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 O 2 carried in red blood cells (hemoglobin) –Most CO 2 carried in blood plasma ( as bicarbonate) –Direction of flow opposite in lungs – O 2 diffuses out of alveoli into the blood stream; CO 2 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