RESPIRATORY SYSTEM
Jan 02, 2016
• 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