Directions: Each of the numbered items or incomplete statements in this section is followed by answers or by completions of the statement. Select the ONE lettered answer or completion that is BEST in each case.
1. The inability to perform rapidly alternating movements (dysdiadochokinesia) is associated with lesions of the
(A) premotor cortex
(B) motor cortex
(D) substantia nigra
2. A patient with chronic hypertension is treated with prazosin by his physician. The treatment successfully decreases the patient's blood pressure to within the normal range. What is the mechanism of the drug's action?
(A) Inhibition of p, receptors in the sinoatrial (SA) node
(B) Inhibition of (32 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 3, receptors in ventricular muscle
(F) Stimulation of Pi receptors in ventricular muscle
(G) Inhibition of a, receptors in ventricular muscle
(H) Stimulation of a] receptors in the SA node
(I) Inhibition of a! receptors in the SA node (J) Inhibition of oti receptors on vascular smooth muscle
(K) Stimulation of ctj receptors on vascular smooth muscle (L) Stimulation of a2 receptors on vascular smooth muscle
3. Which of the following responses is mediated by parasympathetic muscarinic receptors?
(A) Dilation of bronchiolar smooth muscle
(D) Constriction of gastrointestinal (GI) sphincters
(E) Increased cardiac contractility
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
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
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 heli-cotrema
(E) The apex is relatively stiff compared to the base
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
8. 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
9. 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
10. 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 lb afferents
(D) They are innervated by a-motoneurons
11. Which type of cell in the visual cortex responds best to a moving bar of light?
12. Administration of which of the following drugs is contraindicated in a 10-year-old child with a history of asthma?
13. Which adrenergic receptor produces its stimulatory effects by the formation of inositol 1,4,5-triphosphate (IP3) and an increase in intracellular [Ca2+]?
(A) oi! Receptors
(B) a2 Receptors
(C) Pi Receptors
(D) p2 Receptors
(E) Muscarinic receptors
(F) Nicotinic receptors
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 a-motoneurons
(E) stimulation of -y-motoneurons
15. Which of the following parts of the body has cortical motoneurons with the largest representation on the primary motor cortex (area 4)?
16. 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 ki-nocilia
(C) Rapid ascent in an elevator
(D) Rotating the head to the right
17. 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
18. A ballet dancer spins to the left. During the spin, her eyes snap quickly to the left. This fast eye movement is
(B) post-rotatory nystagmus
19. Which of the following has a much lower concentration in the cerebrospinal fluid (CSF) than in cerebral capillary blood?
20. Which of the following autonomic drugs acts by stimulating adenylate cyclase?
21. Which of the following is a step in photore-ception in the rods?
(A) Light converts all-trans retinal to 11-cts retinal
(B) Metarhodopsin II activates transducin
(C) Cyclic guanosine monophosphate (cGMP) levels increase
(D) Rods depolarize
(E) Release of neurotransmitter increases
22. Pathogens that produce fever cause
(A) decreased production of interleukin-1 (IL-1)
(B) decreased set-point temperature in the hypothalamus
(D) vasodilation of blood vessels in the skin
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
Directions: Each set of matching questions in this section consists of a list of four to twenty-six lettered options (some of which may be in figures) followed by several numbered items. For each numbered item, select the ONE lettered option that is most closely associated with it. To avoid spending too much time on matching sets with large numbers of options, it is generally advisable to begin each set by reading the list of options. Then, for each item in the set, try to generate the correct answer and locate it in the option list, rather than evaluating each option individually. Each lettered option may be selected once, more than once, or not at all.
(A) Adrenergic a receptors
(B) Adrenergic (J, receptors
(C) Adrenergic (32 receptors
(D) Cholinergic muscarinic receptors
(E) Cholinergic nicotinic receptors
Match each phenomenon with the autonomic receptors that mediate it.
24. Increased heart rate
25. Secretion of epinephrine by the adrenal medulla
26. Ion channels for Na+ and K+ at the neuromuscular junction
27. Blocked by hexamethonium at the ganglia, but not at the neuromuscular junction
28. Atropine decreases gastrointestinal (GI) motility by blocking this receptor
29. Low concentrations of epinephrine released from the adrenal medulla cause vasodilation
(A) Optic nerve
(B) Optic chiasm
(C) Optic tract
(D) Geniculocalcarine tract
Match each deficit with the appropriate optic pathway.
30. Cutting on the left side causes total blindness in the left eye
31. Cutting on the right side causes blindness in the temporal field of the left eye and the nasal field of the right eye
32. Cutting causes blindness in the temporal fields of the left and right eyes
(A) Primary motor cortex
(B) Premotor cortex and supplementary motor cortex
(C) Prefrontal cortex
(D) Basal ganglia
Match each description with the correct structure.
33. Active during programming and "mental rehearsal" of complex motor sequences in the absence of movement
34. Primary function is to coordinate rate, range, force, and direction of movement
(A) Stretch reflex (myotatic)
(B) Golgi tendon reflex (inverse myotatic)
(C) Flexor withdrawal reflex
(D) Subliminal occlusion reflex
Match each description with the correct reflex.
35. Polysynaptic excitation of contralateral extensors
36. Monosynaptic excitation of ipsilateral homonymous muscle
(C) Group la fibers
(D) Group lb fibers
Match each description with the correct nerve fiber.
37. Detect increases in muscle tension
38. Stimulation leads to contraction of the bulk of skeletal muscle
39. Muscle stretch leads to a direct increase in its firing rate
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