574 Chapter 16
| CHECKPOINT
16a. Describe the effect of exercise on the PO 2 , PCO 2 , and
pH blood values, and explain how ventilation might
be increased during exercise.
16b. Explain why endurance-trained athletes have a
higher than average anaerobic threshold.- Describe the changes that occur in the respiratory
system during acclimatization to life at a high
altitude.
Peter takes a rescue inhaler containing a short-acting b (^2 2)
adrenergic receptor agonist such as albuterol to cause
bronchodilation. He also sometimes takes an inhaler that
is a combination of a long-acting b 2 -adrenergic receptor
agonist and a glucocorticoid to reduce inflammation. His
asthma is an obstructive lung disorder that would lower
his FEV 1 , but even if he didn’t have asthma his cigarette
smoking might have lowered his FEV 1. He got a pneumo-
thorax from the knife wound, where his punctured chest
allowed air into the pleural space, so that the elastic ten-
sion of the lung caused it to collapse. When the physician
sucked air from the pleural space, his intrapleural pres-
sure again fell below his intrapulmonary pressure so that
his lung could expand. Peter appeared to develop acute
mountain sickness when he went to 9,000 feet because
his low arterial PO 2 caused cerebral vasodilation and gave
him a headache and nausea. Nevertheless, his percent
oxyhemoglobin was normal for that altitude, because the
oxyhemoglobin dissociation curve is relatively flat at the
PO 2 range for the loading reaction and he was still able to
sufficiently oxygenate his blood.
See the additional chapter 16 Clinical Investigations on
COPD and Hypoxemia in the Connect site for this text.