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CNS MCQs

  1. 1. 1. Which of the following synaptic transmission is not peptide, polypeptide, or protein? A. Substance P B. Met-enkephalin C. Β-endorphin D. Serotonin * E. Dynorphin 2. Which of the following would no be expected to enhance nor-adrenergic transmission? A. A drug that increases the entry of arginine into neurons. * B. A drug that enhances tyrosine hydroxylase activity C. A drug that enhances dopamine β-hydroxylase D. A drug that inhibits monoamine oxidase E. A drug that inhibits norepinephrine reuptake 3. Pacinian corpuscles are A. A type of thermoreceptor B. Usually innervated by A δ nerve fibers C. Rapidly adapting touch receptors * D. Slowly adapting touch receptors E. Nociceptors 4. Adaptation to a sensory stimulus produces A. A diminished sensation when other types of sensory stimuli are withdrawn B. A more intense sensation when a given stimulus is applied repeatedly C. A sensation localized to the hand when the nerves of the brachial plexus are stimulated D. A diminished sensation when a given stimulus is applied repeatedly over time * E. A decreased firing rate in the sensory nerve from the receptor when one’s attention is directed to another matter. 5. Sensory systems code for the following attributes of a stimulus: A. Modality, location, intensity, and duration B. Threshold, receptive field, adaptation, and discrimination C. Touch, taste, hearing and smell D. Threshold, laterality, sensation and duration E. Sensitization, discrimination, energy, and projection 6. In which of the following is the frequency of stimulation not linearly related to the strength of the sensation felt? A. Sensory area of the cerebral cortex B. Specific projection nuclei of the thalamus C. Lateral spinothalamic tract D. Dorsal horn E. Cutaneous receptors 7. Which of the following receptors and sense organs are incorrectl paired? A. Rods and cones : eye B. Receptors sensitive to sodium : taste buds C. Hair cells : olfactory epithelium * D. Receptors sensitive to stretch : carotid sinus E. Glomus cells : carotid body
  2. 2. 8. Which best describes the law of specific nerve energies? A. No matter where a particular sensory pathway is stimulated along its course to the cortex, the conscious sensation produced is referred to the location of the receptor B. A nerve can only be stimulated by electrical energy C. Receptors can respond to forms of energy other than their adequate stimuli, but the threshold for these nonspecific responses is much higher D. For any given sensory modality, the specific relationship between sensation and stimulus intensity is determined by the properties of the peripheral receptors E. The sensation evoked by impulses generated in receptor depends in part on the specific part of the brain they ultimately activate 9. Which of the following does not contain cation channels that are activated by mechanical distortion, producing depolarization? A. Olfactory receptors B. Pacinian corpuscles C. Hair cells in cochlea D. Hair cells in semicircular canals * E. Hair cells in utricle 10. The inverse stretch reflex A. Has a lower threshold than the stretch reflex B. Is am monosynaptic reflex C. Is disynaptic reflex with a single interneuron inserted between the afferent and efferent limbs * D. Is a polysynaptic reflex with many interneurons inserted between the afferent and efferent limbs E. Requires the discharge of central neurons that release 11. When γ-motor neuron discharge increases at the same time as α-motor neuron discharge to muscle A. Prompt inhibition of discharge in spindle Ia afferents takes place B. The contraction of the muscle is prolonged C. The muscle will not contract D. The number of impulses n spindle Ia afferents is smaller than when α discharge alone is increased E. The number of impulses in spindle Ia afferents is greater than when α discharge alone is increased * 12. Which of the following is not characteristic of a reflex? A. Modification by impulses from various parts of the CNS B. May involve simultaneous contraction of some muscle and relaxation of others C. Chronically suppressed after spinal cord transaction * D. Always involves transmission across at least one synapse E. Frequently occurs without conscious perception
  3. 3. 13. The distance by which two touch stimuli must be separated to be perceived as two separate stimuli is greatest on the A. Lips B. Palm of the hand C. Back of the scapula * D. Dorsum of the hand E. Tips of the fingers 14. Visceral pain A. Shows relatively rapid adaptation B. Is mediated by B fibers in the dorsal roots of the spinal nerves C. Is poorly localized * D. Resembles ‘fast pain’ produced by noxious stimulation of the skin E. Causes relaxation of nearly skeletal muscles 15. Nociceptors A. Are activated by strong pressure, severe cold, severe heat, and chemicals * B. Are absent in visceral organs C. Are specialized structures located in the skin and joints D. Are innervated by group II afferents E. Allof the above 16. Thermoreceptors A. Are activated only by severe cold or severe heat B. Are located on superficial layers of the skin C. Are a subtype of nociceptors D. Are on dendtric endings of Aδ fibers and C fibers * E. All of the above 17. Patients with transected spinal cords frequently have a negative nitrogen balance because A. They develop hypercalcemia, and this causes dissolution of the protein in bone B. They are paralyzed below the level of the transaction * C. They lack the afferent input that normally maintains growth hormone secretion. D. They have difficulty voiding, and this causes nitrogen to accumulate n the urine in the bladder. E. Their corticotropin response to stress is reduced 18. A ventrolateral cordotomy is performed that produces relief of pain in the right leg. It is effective ecause it interrupts the: A. Left dorsal column B. Left ventral spinothalamic tract C. Right lateral spinothalamic tract D. Left lateral spinothalamic tract * E. Right corticospinal tract 19. Which of the following does not exert an analgesic effect? A. Morphine B. Cholinergic antagonists *
  4. 4. C. Adrenergic antagonists D. Substance P antagonists E. Anandamide 20. A 50-year-old woman undergoes a neurological exam that indicates loss of pain and temperature sensitivity, vibratory sense, and proprioception in both legs. These symptoms could be explained by: A. A tumor on the medial leminiscal pathway in the sacral spinal cord B. A peripheral neuropathy C. A large tumor in the sacral dorsal horn D. A large tumor affecting the posterior paracentral gyri* E. A large tumor in the ventral posterolateral and posteromedial thalamic nuclei 21. In a patient who has become dehydrated, body water should be replaced by intravenous infusion of A. Distilled water B. 0.9% sodium chloride solution C. 5% glucose solution * D. Hyperoncotic albumin E. 10% glucose solution 22. When a woman who has been on a low-sodium diet for 8d is given an intravenous injection of captopril, a drug that inhibits angiotensin-converting enzyme, one would expect A. Her blood pressure to rise because her cardiac output would fall B. Her blood pressure to rise because her peripheral resistance would fall C. Her blood pressure to fall because her cardiac output would fall D. Her blood pressure to fall because her peripheral resistance would fall E. Her plasma rennin activity to fall because her circulating angiotensin I level would rise * 23. Intravenous lactic acid increases ventilation. The receptors responsible for this effect are located in the: A. Medulla ablongata B. Carotid bodies * C. Lung parenchyma D. Aortic baroreceptors E. Trachea and large bronchi 24. Injection of a drug that stimulates the carotid bodies would be expected to cause: A. A decrease in the pH of arterial blood B. A decrease in the PCO2 of arterial blood * C. An increase in the HCO3- concentration of arterial blood D. An increase in urinary Na+ excretion E. An increase in plasma Cl- 25. On the summit of Mt. Everest, where the barometric pressure is about 250mmHg, the partial pressure of O2 is about: A. 0.1 mmHg B. 0.5 mmHg C. 5 mmHg D. 50 mmHg * E. 100 mmHg
  5. 5. 26. Injection of tissue plasminogen activator (t-PA) would probably be most beneficial: A. After at least 1 year of uncomplicated recovery following occlusion of a coronary artery B. After at least 2 months of rest and recuperation following occlusion of a coronary artery C. During the second week after occlusion of a coronary artery D. During the second day after occlusion of a coronary artery E. During the second hour after occlusion of a coronary artery * 27. Which of the following organs has the greatest blood flow per 100 g of tissue? A. Brain B. Heart muscle C. Skin D. Liver E. Kidney * 28. When a pheochromocytoma (tumor of the adrenal medulla) suddenly discharges a large amount of epinephrine into the circulation, the patient’s heart rate would be expected: A. Increase, because the increase in blood pressure stimulates B. Increase, because epinephrine has a direct chronotropic effect on the heart * C. Increase, because of increased tonic parasympathetic discharge to the heart D. Decrease, because the increase in blood pressure stimulates the carotid and aortic chemoreceptors E. Decrease, because of increased tonic parasympathetic discharge to the heart 29. The fourth heart sound is caused by A. Closure of the aortic and pulmonary valves B. Vibrations in the ventricular wall during systole C. Ventricular filling * D. Closure of the mitral and tricuspid E. Retrograde flow in the vena cava 30. Removal of the entire colon would be expected to cause: A. Death B. Megaloblastic anemia C. Severe malnutrition D. A decrease in the blood level of ammonia in patients with cirrhosis of the liver E. Decreased urinary urobilinogen * 31. After complete hepatectomy, a rise would be expected in the blood level of: A. Glucose B. Fibrinogen C. 25-hydroxycholecalciferol D. Conjugated bilirubin E. Estrogens * 32. A patient with a tumor secreting abnormal amounts of gastrin (gastrinoma) would be most likely to exhibit which of the following? A. Decreased chief cell exocytosis B. Duodenal ulceration * C. Increased gastric pH in the period between meals D. A reduced incidence of gastroesophageal reflux disease
  6. 6. E. Protein malabsorption 33. Full development and function of the semniferous tubules require A. Somatostatin B. LH C. Oxytocin D. FSH E. Androgens and FSH * 34. A scientist finds that infusion of growth hormone into the median eminence of the hypothalamus in experimental animals inhibits the secretion of growth hormone and concludes that this proves that growth hormone feeds back to inhibit GHRH secretion. Do you accept this conclusion? A. No, because growth hormone does not cross the blood brain barrier B. No, because the infused growth hormone could be stimulating dopamine secretion C. No, because substances placed in the median eminence could be transported to the anterior pituitary * D. Yes, because systemically administered growth hormone inhibits growth hormone secretion E. Yes, because growth hormone binds GHRH, inactivating it 35. In osteopetrosis, which of the following is defective? A. Phosphate deposition in trabecular bone B. Structure of parathyroid hormone related protein (PTHrP) C. Osteoblasts D. Osteoclasts * E. Bone collagen 36. When the plasma glucose concentration falls to low levels, a number of different hormones help combat the hypoglycemia. After intravenous administration of a large dose of insulin, the return of a low blood sugar level to normal is delayed in A. Adrenal medullary insufficiency B. Glucagon deficiency C. Combined adrenal medullary insufficiency and glucagon * D. Thyrotoxicosis E. Acromegaly 37. A lesion of Wernicke’s area (the posterior end of the superior temporal gyrus) in the categorical hemisphere causes patients to: A. Lose short-term memory B. Speak in a slow, halting voice C. Experience déjà vu D. Talk rapidly make little sense * E. Lose the ability to recognize faces 38. Patients with transected spinal cords frequently have a negative nitrogen balance because A. They develop hypercalcemia, and this causes dissolution of the protein in bone B. They are paralyzed below the level of the transection * C. They lack the afferent input that normally maintains growth hormone secretion D. They have difficulty voiding, and this causes nitrogen to accumulate in the urine in the bladder E. Their corticoptropin response to stress is reduced
  7. 7. 39. As result of an automobile accident, a 10-year-old boy suffered damaged to the brain including the perimygdaloid, piriform, and entorhinal cortices. Which of the following sensory deficits is he most likely to experience? A. Visual disturbance B. Hyperosmia C. Auditory problems D. Taste and odor abnormalities * E. No major sensory deficits 40. A 40-year-old man loses his right hand in a farm accident. Four years later, he has episodes of severe pain in the missing hand (phantom limb pain). A detailed PET scan study of his cerebral cortex might be expected to show A. Expansion of the right hand area in his right somatic sensory area I (SI) B. Expansion of the right-hand area in his left SI C. A metabolically inactive spot where his hand area in his left SI would normally be D. Projection of fibers from neighboring sensory areas into the right-hand area of his right SI E. Projection of fibers from neighboring sensory areas into the right-hand area of his left SI * 41. Activation of which of the following receptors would be expected to decrease anxiety? A. Nicotinic cholinergic receptors B. Glutamate receptors C. GABAA receptors D. Glucocorticoid receptors * E. α1-adrenergic receptors 42. Withdrawal reflexes are not A. Initiated by nociceptive stimuli B. Prepotent C. Prolonged if the stimulus is strong D. An example of a flexor reflex E. Accompanied by the same response on both sides of the body

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