Question 1

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

Accepted Answer

[ $\mathrm{C} 2 \mathrm{a}$ ]. Hexamethonium is a nicotinic blocker, but it acts only at ganglionic (not neuromuscular junction) nicotinic receptors. This pharmacologic distinction emphasizes that nicotinic receptors at these two locations, although similar, are not identical.

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?

Accepted Answer

[ $\mathrm{C} 1 \mathrm{a}$; Table 2.2]. Prazosin is a specific antagonist of $\alpha_{1}$ receptors, which are present in vascular smooth muscle, but not in the heart. Inhibition of $\alpha_{1}$ receptors results in vasodilation of the cutaneous and splanchnic vascular beds, decreased total peripheral resistance, and decreased blood pressure.

Question 3

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

Accepted Answer

[ $\mathrm{I} \mathrm{C} 2 \mathrm{~b}$; Table 2.6]. Erection is a parasympathetic muscarinic response. Dilation of the bronchioles, ejaculation, constriction of the gastrointestinal (GI) sphincters, and increased cardiac contractility are all sympathetic $\alpha$ or $\beta$ responses.

Question 4

Which of the following is a property of C fibers?

Accepted Answer

[II F 1 b; Table 2.5]. C fibers (slow pain) are the smallest nerve fibers and therefore have the slowest conduction velocity.

Question 5

When compared with the cones of the retina, the rods

Accepted Answer

[II C 2 c (2); Table 2.7]. Of the two types of photoreceptors, the rods are more sensitive to low-intensity light and therefore are more important than the cones for night vision. They adapt to darkness after the cones. Rods are not present in the fovea. The cones are primarily involved in color vision.

Question 6

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

Accepted Answer

[II D 4]. Sound frequencies can be encoded by the organ of Corti because of differences in properties along the basilar membrane. The base of the basilar membrane is narrow and stiff, and hair cells on it are activated by high frequencies. The apex of the basilar membrane is wide and compliant, and hair cells on it are activated by low frequencies.

Question 7

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

Accepted Answer

[I A, B; Table 2.1; Figure 2.1]. Sympathetic preganglionic neurons originate in spinal cord segments T1-L3. Thus, the designation is thoracolumbar. The sympathetic nervous system is further characterized by short preganglionic neurons that synapse in ganglia located in the paravertebral chain (not in the effector organs) and postganglionic neurons that release norepinephrine (not epinephrine). Common features of the sympathetic and parasympathetic nervous systems are preganglionic neurons that release acetylcholine (ACh) and postganglionic neurons that synapse in effector organs.

Question 8

Which autonomic receptor mediates an increase in heart rate?

Accepted Answer

[ $\mathrm{IC} 1 \mathrm{c}$ ]. Heart rate is increased by the stimulatory effect of norepinephrine on $\beta_{1}$ receptors in the sinoatrial (SA) node. There are also sympathetic $\beta_{1}$ receptors in the heart that regulate contractility.

Question 9

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

Accepted Answer

[II C 3 a]. Cutting the optic nerve from the left eye causes blindness in the left eye because the fibers have not yet crossed at the optic chiasm.

Question 10

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

Accepted Answer

[III C 1]. The stretch reflex is the monosynaptic response to stretching of a muscle. The reflex produces contraction and then shortening of the muscle that was originally stretched (homonymous muscle).

Question 11

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

Accepted Answer

[II C $5 \mathrm{~b}$ (2)]. Complex cells respond to moving bars or edges with the correct orientation. Simple cells respond to stationary bars, and hypercomplex cells respond to lines, curves, and angles. Bipolar and ganglion cells are found in the retina, not in the visual cortex.

Question 12

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

Accepted Answer

[I $\mathrm{C} 1 \mathrm{~d}$; Table 2.2]. Asthma, a disease involving increased resistance of the upper airways, is treated by administering drugs that produce bronchiolar dilation (i.e., $\beta_{2}$ agonists). $\beta_{2}$ Agonists include isoproterenol, albuterol, epinephrine, and, to a lesser extent, norepinephrine. $\beta_{2}$ Antagonists, such as propranolol, are strictly contraindicated because they cause constriction of the bronchioles.

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 $\left[\mathrm{Ca}^{2+}\right]$ ?

Accepted Answer

[ I C 1 a]. Adrenergic $\alpha_{1}$ receptors produce physiologic actions by stimulating the formation of inositol 1,4,5-triphosphate $\left(\mathrm{IP}_{3}\right)$ and causing a subsequent increase in intracellular $\left[\mathrm{Ca}^{2+}\right]$. Both $\beta_{1}$ and $\beta_{2}$ receptors act by stimulating adenylate cyclase and increasing the production of cyclic adenosine monophosphate (cAMP). $\alpha_{2}$ Receptors inhibit adenylate cyclase and decrease cAMP levels. Muscarinic and nicotinic receptors are cholinergic.

Question 14

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

Accepted Answer

[III E $3 \mathrm{a}, \mathrm{b}$ ]. Decerebrate rigidity is caused by increased reflex muscle spindle activity. Stimulation of group Ia afferents would enhance, not diminish, this reflex activity. Cutting the dorsal roots would block the reflexes. Stimulation of $\alpha$ - and $\gamma$-motoneurons would stimulate muscles directly.

Question 15

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

Accepted Answer

[II B 4]. Representation on the motor homunculus is greatest for those structures that are involved in the most complicated movements--the fingers, hands, and face.

Question 16

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

Accepted Answer

[I $\mathrm{C} 2$ a; Figure 2.1]. Preganglionic sympathetic fibers synapse on the chromaffin cells of the adrenal medulla at a nicotinic receptor. Epinephrine and, to a lesser extent, norepinephrine are released into the circulation.

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?

Accepted Answer

[II C 3 c]. Fibers from the left temporal field and the right nasal field ascend together in the right optic 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

Accepted Answer

[II E 3]. The fast eye movement that occurs during a spin is nystagmus. It occurs in the same direction as the rotation. After the spin, postrotatory nystagmus occurs in the opposite direction.

Question 19

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

Accepted Answer

[V B; Table 2.9]. Cerebrospinal fluid (CSF) is similar in composition to the interstitial fluid of the brain. Therefore, it is similar to an ultrafiltrate of plasma and has a very low protein concentration because large protein molecules cannot cross the bloodbrain barrier. There are other differences in composition between CSF and blood that are created by transporters in the choroid plexus, but the low protein concentration of CSF is the most dramatic difference.

Question 20

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

Accepted Answer

[I C $1 \mathrm{c}$, d; Table 2.2]. Among the autonomic drugs, only $\beta_{1}$ and $\beta_{2}$ adrenergic agonists act by stimulating adenylate cyclase. Norepinephrine is a $\beta_{1}$ agonist. Atropine is a muscarinic cholinergic antagonist. Clonidine is an $\alpha_{2}$ adrenergic agonist. Curare is a nicotinic cholinergic antagonist. Phentolamine is an $\alpha_{1}$ adrenergic antagonist. Phenylephrine is an $\alpha_{1}$ adrenergic agonist. Propranolol is a $\beta_{1}$ and $\beta_{2}$ adrenergic antagonist.

Quiz 2: Neurophysiology

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

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?

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

Which of the following is a property of C fibers?

When compared with the cones of the retina, the rods

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

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

Which autonomic receptor mediates an increase in heart rate?

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

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

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

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

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 $\left[\mathrm{Ca}^{2+}\right]$ ?

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

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

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

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

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

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

Quiz 2: Neurophysiology

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

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?

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

Which of the following is a property of C fibers?

When compared with the cones of the retina, the rods

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

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

Which autonomic receptor mediates an increase in heart rate?

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

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

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

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

Which adrenergic receptor produces its stimulatory effects by the formation of inositol 1,4,5-triphosphate ( IP3) \left.\mathrm{IP}_{3}\right) IP3​) and an increase in intracellular [Ca2+]\left[\mathrm{Ca}^{2+}\right][Ca2+] ?

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

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

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

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

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

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

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 $\left[\mathrm{Ca}^{2+}\right]$ ?