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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
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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