CHAPTER 38: Pulmonary Circulation and Pulmonary Pressures

Question 1

Pulmonary Circulatory System

1. Pulmonary Artery leaves the right ventricle and branches into the right and left main branches that carry blood to the two respective lungs. This is considered _______-_______, _______-_____________ circulation for pulmonary diffusion to occur (CO2 removed and O2 is added). The oxygenated blood returns to the left atrium via the pulmonary veins.
2. Bronchial Arteries are branches of the thoracic aorta and supplies blood from the systemic system to the trachea, bronchi, bronchioles and all supporting tissues in the lungs. This is considered a ____–_____, ___ –______circulation.

Answer 1

low-pressure, high-flow

high-pressure, low-flow

Question 2

Blood volume in the lungs is about 450 ml (9% of total blood volume).
• Of the 450 ml,_______ml of blood is in the pulmonary capillaries.
• The other 380 ml of blood are divided equally between the branches of the pulmonary arteries and the pulmonary veins.

Answer 2

70

Question 3

Lungs as a blood reservoir—during a _________, there is an automatic shift of some blood from the lungs into the systemic circulation. This can be more than half of the 450 ml (250 ml shifted to systemic vessels).

• Conversely, left side heart or valve problems (mitral valve stenosis or mitral valve regurgitation) can cause a damming of blood in the pulmonary vessels and increasing blood volume as much 100%.

Answer 3

hemorrhage

Question 4

Blood Flow Through the Lungs–1

1–Blood flow through the lungs each minute is essentially equal to ____

2–In order for blood to be properly oxygenated, blood must be distributed to the places where the ______contain the most O2.

Answer 4

CO.

alveoli

Question 5

Blood Flow Through the Lungs–2

If the concentration of O2 _______ in any alveoli, the adjacent blood vessels vasoconstrict (this is the opposite of systemic blood vessels which vasodilate in response to low O2 concentrations).

This reaction is thought to be regulated by a vasoconstrictor substance (unknown at this time) released by the alveolar epithelial cells when they become _________.

The effect of vasoconstriction in the hypoxic areas is that blood flow to more oxygenated alveoli increases.

Answer 5

decreases

hypoxic

Question 6

Blood Flow Through the Three “Zones” of
the Lungs
• Blood flow through the three zones of the lungs is regulated by _________ _____________.

Answer 6

hydrostatic pressure

Question 7

Blood Flow Through the Three “Zones” of
the Lungs–1

Zone 1—NO BLOOD FLOW DURING ALL PORTIONS OF THE CYCLE because pulmonary capillary pressure never increases above ________ air pressure in any part of the cycle. This
only happens in abnormal situations such as severe blood loss.

Answer 7

alveolar

Question 8

Blood Flow Through the Three “Zones” of
the Lungs–2

Zone 2– INTERMITTENT BLOOD FLOW during the peaks of pulmonary arterial pressure because systolic is _______ than the alveolar air pressure but diastolic pressure is lower
than alveolar air pressure. This zone 2 pattern of blood flow occurs in the ________of the lungs.

Answer 8

greater

apices (top portion)

Question 9

Blood Flow Through the Three “Zones” of
the Lungs–3

Zone 3—CONTINUOUS BLOOD FLOW because the pulmonary arterial pressure is always_______ than alveolar air pressure. This occurs in the middle and lower portions of the lungs.

Answer 9

greater

Question 10

During heavy exercise, blood flow through the lungs increases _____ TO ____ FOLD.. This is accommodated by the lungs in three ways:

1. Increasing the number of open capillaries as much as _______ FOLD
2. Distending the capillaries and increasing rate of blood flow as much as _____FOLD
3. Increasing pulmonary arterial pressure essentially making it a Zone __ blood flow pattern throughout the lungs.

Answer 10

4 TO 7

threefold.
twofold.

3

Question 11

Pressures in the Pulmonary System—1

The pressure pulse curves of the right ventricle and the pulmonary artery are compared to the pressures in the _______.

Right ventricular ________ pressure is about 25 mmHg in comparison to aortic systolic pressure of 120 mmHg

When the pulmonary valve closes, Rt. Ventricular __________ pressure drops to 1 mmHg compared to when the aortic valve closes and aortic diastolic pressure falls to 75- 80 mmHg.

Answer 11

aorta

systolic

diastolic

Question 12

Pressures in the Pulmonary System–2

During systole, the pressure in the pulmonary artery is ______ to Rt. Ventricular pressure (25 mmHg).

However, when the pulmonary valve closes , the __________ pressure in the pulmonary artery falls much slower and only drops to about 8 mmHg.

Answer 12

equal

diastolic

Question 13

Capillary Exchange of Fluid Between the Lungs and the Pulmonary Interstitial Fluid—1

The fluid exchange across the capillary membranes in the lungs is similar to the fluid exchange in _______ tissues although the mean filtration pressure is lower in the ________:

1. Pulmonary capillary pressure = 7 mmHg (in comparison to 17 mmHg in peripheral tissues)

Answer 13

peripheral

lungs

Question 14

Capillary Exchange of Fluid Between the Lungs and the Pulmonary Interstitial Fluid—-2

2. Interstitial fluid pressure in the lungs =___mmHg (in comparison to the -3 mmHg in the peripheral tissues)
3. Interstitial osmotic pressure in the lungs = 14 mmHg (in comparison to 8 mmHg in the peripheral tissues)
4. Plasma colloid osmotic pressure is the same = ___ mmHg
5. The alveolar capillary walls are much thinner and rupture easily so more fluid goes from the interstitial spaces into the _______

Answer 14

-8

28

alveoli.

Question 15

Capillary Exchange of Fluid Between the Lungs and the Pulmonary Interstitial Fluid–3

NAME 3 Forces tending to move fluid OUTWARD from the capillaries into pulmonary interstitial spaces:

Answer 15

1. Pulmonary Capillary Pressure 7 mmHg
2. Interstitial fluid colloid osmotic pressure 14 mmHg
3. Negative interstitial fluid pressure 8 mmHg
   TOTAL OUTWARD FORCE 29 mmHg

Question 16

Capillary Exchange of Fluid Between the Lungs and the Pulmonary Interstitial Fluid–4

NAME ONE FORCE tending to cause absorption of fluid INTO the capillaries:

KNOW THIS BELOW!!!
Total outward force 29 mmHg
Total inward force -28 mmHg
NET FILTRATION PRESSURE + 1 mmHg
(more fluid filters OUT of capillaries than is reabsorbed)!!

Answer 16

1. Plasma colloid osmotic pressure 28 mmHg

TOTAL INWARD FORCE 28 mmHg

Question 17

Capillary Exchange of Fluid Between the Lungs and the Pulmonary Interstitial Fluid–5

This slightly (+) mean filtration pressure causes a slight continual flow of fluid ____ of the pulmonary capillaries into the interstitial spaces:
Total outward force 29 mmHg
Total inward force -28 mmHg
NET FILTRATION PRESSURE + 1 mmHg

All this fluid, except for a small amount that evaporates, is pumped back into blood circulation through the _______ ___________ system.

Answer 17

OUT

pulmonary lymphatic

Question 18

Pulmonary Edema—1

Pulmonary edema occurs in the same way as edemas occur in other areas of the body. Any factor that increases fluid build-up in the pulmonary _______ ________ will cause pulmonary edema. These factors include an increase in filtration OUT of the pulmonary capillaries or the__________ vessels are impeded from moving fluid back to blood circulation.

Answer 18

interstitial spaces

lymphatic

Question 19

Pulmonary Edema–2
Two common causes of pulmonary edema include:

1. _______-side heart failure or ____ ______ disease—increases pulmonary capillary pressure so more fluid leaves the capillaries and floods the interstitial spaces.
2. Damage to the pulmonary capillary membranes—this can be caused by _________(infection) or by breathing noxious gases (ex. chlorine gas). These cause rapid leakage of _______ ________ and fluid OUT of the pulmonary capillaries and into the interstitial spaces.

Answer 19

Left

mitral valve

pneumonia

plasma proteins

Question 20

Pulmonary Edema—-3

“Pulmonary Edema Safety Factor”—experiments in animals have shown that pulmonary capillary pressure must ______ to a value at least _____ to plasma colloid osmotic pressure before significant pulmonary edema occurs.

Therefore, pulmonary capillary pressure must increase from normal 7 mmHg to plasma colloid osmotic pressure of 28 mmHg to cause pulmonary edema. (28-7 = 21 mmHg) This 21 mmHg is referred to as the “______ ______ _________ against edema.”

Answer 20

rise

equal

acute safety factor

Question 21

Pulmonary Edema—4

In chronic conditions when pulmonary capillary pressure remains HIGH over time (at least two weeks), the lungs become even more _______ to edema as the lymph vessels expand which increases their capacity to carry away fluid. It has been documented that chronic pulmonary capillary pressures as high as 40-45 mmHg have been measured without evidence of ______ ______.

Answer 21

resistant

pulmonary edema.

Question 22

Pulmonary Edema—-5

Rapidity of Death from _______-_______ Pulmonary Edema: When pulmonary capillary pressure suddenly INCREASES even slightly above the safety factor level, LETHAL pulmonary edema can occur within a few hours (or even within 20-30 minutes if capillary pressure increases 25 to 30 mmHg over safety factor level).
Therefore,______-side heart failure, in which capillary pressure rapidly increases to 50 mmHg, death from pulmonary edema occurs in less than __ minutes.

Answer 22

Acute-Onset

left

30