Lec 18 Respiratory Physiology Flashcards
The total pressure exerted by a gas is equal to
The sum of the partial pressures of each individual gas in the mixture
How do you calculate Pgas ?
Pgas= fraction x total pressure
What is atmospheric pressure at sea level
760 mmHg
What is the partial pressure of nitrogen at sea level ?
600.6 mmHg
What is the partial pressure of oxygen at sea level ?
159.1 mmHg
What is the partial pressure of carbon dioxide at sea level ?
0.3 mmHg
Gas exchange occurs via?
Where does it occur
Diffusion
Lungs to blood and blood to tissues
When does perfusion occur
Transporting in the blood
Deoxygenated blood is pumped to _______ by the ________ ventricle
Lungs by the right ventricle
Oxygenated blood is pumped to the __________ by the _______ ventricles
Muscles by the left ventricles
What is the Po2 at the level of atmosphere
159 mmHg
What is the Po2 at the level of trachea
149 mmHg
What is the Po2 at the level of alveolar
103 mmHg
What is the Po2 at the level of arterial
100 mmHg
What is the Po2 at the level of mean capillary
40 mmHg
What is the Po2 at the level of mitochondria
2-3 mmHg
What is the order that o2 moves from lungs to cells
Atmosphere, trachea, alveolar, arterials, mean capillary, mitochondria
Why is o2 decreased at the level of the trachea
Air is humidified
- volume of air include gas and water
- partial pressure of water in humidified air is different is subtracted
- constant across all conditions
Why is o2 decreased at the level of the alveolar
Because carbon dioxide continuously enters the alveoli from blood therefore alveoli air contains different concentrations then atmospheric air
CHANGE IN FRACTION OF O2
Oxygen 20.93%—>14.5%
Carbon dioxide 0.03—>5.5%
Nitrogen 79.03%—>80%
Why is o2 decreased at the level of the arterial
Shunting blood and some poorly ventilated alveoli
Why is o2 decreased at the level of the mean capillary
Mix of arterial and venous blood
Muscle o2 extraction?
During the process to the lungs which are unchanged during exercise
Why ?
Atmospheric, trachea, alveolar and arterial po2 are UNCHANGED
Everything on the arterial side stays the same only the venous side changes
Increased ventilation offsets increased o2 uptake
With intense exercise what value does venous PO2 DECREASE to
15 mmHg
With intense exercise what value does venous PCO2 INCREASE to
60 mmHg
