The Respiratory System
The functions of the respiratory system are; inhalation and exhalation, External Respiration exchanges gases between the Lungs and the bloodstream, Internal Respiration Exchanges gases between the bloodstream and body tissues and generates sound with speech. The respiratory system includes the nose, pharynx, larynx, trachea, bronchi and lungs. The respiratory system has two important functions: it brings oxygen into our bodies, which we need for our cells to live and function properly; and it helps us get rid of carbon dioxide, which is a waste product of cellular function.
The lung apex is at the top of the lung and is somewhat pointed; the lung base is broad and concave. The lung extends from above the first rib (above the clavicles) to the 6th rib in the front and the 11th rib posteriorly. At the center of the mediastinal border is the hilum, where the right and left main stem bronchi, blood vessels, lymph vessels and various nerves enter and exit the lungs. The right lung is larger and heavier than the left. It has three lobes that are divided by the oblique and horizontal fissures. The horizontal fissure is only found on the right side and separates the upper and middle lobes.
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The oblique fissure separates the upper and middle lobe from the lower lobe. The lung has Pleural Membranes; Visceral Pleura attaches to the outer surface of each lung and extends into each of the interlobular fissures. Parietal Pleura lines the inside of the thoracic walls, the thoracic surface of the diaphragm and the lateral portion of the mediastinum. Both pleura are moist, slick surfaced membranes.
The space between the two surfaces is called the pleural cavity. The two surfaces are held together by a thin film of serous fluid. They glide over each other during inspiration and expiration. The left lung is divided into two lobes: the upper and lower lobes that are divided by the oblique fissure. All lobes are divided into segments. There are 10 segments on the right and 8 segments on the left. The function of the lungs is to provide ventilation and respiration. (Egan 10th edition) Ventilation is the process of moving gas into and out of the lungs.
Respiration is the exchange of oxygen and carbon dioxide between the air and blood and between blood and tissue. The lungs must also protect itself from the numerous contaminants widespread in the environment. The lung and heart must work together to provide the necessary oxygen vital to the body. Another function of the lungs is to remove CO2. Failure of the lung to adequately oxygenate can result in hypoxemia and/or hypoxia. Hypoxemia is decreased oxygen in the blood. Hypoxia is decreased oxygen at the tissue level.
Tissue found in the respiratory system is Pseudostratified Columnar. This tissue can be found in the lining of the air passages of the respiratory system. Stratified squamous epithelium can be found in the anterior portion of nasal cavity, oral cavity, oropharynx and the laryngopharynx. Pseudostratified columnar epithelium can be found in the posterior 2/3 of nasal cavity and the tracheobronchial tree.
Simple cuboidal epithelium can be found in the bronchioles. Simple squamous epithelium can be found in the alveoli and the pulmonary capillaries. (Egan 10th edition) The Respiratory System is divided into 2 parts upper and lower airways. The Upper Airway contains the nose, oral cavity and pharynx. The Function of the upper airway is to conduct air, prevent foreign materials from entering the lower airway and coordinates smell and speech. The function of the nose is to heat, humidity and filter incoming gas, which is the first line of defense.
There are bony protrusions on the lateral walls of the nasal cavity called the superior, middle and inferior nasal turbinates or conchae; the turbinate’s separate the incoming gas into airstreams which increases contact area between inspired air and the warm moist surface of the nose. (Egan 10th edition) The Oral Cavity is composed of a hard and soft palate that forms roof of the mouth; also containing the Uvula, the soft fleshy structure.
Epithelium is stratified squamous epithelium that is nonciliated. The palatine, known as faucial tonsils are located on each side of the oral cavity. These tonsils are lymphatic tissue believed to serve a protective function. Pharynx, which means throat, includes the following; Nasopharynx located posterior to the nasal cavity. It is lined with pseudostratified ciliated columnar epithelium. The pharyngeal tonsils or adenoids are located in this area.
Oropharynx lies behind the oral cavity. The lingual tonsils lie in this area at the root on the tongue; it is lined with stratified squamous epithelium Laryngopharynx lies between the base of the tongue and the entrance to the esophagus and lies posterior to the epiglottis. This area is lined with stratified squamous epithelium. (Egan 10th edition) The lower airway includes the Larynx, Referred to as the voice box. It is the opening between the trachea and the pharynx. Its function is to conduct air between pharynx and trachea. Protects against aspiration of solid and liquids.
Generates sound for speech. The Larynx is composed of nine cartilages, 3 single cartilages; thyroid, cricoid, and the epiglottis. It also has 3 paired cartilages; arytenoids, corniculates and cuneiform. The cartilages are held in place by ligaments, membranes and muscles. The largest cartilage is the thyroid cartilage (Adam’s apple); it is suspended by the hyoid bone. (Egan 10th edition) The false vocal cords and the true vocal cords are found in the interior of the larynx.
The space between the true vocal cords is termed the rima glottidis or glottis. The subglottic area is the area directly below the glottis and the supraglottic area is the area directly above the glottis.The glottis is the opening of the trachea and is the narrowest portion of the airway (adult). Swelling (edema) at the glottis, subglottic or supraglottic region can cause stridor. Stridor is a high-pitched crowing sound usually heard on inspiration from air traveling through a narrow opening. Stridor is often heard in children with croup or epiglottitis.
The cricothyroid membrane connects the cricoid and thyroid cartilages and is the site for an emergency airway when there is an occlusion above this point. An entrance made into this membrane is called a cricothyrotomy. The vocal cords ability to open and close the airway is essential for generating and releasing high pressure in the lungs needed for coughing. If you place an ET/trach tube you render the cough ineffective because there is no way to seal the airway. The vocal cords are wider apart during inspiration than expiration.
Swelling (edema) of the vocal cords cause increased resistance to breathing. Vocal cord abduction implies the cords are opening or moving away from the midline. Vocal cord adduction implies the cords are moving toward the midline or coming together. (Egan 10th edition) The laryngeal reflex can close the vocal cords inside the larynx which will close the tracheal opening. This is called laryngospasm. This may occur during endotracheal tube removal (extubation), drowning, inhaling noxious substances. Another function of the larynx is the effort closure during exhalation, known as the Valsalva maneuver.
During this maneuver, there is a massive undifferentiated adduction of the laryngeal wall, including both the true and false vocal cords. As a result the larynx is tightly sealed preventing air from escaping during physical work such as lifting, pushing coughing, throat clearing, vomiting, urination, defecation and parturition (giving birth). The Tracheobronchial (TB) Tree is divided into two divisions’ cartilaginous airways and non- cartilaginous airways. Cartilaginous airways which conduct air between environment and the site of gas exchange.
Cartilage is found in the trachea, main stem bronchi, lobar bronchi, segmental bronchi, and sub segmental bronchi. (Egan 10th edition) Non-cartilaginous airways conduct air and are sites of gas exchange; no cartilage is found from the bronchioles down to the alveoli. The TB tree divides in a pattern known as dichotomous branching in which each airway divides into two “daughter” airways. Each division called a bifurcation gives rise to a new generation of airways. (Egan, 10th edition) Gas Exchange of the respiratory system includes functional Units which are respiratory bronchioles, alveolar ducts and alveolar sacs. There are approximately 300 million alveoli.
Average surface area of the lung is 70-85 square meters. The respiratory bronchioles, alveolar ducts and alveolar sacs that arise from a single terminal bronchiole are called the primary lobule, parenchyma, or acinus. (Egan, 10th edition) There are many types of respiratory diseases that can be life threating, and also that can effect someone’s everyday respirations. Lung cancer, asthma, pulmonary embolisms, pneumonia, and tuberculosis are just a few diseases that will be discussed. The Respiratory diseases have very noticeable symptoms such as, coughing, palpations, shortness of breath, low oxygen levels, fevers, hemoptysis, fatigue, and many more symptoms.
Lung Cancer also known as “The deadliest form of cancer (Davis, 2017)” is a life threatening disease caused by a tumor on the lungs and the bronchi (Chabner 476). Lung cancer can be caused by smoking, second-hand smoking, also inhaling pollution (Davis, 2017). Some symptoms of lung cancer are pneumonia, bronchitis, and arm and shoulder pain, swelling of the upper body, dyspnea, palpations, and weight loss (Davis, 2017). Asthma is a well know chronic respiratory disease. Individuals with Asthma have difficulty breathing, due to narrow or inflamed airways, also due to excessive mucous that the individual produces (Davis, 2017).
People with asthma may experience, dyspnea, wheezing, chest pains, rapid breathing, also rapid heart rate (Chabner 476). It is very important for asthmatic people to carry an inhaler with them at all times. Another respiratory disease is a pulmonary embolism; this disease can be deadly, if it is not detected. A pulmonary embolism is a blood clot that has traveled to the artery or arteries in the lung, the blood clot usually comes from the lower extremities (Chabner 476). Pulmonary embolisms can be hard to detect due to this disease not having any real symptoms. Pneumonia is another well know respiratory disease. Pneumonia “Acute inflammation and infection of alveoli, which fill with pus or products of the inflammatory reaction (Chabner 476).”
Pneumonia can be caused by viral infection, bacterial infection, or fungi. According to the Tabbers Medical Dictionary ” In the U.S., about 4,500,000 people contract pneumonia each year, and pneumonia is the sixth most common cause of death in the U.S.; (David, 2017).” This informs us that pneumonia can be a deadly disease if it is not treated properly. Individuals with pneumonia have experienced chills, fevers, chest pains, shortness of breath, and coughing (Davis, 2017). Also tuberculosis is a well know respiratory disease.
Tuberculosis is a bacterial disease that affects the lungs and is known for affecting other organs. Tuberculosis happens when a “bacteria called bacilli invade the lungs, producing small tubercles (Chabner 476)”. Tuberculosis is treated with multiple antibiotics, and can take up to years to fully exit the body (Davis, 2017). Some symptoms that are associated with tuberculosis chronic cough, sputum, fevers, sweats, and weight loss, bone infections, and urinary bleeding (Davis, 2107). The respiratory system is very important to the human anatomy, due to the gases being exchanged. If any respiratory disease goes untreated, it could lead to death.