Respiratory System

Respiratory system 

Definition 

"The respiratory system allows oxygen to enter the body, as well as carbon dioxide to escape."

Mechanism 

To stay alive, the body needs to produce enough energy. This energy is produced by the combustion of nutrient molecules, which are oxidized when they combine with oxygen. Oxidation involves the combination of carbon and hydrogen with oxygen to form carbon dioxide and water. The consumption of oxygen and the production of carbon dioxide is an essential process for life. Consequently, the human body needs an organic system specialized in the elimination of carbon dioxide from the circulating blood and the absorption of oxygen from the atmosphere, at a speed appropriate to the needs of the organism and even at the moment of maximum effort. The respiratory system allows oxygen to enter the body, as well as carbon dioxide to escape.

Anatomy 

 The respiratory system begins in the nose and mouth and continues through the airways and lungs. Air enters the respiratory system through the nose and mouth and descends through the throat (pharynx) to reach the organ of speech (larynx). The entrance to the larynx is covered by a small fragment of tissue, the epiglottis, which closes automatically during swallowing, thus preventing food from reaching the airways.


The trachea is the largest airway. The trachea branches into two smaller airways: the left and right main bronchi.


 Each lung is divided into sections (lobes): three in the right lung and two in the left. The left lung is slightly smaller than the right because it shares space with the heart, also on the left side of the chest.


The bronchi, in turn, branch multiple times into thinner airways, ending in the thinnest of all (bronchioles), which have a diameter of less than half a millimeter (or 2/100 of an inch). The airways resemble an inverted tree, so this part of the respiratory system is often called the bronchial tree. Large airways are kept open by semi-flexible, fibrous connective tissue called cartilage. Small airways are supported by the lung tissue that surrounds and adheres to them. The walls of the smaller airways have a thin circular layer of smooth muscle. The airway muscle can relax or contract, thereby changing the caliber of the airway.


 At the end of each bronchiole are thousands of alveoli (small air sacs). Together, the millions of alveoli in the lungs form an area of ​​more than 100 square meters (1,111 square feet). Inside the alveolar walls is a dense network of tiny blood vessels called capillaries. The extremely thin barrier between the air and the capillaries allows oxygen to pass from the alveoli into the blood and carbon dioxide to pass from the blood inside the capillaries to the air inside the alveoli.

The pleura is a thin transparent membrane that covers the lungs and also lines the inside of the chest wall. It allows the lungs to move smoothly during breathing, even when the person is moving. Normally, there is only a small amount of lubricating fluid between the two layers of the pleura. The two layers slide smoothly over each other as the lungs change size and shape.


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