Gas Exchange Vocab

Atmospheric pressure (P_atm)

Amount of force that is exerted by gases in the air surrounding any given surface

Intrapulmonary pressure (P_alv)

Pressure of air within the respiratory system that is measured at the alveoli

Intrapleural pressure (P_ip)

Pressure in the pleural cavity

Mesothelial cell

Cells that monitor the level of pleural fluid in the pleural cavity

Transpulmonary pressure

Difference between the intrapleural and intrapulmonary pressures at a given time

Boyle’s law

The pressure of a gas is inversely proportional to its volume at a constant temperature; P = k/V

Surface tension

Cohesive force at the surface of a liquid that makes it contract and resist being stretched or broken; important in liquid film lining alveoli

Thoracic wall compliance

Ability of the thoracic wall to stretch while under pressure

Pulmonary fibrosis

A condition where lung tissue becomes thick, stiff, and scarred, resulting in decreased lung compliance

Quiet breathing/eupnea

Mode of breathing that occurs at rest and does not require conscious control; inhalation is active and exhalation is passive

Diaphragmatic breathing

Type of breathing where the diaphragm contracts and flattens to increase lung volume

Costal breathing

Type of breathing where the external intercostal muscles contract and elevate the ribs, slightly increasing the thoracic volume

Forced breathing/hyperpnea

Mode of breathing where there is an active manipulation of breathing; both inhalation and exhalation are active and require the use of accessory muscles in addition to primary ones

Cough

Taking a deep breath, closing the glottis, and then forcing air superiorly from the lungs against the glottis, causing it to open suddenly and release a burst of air through the oral cavity; used to clear lower respiratory passageways

Sneeze

Expelling a burst of air through the nasal cavity while the uvula depresses and closes off the oral cavity; used to clear upper respiratory passageways

Hiccups

Sudden inspirations resulting from the spasm of the diaphragm; sound occurs as air hits the vocal folds

Yawn

Very deep inspiration that ventilates all alveoli, opening any that may have become closed during regular respiration

Pneumothorax

Condition where air enters the pleural cavity, breaking the fluid bond that pulls the lungs outward towards the chest; often the cause of lung collapse

Atelectasis

Partial lung collapse

Dalton’s law

The total pressure of a mixture of gases is equal to the sum of the partial pressures of each gas that is present; P_total = P₁ + P₂ + P₃ + …

Residual volume

Amount of air that can never be exhaled

Charles’ law

At a constant pressure, the volume of a gas is directly proportional to its temperature; V₁/T₁ = V₂/T₂

Henry’s law

The concentration of gas dissolved in a liquid is directly proportional to the solubility and partial pressure of that gas

Nitrogen narcosis

High amounts of nitrogen dissolving in deep waters due to an increased partial pressure of nitrogen

Ventilation

Movement of air into and out of lungs

Perfusion

Flow of blood in the pulmonary capillaries

Ventilation-perfusion coupling

The matching of airflow and blood flow in the lungs to ensure efficient gas exchange