Gas exchange in tissues and lungs how is?

To provide cells, tissues and organs with oxygen in the human body there is the respiratory system. It consists of the following organs: nasal cavities, nasopharynx, larynx, trachea, bronchi and lungs. In this article we will study their structure. And also consider gas exchange in tissues and lungs. Define the features of external respiration that takes place between the organism and the atmosphere, and internal, occurring directly at the cellular level.

Why do we breathe?

Most people did not hesitate to answer: to get oxygen. But they don't know why we need it. The answer is simple: oxygen is necessary to breathe. It turns out a vicious circle. Break it will help us biochemistry, studying cellular metabolism.

Bright minds who study this science have long come to the conclusion that the oxygen in tissues and organs oxidizes carbohydrates, fats, and proteins. In this form the energy-poor compounds: carbon dioxide, water, ammonia. But the main thing is that as a result of these reactions synthesize ATP-the universal energy substance used by the cell for their livelihoods. We can say that the gas exchange in tissues and lungs will be put to the organism and its structures for the oxidation of oxygen.

Mechanism of gas exchange

It implies the presence of at least two substances whose circulation in the body provides for metabolic processes. In addition to the aforementioned oxygen gas exchange in the lungs, blood and tissues occurs with another connection – with carbon dioxide. It is formed in reactions of dissimilation. Being a toxic substance metabolism, it needs to be removed from the cytoplasm of cells. Consider this process in more detail.

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Carbon Dioxide by diffusion penetrates through the cell membrane into the interstitial fluid. Because it enters the blood capillaries-venules. Further, these vessels merge, forming the lower and upper hollow veins. They collect blood saturated with CO_2. And submit it to the right atrium. With the reduction of its walls a portion of venous blood enters the right ventricle. Here begins the pulmonary (lesser) circulation. Its task is the blood oxygen saturation. Venous blood in the lungs becomes. And CO₂, in turn, comes from the blood and is removed to the outside through the respiratory system. To understand how this occurs, we must first study the structure of the lungs. Gas exchange in lungs and tissues is carried out in special structures – the alveoli and the capillaries.

Lung Structure

This pair of organs located in the chest cavity. The left lung consists of two lobes. Right larger. It has three lobes. Through the gate of light they include two bronchi, which, branching, forming a so-called tree. On its branches the air moves in during inhalation and exhalation. Into smaller respiratory bronchioles are the bubbles-the alveoli. They are collected in the acini. Those, in turn, form the pulmonary parenchyma. It is important that each respiratory bottle densely braided capillary network of small and big circles of blood circulation. Bringing branches of the pulmonary arteries, which supply the venous blood from the right ventricle, transporterowych into the lumen of the alveoli carbon dioxide. And efferent pulmonary venules are taken out of the alveolar air oxygen.

The Arterial blood enters via the pulmonary veins to the left atrium and from there into the aorta. Its branching in the form of arteries to provide the body's cells necessary for internal respiration with oxygen. It is in the alveoli from venous blood becomes arterial. Thus, gas exchange in lung and tissue directly effected by the circulation of blood around small and big circles of blood circulation. This happens due to the continuous muscle contractions of the walls of the heart chambers.

External respiration

It is also called respiration. Is an exchange of air between the external environment and the alveoli. Physiologically correct breath through the nose provide the body with a portion of the air of such a composition: about 21% O₂, 0.03 per cent CO₂ and 79% nitrogen. In the pneumatic paths he enters the alveoli. They have their own portion of the air. Its composition is the following: 14.2% of O₂, of 5.2% CO₂, 80% N₂. Inhale, and exhale, is regulated in two ways: the nervous and endocrine (concentration of carbon dioxide). Thanks to the stimulation of the respiratory centre of the medulla oblongata, nerve impulses are sent to respiratory intercostal muscles and the diaphragm. The volume of the chest increases. Lightweight, passively moving with contractions of the thoracic cavity expand. The air pressure in them falls below atmospheric. Therefore, the portion of the air from the upper respiratory tract goes to the alveoli.

The Exhalation is followed by inhalation. It is accompanied by relaxation of intercostal muscles and raising of the arch of the diaphragm. This leads to a decrease in lung volume. The air pressure in them becomes higher than the atmospheric. And air with excess carbon dioxide rises in the bronchioles. Further, in the upper respiratory tract, it should be in the nasal cavity. Compositionbreath following: 16,3% O₂, 4% CO₂, 79 N₂. At this stage there is external gas exchange. Pulmonary gas exchange performed by the alveoli, provides oxygen to cells needed for internal breathing.

Cellular respiration

Logs in catabolic reactions of metabolism and energy. These processes studies such as biochemistry and anatomy, and human physiology. Gas exchange in lungs and tissues are interrelated and without one another impossible. So, external respiration deliver to interstitial fluid the oxygen and remove from it carbon dioxide. And internal, carried out directly in the cell, its organelles-the mitochondria that provide the oxidative postulirovana and the synthesis of ATP, uses the oxygen for these processes.

Krebs Cycle

The tricarboxylic acid Cycle is the leader in cell respiration. It combines and adapts reactions of oxygen stage of energy exchange and processes involving transmembrane proteins. It also performs the role of supplier of building cell material (amino acids, simple sugars, higher carboxylic acids) formed in the intermediate reactions used by the cell for growth and division. As you can see, this article has studied the gas exchange in lung and tissue, and determined its biological role in the functioning of human body.