Nose:
external nose nasal cavity
Functions:passageway for air, cleans the air, humidities, warms air, smell
along with paranasal sinuses are resonating chambers for speech
Pharynx: common opening for digestive and respiratory systems
Three regions: nasopharynx, oropharynx, laryngopharynx
nose and pharynx
composition of Air
The composition of normal, dry, atmospheric air is 20.95% oxygen, 0.03% carbon dioxide and 78.08% nitrogen. The normal atmospheric pressure at sea level is about 76 mmHG. the total pressure exterted by a gas mixture is equal to the sum of pressures exerted by each constituents gas ( Dalton's law)
pO2= 159.2 mmHg
pCO2= 0.003 mmHg
pN2=600.6 mmHg
Atmospheric pressure increases markedly underwater.
physical principles of gas exchange
Partial pressure: the pressure exerted by each type of gas in a mixture, dalton's law, water vapor pressure.
Diffusion of gases through liquids: concentation of gas in a liquid is determined by its partial pressure and its solubility coefficient. Henry's law
minute and alveolar ventilation
Minute ventilation : total amount of air moved into and out of respiratory system per minute. Respiratory rate or frequency : number breaths taken per minute. Anatomic dead space : part of respiratory system where gas exchange does not take place.
Alveolar ventilation : how much air per minute enters the parts of the respiratory system in which gas exchange takes place.
residual volume
volume of air remaining in respiration passages and lungs after the most forceful expiration
inspiratory reserve volume
amount of air inspired forcefully after inspiration of normal tidal volume
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