Flashcards in Quiz 3 Pulmonary & Bronchial Circulations Deck (63):
Is the pulmonary blood pressure lower than the systemic system?
The pulmonary resistance is one tenth than that of the systemic system
What is different about the pulmonary artery compared to the aorta?
The pulmonary is 1/3 thickness and is ver0y compliant.
What is the pressure in the right atrium?
3 to 5
What is the pressure in the right ventricle?
what is the pressure in the pulmonary artery?
-Mean = 14
What is the pressure in the pulmonary capillaries?
What is the pressure in the left atrium?
What is the pressure in the left ventricle?
What is the pressure in the aorta?
-Mean = 90
Will high positive pressure during lung expansion collapse the alveolar vessels?
What do alveolar vessels closely relate?
How much of CO goes into the bronchial vessels to feed the respiratory units?
1-2% of the cardiac output from systemic circulation and empty into the left atrium.
How much do the alveolar capillary walls contribute to resistance in the pulmonary system?
How much do the alveolar arterioles contribute to the resistence in the pulmonary system?
How much of the alveolar surface area is covered by capillary be?
70 - 80 %
What is the normal capillary volume at rest in the pulmonary system?
70 mL (1 mL/kg)
Does the total capillary volume equal one right ventricular stroke volume?
How long does it take for gas exchange equilibrium?
How much weight is blood in the lung?
40 - 50 %
How much can the pulmonary vasculature alter its volume for capacitance of the left atrium?
Can alter from 50% to 200% of resting volume
What is the length of time the blood remains in the pulmonary vasculature?
What is recruitment in the pulmonary system?
Increasing capillary volume by opening closed vessels.
What happens to the pulmonary vascular resistance when increased CO raises pulmonary vascular pressures?
Decreases the pulmonary vascular resistance.
How great does the pleural pressure have to be for inspiration to occur?
Greater than -5cm H2O of pressure
What occurs to the pressure gradient in the ventricle and stoke volume during expiration?
reduction in the pressure gradient allows a greater LV stroke volume.
Pulmonary vascular resistance increases with higher and lower lung volumes.
Bronchial blood circulation returns to right atrium via WHAT?
Approximately 50 % of the bronchial blood exits lung by small anastomoses with ulmonary veins contributing to normal venous admixture?
How fast does the pulmonary lymphatic system drain fluid out?
20 mL /hr
The interstitium is keep at a slight negative pressure.
What are the measurement techniques of Fick's Principle?
-Determining CO by using bloodflow through lungs/min
-oxygen consumption/min=oxygen uptake by blood in lungs/min (VO2 at rest is 300mL/min.
-Measurement of arterial and mixed vnous blood and determination of O2 consumption.
- CO = O2 consumption (VO2)/ arteriovenous (O2) difference.
What is the minimum VO2 needed to stay alive at rest?
What affect does exercising have on blood flow to the lungs?
increases flow 4 to 7 fold and turns entire lung into zone 3.
What are considered Zero Reference Points for hydrostatic pressure?
Right Atrium level and middle of the lung
How does gravity affect the differenct zones in the lung?
Lung bases recieve more of the RV ejection fraction than do the apex.
- hydrostatic pressure cause distension and recruitment of pulmonary capillaries in base of lung (when standing). Also, gravity pulls down on the lung causing alveoli at apex to be more open compared to the bases. ventilation and perfusion are affected by gravity.
Which lung zone is optimum for gas exchange?
Is a low or high V/Q mismatch better for gas exchange?
A low V/Q mismatch means that ventilation and perfusion are nearly equal
which zone of the lungs has intermittant gas exchange?
Which zone has no gas exchange and why?
zone 1 because PA>Pa>Pv
- higher PA (alveolar pressure) will colapse the pumonary capillaries
What are some factors that create more zone 1 conditions?
- Decreased Pulm Artery pressure (shock, sepsis)
- Increased alveolar pressure (PEEP)
- Occlusion of vessels (PE)
What are some factors that decrease zone 1 conditions?
- Increased Pulm Artery pressure (infusion of blood or fluid)
- reduced hydrostatic effect (change pt position, standing to supine)
What can increase and what can decrease PVR?
Increase PVR - Hypoxia
Decrease PVR - Increased CO
How does Active regulation of blood flow throught the pulmonary system occur?
by altering vascular smooth muscle tone in arterioles and capillaries. Alters PVR
- sympathetic outflow causes vasoconstriction
***most active regulation of pulm vessels is mediated by local metabolic influences***
What are 4 of the many vasoconstrictors?
- Reduced PAO2
- Increased PCO2
- Thromboxane A2
What are 3 of the many vasodilators?
- increased PAO2
- Nitric Oxide
What is unique about Nitric Oxide?
- Produced right in area where it works
- is very toxic in high concentrations
- binds to heme 200,000 times > oxygen
What happens if theres a global reduction in alveolar oxygen tension?
Increased PVR through constriction of arterioles and small arteries.
How is the pulmonary vasculature opposite of the systemic vasulature when it becomes hypoxic?
Hypoxia produces hypoxic pulmonary vasoconstriction (HPV) whereas hypoxia in the systemic vasculature causes vasodilation
Why is hypoxic pulmonary vasoconstriction (HPV) important for balancing the V/Q ratio?
It will help shunt blood to better perfused areas of the lungs.
What is pulmonary Hypertension?
Increased resistance to blood flow in the lung
What causes high PVR and elevated pulmonary artery pressures?
- Low PO2, High PCO2
- Histamine release
- High altitudes
Which side of the heart does pulmonary HTN cause increased work?
- RV hypertrophy
- Tricuspid regurg
- R heart failure (cor pulmonale)
What is the only effective treatment for pulmonary htn?
Which portion of the lung tends to be better ventilated?
the lower portion of the lung. (upper lung is open 60% vs lower lung open 40% at FRC. With inspiration, both will open to 100% but the lower portion actually opens more than the upper lung can.
What is a normal A-a gradient? What does an elevated A-a gradient indicate?
Normal - 10-15mm Hg
indicates intrinsic pulm disease --> shunting
What is a R-->L heart shunt?
Shunt = Perfused but not ventilated
blood goes through pulm circ does not participate in gas exchange.
What is a L-->R heart shunt?
portion of CO return to right heart without flowing to body (does not affect systemic arterial O2 tension)
What is the pressure gradient on the systemic system due to gravity?
0.74 mm Hg/cm
It the blood pressure higher or lower in the feet when a person is in the supine position?
Higher pressures in the feet.
Is the distribution of blood in the lung affected by gravity?
When a person is exercising blood flow increases to the lung by how much and what zone is the lung converted to?
Increases 4 to 7 folds and converts the entire lung to zone 3.
What is hydrostatic pressure?
Pressure effect gravity has on a column fluid.