physiologybreathing

Physiologybreathing refers to the physiological processes that govern respiration in living organisms. It encompasses the generation of ventilation, the diffusion of gases in the lungs, gas transport in the bloodstream, and the regulatory mechanisms that maintain arterial oxygen and carbon dioxide levels within narrow limits. The study spans mammals and other organisms, acknowledging variation in anatomy and breathing strategies.

Ventilation: Air enters the lungs through the airways and moves by pressure gradients generated mainly by the diaphragm and intercostal muscles. Inhalation expands the thoracic cavity, reducing intrapulmonary pressure and drawing air in; exhalation is usually passive but can be augmented by abdominal and intercostal muscles during effort.

Gas exchange: In the alveoli, oxygen diffuses into the blood while carbon dioxide diffuses out, driven by partial pressure differences. Oxygen is mainly carried bound to hemoglobin, with a small fraction dissolved in plasma; CO2 is carried as bicarbonate, dissolved CO2, or carbamino compounds. Tissue gas exchange relies on capillary blood flow and diffusion gradients.

Regulation: Breathing is regulated by neural centers in the brainstem (medulla oblongata and pons) and by chemoreceptors that sense CO2, O2, and pH. Central chemoreceptors respond to CO2 and pH changes in cerebrospinal fluid; peripheral chemoreceptors in the carotid and aortic bodies respond to arterial PO2 and PCO2. Respiratory patterns adjust for metabolic demand during rest and activity.

Clinical and environmental influences: The physiology of breathing adapts to exercise, high altitude, disease, and anesthesia. Disturbances in ventilation, diffusion, or circulation can lead to hypoxemia or hypercapnia and require diagnostic assessment and management.