Autonomic Control of Pulmonary System I & II

What is the pressure of gas within the alveoli during inspiration?? A. Less than atmospheric air B. Greater than atmospheric air C. Cannot be predicted without more information D. The same as atmospheric air

*The answer is A.* During inspiration, the diaphragm contracts which generates a negative pressure within the alveoli, which draws air into the lungs.

What is the pressure of gas within the alveoli during expiration?? A. Less than atmospheric air B. Greater than atmospheric air C. Cannot be predicted without more information D. The same as atmospheric air

*The answer is B.* During expiration, the elastic force of the thoracic wall and the alveoli themselves exert a positive pressure on the air within the alveoli. This pressure is greater than that of atmospheric air, and the air flows out of the lungs.

During inhalation, the diaphragm contracts upward to create positive pressure in the chest which allows the body to inhale oxygen. A. True B. False

*The answer is B.* During inhalation, the diaphragm contracts DOWNWARD to create NEGATIVE pressure in the chest which allows the body to inhale oxygen.

Which of the following does NOT happen during inspiration? A. The ribs move upward. B. The diaphragm lifts up. C. The antero-posterior dimensions of the chest are increased. D. The tranverse dimensions of the thorax are increased. E. The scalene and sternocleidomastoid muscles can be recruited for inspiration.

*The answer is B.* During inspiration, the diaphragm contracts and moves downward to make more room for the lungs to expand.

Everything below is part of the lower respiratory system EXCEPT (select-all-that-apply)? A. Trachea B. Carina C. Pharynx D. Bronchioles E. Nasal cavities

*The answer is C and E.* The pharynx and nasal cavities are part of the upper respiratory system.

A 12-year-old boy has a severe asthmatic attack with wheezing. He experiences rapid breathing and becomes cyanotic. His arterial PO2 is 60 mm Hg and his PCO2 is 30 mm Hg. (A) an α1-adrenergic antagonist (B) a β1-adrenergic antagonist (C) a β2-adrenergic agonist (D) a muscarinic agonist (E) a nicotinic agonist

*The answer is C.* A cause of airway obstruction in asthma is bronchiolar constriction. β2-adrenergic stimulation (β2-adrenergic agonists) produces relaxation of the bronchioles.

What produces the force which drives normal exhalation, and is the process active or passive? A. Diaphragm, active B. Intercostal muscles, active C. Elastic force, passive D. Reflex arcs, passive

*The answer is C.* During exhalation, the diaphragm relaxes, and the recoil force of the thoracic wall and elastic force of the alveoli produce a positive pressure change on the air in the lungs. This pressure exceeds that of atmospheric air, and thus air flows outward.

Gas exchange in the lungs occurs in the? A. Bronchioles B. Alveolar sinus C. Alveolar sacs D. Segmental Bronchi

*The answer is C.* Gas exchange in the lungs occurs in the alveolar sacs.

A healthy, 45-year-old man is reading the newspaper. Which of the following muscles are used for quiet breathing? A) Diaphragm and external intercostals B) Diaphragm and internal intercostals C) Diaphragm only D) Internal intercostals and abdominal recti E) Scaleni F) Sternocleidomastoid muscles

*The answer is C.* The lungs can be expanded and contracted by increasing and decreasing the volume of the chest cavity. The volume of the chest cavity can be changed in two ways: (a) downward and upward movement of the diaphragm increases and decreases the length of the chest cavity, and (b) elevating and depressing the rib cage increases and decreases the anteroposterior diameter of the chest cavity. Normal breathing during resting conditions is accomplished entirely by the diaphragm. The diaphragm contracts causing inspiration and relaxes causing expiration. The other muscles listed in the question elevate or depress the rib cage and are used during heavy breathing associated with exercise as well as respiratory abnormalities characterized by excessive respiratory effort.

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? A) Diaphragm and external intercostals B) Diaphragm and internal intercostals C) Diaphragm only D) Internal intercostals and abdominal recti E) Scaleni F) Sternocleidomastoid muscles

*The answer is D.* Contraction of the internal intercostals and abdominal recti pull the rib cage downward during expiration. The abdominal recti and other abdominal muscles compress the abdominal contents upward toward the diaphragm, which also helps to eliminate air from the lungs. The diaphragm relaxes during expiration. The external intercostals, sternocleidomastoid muscles, and scaleni increase the diameter of the chest cavity during exercise and thus assist with inspiration, but only the diaphragm is necessary for inspiration during quiet breathing.

_____________ delivers unoxygenated blood to the lungs. A. Pulmonary vein B. Aorta C. Left ventricle D. Pulmonary artery

*The answer is D.* The pulmonary artery delivers unoxygenated blood to the lungs.

Which of the following is NOT an effector of respiration? A. Heart B. diaphragm C. intercostals D. Trapezius.

*The answer is D.* The trapezius is not an effector of respiration.

A 25-year-old man was diagnosed with asthma. He was prescribed with a beta-2 agonist (albuterol) and a inhaler steroid (budesonide). Which one of the following is not an action of albuterol? a) Activation of β2 receptors b) Activation of adenylyl cyclase (AC) via a stimulatory G protein (Gs) c) Increase in intracellular cyclic AMP d) Activation of protein kinase A (PKA) e) Inhibition of 5-AMP formation from cyclic AMP

*The answer is E.* Albuterol does not inhibit 5-AMP formation from cyclic AMP.

Which of the following is true during inspiration? (A) Intrapleural pressure is positive (B) The volume in the lungs is less than the functional residual capacity (FRC) (C) Alveolar pressure equals atmospheric pressure (D) Alveolar pressure is higher than atmospheric pressure (E) Intrapleural pressure is more negative than it is during expiration

*The answer is E.* During inspiration, intrapleural pressure becomes more negative than it is at rest or during expiration (when it returns to its less negative resting value). During inspiration, air flows into the lungs when alveolar pressure becomes lower (due to contraction of the diaphragm) than atmospheric pressure; if alveolar pressure were not lower than atmospheric pressure, air would not flow inward. The volume in the lungs during inspiration is the functional residual capacity (FRC) plus one tidal volume (TV).