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RESPIRATORY SYSTEM • Pathway of inhaled air: nasal cavity pharynx larynx trachea bronchi bronchioles alveoli • Nasal cavity – Hairs and mucus filter particles, pathogens – Warms and moistens inhaled air – Contains olfactory bulb • Pharynx – Passageway that connects nasal and oral cavities • Glottis – Space between the vocal cords; opening to larynx • Larynx – voice box – Moves up to epiglottis to close trachea when swallowing – you can feel this – Contains vocal cords • Vibrate when speaking • Loudness: air pressure • Pitch: thinning of vocal cords is higher pitch • Normal bacterial and fungal flora here Lower Respiratory Tract • Bronchial Tree – Trachea branches into two bronchi (L & R) – Continued branching of bronchioles – Each ends in cluster of alveoli • Alveoli in the Lung – Thin-walled, rounded sacs surrounded by capillaries – Gas exchange takes place here – Surfactant counteracts water surface tension • The alveoli of human lungs are lined with a surfactin that keeps them open and therefore functional • A surfactin is a thin layer of lipoprotein that lowers the surface tension of water • Infant respiratory distress syndrome • Gas exchange – Most of O2 carried in red blood cells (hemoglobin) – Most CO2 carried in blood plasma ( as bicarbonate) – Direction of flow opposite in lungs – O2 diffuses out of alveoli into the blood stream; CO2 diffuses out of the blood stream into the alveoli • Breathing – Lungs do not work; inflate and deflate passively – Changes in chest cavity size vary pressure – Diaphragm – Intercostal muscles (between ribs) • Lung Volumes – Normal breaths = tidal volume – Forced breathing (much larger volume) = vital capacity – Lungs never completely empty: residual volume – Total lung capacity = vital + residual – Approximately 6 liters for men, 4.2 for women • Exercise – Muscles work, use oxygen for cellular respiration – Carbon dioxide and heat are produced – Carbon dioxide bicarbonate in blood (acidity) – Sensed by medulla (brainstem) – Breathing signals increased, pulse/blood pressure increase – More oxygen circulated faster to tissues – When muscles stop, lag time as breathing, pulse, carbon dioxide concentrations return to normal – Do you consciously control breathing? Diseases of the Respiratory tract • Pneumonia – viral, bacterial, fungal – Inability of the lining of the lung to get rid of fluid – interferes with gas exchange – Inflluenza virus – Pneumocyctis jiroveci – Streptococcus pneumaoniae – Klebsiella pneumaniae • Tuberculosis – bacterial – Mycobacterium tuberculosis