Pulmonary Circulation Flashcards

1
Q

What is the only vascular bed to receive the entire cardiac output?

A

pulmonary circulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Is the series circulation in parallel or series with the pulmonary circulation?

A

series

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why is ischemic damage rare in the lung?

A

multiple supplies of O2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Why is the pulmonary blood pressure lower than the systemic blood pressure?

A

vascular resistance is less than TPR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Is the afterload lower in the left ventricle or right ventricle?

A

right ventricle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the normal anatomic shunt and what percentage of CO does it carry?

A

Left to left shunt

1-2% of cardiac output

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where does the lymphatic system drain into ?

A

caudal mediastinal lymph node and thoracic duct

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How are the valves of the lymphatic system regulated?

A
  • By mechanical pumping during breathing

- by sympathetic activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Are there arterioles in the pulmonary circulation?

A

No

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Why does pulsatile pressure still exist in the pulmonary circulation?

A

Since resistance is so low

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the mean Ppa?
What Ppa indicates pulmonary hypertension?
What Ppa indicates pulmonary edema?

A

Mean = 11 mmHg
If Mean Ppa>20 - pulm hypertension
If mean Ppa>25 - pulmonary edema

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Diastolic P in pulmonary artery is nearly equal to what?

A

Left ventricular P

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What occurs during exercise in the pulmonary circulation?

A
  • radius of the vessels increases and resistance therefore decreases passively
  • Compliance of the vessels is high so P doesn’t increase much

(There is not autoregulation, this all occurs passively)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Vessels in the alveoli are exposed to what type of P? Extraalveolar vessels are exposed to what type of P?

A

Alveolar vessels - alveolar P

extralveolar vessels - intrapleural P

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What occurs to the alveolar blood vessels during inflation?

A
  • they are stretched and become narrower
  • radius decreases and so resistance increases
  • This reduces their pressure
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What happens to extraalveolar blood vessels in response to inflation?

A
  • There is a more negative intrapleural P as the lung inflates
  • their transmural P increases
17
Q

What is the relationship btwn alveolar and extra-alveolar vessels? How does this affect total resistance?

A

They are in series, so resistance is additive

18
Q

When is PVR at a minimum?

A

FRC

PVR increases at any other value

19
Q

During normal breathing what is the normal alveolar pressure, and what effect does this have on the alveolar vessels?

A

alveolar P fluctuates around zero and so all the vessels remain open

20
Q

During mechanical ventilation what happens to alveolar pressure? What does this mean for you as a physician?

A

It becomes slightly positive

  • capillaries can collapse and inc their R
  • must ventilate at lowest possible P near the FRC
21
Q

Name some vasodilators that affect pulmonary vascular resistance? (4)

A
  • prostacycline
  • histamine (bronchoconstrictor)
  • calcium channel blockers
  • Nitric oxide
22
Q

What happens in the lung when a certain area is not able to be ventilated and becomes hypoxic?

A

blood is shunted to a better ventilated region of the lung by hypoxic vasoconstriction

23
Q

Name some vasoconstrictors that affect pulmonary vascular resistance? (3)

A
  • inc PCO2, low pH
  • norepinephrine - weak effect
  • angiotensin II
24
Q

In what part of the lung is blood flow greatest? Why?

A

at the base of the lung

-due to gravity and passive distension

25
What happens to the pressure inside the capillaries as you distend down the lung?
it gradually increases | -due to the pressure from intrapleural fluid under the influence of gravity
26
When a person is standing upright what is their apex pressure? What is their base pressure?
``` Apex= Ppa -10 Base= Ppa + 10 ```
27
What zone does this describe and what occurs: | PA>Pa>Pv
Zone 1 - not normally present - capillaries will collapse and flow stops-no perfusion - can occur during blood loss or cardiac output decrease
28
What zone does this describe and what occurs here: | Pa>Pv> PA
zone 3 - flow inc due to gravity and passive distension - capillaries are wide open
29
How is flow determined in zone 3?
by the difference btwn PA-Pv
30
What zone does this describe and what occurs here: | Pa>PA>Pv
Zone 2 | -partial collapse of capillaries on low pressure side but with maintenance of flow
31
How would you determine the flow in zone 2?
Difference btwn Pa and PA | -Pv has no effect - it is downstream
32
Describe what changes in the four starling filtration pressures cause pulmonary edema?
1. inc capillary permeability 2. inc in capillary hydrostatic pressure - mitral valve stenosis 3. dec interstitial hydrostatic P 4. dec colloid osmotic P
33
Does high or low protein in the blood cause pulmonary edema?
low protein ---hypo
34
In the equation: QS/QT = (C”c”O2-CaO2)/ (C”c”O2-CvO2), what occurs if QS =0?
normal condition of no shunt | CaO2 = C"c"O2
35
In the equation: QS/QT = (C”c”O2-CaO2)/ (C”c”O2-CvO2), what occurs if QS =QT?
all blood is shunted - no oxygenation | CaO2 = CvO2
36
In the equation: QS/QT = (C”c”O2-CaO2)/ (C”c”O2-CvO2), what occurs if QS =QT/2?
50% Shunt- aterial oxygen content is average of shunt and functional capillary content -CaO2 = (C"c"O2+ CvO2)/2
37
Does shunting give more hypoxemia or hypercapnea?
more hypoxemia due to the O2 dissociation curve | -CO2 curve is linear
38
Can breathing O2 rich gas help people with abnormal shunts?
NO - they physically cannot be oxygenated so this is just a waste