Respiratory System Gas Exchange and Transport

Comprehensive vocabulary flashcards covering gas exchange mechanisms, partial pressures, ventilation-perfusion coupling, oxygen and carbon dioxide transport, dissociation curve dynamics, and respiratory system aging.

Total atmospheric pressure

The combined pressure exerted by all gases in the surrounding air, equal to $760\,mm\,Hg$ at sea level.

Partial pressure

The pressure contribution of a single gas in a mixture of gases, calculated by multiplying its percentage concentration by total atmospheric pressure and symbolized by $P$ followed by the gas formula (such as $PCO_2$ or $PO_2$).

Atmospheric gas composition

The proportion of gases in atmospheric air, consisting of approximately $78\%$ nitrogen, $21\%$ oxygen, and $1\%$ other gases (of which $0.03\%$ is carbon dioxide).

Abdominal thrusts

A emergency maneuver (formerly called the Heimlich maneuver) that utilizes the residual volume of air in the lungs to dislodge a foreign object from an obstructed airway.

Alveolar gas partial pressures

The partial pressures of gases within the alveoli, defined by a $PO_2$ of $104\,mm\,Hg$ and a $PCO_2$ of $40\,mm\,Hg$.

Deoxygenated blood partial pressures

The partial pressures of gases in pulmonary capillary blood arriving at the alveoli (and systemic venous blood), characterized by a $PO_2$ of $40\,mm\,Hg$ and a $PCO_2$ of $46\,mm\,Hg$.

Oxygenated blood partial pressures

The partial pressures of gases in oxygen-enriched blood leaving the pulmonary capillaries (and systemic arterial blood), defined by a $PO_2$ of $100\,mm\,Hg$ and a $PCO_2$ of $40\,mm\,Hg$.

Ventilation-perfusion coupling

The ratio between the amount of air flowing into the alveolus (ventilation) and the flow of blood through surrounding capillaries (perfusion).

Pulmonary vascular response to hypoxia

An automatic compensatory mechanism in which pulmonary blood vessels constrict in lung areas with poor airflow and low oxygen levels to redirect blood to better-ventilated alveoli.

Systemic vascular response to hypoxia

An automatic reaction in which systemic arterial vessels dilate in response to a lack of oxygen to increase local blood flow and deliver oxygen where needed.

Gas transport

The physiological process of carrying oxygen and carbon dioxide between the alveoli of the lungs and the tissue cells throughout the body.

Oxyhemoglobin

A compound formed in the lungs when oxygen creates a weak bond with the iron portion of hemoglobin, transporting $98.5\%$ of the oxygen in the body.

Oxygen saturation

The degree to which hemoglobin molecules are bound to oxygen, reaching $100\%$ saturation when each hemoglobin molecule contains four bound oxygen molecules.

Oxyhemoglobin dissociation curve

A graphical representation illustrating the relationship between the partial pressure of oxygen ($PO_2$) and the percent oxygen saturation of hemoglobin.

Right shift of the oxyhemoglobin dissociation curve

A shift in hemoglobin binding affinity caused by increased temperature and decreased pH, which enhances oxygen unloading into tissues.

Left shift of the oxyhemoglobin dissociation curve

A shift in hemoglobin binding affinity caused by lowered temperature and increased pH, which decreases oxygen unloading.

Carbaminohemoglobin

A molecule formed when carbon dioxide binds to hemoglobin at sites separate from oxygen, accounting for approximately $20\%$ of carbon dioxide transport in the blood.

Bicarbonate ion ($HCO_3^-$)

The principal form carrying approximately $70\%$ of carbon dioxide in the blood, produced when dissolved $CO_2$ reacts with plasma water to form carbonic acid, which dissociates into bicarbonate and hydrogen ions.

Carbon monoxide affinity

The strong binding property of hemoglobin for carbon monoxide compared to oxygen, which blocks oxygen transport once bound and can be fatal.

Factors affecting gas exchange

The critical physiological factors determining optimal oxygenation, including adequate airway, respiratory rate, alveolar surface area, pressure gradients, tissue compliance, and blood supply.

Respiratory system aging changes

Age-related changes in the respiratory system including decreased chest wall mobility, increased lung rigidity, reduced alveolar count and dilation, weakened muscles, and diminished protective fluids.