Physiology - An Illustrated Review

Questions & Answers

Review Questions

1. Characteristics of the sympathetic division of the autonomic nervous system (ANS) include

A.   effector organs that have muscarinic receptors.

B.   norepinephrine as the transmitter at preganglionic nerve terminals.

C.   acetylcholine as the transmitter at preganglionic nerve terminals.

D.   little divergence between pre- and postganglionic neurons.

E.   primary innervation of ciliary muscles.

2. Activation of the parasympathetic division of the autonomic nervous system may produce

A.   increased release of epinephrine from the adrenal medulla.

B.   increased basal metabolic rate.

C.   cutaneous vasodilation.

D.   decreased heart rate.

E.   thick, viscous saliva.

3. An anxious patient presents with dilated pupils. How do you explain this sign?

A.   The patient is trying to avoid squinting to see more clearly.

B.   The patient is overly sensitive to bright lights.

C.   There is subconscious relaxation of radial muscle fibers.

D.   There is parasympathetic activation to contract circular muscle fibers of the pupil.

E.   There is sympathetic activation to contract radial muscle fibers of the pupil.

4. How does the body respond when a patient starts to develop a fever?

A.   By shivering

B.   By sweating

C.   By blocking the response to pyrogens

D.   By decreasing the body temperature set point

E.   By inhibiting prostaglandin production

5. Thermal stress causes a person to collapse. The patient’s core body temperature is 105°F (40.6°C), and the skin is warm and dry. What is this condition?

A.   Accidental hypothermia

B.   Heat stroke

C.   Heat cramps

D.   Heat exhaustion

E.   Not a medical emergency

6. Which of the following remains after removal of the human cerebral cortex?

A.   Postural control

B.   Conditioning to patterned tonal stimuli

C.   The capacity to regulate body temperature

D.   Patterned vision

E.   Hypotonia in the extensor muscles

7. Chronic stimulation of the hypothalamic satiety center would

A.   produce the hypothalamic obesity syndrome.

B.   produce anorexia.

C.   cause hyperphagia.

D.   activate the feeding center.

E.   produce bulimia.

8. Adaptation to a prolonged constant stimulus in a sensory receptor

A.   occurs when the receptor receives a subthreshold stimulus.

B.   is characterized by a decreasing frequency of action potentials.

C.   is characterized by decreasing amplitude of action potentials.

D.   is identical to accommodation in neurons.

9. Optimal discrimination between closely spaced tactile stimuli, as in two-point discrimination, is found in skin regions where the

A.   receptive field sizes are largest.

B.   receptive field sizes are smallest.

C.   density of receptors is lowest.

D.   receptor thresholds are lowest.

E.   sensory axons leaving the region have uniform conduction velocities.

10. A 45-year-old man is diagnosed with a heart attack partly due to pain in his left upper arm. Why does he experience pain in his arm?

A.   The heart attack limits blood flow to the arm.

B.   Afferent fibers from the heart and arm converge onto the same spinal neuron.

C.   Sensory input from the heart projects to relays in the thalamus.

D.   Sympathetic efferent fibers innervate both the heart and blood vessels in the arm.

E.   Afferents from the heart cause reflex muscle contractions in the arm.

11. What mediates analgesia produced by brain stimulation?

A.   Prostaglandins

B.   Histamine

C.   Serotonin

D.   Substance P

E.   Opiate receptors

12. If the near point is closer to the eye than normal, then

A.   correction to normal vision requires a cylindrical lens.

B.   correction to normal vision requires a positive lens.

C.   the patient has presbyopia.

D.   the patient has hyperopia.

E.   the patient has myopia.

13. The macula (fovea centralis) of the retina

A.   is the area of most acute vision.

B.   contains the highest concentration of rods.

C.   has the lowest threshold for excitation in the retina.

D.   is specialized for excitation in the dark.

E.   is not used during routine vision.

14. What would you suspect was the cause of weak vision bilaterally and temporally (the outside half of both visual fields)?

A.   Macular degeneration

B.   Early stages of cataracts

C.   A pituitary tumor

D.   Damage to the fovea centralis of both eyes

E.   Trauma to the occipital cortex

15. A 62-year-old woman has a tumor in the nucleus of her left lateral lemniscus. Which hearing loss would you expect her to have?

A.   Deafness in her left ear

B.   Deafness in her right ear

C.   Slight hearing loss only in her left ear

D.   Slight hearing loss only in her right ear

E.   Slight hearing loss in both ears

16. A patient presents with dizziness and disorientation. The caloric nystagmus test is normal. Which of the following do you observe?

A.   Quick flick of the eyes to the left from warm water in the left ear

B.   Quick flick of the eyes to the right from warm water in the left ear

C.   Quick flick of the eyes to the left from warm water in the right ear

D.   Slow movement of the eyes to the left from cold water in the right ear

E.   Slow movement of the eyes to the right from cold water in the left ear

17. A lesion in which location would produce deafness limited to high tones?

A.   Tympanic membrane

B.   Ossicular chain

C.   Apical portion of the basilar membrane

D.   Basal portion of the basilar membrane

E.   Medial geniculate body

18. What would cause sensorineural deafness?

A.   Blocked eustachian tubes

B.   Punctured eardrums

C.   Destruction of cochlear hair cells by antibiotics

D.   Immobilized stapes

E.   Caloric nystagmus

19. The taste of sweet

A.   is associated with some organic chemicals.

B.   is associated with acids.

C.   is associated with alkaloids and some plant-derived poisons.

D.   may stimulate a sneeze.

E.   is a combination of two basic tastes, minty and salty.

20. The action potential frequency in 1a afferent fibers from the muscle spindle signals

A.   muscle length only.

B.   the rate of change of muscle length only.

C.   both muscle length and the rate of change of muscle length.

D.   muscle tension only.

E.   rate of change of muscle tension only.

21. Muscle relaxation evoked by the inverse myotatic reflex

A.   is initiated monosynaptically.

B.   is initiated by annulospiral endings in the relaxing muscle.

C.   requires inhibition of motoneurons supplying the relaxing muscle.

D.   supports the weight of the body.

E.   occurs simultaneously with a crossed flexor reflex in the opposite limb.

22.“Voluntary” movements are produced by

A.   the simultaneous activation of both α and γ motoneurons.

B.   impulses traveling via “upper” motoneurons directly from the brain to muscle extrafusal fibers.

C.   direct activation of the γ loop and reflex activation of α motoneurons.

D.   direct activation of α motoneurons with little or no response of γ motoneurons.

E.   selective activation of γ motoneurons.

23. Postural tone in antigravity muscles depends most upon sustained activity of

A.   cerebellar Purkinje cells.

B.   neurons of the reticulospinal tracts.

C.   neurons of the vestibulospinal tracts.

D.   neurons in the red nucleus.

E.   corticospinal neurons.

24. Which of the following characterizes lower motoneuron disease?

A.   Exaggerated reflexes

B.   Enhanced recurrent activation of Renshaw cells

C.   Being a later stage from the development of upper motoneuron disease

D.   Atrophy of the affected muscles

E.   Spasticity

25. The alpha rhythm of the electroencephalogram (EEG)

A.   results from cortical desynchronization during mental excitation.

B.   is in the frequency range of 4 to 7 Hz, seen in drowsy states.

C.   is indicative of cortical hypoxia.

D.   is the intrinsic cortical frequency in deep sleep.

E.   is prominent during supine relaxation with eyes closed.

26. Rapid eye movement (REM) sleep is characterized

A.   by an EEG pattern of low-amplitude desynchronized activity.

B.   by a cortical EEG pattern of delta range (2−4 Hz) activity.

C.   by a significant increase in muscle tone.

D.   as paradoxical because it occurs only once during the night, whereas other sleep stages occur several times.

E.   by a low arousal threshold.

27. During which stage of sleep is there the greatest variability of autonomic excitability?

A.   Stage 1

B.   Stage 2

C.   Stage 3

D.   Stage 4

E.   Stage REM

28. An obese 37-year-old man complains of falling asleep frequently during the day. A sleep laboratory study shows frequent airway blockage during the night. What is your diagnosis?

A.   Narcolepsy

B.   Hypersomnia

C.   Sleep apnea

D.   Somnambulism

E.   Enuresis

29. Why will a 5-year-old boy with amblyopia (lazy eye) become blind in one eye unless his convergence is corrected?

A.   Patching his weaker eye will preserve his vision.

B.   The lazy eye will suppress the stronger eye.

C.   The visual pathways from the stronger eye will degenerate.

D.   The visual cortex suppresses the image from the weaker eye to avoid diplopia (double vision).

E.   The plasticity of the brain will compensate for the loss of vision.

30. Which sign would you expect a right-handed patient with a tumor in the right parietal lobe to exhibit?

A.   Speech defects

B.   Right homonymous hemianopsia

C.   Psychomotor seizures

D.   Neglect of the left extremities

E.   Recent memory loss

31. A 23-year-old man presents with spastic limb movements after being poisoned with strychnine, which was added to his methamphetamine. What is the mechanism of this symptom?

A.   Excess excitation onto spinal motoneurons

B.   Hyperactivity of upper motoneurons

C.   Hypoactivity of upper motoneurons

D.   Block of excitatory afferent fibers

E.   Block of inhibitory transmitters acting on spinal motoneurons

Answers and Explanations

1. C Acetylcholine (not norepinephrine [B]) is the transmitter for all preganglionic nerve terminals and parasympathetic postganglionic nerve terminals (p. 35).

A,D,E The parasympathetic division has muscarinic receptors, little divergence, and is the primary innervation of ciliary muscles.

2. D Activity of the vagus nerve slows the heart (p. 40).

A,B,E Sympathetic, not parasympathetic, activity releases epinephrine, increases metabolism, and produces viscous saliva.

C Sympathetic, not parasympathetic, cholinergic fibers produce cutaneous vasodilation.

3. E Anxiety would produce sympathetic activation, which dilates the pupils by contracting the radial muscle dilator pupillae (p. 41).

A Squinting is characteristic of patients with diplopia (double vision) or a response to bright lights.

B–D The pupils are constricted in response to bright lights, by relaxation of radial muscle fibers, or by parasympathetic activation of the cicular muscle sphincter pupillae.

4. A The pyrogens that cause a fever act on the anterior hypothalamus to increase prostaglandin synthesis. These prostaglandins stimulate the thermoregulatory center to reset the set point temperature to a higher temperature (not D). The body tries to raise its temperature to this new set point temperature by shivering (pp. 4344).

B,C,E Sweating decreases body temperature, as would blocking the response to pyrogens or inhibiting prostaglandin production.

5. B Heat stroke occurs with prolonged hyperthermia (elevated body temperature) and no sweating (p. 44).

A Hypothermia is abnormally low core body temperature (< 95°F [35°C]).

C Heat cramps are muscular spasms.

D Heat exhaustion is associated with excessive sweating.

E Heat stroke is a medical emergency.

6. C An intact hypothalamus will remain if the human cerebral cortex is removed. Thus the capacity to adequately regulate body temperature will remain (p. 43).

A Although posture is at least partially controlled through the basal ganglia, postural control will be impaired by destruction of the cortex.

B,D Behaviors conditioned to patterned tones require association cortex, as does mediation of patterned vision.

E Decerebration would produce hypertonia (abnormal increase in muscle tension and a reduced ability of a muscle to stretch).

7. B Stimulation of the satiety center depresses food intake and produces anorexia, or loss of appetite (p. 44).

A,C Stimulation of the feeding center would override phasic satiety center inhibition and produce hyperphagia (overeating) with consequent obesity if stimulation were chronic.

D Such stimulation inhibits the feeding center.

E Bulimia (episodic binge eating) is a behavioral response of half of anorexics.

8. B Adaptation occurs when the sensitivity of a sensory receptor to a constant stimulus declines, decreasing the frequency of action potentials initiated by the receptor (pp. 4748).

A A subthreshold stimulus will not generate any action potentials.

C Action potential amplitudes are constant.

D Accommodation in neurons is the increase in threshold due to inactivation of some Na+ channels.

9. B To discriminate closely spaced stimuli, sensory nerves involved must have small receptive fields (p. 48).

A Large receptive fields for sensory nerves make discriminating closely spaced stimuli difficult.

C Low density of receptors implies larger areas, not smaller, for each receptive field.

D,E Neither receptor threshold nor afferent axon conduction velocity is relevant.

10. B The basis of referred pain is convergence of the afferent pain fibers from the heart and arm onto the same spinal neuron (p. 51).

A The heart attack limits blood flow to all parts of the body, but pain from this would not be localized to the left arm.

C Sensory input projects from the heart, but that does not explain pain in the arm.

D Afferent, not efferent, fibers are required to feel a sensation.

E There is no splinting pain associated with the heart.

11. E Endorphins act on opiate receptors in the midbrain to suppress descending pain transmission at the level of the spinal cord (p. 52).

A–C Prostaglandins, histamine, and serotonin are released as the result of tissue injury and lead to pain.

D Substance P is a common transmitter for nociceptive (pain) pathways.

12. E In myopia (nearsightedness), the near point is closer than normal. A concave, or negative lens, is needed to move the near point further from the eye (pp. 5354).

A Cylindrical lenses are used to correct for astigmatism (refractive error that causes blurred vision).

B A negative, or concave, lens is needed to correct for myopia (nearsightedness), moving the near point further from the eye.

C In presbyopia (inability to focus on near objects), the near point gradually increases with age as the lens becomes less elastic.

D In hyperopia (farsightedness), the eyeball is too short or the lens is too flat. In either case, the closest focus is beyond the normal near point for a person’s age. It is corrected with a convex, or positive, lens.

13. A The fovea centralis, located in the center of the macular region of the retina, is the area of most acute vision (p. 54).

B The fovea has the highest concentration of cones, not rods.

C–E Eye movements (saccades) normally tend to place targets on the fovea for the greatest visual acuity, away from the low threshold rods used under low levels of illumination.

14. C A pituitary tumor would put pressure on the optic chiasm where optic nerves cross. The pituitary is closer to nerves from the nasal fields of both retinas, which respond to light in the temporal visual fields (p. 57).

A Macular degeneration affects central vision in one or both eyes.

B Cataracts produce fuzzy vision.

D Damaged maculae affect central vision.

E Damage to the visual cortex produces generalized visual impairment rather than in specific fields.

15. E Because afferents from both ears relay on both sides of the brain, hearing from both ears is diminished (not answers C and D) (p. 61).

A,B Most auditory input is still transmitted to the auditory cortex because afferents from both ears relay on both sides of the brain; therefore, answers A and B are incorrect.

16. A The direction of nystagmus is determined by quick flick recovery after a slow movement in the opposite direction. Warm water in the left ear produces nystagmus to the left (not to the right, as in B) (p. 53).

C Warm water in the right ear does not produce nystagmus to the right.

D,E The slow movements from cold water are normally in the direction of the ear being tested. The mnemonic is COWS: cold, opposite; warm, same.

17. D The basal portion of the basilar membrane transduces high frequencies, therefore a lesion at this location would result in deafness to high tones (p. 61).

A Perforation of the tympanic membrane causes more loss of low frequencies, not high frequencies.

B Damage to the middle ear bones would cause general hearing deficits.

C The apical portion of the basilar membrane transduces low frequencies.

E Lesions of the medial geniculate body would produce hearing deficits dependent on the exact site of the lesion.

18. C Loss of cochlear hair cells is a common cause of sensorineural deafness (p. 60).

A,B,D Blocked eustachian tubes, punctured tympanic membranes (eardrums), or immobilized stapes would produce conduction deafness.

E Caloric nystagmus is a clinical test for vestibular pathology. It involves slow then fast eye movements induced by stimulation with warm or cool water in the ear.

19. A Sweet is associated with sugars and amino acids (p. 63).

B Most acids produce a sour, not a sweet, taste.

C, D Alkaloids taste bitter; no taste normally causes sneezes.

E Minty is not a basic taste.

20. B 1a afferents that arise from annulospiral endings signal the rate of change of muscle length (not A and C) (pp. 6566).

D,E Golgi tendon organs, not 1a afferent fibers from the muscle spindle, signal muscle tension responses.

21. C The inverse myotatic reflex inhibits muscle contraction by inhibiting extensor motor neurons, allowing the limb to flex (pp. 6768).

A,B The reflex is initiated by Golgi tendon organs and is at least disynaptic through an inhibitory interneuron to motoneurons.

D The body would collapse if supported by the affected limb.

E A crossed extensor, not flexor, reflex could support the body with the opposite limb.

22. A Voluntary movements involve coactivation, activation of both α and γ motoneurons (p. 66).

B Movements require activation of “lower” motoneurons that innervate skeletal muscle fibers.

C–E Alpha motoneurons may be activated from higher centers only a few milliseconds before γ motoneurons.

23. B Neurons of the lateral and medial reticulospinal tracts control axial and girdle muscles that are important for posture. The γ-motoneurons facilitate extensor tone for postural support (pp. 677071).

A Purkinje cells inhibit cerebellar subcortical nuclei and do not affect muscle tone.

C Vestibulospinal neurons innervate neck muscles and are important for head movements.

D Rubrospinal neurons activate flexors and inhibit extensors, similar to corticospinal neurons.

E Corticospinal neurons initiate movements and usually decrease muscle tone.

24. D Lower motoneuron lesions sever the connection between the muscle and the CNS. This denervation results in muscle atrophy (p. 72).

A,E Upper motoneuron diseases release spinal lower motoneurons from descending inhibition, resulting in spasticity and exaggerated reflexes.

B Lower motoneuron lesions result in less activation of recurrent pathways.

C Pathologies of upper and lower motoneurons usually have different causes.

25. E The alpha rhythm is a normal response of the neocortex in the frequency range of 8 to 13 Hz, seen when the patient is relaxed with their eyes closed (not A-C) (p. 78).

D The predominant frequency in deep sleep is lower (2−4 Hz).

26. A REM sleep is characterized by an EEG pattern of low-amplitude desynchronized activity. This is paradoxical because this pattern is normally seen in an awake EEG (p. 80).

B Delta activity is characteristic of sleep stages 3 and 4, not REM sleep.

C There is a significant decrease in muscle tone during REM sleep.

D REM is cyclical with other sleep stages, occurring a few times during the night.

E The arousal threshold is high.

27. E Autonomic excitability is high during REM sleep (p. 80).

A–D Autonomic excitability decreases in deeper non-REM stages.

28. C Sleep apnea is characterized by airway blockage, typically in obese persons (pp. 7980).

A Narcolepsy patients go quickly from awake to REM sleep.

B Hypersomnia patients have excessive slow-wave sleep.

D Somnambulism is sleepwalking.

E Enuresis is bedwetting.

29. D The blindness that can result from amblyopia (lazy eye) occurs in the cortex (p. 53).

A,B Patching his stronger, not weaker, eye is part of the treatment because the stronger eye suppresses the image from the weaker eye.

E The plasticity of the brain does not compensate for the loss of vision.

30. D A right-handed patient with a tumor in the right parietal lobe would neglect their left extremities because body image is maintained by the contralateral parietal cortex in parallel with contralateral somesthetic sensory projection (pp. 4969).

A,C,E Speech defects, recent memory loss, and psychomotor seizures are problems associated with the temporal, not parietal, lobes.

B Right homonymous hemianopsia is the lack of vision in the right half of the visual field due to a damaged left optic tract.

31. E Strychnine blocks transmission from spinal inhibitory interneurons postsynaptically (p. 67).

A This produces disinhibition of motoneurons, not excess excitation.

B–C Upper motoneurons are not affected.

D Afferent fibers are not affected.