Resp 1 - West Ch 4 Blood Flow And Metabolism

Front 1

Pulmonary pressures are remarkably low: __/__mmHg. The pressure is therefore very _____. Why so low?
Also, the walls of the pulmonary arter and branches are ____ and contain relatively little _____

Back 1

25/8
pulsatile
Keeps the work of the R heart small, high enough to perfuse top of lung
thin
smooth muscle (easily mistaken for veins)

Front 2

The effective pulmonary capillary pressure is ______ pressure, and when this rises above the pressure inside the capillaries, they collapse (alveolar vessels)
The pressure difference between the inside and outside of capillaries is called the _____ pressure

Back 2

alveolar (which is very close to atmospheric pressure)

transmural

Front 3

Both arteries and veins (extra-alveolar vessels) are exposed to a pressure less than _____ increase with what?

Back 3

alveolar
Lung expansion - radial traction of the elastic lung parenchyma pulls them open

Front 4

What is the chief mechanism for the fall in pulmonary vascular resistance when pulmonary artery pressure is raised
What is the other mechanism used at even higher pressures/sometimes on top of the first?

Back 4

Recruitment - some capillaries are normally closed or open w/ no blood flow. conduct blood when pressure rises
Distension - widening of individual capillary segments

Front 5

Extra-alveolar vessels have a __ vascular resistance at large lung volumes. They have a ___ resistance when lungs volume is low
What is critical opening pressure?

Back 5

low
high

Pressure it takes to get flow if the lung is completely collapsed

Front 6

Serotonin, histamine, and NE do what to pulmonary vascular resistance?
How about acetylcholin and isproterenol?

Back 6

Increase it = contraction of the smooth muscle of extra-alveolar vessels
Relax smooth muscle - decrease resistance

Front 7

Why does pulmonary vascular resistance decrease with exercise?

Back 7

Recruitment and distention of capillaries

Front 8

Pulmonary vascular resistance _______at high and low lung volumes

Back 8

increases:
low volumes - extra alveolar vessels collapsed, capillaries open
high volumes - extra-alveolar vessels open, capillaries stretched and caliber reduced

Front 9

Pulmonary vascular resistance ______ with alveolar hypoxia. Why?

Back 9

increases - constrction of small pulmonary arteries

Front 10

ZONE 1:
Pulmonary arterial pressure is ____ than alveolar pressure
No flow is possible => alveolar ____ ____
Doesn't occur in normal conditions - but maybe in hemorrhage, positive pressure ventilation.

Back 10

lower
dead space

Front 11

ZONE 2:
Pulmonary arterial pressure is ____ than alveolar pressure, blood flow determined by difference of the two.
Starling resistor effect
Increasing ______ of capillaries

Back 11

higher (due to hydrostatic effect)

recruitment

Front 12

ZONE 3
_____ pressure exceeds alveolar pressure and flow is determined by a-v pressure difference.
Increase in blood flow chiefly by _______ of capillaries

Back 12

Venous
distention, also some recruitment

Front 13

ZONE 4
Regional reduction of blood flow
Due to narrowing of which vessels?
Lung poorly inflated

Back 13

extra-alveolar

Front 14

Low PO2 of the alveolar gas (NOT the pulmonary ____ ____) can cause a hypoxic ______

Back 14

arterial blood
vasoconstriction

Front 15

The ratio of total systemic vascular resistance to pulmonary vascular resistance is about:
A. 2 : 1
B. 3 : 1
C. 5 : 1
D. 10 : 1
E. 20 : 1

Back 15

D. Mean systemic arterial pressure = 100 mmHg
Right atrial pressure = 2 mmHg
Systemic vascular resistance = (100-2)/CO

Note: CO = cardiac output = pulmonary blood flow
Mean pulmonary arterial pressure = 15 mmHg
Left atrial pressure = 5 mmHg
Pulmonary vascular resistance = 15-5/CO
98/10 = 10:1

Front 16

Concerning the extra-alveolar vessels of the lung:
A.Tension in the surrounding alveolar walls tends to narrow them.
B.Their walls contain muscle and elastic tissue.
C.They are exposed to alveolar pressure.
D.Their constriction to alveolar hypoxia mainly takes place in the veins.
E.Their caliber is reduced by lung inflation.

Back 16

B.
Answers A and E: True and have to do with the tethering of these vessels and the fact that they are pulled open when the lung inflates.
Answer D: hypoxic vasoconstriction is an arterial function

Front 17

A patient with pulmonary vascular disease has mean pulmonary arterial and venous pressures of 55 and 5 mmHg, respectively, while the cardiac output is 3 liters per minute. What is his pulmonary vascular resistance in mmHg.liter-1.min.
A. 0.5
B. 1.7
C. 2.5
D. 5
E. 17

Back 17

)55-5)mmHg/3 L/min = 16.7

Front 18

The fall in pulmonary vascular resistance on exercise is caused by:
A.Decrease in pulmonary arterial pressure.
B.Decrease in pulmonary venous pressure.
C.Increase in alveolar pressure.
D.Distension of pulmonary capillaries.
E.Alveolar hypoxia.

Back 18

D. Alveolar hypoxia leads to hypoxic vasoconstriction which leads to increased pulmonary vascular resistance. Answers A,B,C and E result in an increase in pulmonary vascular resistance

Front 19

In a measurement of cardiac output using the Fick Principle, the O2 concentrations of mixed venous and arterial blood are 16 and 20 ml . 100 ml-1, respectively, and the O2 consumption is 300 ml . min-1. The cardiac output in liters . min-1 is:
A. 2.5
B. 5
C. 7.5
D. 10
E. 75

Back 19

C
Fick : CO = VO2/Cao2 - Cvo2
300/ (20-16) x 100
300x100/4 = 7.5 L/min

Front 20

In zone 2 of the lung:
A.Alveolar pressure exceeds arterial pressure.
B.Venous pressure exceeds alveolar pressure.
C.Venous pressure exceeds arterial pressure.
D.Blood flow is determined by arterial pressure minus alveolar pressure.
E.Blood flow is unaffected by arterial pressure minus.

Back 20

D. is the definition of zone2. Answers A is the definition of zone 1. Answer B belongs in zone 3. Answer C does not exist. Answer E is not true in the lung (lung blood flow is not autoregulated).

Front 21

Pulmonary vascular resistance is reduced by:
A.Removal of one lung.
B.Breathing a 10% oxygen mixture.
C.Exhaling from functional residual capacity to residual volume.
D.Acutely increasing pulmonary venous pressure.
E.Mechanically ventilating the lung with positive pressure.

Back 21

D An increase in pulmonary venous pressure reduces pulmonary vascular resistance due to a combination of recruitment and distension of the pulmonary vessels. Answer A: An increase due to a decrease in total number of parallel pathways available. Answer B: Hypoxic vasoconstriction with an increase in vascular resistance. Answer C: Compression of extra-alveolar vessels with an increase in vascular resistance. Answer E: Positive alveolar pressure will compress alveolar vessels, leading to an increase in vascular resistance.

Front 22

Hypoxic pulmonary vasoconstriction:
A.Depends more on the PO2 of mixed venous blood than alveolar gas.
B.Is released in the transition from placental to air respiration.
C.Involves CO2 uptake in vascular smooth muscle.
D.Partly diverts blood flow from well ventilated regions of diseased lungs.
E.Is increased by inhaling low concentrations of nitric oxide.

Back 22

B: In fetal life the alveolar spaces are filled with fluid and are relatively hypoxic.The first breath drops the hypoxia. Answer A. Only hypoxia in the alveolar space initiates hypoxic vasoconstriction. Answer C If anything would result in vasodilation. . Answers D diverts blood flow from the poorly ventilated regions . Answer E: Nitric oxide is a vasodilator.

Front 23

If the pressure in the capillaries and interstitial space at the top of the lung are 3 and 0 mmHg, respectively, and the colloid osmotic pressures of the blood and interstitial fluid are 25 and 5 mmHg, respectively, what is the net pressure in mmHg moving fluid into the capillaries?
A. 17
B. 20
C. 23
D. 27
E. 33

Back 23

A
(Pc-Pt) - (osc - ost)
Net filtration = (3-0) - (25-5) = -17mmHg (movement into the capillaries)

Front 24

The metabolic functions of the lung include all of the following EXCEPT:
A.Converting angiotensin-II to angiotensin-I
B.Producing bradykinin.
C.Secreting serotonin.
D.Removing leukotrienes.
E.Generating erythropoietin.

Back 24

Answer A, B and C the opposite is true. Answer E. Erythropoietin is produced by the kidneys in response to hypoxia

Front 25

It is the PO2 of the _____ gas, not the pulmonary _____ blood, that chiefly determines the hypoxic vasoconstrictor response

Back 25

alveolar
arterial

Front 26

Inhibitors of __ synthase augment hypoxic pulmonary vasoconstriction.
Pulmonary vascular endothelial cells also release what two vasoconstrictors?
Also high/low blood pH

Back 26

NO
endothelin-1
thromboxane A2
low

Front 27

Fluid exchange across the capillary endothelium is believed to obey _____ law which is what?

Back 27

Starling's
Difference of capillary and interstitial hydrostatic pressure minus difference of capillary and interestitial osmotic pressure.

Front 28

The net pressure of the Starling equation in the lungs is ______ causing a small ____ flow of perhaps 20ml/hr under normal conditions

Back 28

outward

lymph

Front 29

Where does fluid go first when leaving the capillaries?
When it gets more severe? What is impaired?

Back 29

First - intersittum of the alveolar wall trackes through the interestitial space to the pervascular and peribronchial space in the lung... to hilar lymph nodes. Interstitial edema with engorgement.
Cross alveolar epithelium into the alveolar spaces - alveoli fill and gas exchange can no longer happen

Front 30

What substance is actually ACTIVATED by the lungs... unlike most which are inactivated/removed

Back 30

Angiotensin I -> Angiotensin II which is 50x more active than its precursor