Study 5 Respiratory System Physiology with 12 free online flashcards. Review key terms, definitions, and concepts with this interactive flashcard deck.
What pressure changes draw air into the lungs during quiet inhalation?
The diaphragm contracts and flattens, while external intercostal muscles help expand the chest. Lung volume rises, alveolar pressure falls below atmospheric pressure, and air flows inward.
How is minute ventilation calculated?
Minute ventilation is the total air moved per minute: tidal volume multiplied by breathing rate.
What determines the direction of gas diffusion?
Each gas diffuses down its own partial-pressure gradient, moving from higher to lower partial pressure.
How does the lung improve ventilation–perfusion matching?
Gas exchange works best when ventilation (air reaching alveoli) matches perfusion (blood flow through nearby capillaries). Poorly ventilated alveoli trigger local arteriole constriction, redirecting blood toward better-ventilated regions.
How does hemoglobin transport oxygen?
Hemoglobin in red blood cells carries most blood oxygen. Each hemoglobin molecule can bind up to four oxygen molecules.
Why is the oxygen–hemoglobin dissociation curve S-shaped?
Its S-shape reflects cooperative binding: binding one oxygen molecule makes subsequent oxygen binding easier.
What is the Bohr effect?
The Bohr effect is the influence of carbon dioxide and pH on hemoglobin's oxygen binding. Increased carbon dioxide or acidity reduces oxygen affinity and favors oxygen release.
How does the chloride shift relate to carbon dioxide transport?
Most carbon dioxide is converted in red blood cells to bicarbonate, which moves into plasma in exchange for chloride ions. This exchange is called the chloride shift.
How do the brainstem and chemoreceptors regulate breathing?
Brainstem networks generate and adjust breathing: the medulla helps establish rhythm, and pontine input modifies the pattern. Chemoreceptors detect changes in carbon dioxide, pH, and oxygen to adjust respiratory drive.
What drives quiet exhalation?
The breathing muscles relax, and elastic recoil reduces lung volume. Alveolar pressure rises above atmospheric pressure, pushing air outward.
How is alveolar ventilation estimated?
Alveolar ventilation estimates fresh air reaching functioning alveoli per minute: (tidal volume−dead-space volume)×breathing rate.
How do oxygen and carbon dioxide move in lungs versus tissues?
In the lungs, oxygen moves from alveoli into blood and carbon dioxide moves into alveoli; this is external respiration. In tissues, oxygen enters cells and carbon dioxide enters blood; this is internal respiration.