Respiratory Physiology Quiz

A healthy, 25-year-old medical student participates in a 10-km charity run for the American Heart Association. Which of the following muscles does the student use (contract) during expiration?

• Diaphragm and external intercostals

• Diaphragm and internal intercostals

• Diaphragm only

• Internal intercostals and abdominal recti

A patient has a dead space of 150 ml, functional residual capacity of 3 L, tidal volume of 650 ml, expiratory reserve volume of 1.5 L, total lung capacity of 8 L, and respiratory rate of 15 breaths/min. What is the residual volume?

• 500 ml

• 1000 ml

• 1500 ml

• 2500 ml

The resistance of the pulmonary tree is so low that a 1 cm of water pressure gradient is sufficient to cause normal air flow during resting conditions. Which of the following often has a substantial resistance during pulmonary disease states that can limit alveolar ventilation?

• Alveoli

• Bronchioles

• Large bronchi

• Small bronchi

A 65-year-old man with emphysema due to 34 years of cigarette smoking is admitted to hospital due to dyspnea. With further tests the mean pulmonary arterial pressure is determined to be 45 mm Hg at rest. He is hypoxic (Po2 = 49 mm Hg), hypercapnic (85 mm Hg), and slightly acidotic. The cardiovascular and oxygen changes are due to which of the following?

• Increased arterial Pco2

• Increased parasympathetic activity

• Decreased alveolar Po2

• Decreased pulmonary resistance

Which of the following will decrease pulmonary blood flow resistance?

• IV injection of norepinephrine

• Inhalation to total lung capacity

• Breathing 5% O2

• Having the lung at FRC

The diffusing capacity of a gas is the volume of gas that will diffuse through a membrane each minute for a pressure difference of 1 mm Hg. Which of the following gases is often used to estimate the oxygen diffusing capacity of the lungs?

• Carbon dioxide

• Carbon monoxide

• Cyanide gas

• Nitrogen

The basic rhythm of respiration is generated by neurons located in the medulla. Which of the following limits the duration of inspiration and increases respiratory rate?

• Apneustic center

• Dorsal respiratory group

• Nucleus of the tractus solitarius

• Pneumotaxic center

When respiratory drive for increased pulmonary ventilation becomes greater than normal, a special set of respiratory neurons that are inactive during normal quiet breathing then becomes active, contributing to the respiratory drive. These neurons are located in which of the following structures?

• Apneustic center

• Dorsal respiratory group

• Pneumotaxic center

• Ventral respiratory group

Alveolar ventilation increases several-fold during strenuous exercise. Which of the following factors is most likely to stimulate ventilation during strenuous exercise?

• Collateral impulses from higher brain centers

• Decreased mean arterial pH

• Decreased mean arterial Po2

• Decreased mean venous Po2

Which of the following decreases with emphysema?

• Alveolar Pco2

• Cardiac output

• Diffusion area

• Pulmonary artery pressure