Circulatory and Respiratory Physiological Phenomena

Physiological processes involving blood flow, gas exchange, and the transport of oxygen and carbon dioxide between the lungs and body tissues.

Connect

Pulmonary ventilation: The movement of air into and out of the lungs. Ventilation renews alveolar air so oxygen can enter blood and carbon dioxide can leave it.
Diffusion: The net movement of particles from regions of higher concentration to regions of lower concentration. Oxygen and carbon dioxide cross respiratory surfaces down partial-pressure gradients by diffusion.
Pulse oximetry: A noninvasive method that estimates arterial oxygen saturation using light transmitted through or reflected from tissue. It provides a rapid estimate of blood oxygenation during respiratory and circulatory assessment.
Hypocapnia: An abnormally low concentration of carbon dioxide in arterial blood. It contrasts with carbon dioxide retention, showing how excessive ventilation shifts blood gas levels.
Alveolar gas exchange: Diffusion of oxygen and carbon dioxide between lung alveoli and pulmonary capillary blood. This exchange connects breathing directly to the composition of circulating blood.
Partial pressure: The pressure contributed by one gas in a mixture of gases. Differences in oxygen and carbon dioxide partial pressures drive their exchange between air, blood, and tissues.
Arterial blood gas test: A blood test measuring oxygen, carbon dioxide, and acid–base status in arterial blood. Its measurements assess gas exchange and the respiratory contribution to blood pH.
Hypercapnia: An abnormally high concentration of carbon dioxide in arterial blood. It is the opposite blood-gas disturbance from hypocapnia and often signals inadequate ventilation.
Oxygen transport: The carriage of oxygen in blood, chiefly bound to hemoglobin in red blood cells. It carries oxygen acquired in the lungs to tissues throughout the body.
Hemoglobin: The iron-containing protein in red blood cells that binds oxygen reversibly. Its binding lets blood carry far more oxygen than plasma can dissolve.