Without respiration there is no metabolism and without metabolism there is no life. Thus, humans and all vertebrates depend on gas exchange via pulmonary respiration.
What is gas exchange?
Without respiration no metabolism and without metabolism no life. Thus, humans and all vertebrates depend on gas exchange via pulmonary respiration. Oxygen, which is so vital to us, is extracted from the inhaled air, transported in the body via the bloodstream, and metabolized in the cells. In turn, the waste product carbon dioxide is excreted again via the lungs. The path of respiratory gases leads from the outside world via the respiratory organs mouth or nose, pharynx, trachea, bronchi and lungs. As a mixture of gases, air can be divided into the components oxygen, nitrogen, carbon dioxide and various noble gases. However, the organism can utilize only oxygen. It serves as an activator of nutrients to provide energy for mitochondria, the power plants of our cells.
Function and task
When breath is inhaled, the chest expands. The attached diaphragm moves toward the abdomen, creating a vacuum and filling the lungs. When exhaled, the diaphragm moves back up and, due to the corresponding ambient air pressure, can be exhaled. This mobility of the thorax is necessary to breathe and, in the event of illness, to cough up incriminating mucus. Ventilation is needed so that the oxygen in the blood can take its course. This refers to the activities in the respiratory organs that distribute air to the alveoli. The blood circulation acts as a transport system. The main focus of gas exchange in the body is the lungs. The air breathed, preheated and humidified in the bronchi, enters the two lobes of the lungs. They consist of the smallest alveoli, the alveoli. These are connected to the finest capillary vessels via a permeable membrane. They in turn connect via ramifications into ever larger blood vessels until they take over their transport function as arteries and veins via the heart. The exchange of used exhaust air works in exactly the opposite way. Here, the harmful carbon dioxide enters the alveoli. There it is stored for a short time before leaving the organism again with the exhaled air. The human organism needs about 0.3 liters of oxygen per minute if it is not in heavy motion. If a person is physically active, the oxygen consumption increases proportionally, since more oxygen is metabolized in the muscle cells. This amounts to approximately 10,000 to 20,000 liters of air per 24 hours, which the organism must process in the lungs. In the process, the individual elements of the respiratory tract have additional tasks. Thus, there are three phases of gas exchange: first, the respiratory air is actively transported into the lungs, from there it reaches the bloodstream by diffusion, and then it has reached its destination in the cells of the tissue. Oxygen is needed everywhere in the human organism, especially in the brain. Oxygen is transported to all parts of the body via the red blood cells, the erythrocytes. There it is bound to the blood pigment hemoglobin. Hemoglobin is an organic, iron-containing protein to which oxygen is chemically bound. Oxygen demand contributes significantly to the control of respiration. When oxygen is deficient, respiration becomes deeper or faster. During prolonged oxygen deficiency, the blood vessels of the lungs constrict and put increased resistance to the heart during blood flow. This puts a strain on the heart.
Diseases and ailments
Only when there is a smooth exchange of gases can the body make optimal use of oxygen. However, various diseases can severely disrupt this exchange. For example, pulmonary fibrosis. Here, healthy lung tissue is remodeled into connective tissue resembling scars. This can be caused by infections caused by certain pathogens or by cardiac insufficiency. But also inhaled harmful substances, such as dust or certain solvents can be causative. Another disease that impedes the oxygen supply is emphysema. In this case, the alveoli are destroyed and their partition walls, the membranes, are dissolved. This results in the formation of bubble-like structures in which the air that is breathed accumulates. Air is then present in the lungs, but breathing becomes difficult and the organism suffers increasingly from a lack of oxygen.Smoking, toxic substances and frequent infections of the respiratory tract can cause this. An acute danger for the functioning gas exchange can be a so-called pneumonia. This pneumonia is triggered by bacteria – Streptococcus pneumoniae. But viruses and fungal infections can also be a trigger. Affected by this inflammatory process can be the alveoli, the lung tissue and also the attached capillary vessels. Chronic obstructive pulmonary disease is another clinical picture that significantly disturbs the oxygen supply to the body. It is certainly an umbrella term of airway constricting conditions. Too little oxygen can be inhaled and just as little carbon dioxide can be exhaled. This can lead to respiratory depression, which significantly disturbs gas exchange. Cystic fibrosis becomes life-threatening as it progresses. Affected patients suffer from thick mucus that is difficult to cough up. It forms a breeding ground for bacteria and disease-causing germs. Defense cells are produced by the body, which release inflammatory substances. The mucous membrane is damaged and nuclear material is released from the cells, further increasing the viscosity of the mucus. Clarification in respiratory disease can be provided by a blood gas analysis. The levels of oxygen versus carbon dioxide are compared, and the ph level is also determined.
