lélegzetvétel
Lélegzetvétel, commonly translated as breathing, is the fundamental physiological process by which living organisms take in oxygen and release carbon dioxide. In humans and many other animals, this is an involuntary action controlled by the respiratory system, primarily involving the lungs and diaphragm. The process begins with inhalation, where the diaphragm contracts and the rib cage expands, drawing air into the lungs. This air, rich in oxygen, then travels to tiny air sacs called alveoli. Here, oxygen diffuses into the bloodstream, while carbon dioxide, a waste product of metabolism, diffuses from the blood into the alveoli. Exhalation then occurs as the diaphragm relaxes and the rib cage contracts, forcing the air, now laden with carbon dioxide, out of the lungs. This continuous cycle is essential for cellular respiration, the process that generates energy for all bodily functions. While largely automatic, breathing can also be consciously controlled, allowing for activities like speech, singing, or holding one's breath. Disruptions to lélegzetvétel, such as during intense physical exertion or in certain medical conditions, highlight its vital importance to survival.