Lungs 2 Flashcards
At FRV, the alveoli at the apex of the lung are ______ compliant
less
At FRV, the alveoli at the base of the lung are ________ compliant
more
At RV, the alveoli at the apex of the lung are ______ compliant
more
At RV, the alveoli at the base of the lung are ______ compliant
not at all
Formula for alveolar pressure
PA = PIP + PTP/PER
Expiration occurs passively based on
diaphragm relaxes, raising intrapleural pressure. Elastic recoil pressure is then greater than intrapleural pressure causing a positive alveolar pressure -> results in air leaving
The other name for elastic recoil pressure
transpulmonary pressure
If transpulmonary pressure rises volume _______ in the lung
increases
positive pressure ventilation does what to transpulmonary pressure
increases
The pressure available to distend the lung/fill the lung up with air is
transpulmonary pressure
Passive influences that increase pulmonary vascular resistance include
- Increased lung volume (above FRC)
- decreased lung volume (below FRC)
- Increased intrapleural pressure
- increased blood viscosity
- increased alveolar pressure
Passive influences that decrease pulmonary vascular resistance include
- Greatest factor = gravity/body position (decreases in gravity dependent regions of the lungs)
- Increased PAP/LAP
- increased pulmonary blood volume
- increased cardiac output
Active influences that increase pulmonary vascular resistance include
- SNS stimulation
- catecholamines
- a-adrenergic agonists
- prostaglandins (PGF2a and PGE2)
- thromboxane
- endothelin
- angiotensin
- histamine (pulm venosconstriction)
- alveolar hypoxia
- alveolar hypercapnia
- low pH of mixed venous blood
Active influences that decrease pulmonary vascular resistance include
- PNS stimulation
- ACh
- B-adrenergic agonists
- prostaglandins (PGE1)
- prostaclyclin (PGI2)
- Nitric oxide
- Bradykinin
PVR is highest at what points
RV and TLC
higher at RV
PVR is at its lowest at which point
FRC
Increasing lung volume from FRC makes alveolar pressure _______ and extraalveolar pressure ________
higher, lower
decreasing volume from FRC makes alveolar pressure _______ and extraalveolar pressure ________
lower, higher
extraalveolar pressures/resistance refer to
larger blood vessels
- pulmonary arteries
Larger blood vessels in the lungs are primarily affected by
pleural pressure
negative pleural pressure pulls vessel wall, increasing diameter
alveolar capillaries are primary affected by
volume of air in alveoli, capillaries get stretched out which increases vascular resistance
When RH cardiac output increases, PVR _______
decreases
(opposite of systemic system, bcuz pulmonary vessels very compliant and recruitment of more pathways for blood to go)
distention of compliant blood vessels causes PVR to
decrease
Normal concentration and partial pressure of N2 at sea level, dry
79%, 600.3 mmHg
Normal concentration and partial pressure of O2 at sea level, dry
21%, 159 mmHg
Normal concentration and partial pressure of CO2 at sea level, dry
negligible: 0.04%, 0.3 mmHg
Partial pressure of water is always _____ mmHg
47
Partial pressure of N2 at sea level, humidified
564 mmHg
Partial pressure of O2 at sea level, humidified
149 mmHg
Equation to find partial pressure of O2
PIO2 = FIO2 (PB - 47)
Which gas gets displaced most by humidification
nitrogen, largest decrease in partial pressure
Normal PaO2
100 mmHg
Normal PaCO2
40 mmHg
Normal deoxygenated pulmonary arterial blood Po2
40 mmHg
Normal pulmonary artery PCO2
45 mmHg
average alveolar PAO2
100mmHg
average alveolar PACO2
40mmHg
The amount of O2 and CO2 exchange is ______
equal; despite O2 having larger change in partial pressure. D/t solubility of CO2 in blood
How many mL of tidal volume actually reaches gas exchange
350mL
Why is alveolar pressure of PAO2 104 and PaO2 100?
~1% of CO gets delivered to tissue of lung for tissue perfusion. venous portion of the bronchial blood drains into LA diluting the PaO2 down to 100
