Respiratsioonitsükli

Respiratsioonitsükkel, commonly referred to as the respiratory cycle, encompasses the sequence of events involved in the process of breathing. It is a fundamental physiological process for most living organisms, enabling the exchange of gases between the organism and its environment. The primary function of the respiratory cycle is to take in oxygen, which is essential for cellular respiration and energy production, and to expel carbon dioxide, a waste product of this metabolic process.

In mammals, the respiratory cycle is primarily driven by the action of the diaphragm and the intercostal muscles. The cycle consists of two main phases: inspiration (inhalation) and expiration (exhalation). Inspiration is an active process where the diaphragm contracts and flattens, and the external intercostal muscles contract, lifting the rib cage upwards and outwards. This increases the volume of the thoracic cavity, leading to a decrease in intrapleural and intrapulmonary pressure, causing air to flow into the lungs.

Expiration is typically a passive process, especially at rest. When the inspiratory muscles relax, the elastic recoil of the lungs and chest wall causes the thoracic cavity to decrease in volume. This increases the intrapulmonary pressure above atmospheric pressure, forcing air out of the lungs. Forced expiration, such as during strenuous activity or coughing, involves the contraction of abdominal and internal intercostal muscles to further reduce the thoracic volume and expel air more rapidly. The efficiency of the respiratory cycle is crucial for maintaining adequate oxygen levels and removing carbon dioxide from the body.