1. What are the four pulm arterial/capillary pressures?
1. Systolic 25mmHg
2. Diastolic 8mmHg
3. Mean 15 mmHg
4. capillary 7mmHg
1. In systole PA pressure = ?
1. RV pressure
1. What is a normal LA pressure?
1. Ratio of SVR to PVR is about?
1. The pulmonary system is a______ pressure, _______ resistance, but ______ compiance system
2. What does this allow?
1. Low, Low, High
2. allow total blood flow to go through lungs. < 1/10th the resistance of systemic circulation.
1. What causes low pulm R?
1. Vessels are shorter and wider
2. Larger amt of Arteriols
3. Far less muscular arterioles
4. resting tone is low
5. Vessel walls are thin with less smooth muscle
1. Alveolar Vessels are?
2. Alveolar vessel resistance is dependent on what 2 things
1. capillaries and slightly larger vessels that are surrounded on all sides by alveoli.
2. - Transmural pressure gradient (PTM). Diff in pressure outside vs. inside capillary
- Lung volume
1. Alveolar Pressure INSIDE the vessels depend on what two things?
1. - Cardiac cycle - pulsatile flow
- vertical location in relation to LA - higher the position, the lower the pressure.
1. Alveolar pressure varies with?
2. With no airflow, and glottis is open, PA = PB 0cm of H2O
3. What is PA pressure during inspiration? Expiration?
1. Respiratory cycle
3. negative. positive
1. What dialates Alveolar Vessels? What does this do to resistance
2. What increases resistance?
1. High intravascular pressure and neg PA pressure. Decreases
2. Increase in lung volume VL. = Stretching.
increase in VL causes flattening, crushing capillaries.
1. what are extra alveolar vessels?
2. What are extra alveolar vessels more sensative too?
3. as VL increases extra-alveolare Resistance?
1. Arteries and Veins that run though lung parenchyma NOT surrounded by alveoli.
2. Intrapleural pressure
1. PVR = ~ 1.7mmHg/L/min
2. As pulm arterial or venous pressure rises, PVR increases or decreases?
3. What 2 mechanisms contribute to this ability
3. Recruitment and distention of alveolar vessels
1. What is Recruitment of Alveolar vessels?
2. What is distention?
3. Which mechanism is most responsible for decrease in Pulm Vasc Resistance when vascular pressure is high?
1. As perfusion pressure increases, capillaries that are either closed or open but unperfused, will begin to conduct blood.
2. increase in caliber = increased blood flow
1. Which pulm vascular ability is most responsible for decrease PVR at lower elevations of arterial pressure?
1. When pt stands, where is flow the greatest?
2. PA blood pressure lowest in the?
3. So distribution of blood flow is affected by what 2 things
1. In the bases - lowest in the apex
2. posture and gravity
1. What happens in zone 1
2. Is there perfusion in zone 1?
3. Is there normally present a zone 1 physiological state?
4. When would there be a zone 1 physiological occurrence?
1. PA > Pa > Pv
4. - low pulmonary pressure. ex hemorrhage, or
- higher than normal PA pressure. ex. PEEP
1. Alveolar dead space occurs in what zone and why is this dead space?
1. Zone 1
2. Bc it is ventilated but not perfused.
1. Characteristics of Zone 2 physiological state?
1. Pa > PA
2. perfusion is intermittent bc during syst > alveolar, but during diastole, alveolar > diastolic pressure
3. driving pressure (Pa-PA)
1. Continuous flow occurs in what zone?
1. Zone 3 flow is dependent on what factors?
1. (Pa - Pv) arteriol - venous
1. Increase in PIP leads to what in zone 4
1. partial extra alveolar collapse
1. lung zones are described as physiological and not anatomical?
2. Boundaries of zones are sharp and fixed
3. What would cause a downward shift of physiological boundaries? Upward shift?
4. What 2 zones are normally present