Öndun

Öndun is the process by which living organisms exchange gases with their environment, taking in oxygen and releasing carbon dioxide. In humans, it encompasses breathing (pulmonary ventilation) and cellular respiration, the use of oxygen by cells to produce energy.

Pulmonary ventilation involves inhalation (inspiration) and exhalation (expiration). During inhalation, the diaphragm contracts and moves downward, expanding the chest cavity and drawing air into the lungs. Exhalation is usually passive, driven by the relaxation of chest muscles, though it can be active during exertion. Gas exchange occurs in the alveoli, where oxygen passes into the blood and carbon dioxide moves from the blood into the airways to be exhaled. Blood transports oxygen to tissues and brings carbon dioxide back to the lungs.

Breathing is regulated by the respiratory center in the brainstem, which receives sensory input from chemoreceptors that monitor carbon dioxide, oxygen, and pH levels. The rate and depth of breathing adjust to metabolic demand, emotion, posture, and environmental conditions.

Maintaining effective öndun is essential for health. Disruptions can arise from infections, obstructive or restrictive lung diseases, or problems with neural control. Common conditions include asthma, chronic obstructive pulmonary disease (COPD), pneumonia, and sleep apnea. High altitude, pollution, and smoking can impair function and increase risk of disease.

In medical contexts, assessment of öndun relies on measurements such as spirometry, oxygen saturation and carbon dioxide levels, which help evaluate ventilation and gas exchange.