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The Respiratory System • System Evolution • Major Parts of the Respiratory System • Functions of the Respiratory System The Evolution of the Respiratory System • Early creatures did not have a “respiratory system” but rather exchanged gasses through their skin. (Still true today as with planarians, hydra, and some amphibians) These animals usually have very large surface areas to maximize respiration. • More Advanced and Evolved animals have developed systems that include lungs, trachea, bronchial tubes and other tissue structures that help with respiration Simple to Complex Respiratory Systems Breathing • Diaphragm and Intercostal Muscles – Separate the Thoracic Cavity from the Pelvic and Abdominal cavities. – Diaphragm also expands and contracts leading to intake and expulsion of air from the lungs. Breathing Cont. • Diaphragm contracts chest cavity expands pressure goes down air goes into lungs • Diaphragm relaxes chest cavity gets smaller pressure goes up air goes out of lungs Moving Air • Nose- filters bacteria and dirt through tiny hairs and cilia • Pharynx-Throat – Mouth and nose come together • Larynx- Voicebox – Vocal Chords (ligaments that vibrate when air goes past) – Adam’s Apple (larynx swells during puberty) • Trachea-Windpipe goes to lungs – Made of cartliage – Cilia line the inside and make mucous – Epiglottis- flap of tissue that closes over trachea when you swallow Lungs • Location of Gas Exchange • Trachea to the Bronchi to Bronchioles to Alveoli – Alveoli are tiny air sacs in lungs How Blood Gets O2 Happy • Deoxygenated blood flows into the heart form vena cava – Right atrium and ventricle • Then into the Pulmonary Artery – Goes to lungs – Gets oxygen – Returns through pulmonary veins • Goes to heart – Left atrium and ventricle – Rest of body Diseases of the Mighty Lungs! • Pneumonia – Infection of the lungs where the lungs fill with pus and fluid; (Sometimes the fluid becomes thicker, more like peanut butter than liquid.) – Most forms caused by either a bacterium or a virus that infects the lungs. – AIDS patients (With weakened immune systems) are subject to a very rare form (Rare in non-AIDS patients) caused by the protozoan Pneumocystis carinii. – Affected parts of the lungs become non-functional as they fill with fluid. – In some advanced cases, people must wear masks to avoid spraying pus and mucus on people around them. Lung Cancer Normal Cancer • Lung Cancer follows related steps: – Thickening and Callusing of cells lining the bronchi. (Cells callus whenever cells are exposed to irritants.) – Loss of Cilia in air way = now impossible to filter dust and dirt from settling in the lungs. – A tumor begins to develop. – The tumor then grows until the bronchus is blocked, cutting off air supply to the affected lung. – Then, the lung collapses and and the secretions in the lung spaces become infected and pneumonia or localized areas or pus result.