Understanding the Human Respiratory System
Respiratory System
The respiratory system is responsible for providing oxygen to the blood, for distribution to all body tissues. Cellular metabolism in the body forms a gaseous compound called carbon dioxide, which is useless and very toxic. Therefore, it should be eliminated, which is also a function of this system.
Upper and Lower Airways
The respiratory system consists mainly of two large sections, also known as the upper and lower airway.
The upper airway consists of the mouth and nostrils, pharynx, larynx, and trachea.
The larynx is the organ that produces the voice. It contains the vocal cords and a kind of cap called the epiglottis that prevents food from passing through the airways.
The trachea is a tube formed by about twenty rings of cartilage that keep it always open. Its end is divided into two branches, the bronchi.
The lower airway is composed of the bronchi, bronchioles, lungs, pulmonary alveoli, and other subdivisions.
The bronchi and bronchioles are the various branches of the interior of the lung, ending in lung sacs called alveoli. These, in turn, have smaller bags or pulmonary vesicles surrounded by a multitude of capillaries through which blood is purified and gas exchange takes place.
The lungs are two spongy masses of reddish color, located in the chest on both sides of the heart. The right lung has three parts or lobes; the left has two parts.
The pleura is a double-walled membrane surrounding the lungs.
Gas Exchange
Air enters the nostrils during inspiration and creates an inward current. This air stream reaches a very high point within these nostrils, which is where the organ of smell is located. This air is humidified and passed through the larynx on its way to the lungs. It does not ruin this organ, reaching it saturated with water properly.
This air is also filtered, leaving in the nose or nostrils all particles that are harmful to the larynx and trachea. This filter can be, and actually is, very useful for the prevention of allergy and asthma processes.
This air is heated, i.e., it penetrates into the nostrils at room temperature, which can sometimes be very cold. Upon contact with the mucosa, the air takes on body temperature, which is necessary and essential to avoid damage to the larynx, trachea, and lungs.
Blood Stage
Gas exchange occurs in the lungs. It relates the respiratory tract (alveoli) to the transport system, the circulatory system (capillaries). This is an important phase in the incorporation of oxygen and the removal of carbon dioxide.
Gas exchange by diffusion is performed due to the partial pressure difference. Oxygen is carried in the blood bound by respiratory pigments, which in vertebrates is hemoglobin, located inside red blood cells. This increases the transport capacity of oxygen (O2) in the blood by 70 times. CO2 is more soluble than O2 in plasma and is transported in part as such and the remainder in the form of carbonic acid and bicarbonate ions. When the blood reaches the lungs, it releases CO2 into the alveoli. When the blood reaches the tissues, CO2 is excreted into the blood.
Tissue Phase
This is the final stage of respiration when electrons are “pulled” to the molecules that are breathed and “stored” in the molecules contained within cells. They go through a series of conveyors located in the mitochondrial cristae, forming three large enzyme complexes.
The electron transport chain moves electrons and protons in each of the ten hydrogen atoms. The ten electrons are sent along the chain and eventually combine with oxygen and protons to form water. Energy is released as electrons pass from the coenzymes to oxygen atoms and compounds stored in the electron transport chain.