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