Question 19

Which of the following has a much lower concentration in the cerebrospinal fluid (CSF) than in cerebral capillary blood?

A) $\mathrm{Na}^{+}$
B) $\mathrm{K}^{+}$
C) Osmolarity
D) Protein
E) $\mathrm{Mg}^{2+}$

Question 20

Which of the following autonomic drugs acts by stimulating adenylate cyclase?

A) Atropine
B) Clonidine
C) Curare
D) Norepinephrine
E) Phentolamine
F) Phenylephrine
G) Propranolol

Question 21

Which of the following is a step in photoreception in the rods?

A) Light converts all-trans retinal to 11-cis retinal
B) Metarhodopsin II activates transducin
C) Cyclic guanosine monophosphate (cGMP) levels increase
D) Rods depolarize
E) Glutamate release increases

Question 22

Pathogens that produce fever cause

A) decreased production of interleukin-1 (IL-1)
B) decreased set-point temperature in the hypothalamus
C) shivering
D) vasodilation of blood vessels in the skin

Question 23

Which of the following statements about the olfactory system is true?

A) The receptor cells are neurons
B) The receptor cells are sloughed off and are not replaced
C) Axons of cranial nerve (CN) I are A-delta fibers
D) Axons from receptor cells synapse in the prepiriform cortex
E) Fractures of the cribriform plate can cause inability to detect ammonia

Question 24

A lesion of the chorda tympani nerve would most likely result in

A) impaired olfactory function
B) impaired vestibular function
C) impaired auditory function
D) impaired taste function
E) nerve deafness

Question 25

Which of the following would produce maximum excitation of the hair cells in the right horizontal semicircular canal?

A) Hyperpolarization of the hair cells
B) Bending the stereocilia away from the kinocilia
C) Rapid ascent in an elevator
D) Rotating the head to the right

Question 26

The inability to perform rapidly alternating movements (dysdiadochokinesia) is associated with lesions of the

A) premotor cortex
B) motor cortex
C) cerebellum
D) substantia nigra
E) medulla

Question 27

Which autonomic receptor is activated by low concentrations of epinephrine released from the adrenal medulla and causes vasodilation?

A) Adrenergic $\alpha$ receptors
B) Adrenergic $\beta_{1}$ receptors
C) Adrenergic $\beta_{2}$ receptors
D) Cholinergic muscarinic receptors
E) Cholinergic nicotinic receptors

Question 28

Complete transection of the spinal cord at the level of T1 would most likely result in

A) temporary loss of stretch reflexes below the lesion
B) temporary loss of conscious proprioception below the lesion
C) permanent loss of voluntary control of movement above the lesion
D) permanent loss of consciousness above the lesion

Question 29

Sensory receptor potentials

A) are action potentials
B) always bring the membrane potential of a receptor cell toward threshold
C) always bring the membrane potential of a receptor cell away from threshold
D) are graded in size, depending on stimulus intensity
E) are all-or-none

Question 30

Cutting which structure causes blindness in the temporal fields of the left and right eyes?

A) Optic nerve
B) Optic chiasm
C) Optic tract
D) Geniculocalcarine tract

Question 31

Which of the following structures has a primary function to coordinate rate, range, force, and direction of movement?

A) Primary motor cortex
B) Premotor cortex and supplementary motor cortex
C) Prefrontal cortex
D) Basal ganglia
E) Cerebellum

Question 32

Which reflex is responsible for polysynaptic excitation of contralateral extensors?

A) Stretch reflex (myotatic)
B) Golgi tendon reflex (inverse myotatic)
C) Flexor withdrawal reflex
D) Subliminal occlusion reflex

Question 33

Which of the following is a characteristic of nuclear bag fibers?

A) They are one type of extrafusal muscle fiber
B) They detect dynamic changes in muscle length
C) They give rise to group Ib afferents
D) They are innervated by $\alpha$ -motoneurons

Question 34

Muscle stretch leads to a direct increase in firing rate of which type of nerve?

A) $\alpha$ -Motoneurons
B) $\gamma$ -Motoneurons
C) Group Ia fibers
D) Group Ib fibers

Question 35

A 42-year-old woman with elevated blood pressure, visual disturbances, and vomiting has increased urinary excretion of 3-methoxy-4-hydroxymandelic acid (VMA). A computerized tomographic scan shows an adrenal mass that is consistent with a diagnosis of pheochromocytoma. While awaiting surgery to remove the tumor, she is treated with phenoxybenzamine to lower her blood pressure. What is the mechanism of this action of the drug?

A) Increasing cyclic adenosine monophosphate (cAMP)
B) Decreasing cAMP
C) Increasing inositol 1,4,5-triphosphate $\left(\mathrm{IP}_{3}\right) / \mathrm{Ca}^{2+}$
D) Decreasing $\mathrm{IP}_{3} / \mathrm{Ca}^{2+}$
E) Opening $\mathrm{Na}^{+} / \mathrm{K}^{+}$ channels
F) Closing $\mathrm{Na}^{+} / \mathrm{K}^{+}$ channels

Question 36

Patients are enrolled in trials of a new atropine analog. Which of the following would be expected?

A) Increased AV node conduction velocity
B) Increased gastric acidity
C) Pupillary constriction
D) Sustained erection
E) Increased sweating