Pulmonary circulation Flashcards Preview

Physiology > Pulmonary circulation > Flashcards

Flashcards in Pulmonary circulation Deck (47):
1

How compliant are the vessels of the pulmonary circulation?

Highly

2

What happens to blood flow in alveolar capillaries when PO2 drops? Why?

local vasoconstriction

To redistribute the blood to better aerated alveoli

3

What are the five scenarios mentioned in class that trigger abnormal hypoxic pulmonary vasoconstriction (HPV) response?

Airway obstruction
Failure of ventilation
Acute lung damage
High altitude
COPD

4

What triggers hypoxic pulmonary vasoconstriction?

Alveolar hypoxia

5

How do PA, Pa, and Pv relate to each other in the upper part of the lungs?

(recall that PA = alveolar pressure, Pa = arterial pressure, and Pv = veins).

PA > Pa > Pv

6

How do PA, Pa, and Pv relate to each other in the middle part of the lungs?

(recall that PA = alveolar pressure, Pa = arterial pressure, and Pv = veins).

Pa > PA > Pv

7

How do PA, Pa, and Pv relate to each other in the lower part of the lungs?

(recall that PA = alveolar pressure, Pa = arterial pressure, and Pv = veins).

Pa > Pv > PA

8

Conditions that affect blood vasculature affect what part of the lungs more, the base or the apex?

Base

9

Blood flow is greater in the base or the apex of the lungs?

Base

10

What happens to hydrostatic pressure in CHF? What does this cause?

increases

Causes increase in edema in the interstitium

11

Why does ventilation have to match perfusion?

Need to have blood flow with oxygen

12

What is the average value of V/Q?

0.8

13

What happens to the ventilation and perfusion when going from the base to the apex of the lung?

Both decrease, but perfusion drops more

14

What happens to the V/Q ratio when moving from the base of the lungs, to the apex? Why?

Increases

Q drops faster than V

15

Why does TB reactivate in the upper lung zones?

Because there is more ventilation relative to perfusion (it is an aerobe)

16

What is the V/Q ratio in the dead space?

infinite ventilation, no blood flow

17

What is the V/Q ratio in a shunt?

0 (no ventilation, but tons of blood flow)

18

What happens to the V/Q as you progress down the airway tree? Why?

more perfusion, less ventilation, thus gets smaller

19

What is the physiological shunt?

The bronchial circulation

20

If there is a communication between the left and right side of the heart, what always occurs? How?

Hypoxemia from RVH

21

Why doesn't hypoxemia occur with right to left shunts right away?

Blood flow from left to right due to pressure initially, but RVH eventually wins, and causes non oxygenated blood to shunt from the right to the left

22

What happens to the V/Q ratio in PEs?

Infinite d/t normal ventilation, but 0 blood flow

23

Which side of the heart is affected more in a PE?

Right d/t blockage

24

What are the two major outcomes of a PE?

1. Right to left shunting in areas of atelectasis
2. V/Q mismatch

25

What is the gold standard for PE detection?

V/Q (ventilation) scan

26

What is a ventilation scan?

Looking at lung perfusion with radioactive substance

27

What is the V/Q ratio in normal patients?

1.0, thus usually the curves will superimpose over one another

28

What is the function of the bronchial arteries? What effects does this have on systemic oxygen content?

Supply oxygen to the lung tissues.

This blood is then shunted to the left side of the heart, decreasing the overall oxygen content slightly

29

What is the function of the pulmonary circulation (capacitors or resistors)?

Capacitors

30

What happens to the bronchial arteries in CF?

Increase in size

31

What is the effect of persistent hypoxic vasoconstriction?

Vascular structural remodeling, leading to pulmonary arterial HTN (PAH)

32

In normal upright subjects at rest, blood flow
(BLANKS) from the apex of the lung to the base
of the lung.

In normal upright subjects at rest, blood flow INCREASES from the apex of the lung to the base
of the lung.

33

Are the effects of gravity felt equally in pulmonary veins and arteries?

Yes

34

Where is pulmonary edema seen in the lungs? Why?

Lower lobes d/t increase flow of blood there relative to the other parts

35

What is the effect of positive pressure ventilation on the upper part of the lungs (zone 1) relative to the Pa and PA?

PA >>>Pa, meaning that arteries could collapse

36

How permeable are pulmonary capillaries to proteins? What is the consequence of this?

Very

Higher propensity to develop interstitial edema

37

The capillary pressure in the pulmonary circulation favors what (filtration or reabsorption? What is the consequence of this?

Filtration

Thus lymphatics play a large role in pumping out this excess fluid

38

Why is there a negative hydrostatic pressure in the pulmonary interstitium? When can this become positive?

Lung expansion lowers it

Can become positive if there is inflammation of the capillaries

39

Which way does fluid flow between the alveoli and the interstitium? Why?

From alveoli to the interstitium d/t lower pressure in the interstitium

40

What is the effect of an increase in intravascular hydrostatic pressure in the pulmonary circulation?

Pulmonary edema

41

What is the effect of an decrease in capillary osmotic pressure in the pulmonary circulation?

Pulmonary edema

42

What is the effect of an increase in capillary permeability in the pulmonary circulation?

Pulmonary edema

43

In regions of dead space, alveolar gas has what composition relative to the inspire humidified air?

Same (all oxygen, no CO2)

44

When do right to left shunts occur?

If there is a defect in the
wall between the right and left ventricles

45

A defining characteristic of the hypoxemia caused by a right-to-left shunt is that it cannot be
corrected by having the person breathe a high O2 gas (e.g., 100% O2).

Why?

because the shunted
blood never goes to the lungs to be oxygenated.

46

Do left to right shunts cause hypoxemia? Why or why not?

No, because oxygenated blood flows into right ventricle to be oxygenated again.

47

What are the causes of a left-to-right shunt? (2)

Patent ductus arteriosus or traumatic injury