Zhu: Pulmonary Circulation Flashcards
Pulmonary capillaries carry ___________ blood. Pulmonary veins carry ____________ blood to the left atrium. (this is opposite of systemic circulation).
deoxygenated; oxygenated
Describe the bronchial circulation.
Supplies oxygen to the lungs; originates from systemic system (branch of aorta). Carries oxygenated blood to the lungs; deoxygenated blood is carried away by bronchial veins and 2/3 of it empties into pulmonary veins (physiological shunt). (plum veins has oxygenated blood, so you’re contaminating it with deoxygenated blood –> shunt)
What are the three main important features of the pulmonary circulation?
Low pressure/low resistance high capacity hypoxic vasoconstriction (opposite of systemic)
Pulmonary Vascular Resistance - equation in relation to flow, PA pressure and LA pressure
PVR = (Ppa - Pla)/Q (resistance = change in pressure/flow) Flow here, Q, is Cardiac Output since the lungs receive it all
Pulmonary blood pressure?
25/8
What features cause the pulmonary artery to have a higher compliance?
very thin wall (in comparison to aorta) and large diameter
Your patient has left ventricular heart failure and you suspect pulmonary involvement/congestive heart failure. What do you want to measure and how?
Left atrial pressure; Pulmonary wedge pressure
How do you measure pulmonary wedge pressure?
A catheter balloon is wedged in a small pulmonary artery; it’s approx pressure = 5mmHg
Pressure differences in an upright lung; above the heart compared to below the heart?
23 mmHg pressure difference from top to bottom: top of lung is 0 to mid-heart: +15; then from mid-heart to below heart/bottom of lung: + another 8. Total:23mmHg
In left ventricular failure, blood flow will back up into the left atrium, then the lungs. What compensatory mechanism is in place?
Pulmonary circulation can serve as a blood reservoir due to HIGH CAPACITY
In systemic flow, hypoxia causes __________ because tissues need ____________. In pulmonary flow, hypoxia causes ______________ because tissues need ___________.
vasodilation; oxygen. vasoconstriction; gas exchange. Constriction occurs so blood can be redistributed to where it will be better ventilated.
What two pressures determine gas exchange? What will determine blood flow?
the capillaries are stretched by the BP inside and compressed by the air pressures of the alveolus from the outside. Blood Flow determined by pressure difference: Pcap>Palv = FLOW Pcap
Describe the three zones/types of blood flow during the cardiac cycle.
Zone 1: no flow because Pcap Palv; but no flow in diastole Zone 3: Continuous flow because Pcap>>Palv always
Under normal conditions in an upright lung, which zones of blood flow are where?
Systolic at 25mmHg: upper is 25-15 = 10; lower is 25+8=33 Diastolic at 8mmHg: upper lung is 8-15=no flow; lower lung is 8+8=16, therefore: Zone 1: nowhere. Zone 2: upper lung (flow in systole but not diastole) Zone 3: lower lung (flow in both systole and diastole) Zone 1 is only seen in hemorrhage/hypovolemia or while i.e. playing a trumpet (high Palv compresses cap’s)
During heavy exercise, pulmonary blood flow increases 4-7 times while the pressure only doubles. Why?
RECRUITMENT AND DISTENSION. Recruitment of other not always used capillaries Distension beyond normal of capillaries already used. change in pressure = flow*resistance BUT and flow increases, resistance DECREASES due to recruitment and distension
Total outward and inward forces?
pic
What happens with outward and inward forces in edema?
pic
