Respiratory system PDF

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Keywords Respiratory system A&P 2...

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• Respiratory System • • • • • • • •

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Functions Provides an area for gas exchange between the blood and air. ▫ Carbon dioxide diffuses into the lungs, oxygen diffuses into blood. Prepare air for the lungs by warming, moistening, and filtering it. Produces sounds as air passes through the vocal folds. Pathway of Breathing Breathing starts through either the nasal cavity or oral cavity. The two cavities are separated by: ▫ Hard palate: Flat bone made from part of the maxilla. ▫ Soft palate: Cartilage The lining of the nasal cavity helps to filter air: ▫ Mucous cells produce a sticky secretion to trap foreign particles. ▫ Ciliated columnar epithelium propels the mucous towards the pharynx, where it is swallowed. Nasal conchae are three curled bone shelves in the nasal cavity that force air flow over the largest surface area of cilia possible. Additional mucous is produced in the paranasal sinuses; empty spaces in the frontal, sphenoid, ethmoid, and maxilla bones. Larynx The epiglottis is a flap of tissue that remains open during breathing, but closes during swallowing to prevent food and drink from entering the larynx. The larynx contains the vocal cords, which vibrate to produce sound. The vocal cords are located directly posterior to the thyroid cartilage, which is externally described as the “Adam’s apple.” Thoracic Cavity A cavity is an empty space within the body. The thoracic cavity contains the lower respiratory organs, the heart, and the thymus gland. ▫ Separated from the abdominopelvic cavity by the diaphragm. ▫ Body cavities and some organs are lined by a special tissue called a serous membrane. ▫ Combination of simple squamous, areolar tissue, and fluid. Visceral pleura is a serous membrane that covers the surface of the lungs. Parietal pleura is a serous membrane that covers the wall of the cavity. Empty space is found between the two pleura. Trachea The trachea is an open tube that delivers air into the bronchi of the lungs. ▫ Lined with 15-20 C-shaped tracheal cartilages that stiffen the walls of the trachea and prevent it from closing. Bronchi Bronchi are formed by the division of the trachea. ▫ The bronchi continue to subdivide, becoming more and more narrow. Primary bronchi → secondary bronchi → tertiary bronchi → bronchioles The Lungs The bronchi deliver air into the lungs, where gas exchange with the blood occurs.

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The right lung has three lobes: ▫ Superior ▫ Middle ▫ Inferior The left lung has two lobes, to accommodate the heart. ▫ Superior ▫ Inferior The lungs inflate and deflate within the pleural space of the thoracic cavity each time you breathe. Alveoli Gas exchange occurs between the air in air sacs called alveoli and the blood in surrounding capillaries. Alveoli are surrounded by several specialized cells. Surfactant-secreting cells produce a lipid that prevents the wet surfaces of alveoli from sticking together. Macrophages are white blood cells that will ingest bacteria, viruses, or foreign objects. Simple squamous cells provide a barrier thin enough for O2 and CO2 to diffuse through. Mechanics of Breathing In order to inhale: ▫ The diaphragm contracts and moves down. ▫ Intercostal muscles contract, expanding the rib cage. ▫ This increases the volume of the lungs (they inflate). ▫ This lowers air pressure in the lungs, drawing air inwards. ▫ The opposite occurs in exhalation: ▫ The diaphragm relaxes and moves upward. ▫ Intercostal muscles relax. ▫ Lung volume decreases (the lungs deflate) ▫ Air pressure increases in the lungs, forcing air out. ▫ Pathway of Respiration Nasal cavity: Cleans, moistens incoming air. Pharynx: Transports air from mouth/nose to larynx. ▫ Epiglottis: Remains open during breathing. Larynx: Contains vocal folds, which can produce sound while exhaling. Trachea/bronchi: Transports air to alveoli. ▫ Also lined with cilia and mucus for cleaning. Alveoli: Allow oxygen to diffuse into the blood while receiving carbon dioxide. Cardiovascular system: Transports oxygenated blood to body cells. Body cells: Oxygen diffused in from the blood. Mitochondria: Use oxygen in cell respiration to produce ATP. ▫ Release carbon dioxide back into the blood as a waste product. Nonrespiratory Air Movements Cough – Clears the larynx and lower bronchi. Sneeze – Clears the pharynx and upper nasal passages. Hiccups – Spasm of the diaphragm. Yawn – Very deep inspiration; ventilates all of the alveoli.

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Effects of Smoking Smoking directly damages the epithelium of the bronchi and trachea. ▫ Columnar cells (I) die out and are replaced by basal cells (L). ▫ Cilia (H) are gradually destroyed. ▫ Eventually, columnar cells and cilia are completely gone, resulting in Smoker’s Cough. ▫ Tissues that support the shape and function of alveoli in the lungs are destroyed. ▫ Alveoli are unable to maintain their shape after exhaling. The bronchioles and lung tissue can also become filled with tar and other compounds from the smoke. Mesothelioma Mesothelioma is a cancer of the pleura of the lungs or thoracic cavity. ▫ The most common cause is exposure to asbestos, a material that used to be used in building insulation. Asthma Asthma is an inflammatory disease that can obstruct the airway and cause spasms of the bronchi. ▫ The airways narrow, causing symptoms like wheezing and shortness of breath. A combination of factors such as exposure to pollution and genetics cause asthma. Bronchitis Bronchitis is an inflammation of the mucous membranes of the bronchi. ▫ Acute bronchitis is usually the result of infection from a virus or bacteria. ▫ Chronic bronchitis is caused by a prolonged exposure to irritants, such as cigarette smoke or other pollution. Pneumonia Pneumonia is an inflammation of the lungs resulting from an bacterial or viral infection. ▫ Swelling of the bronchioles constricts airways and fluid leaks into the alveoli reducing respiratory function. Cystic Fibrosis (CF) Cystic fibrosis is a genetic disorder where mucous cells produce a dense, viscous mucus that cannot be transported by the cilia. ▫ Inability to remove the mucus causes breathing problems and opens the lungs to bacterial infections. Tuberculosis Tuberculosis is a highly contagious bacterial infection of the lungs. ▫ Treated with antibiotics, although some strains are resistant. Pneumothorax A pneumothorax is a collapsed lobe of a lung that occurs due to a puncture wound, broken rib, or gunshot. ▫ Air escapes from that lobe and fills up the pleural space outside of the lung. ▫ This buildup of air puts pressure on the lung, so it cannot expand like normal. Carbon Monoxide Poisoning Carbon monoxide is a colorless, odorless, gas that interferes with the ability of red blood cells to transport oxygen.. ▫ Released in car exhaust and household appliances that burn natural gas. Aspiration

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Pulmonary aspiration is the entry of material into the lower respiratory tract. ▫ Food, drink, or stomach contents. ▫ Can result in infection, or the destruction of the lining of the respiratory tract and alveoli....