To provide cells, tissues and organsoxygen in the human body there is a respiratory system. It consists of the following organs: the nasal cavity, nasopharynx, larynx, trachea, bronchi and lungs. In this article we will study their structure. And also consider gas exchange in the tissues and lungs. Let us determine the peculiarities of external respiration, which occurs between the organism and the atmosphere, and the internal, which flows directly at the cellular level.
Most people will respond without hesitation:to get oxygen. But they do not know why we need it. Many answer simply: oxygen is needed to breathe. It turns out some kind of vicious circle. Biochemistry, which studies cell metabolism, will help us to break it.
Светлые умы человечества, изучающие эту науку, It has long been concluded that oxygen entering the tissues and organs, oxidizes carbohydrates, fats and proteins. At the same time, energy-poor compounds are formed: carbon dioxide, water, ammonia. But the main thing is that as a result of these reactions, ATP is synthesized - a universal energy substance used by the cell for its vital activity. It can be said that gas exchange in the tissues and lungs will supply the body with the necessary oxygen for oxidation.
It implies the presence of at least two substanceswhose circulation in the body provides metabolic processes. In addition to the aforementioned oxygen, gas exchange in the lungs, blood and tissues occurs with another compound - carbon dioxide. It is formed in dissimilation reactions. Being a toxic substance of metabolism, it must be derived from the cytoplasm of cells. Consider this process in more detail.
Carbon dioxide diffuses throughcell membrane into interstitial fluid. From it, he enters the blood capillaries - venules. Further, these vessels merge, forming the lower and upper vena cava. They collect blood saturated with CO2. And send it to the right atrium.With the reduction of its walls a portion of venous blood enters the right ventricle. From here begins the pulmonary (small) circle of blood circulation. His task is to saturate the blood with oxygen. Venous in the lungs becomes arterial. And WITH2in turn comes out of the blood and is removedout through the respiratory system. To understand how this happens, you first need to study the structure of the lungs. Gas exchange in the lungs and tissues is carried out in special structures - the alveoli and their capillaries.
These are paired organs located in the thoraciccavities. The left lung consists of two lobes. The right one is larger in size. It has three lobes. Through the gates of the lungs they enter two bronchus, which, branching out, form the so-called tree. On its branches the air moves during inhalation and exhalation. On the small, respiratory bronchioles are vesicles - alveoli. They are collected in acini. Those, in turn, form a pulmonary parenchyma. It is important that each breathing vesicle is densely braided by the capillary network of the small and large circulation. The branches of the pulmonary arteries that deliver venous blood from the right ventricle carry carbon dioxide into the lumen of the alveoli. And the outgoing pulmonary venules take oxygen from the alveolar air.
Arterial blood flows through the pulmonary veins inleft atrium, and from it - into the aorta. Its branches in the form of arteries provide the cells of the body with the necessary oxygen for internal respiration. It is in the alveoli that the blood from the venous becomes arterial. Thus, gas exchange in the tissues and lungs is directly carried out by blood circulation through the small and large circles of blood circulation. This happens due to continuous contractions of the muscle walls of the heart chambers.
Оно еще называется вентиляцией легких.Represents the exchange of air between the external environment and the alveoli. Physiologically correct inhaling through the nose provides the body with a portion of air of such composition: about 21% O2, 0.03% WITH2 and 79% nitrogen. Through the airways it enters the alveoli. They have their own portion of air. Its composition is as follows: 14.2% O2, 5.2% WITH2, 80% N2. Inhalation, like exhalation, is regulated in two ways:nervous and humoral (concentration of carbon dioxide). Due to the excitation of the respiratory center of the medulla oblongata, nerve impulses are transmitted to the respiratory intercostal muscles and diaphragm. The volume of the chest increases. The lungs, which passively follow the contractions of the chest cavity, expand. The air pressure in them becomes lower than atmospheric. Therefore, a portion of air from the upper respiratory tract enters the alveoli.
Exhalation is carried out after inhaling.It is accompanied by relaxation of the intercostal muscles and raising the arch of the diaphragm. This leads to a decrease in lung volume. The air pressure in them becomes higher than atmospheric. And the air with excess carbon dioxide rises in the bronchioles. Further, on the upper respiratory tract, it follows into the nasal cavity. The composition of exhaled air is as follows: 16.3% O2, 4% WITH2, 79 N2. At this stage, external gas exchange takes place. The pulmonary gas exchange carried out by the alveoli provides the cells with oxygen, which is necessary for internal respiration.
Входит в систему катаболических реакций обмена substances and energy. These processes are studied both in biochemistry, and anatomy, and human physiology. Gas exchange in the lungs and tissues is interrelated and impossible without each other. Thus, external respiration supplies oxygen to interstitial fluid and removes carbon dioxide from it. And the internal, carried out directly in the cell by its organelles - mitochondria, which provide oxidative phospholation and synthesis of ATP molecules, uses oxygen for these processes.
The tricarboxylic acid cycle is leading incell breathing. It combines and harmonizes the reactions of the oxygen-free stage of energy metabolism and processes involving transmembrane proteins. It also serves as a supplier of cellular building material (amino acids, simple sugars, higher carboxylic acids), which is formed in its intermediate reactions and used by the cell for growth and division. As we see, in this article gas exchange in the tissues and lungs was studied, and its biological role in the vital activity of the human body was determined.
