5)Gas Exchange & Partial Pressure Flashcards

State Dalton’s Law and its relevance to respiration.

states that each gas in a mixture exerts its own pressure independently. In respiration, oxygen and carbon dioxide diffuse based on their individual partial pressures.

What drives oxygen diffusion into pulmonary capillaries?

A pressure gradient: oxygen moves from high partial pressure in alveoli (~104 mmHg) to lower pressure in capillary blood (~40 mmHg).

What causes CO₂ to diffuse into alveoli?

CO₂ moves from higher partial pressure in capillary blood (~45 mmHg) to lower pressure in alveoli (~40 mmHg).

Define partial pressure in the context of respiratory gases.

The pressure exerted by a single gas in a mixture, proportional to its concentration and total pressure.

Name key factors influencing alveolar gas exchange.

Surface area of alveoli, thickness of respiratory membrane, ventilation-perfusion matching, and partial pressure gradients.

Why is V/Q matching important?

It ensures that air reaching alveoli is matched with blood flow, optimizing gas exchange.

How does hemoglobin assist in oxygen transport?

binds oxygen in the lungs and releases it in tissues, enhancing oxygen delivery beyond simple diffusion.

 Describe the structure and function of the respiratory membrane.

A thin barrier between alveolar air and capillary blood, composed of alveolar epithelium, capillary endothelium, and their fused basement membranes; site of gas exchange.

Why does CO₂ diffuse more readily than O₂?

CO₂ is more soluble in plasma and alveolar fluid, allowing efficient diffusion despite smaller pressure gradients.

How can conditions like emphysema or fibrosis impair gas exchange?

They reduce alveolar surface area or thicken the respiratory membrane, hindering diffusion and lowering oxygenation.