Top 550+ Solved Physiology MCQ Questions Answer

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Q. Which is CORRECT?

a. voluntary control of breathing originates in the pons/medulla

b. automatic breathing control descends to the respiratory musculature via the corticospinal tract

c. the reciprocal innervation in automatic breathing is via descending pathways rather than spinal reflexes

d. automatic fibres descend to innervate the external intercostal muscles at each thoracic level to mediate expiration

e. there is no output to the phrenic nerves during expiration

  • c. the reciprocal innervation in automatic breathing is via descending pathways rather than spinal reflexes

Q. Which abolishes automatic respiration? Destruction of:

a. pre-Bottzinger complexes

b. ventral gp respiratory neurons

c. dorsal gp respiratory neurons

d. section at the inferior border of the pons

e. transaction rostral to the pons

  • a. pre-Bottzinger complexes

Q. Which does not stimulate carotid bodies?

a. carbon monoxide poisoning

b. cyanide poisoning

c. hypoxia

d. hypercapnia

e. increased H+ concentration

  • a. carbon monoxide poisoning

Q. All of the following shift the Hb dissociation curve to the right during exerciseEXCEPT:

a. increased 2,3 DPG

b. increased pCO2

c. increased temperature

d. decreased pO2

e. increased H+ concentration

  • d. decreased pO2

Q. Hypoxia at high altitudes:

a. is a form of stagnant hypoxia

b. causes symptoms of cyanosis

c. causes severe symptoms in an unacclimatised person at 3,000m

d. can always be reversed with 100% O2

e. increased H+ concentration

  • b. causes symptoms of cyanosis

Q. Regarding surfactant:

a. infant respiratory distress syndrome can be adequately treated with administration of phospholipids alone

b. cigarette smokers have the same amount of surfactant as non-smokers

c. the phospholipid film is formed by tubular myelin

d. infant respiratory distress syndrome is caused by insufficient surfactant that prevents the alveoli from expanding at first inspiratory effort

e. formation of the phospholipid film is greatly facilitated by the carbohydrate in surfactant

  • c. the phospholipid film is formed by tubular myelin

Q. Regarding the work of breathing during quiet inspiration:

a. elastic work = 80%

b. viscous resistance = 7%

c. airway resistance = 13%

d. when tidal volume versus intrapleural pressure in quiet inspiration are plotted, a straight line results

e. the amount of elastic work required to inflate the whole respiratory system is more than the amount required to inflate the lungs alone

  • b. viscous resistance = 7%

Q. Regarding gas exchange in the lungs:

a. N2O is diffusion limited

b. CO is perfusion limited

c. O2 is between N2O and CO but at rest, is perfusion limited

d. diffusing capacity of the lung for a gas is inversely proportionate to the surface area of the alveolocapillary membrane and directly proportional to its thickness

e. at rest, it takes blood 0.25secs to traverse the pulmonary capillaries

  • c. O2 is between N2O and CO but at rest, is perfusion limited

Q. Regarding bronchial tone:

a. substance P causes bronchoconstriction

b. constriction is caused by sympathetic discharge

c. dilation is caused by parasympathetic discharge

d. maximal bronchoconstriction occurs at 4am

e. VIP causes bronchoconstriction

  • a. substance P causes bronchoconstriction

Q. Regarding pulmonary function, which of the following is NOT true?

a. FRC = ERV + RV

b. IRV in men is about 3,3L

c. RV in women is about 1.1L

d. inspiratory capacity in men = 4.8L

e. total lung capacity = 6L in men, 4.2L in women

  • d. inspiratory capacity in men = 4.8L

Q. Regarding the glottis:

a. when laryngeal adductors are paralysed there is inspiratory stridor

b. abductors contract early in inspiration

c. when abductors are paralysed, aspiration pneumonia may result

d. the adductors are supplied by the vagus nerves, the abduction by the hypoglossal nerve

e. in animals with bilateral cervical vagotomy, pulmonary oedema is purely secondary to aspiration

  • b. abductors contract early in inspiration

Q. Regarding the O2 dissociation curve:

a. O2 affinity of Hb is reduced when the curve is shifted to the left

b. decreased 2,3-DPG shifts the curve to the right

c. the Bohr effect is attributed to the action of PCO2 on H+ concentration

d. temperature has no effect on the curve

e. 2,3-DPG levels are reduced at altitude

  • c. the Bohr effect is attributed to the action of PCO2 on H+ concentration
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