Lecture 3 Flashcards
Define Pulmonary (Minute) ventilation
total air movement into/out of lungs (relatively insignificant in functional terms) L/min
Define Alveolar ventilation
fresh air getting to alveoli and therefore available for gas exchange (functionally much more significant!) L/min
Of 500ml fresh atmospheric air inhaled, how much reaches alveoli?
350ml as first 150ml is “stale air” from dead space.
What is tidal volume and resp rate of healthy man\/
500ml, 12 breaths/min
What is tidal vol (Ml) and resp rate of anxious man?
300ml and 20 (rapid)
What is tidal vol and resp rate of chilled out man?
750ml, 8 (slow)
Therefore what is alveolar ventilation of anxious man?
Tidal vol 300ml, resp 20 breaths/min
3000 (hypOventilation, normal is 4200). tidal vol = 300, -150ml dead space = 150 ml x 20 breaths per min = 3000ml/min
Alveolar ventilation of chilled out man (750 tidal vol, 8 breaths/min) ?
air to alveoli = 750-150 = 600ml x 8 = 4800 (hypERventilation). Normal is 4200
Define Partial Pressure
The pressure of a gas in a mixture of gases is equivalent to the percentage of that particular gas in the entire mixture multiplied by the pressure of the whole gaseous mixture
What is the partial pressure of O2 we breathe? Atmospheric Pressure = 760mmHg
160mmHg BUT only 100mmHg (13.3kPa) in alveoli due to dead space and residual volume (volume that never leaves alveoli) and also becomes saturated with water. And air is in equilibrium (pressure of gas in blood with gas in alveoli)
Atmospheric Pressure = 760mmHg
Pressure of air we breathe therefore = 760mmHg
21% of air we breath = O2
Partial pressure of O2 in air we breath = 21% x 760mmHg
= 160mmHg
What is “normal” alveolar ventilation (L/min)
4.2L/min (4200ml/min)
What is the partial pressure of Oxygen and CO2 during normal ventilation?
13.3kPa p02 (around 100mmHg), 5.3kPa CO2(around 40mmHg). In healthy lungs the partial pressures found in the alveoli are the same as the partial pressures in the blood as equilibrium is reached.
What happens to P02 during Hypo and hyper ventilation?
Hypoventilation decreases PO2, hyper ventilation increases PO2
What is the pressure in the pulmonary circulation?
25/10 mmHg. systolic P ~25mm Hg, diastolic P ~8 mmHg. High flow, low pressure circuit is more susceptible to the effects of gravity and this gives rise to a great degree of variability in blood flow within the lung.
What enters the right atrium and leaves the right ventricle
Superior Vena Cava enters, Pulmonary Artery leaves.
What enters the left atrium and leaves the left ventricle
Pulmonary vein enters, leaves =Aorta
Where does nutritive bronchiole circulation (2% systemic circulation) drain to?
Left atrium.
What is the alveolar pO2 and pCO2?
pO2 100mmHg, pCO2= 40mmHg
What is the pO2 and pCO2 in pumonary Arterys?
pO2 = 40mmHg, CO2 =46mmHg