Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
30 Cards in this Set
- Front
- Back
|
During exercise, why does the apex of the lung shift towards a Zone 3 circulation?
|
pulmonary vascular pressure rises enough that even during diastole, the pulmonary artery pressure is positive (above alveolar air pressure of 0)
|
|
|
During exercise, why does pulmonary artery pressure not increase dramatically, even though there is a higher cardiac output?
|
more vessels open up at the apex and vessels dilate to accommodate the increased cardiac output
|
|
|
2 main causes of pulmonary edema?
|
proteins leak out of the pulmonary capillaries (colloid pressure drops and fluid does not move back into capillary) and left heart failure (causes back-up of blood into lungs, fluid collects)
|
|
|
How long does blood stay in the pulmonary capillaries under normal conditions?
|
.8 seconds
|
|
|
How long does blood stay in the pulmonary capillaries during exercise?
|
.3 seconds
|
|
|
For pulmonary edema to occur, pulmonary capillary pressure must at least = what?
|
colloid osmotic pressure of the plasma
|
|
|
What are 4 reasons fluid movement is more likely in the pulmonary tissue than the rest of the body?
|
lower capillary pressure (7), lower interstitial fluid pressure (water will move here), leaky pulmonary capillaries (low colloid pressure = edema), thin alveolar walls (fluid can move in easily)
|
|
|
Even though there is a net flow of fluid into the pulmonary interstitium normally, why is there not normally a fluid build-up?
|
lymphatics are constantly keeping it "dry" with their suction
|
|
|
What is the pulmonary edema safety factor?
|
The range of capillary pressure that can occur before edema is likely. For edema to be likely, pulmonary cap. pressure must = colloid pressure. If a patient's colloid pressure is 30 (and we assume their pulmonary cap pressure is a normal 7), their safety factor is 23 mmHg. Left atrial pressure can also be used to estimate this (but it is 1-2 mmHg lower)
|
|
|
How does pulmonary edema safety factor change in patients with chronic edema?
|
safety factor is increased since lymphatics are compensating greatly in chronic disorder.
|
|
|
Fluid in the pleural cavity is taken where by lymph?
|
mediastinum, superior diaphragm, lateral parietal pleura
|
|
|
To prevent collapse of the lungs, what pressure should be maintained in the pleural cavity?
|
-4 mmHg, it is usually around -7
|
|
|
Why do pulmonary arteries need to have a large compliance?
|
To accommodate for the right ventricle stroke volume
|
|
|
Deoxygenated blood form the bronchial veins (systemic circulation) enter the heart where?
|
left atrium
|
|
|
Normal BP for the right side of the heart
|
25/8
|
|
|
Mean pulmonary capillary pressure
|
7 mmHg
|
|
|
Since there is less hydrostatic pressure, the apex of the lung almost always has a lower pressure than the bottom. For circulation to occur, the artery pressure must be higher than the alveolar pressure. During systole, the artery pressure is highest (25-15 due to hydrostatic pressure above the heart = 10) 10 is still greater than 0. But during diastole, the value becomes (8-15=-7). -7 is below 0 so circulation does not occur here.
|
Since there is less hydrostatic pressure, the apex of the lung almost always has a lower pressure than the bottom. For circulation to occur, the artery pressure must be higher than the alveolar pressure. During systole, the artery pressure is highest (25-15 due to hydrostatic pressure above the heart = 10) 10 is still greater than 0. But during diastole, the value becomes (8-15=-7). -7 is below 0 so circulation does not occur here.
|
|
|
Zone 2 circulation is most dependent on the cardiac cycle. During what part of the cardiac cycle will circulation most likely occur?
|
Systole. The pulmonary artery pressure needs to be higher than the alveolar air pressure (0) for circulation to occur there.
|
|
|
Zone 1 circulation of the heart is abnormal. What can cause this?
|
Zone 1 circulation refers to the areas of a lung where there is no blood flow at any point during the cardiac cycle. Caused by blood loss, low pulmonary systolic pressure, high alveolar pressure
|
|
|
Pulmonary artery pressure at lung apex vs. at level of the heart
|
15 mmHg difference
|
|
|
Pulmonary artery pressure at lung apex vs. bottom of them lung
|
23 mmHg difference
|
|
|
Why do we see vasoconstriction in pulmonary blood vessels associated with alveoli with low PO2?
|
To maximize ventilation/perfusion, the body decreases blood flow to these vessels so blood goes to the areas with proper O2 levels.
|
|
|
When alveolar oxygen falls below 73 mmHg, what response occurs in the alveolar blood vessel?
|
vasoconstriction (opposite to what happens in systemic)
|
|
|
What % of blood is normally in the lungs?
|
9%
|
|
|
Normal left Atrium pressure
|
2 mmHg
|
|
|
Normal pulmonary artery pressure
|
15 mmHg (average of 25/8 systole and diastole)
|
|
|
What is pulmonary wedge pressure?
|
way to estimate left atrium pressure
|
|
|
Why can we not measure the left atrium pressure directly?
|
It is hard to pass a catheter directly through the chambers of the heart
|
|
|
Where does the catheter go when measuring pulmonary wedge pressure?
|
Right atrium - right ventricle - pulmonary artery - pulmonary artery branch near left atrium
|
|
|
What could we infer about a patient with high left atrium pressure
|
Left sided heart failure, increased pulmonary capillary pressure, increased chance of pulmonary edema
|
