Passage
Obstructive respiratory illnesses are characterized by an increased difficulty exhaling much of the air in the lungs. Asthma and chronic obstructive pulmonary disease (COPD) are two of the most common obstructive respiratory illnesses. Asthma is due to allergen hypersensitivity and can be identified by temporary airway inflammation, which causes the bronchioles to narrow. The decreased airway diameter increases the resistance to airflow. Subsequently, air becomes "trapped" in the lungs, restricting the amount of air that can be moved in each breath.COPD refers to a spectrum of disorders and can be a result of emphysema, the irreversible destruction of pulmonary tissue. The breakdown of elastic proteins in the lungs results in a loss of pulmonary resiliency and chronic lung hyperinflation. Because the walls between individual alveoli are broken down, the alveolar sacs that remain are larger.Lung diseases can be diagnosed and monitored using spirometry. A spirometer measures the flow rate and volume of inhaled and exhaled air. In one pulmonary test, a patient is asked to exhale forcibly and completely into a spirometer after maximum inhalation. This test is done to measure the patient's forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) , the total amount of air exhaled in a single breath.
Figure 1 Forced expiratory spirogram of a healthy individual
Adapted from T. Barreiro, "An Approach to Interpreting Spirometry." American Family Physician. ©2004 AAFP.
-The regulation of respiratory rate is normally most sensitive to:

Question

Passage
Obstructive respiratory illnesses are characterized by an increased difficulty exhaling much of the air in the lungs. Asthma and chronic obstructive pulmonary disease (COPD) are two of the most common obstructive respiratory illnesses. Asthma is due to allergen hypersensitivity and can be identified by temporary airway inflammation, which causes the bronchioles to narrow. The decreased airway diameter increases the resistance to airflow. Subsequently, air becomes "trapped" in the lungs, restricting the amount of air that can be moved in each breath.COPD refers to a spectrum of disorders and can be a result of emphysema, the irreversible destruction of pulmonary tissue. The breakdown of elastic proteins in the lungs results in a loss of pulmonary resiliency and chronic lung hyperinflation. Because the walls between individual alveoli are broken down, the alveolar sacs that remain are larger.Lung diseases can be diagnosed and monitored using spirometry. A spirometer measures the flow rate and volume of inhaled and exhaled air. In one pulmonary test, a patient is asked to exhale forcibly and completely into a spirometer after maximum inhalation. This test is done to measure the patient's forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) , the total amount of air exhaled in a single breath.

Figure 1 Forced expiratory spirogram of a healthy individual
Adapted from T. Barreiro, "An Approach to Interpreting Spirometry." American Family Physician. ©2004 AAFP.
-The regulation of respiratory rate is normally most sensitive to:

Quizplus · Accepted Answer

11ecba2d_0f79_ade0_a3bf_37e293a5e3c0_MD0008_00 The regulation of respiratory rate is normally most sensitive to the pH of the blood, which is measured by the central and peripheral chemoreceptors. The central chemoreceptors are located in the brain, and the peripheral chemoreceptors are located in the aortic and carotid arteries. Blood pH is determined by the concentration of H⁺ (protons) in the blood, which is determined by the equilibrium of the bicarbonate buffer system: 11ecba2d_0f79_ade1_a3bf_53bbe864c83c_MD0008_00 CO2+H2O⇋H2CO3⇋HCO3-+H+ The equilibrium of this buffer system will shift due to changes to the partial pressure of CO₂ in the blood. These chemoreceptors directly measure the [H⁺] in the blood, and therefore indirectly measure the P_CO2 in the blood. This information is relayed to the respiratory center of the nervous system. (Choice A) Although the peripheral chemoreceptors also measure the partial pressure of O₂ in the blood, the partial pressure of O₂ plays a much less significant role in respiratory regulation. (Choices C and D) The chemoreceptors responsible for the regulation of respiratory rate are located along the major arteries and in the brain, and cannot measure the partial pressures of alveolar gas. Educational objective: The regulation of respiratory rate primarily depends on the pH of the blood as measured by central and peripheral chemoreceptors. These receptors directly detect the [H⁺] in the blood, which is dependent on the partial pressure of CO₂ in the blood through the bicarbonate buffer system.

Passage Obstructive Respiratory Illnesses Are Characterized by an Increased Difficulty Exhaling