The Respiratory System
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Respiratory system
Anatomy:
The respiratory system is one of the ten body systems in the human body that serves as a homeostatic mechanism that constantly supply oxygen to the body while removing carbon dioxide. There are two basic functions that the organs in the respiratory system serve: they distribute air and perform gas exchange. In addition to these functions, the respiratory system warms, humidifies, and filters the air inhaled when it passes through the sinuses, located in the head. Respiratory organs are as follow and function in this sequence: nose, pharynx, larynx, trachea, bronchial trees, and lungs.(See Figure 1.) . These passageways provide a direct connection between the outside air and some of the most delicate tissues in the body- the lung tissue-, and so these passageways must filter out dust, dirt, smoke, bacteria, and a variety of other contaminants found in air.
The nose itself is part of the human face or the forward part of the head of other vertebrates that contains the nostrils and organs of smell and forms the beginning of the respiratory tract. The inner nostrils have little hairs that help the body filter the air that enters. It is there to increase the surface area and lengthen the time it takes for air to reach the nasal cavity, which acts as a passage that warms and humidifies the air we breathe. The nasal cavity is significant since cells in the human body function optimally when supplied with warm and moist oxygen; by the time the air reaches the lungs, it is already warm and humidified. Although air can also be taken in by mouth, the ideal way to supply the body with air is through the nose, since the mouth has no warming/ humidifying mechanisms.
The pharynx is commonly known as the throat and is the next step in respiration. it is about 12.5 inches long and contain three portions: the naso-pharynx, oropharynx, and laryngopharynx. It is located in the back of the mouth and it functions as a passageway for both air and food. When air is breathed in, a flap of cartilage, called the epiglottis, presses down and covers the opening to the esophagus in order to prevent any air from entering the stomach instead of the lungs.
The larynx is commonly known as the voice box- it is made up of cartilage and fibrous bands called the vocal cords. These cords are pulled on by the muscles attached to them when the body wants to make a vocal sound. The larynx also increases surface area in the body, ensuring that the air that reaches the lungs is humidified. As the air moves on, it reaches the trachea, which is a tube about 4 inches long and less than an inch in diameter in most people. The trachea begins just under the larynx and runs down behind the sternum. The trachea then divides into two smaller tubes called bronchi: one bronchus for each lung; the bronchi is often called the bronchial tree it looks like an upside-down tree with extensive branches that become smaller and smaller; the bronchioles. The trachea is composed of about 20 rings of tough cartilage. The back part of each ring is made of muscle and connective tissue. Moist, smooth tissue called mucosa lines the inside of the trachea that contains cilia and mucus. The combination of cilia, little hair-like organelles, and mucus filter out solid particles from the air and warms and moistens the air, preventing damage to the delicate tissues that form the lungs. The trachea widens and lengthens slightly with each breath in, returning to its resting size with each breath out.
The lungs are the site of gas exchange between the atmosphere and the blood. The right lung has three lobes, and is slightly larger than the two-lobed left lung. The lungs are inside the thoracic cavity, which is surrounded by the rib-cage, on the left and right, and the diaphragm, a sheet of muscle that helps support the lungs and push air out of human bodies, underneath. Lining the entire cavity and encasing the lungs are the two pleural membranes that secret pleural fluid. These secreted fluids reduce friction from the movement of the lungs during breathing and hold the lungs to the inside of the ribs, hence allowing them to move with the ribs.
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