Lecture 10 Flashcards
Exam 2 content
Where is the dependent lung?
The part of the lung closest to the planet. “gravity-dependent”
Transpulmonary pressure is synonymous with________.
elastic recoil pressure.
What is the pressure formula for air movement in the alveoli?
Alveolar Pressure = Pleural Pressure + Transpulmonary Pressure
What are some passive influences that decrease pulmonary vascular resistance (PVR)?
- Gravity
- increased PAP
- increased CO
What are some passive influences that increase PVR?
- increased lung volume
- decreased lung volume
- increased blood viscosity
- PPV
- hypoxic pulmonary vasoconstriction
What are some active influences on pulmonary vascular resistance (PVR)? Decreasing PVR
- parasympathetic outflow
- ACh
- Beta agonists
- Some prostaglandins (PGE1)
- Prostacyclin
- NO
- Bradykinin
What are some active influences on pulmonary vascular resistance (PVR)? Increasing PVR
- alpha agonists
- Epi, NE
- sympathetic stimulation
- Prostaglandins (PGF, PGE2)
- Thromboxane
- angiotensin II
- histamine
- endothelin
- decreased O2
- increased CO2
What is the lowest lung volume we can be at? The highest?
lowest: RV (residual volume)
highest: TLC (total lung capacity)
What are the two components that make up the total pulmonary vascular resistance?
- Large extra-alveolar blood vessels
- Smaller alveolar blood vessels
When we put a bunch of extra air into the alveolus what happens to the adjacent alveolar capillary?
It stretches the capillary and increases vascular resistance
Going to a lower lung volume does what to our alveolar pulmonary vascular resistance?
decreases the alveolar PVR
What happens to the larger extra-alveolar vessels in response to higher lung volumes? How?
lower extra-alveolar PVR. Increased negative pressure on inspiration “pulls” the larger vessels apart which decreases their resistance.
What happens to the extra-alveolar vessels in response to lower lung volumes? How does this happen?
increased extra-alveolar PVR, these larger vessels are getting squished by the more positive intrapleural pressure
What are two things that happen when we increase blood flow to the alveolar capillaries?
recruitment and distension (both of these decrease PVR). This helps keep the load on the right heart in check.
What can increase blood flow to the alveolar capillaries?
increased CO
At sea level what is atmospheric pressure?
760 mmHg or Torrs = 1 atm
What % of our atmospheric gas is nitrogen? oxygen? CO2?
nitrogen: 79%
oxygen: 21%
CO2: 0.04% (negligible for our class)
What is the partial pressure for oxygen? nitrogen?
oxygen: 0.21 (760mmHg) = 159 mmHg
nitrogen: 0.79 (760mmHg) = 600.3 mmHg
What is the partial pressure of water vapor? What does this do to the other partial pressures?
water vapor: 47 mmHg (ALWAYS)
Total pressure = 760 mmHg which leaves less room for the other gasses (decreases the partial pressures of oxygen and nitrogen)
oxygen: 149 mmHg
nitrogen: 564 mmHg
What is the formula for partial pressures that includes water vapor?
partial pressure of O2 = 0.21 x (barometric pressure - partial pressure of water vapor)… (0.21 x (760-47)) = 149
If you go to a higher elevation what changes?
the barometric pressure would be less than 760 mmHg
What are the average gas pressures for O2 and CO2 in normal lung alveoli?
alveolar Po2: 100 mmHg (104 mmHg is the more precise #)
alveolar Pco2: 40 mmHg
