Respiratory System — Flashcards

Flashcard 131: Both peripheral and central chemoreceptors contribute to increased ventilation that occurs as a result of decreased _____.

Answer: pH

Extra: Both peripheral and central chemoreceptors respond to a decrease in pH (acidosis) and an increase in PCO2 (hypercapnia). - **Peripheral chemoreceptors** (carotid and aortic bodies): Respond directly to a decrease in **arterial pH**, an increase in PCO2, and a decrease in PO2 (< 60 mmHg). - **Central chemoreceptors** (medulla): Respond to a decrease in the **pH of the CSF/brain extracellular fluid**. Since H+ cannot cross the blood-brain barrier, this is primarily driven by an increase in arterial PCO2 (which crosses easily and is converted to H+ and HCO3-). Note: Only peripheral chemoreceptors respond to changes in arterial pH (e.g., metabolic acidosis) and low PO2. Both respond to changes in PCO2.

Flashcard 132: A deep breath _____ the secretion of surfactant by stretching the type II cells.

Answer: increases

Flashcard 133: Preoxygenation is the process of replacing _____ in the lungs with oxygen.

Answer: nitrogen

Flashcard 134: Time taken by a red cell is about _____ seconds to traverse the pulmonary capillaries at rest

Answer: 0.75

Flashcard 135: The normal value of physiological shunt is _____%

Answer: 2

Flashcard 136: The upper limit for the linear relationship between the increase in % of CO2 in inspired air and respiratory minute volume is _____% CO2.

Answer: 6

Flashcard 137: Which metabolic poison stimulates peripheral chemoreceptors?

Answer: Cyanide

Flashcard 138: Approximately _____ mL of water is lost in expired air every 24 hours

Answer: 400

Flashcard 139: If lung is allowed to undergo elastic recoil without the chest wall, the resultant volume of the lung would be _____.

Answer: minimum volume

Flashcard 140: The response of peripheral chemoreceptors to changes in Pco2 is _____ than that of central chemoreceptors

Answer: faster (slower/faster)