Resp 2

Question 1

“It takes a red blood 
cell about ---
seconds to travel 
through the 
pulmonary circulation 
at resting cardiac 
output; about --- of 
a second of this time 
is spent in pulmonary 
capillaries.”

Answer 1

4 to 5

0.75

Question 2

pulmonary circulation sequence

Answer 2

Vena Cava
Right Atrium
Tricuspid Valve
Right Ventricle
Pulmonary Valve
Pulmonary Artery
Pulmonary 
Capillaries
Pulmonary Vein       
Left Atrium
Bicuspid Valve
Left Ventricle
Aortic Valve
Aorta

Question 3

Pulmonary circulation has
(4) than the
systemic circulation.

Answer 3

lower pressures,
lower resistance,
higher compliance,
& lower volume (~450 ml of 5oo ml)

Question 4

Pulmonary Arteries & Arterioles (2)

Answer 4

– Diameters are larger than systemic arteries and
arterioles
– Walls are thin and distensible–large compliance

Question 5

Pulmonary Capillaries (2)

Answer 5

– More distensible than systemic capillaries

– There is a population that is closed at rest

Question 6

About 280 billion pulmonary capillaries supply approximately
300 million alveoli, resulting in a

Answer 6

potential surface area for

gas exchange estimated to be 50 to 100 m2.

Question 7

Pulmonary Veins (1)

Answer 7

– Much shorter than systemic veins

Question 8

Bronchial Circulation (Part of Systemic Circuit)
Supplies

Answer 8

oxygen and nutrients to the tracheobronchial tree down to the
terminal bronchioles and also pulmonary blood vessels, visceral pleura,
nerves and hilar lymph nodes.

Question 9

Bronchial flow is about -% of
cardiac output of the left
ventricle.

Answer 9

2

Question 10

Bronchial flow is about 2% of
cardiac output of the left
ventricle.

This means that blood in the
LA has slightly

Answer 10

lower O2 
concentration than blood in 
the pulmonary capillaries 
(PaO2 = 95 mmHg (not 100)) 
since some deoxygenated 
blood from the bronchial veins 
mixes with oxygenated blood 
in the pulmonary veins.

Question 11

Structures in the Respiratory Zone receive

oxygen directly by — and receive —

Answer 11

diffusion from the
alveolar air

nutrients from the
mixed venous blood in pulmonary
circulation.

Question 12

The Pulmonary Circulation has Low

2

Answer 12

Pressure & Resistance

Question 13

Pulmonary capillary pressure: ~–mmHg

Answer 13

7

Question 14

Pulmonary venous/Left Atrial pressure: ~–mmHg

Answer 14

2

Question 15

Pulmonary blood volume accounts for ~—% of blood volume

(450ml) but is is highly —.

Answer 15

9

variable

Question 16

Pulmonary blood volume accounts for ~9% of blood volume

450ml) but is is highly variable. (3

Answer 16

– Volume increases during inspiration
– Lying down increases the blood volume
– Disease states (ex. heart failure) can increase volume

Question 17

Pulmonary vessels are far more

Answer 17

distensible (compliant)
and able to alter their size and adjust to changing
pulmonary volumes.

Question 18

Pulmonary vessels are far more distensible (compliant)
and able to alter their size and adjust to changing
pulmonary volumes. (2)

Answer 18

– Even though Cardiac Output increases 4-7 times with heavy
exercise, there is only a small increase in pulmonary artery
pressure.
– At rest, multiple pulmonary capillary networks are closed but are
capable of opening if necessary.

Question 19

The Pulmonary Circulation is not as Prone to

— as the Systemic Circulation.

Answer 19

Hypertension

Question 20

During exercise, CO (flow) may 
increase 7-fold...but MAP in the 
pulmonary circulation will only 
increase 1-2 mmHg. 
How is that possible?

Question 21

An increase in Flow (CO) to lungs
will decrease pulmonary
Resistance through: (2)

Answer 21

1. Recruitment of pulmonary
   capillaries
2. Distension of pulmonary
   capillaries

Question 22

An increase in blood flow 
leads to a decrease in 
pulmonary vascular 
resistance. What is the 
mechanism that 
produces this response?

Question 23

When PAO2 (Alveolar concentration of O2) drops 70% below 
normal,

Answer 23

adjacent blood vessels constrict. The resistance can

increase more than 5X.

Question 24

If instead PAO2 is high, adjacent vessels will dilate.

Answer 24

The functional result is that blood is delivered to alveoli where
it will be most effective at gas exchange.
This matches perfusion (blood flow) with ventilation (air flow).

Question 25

What then would happen throughout the pulmonary

circulation at a high altitude where PAO2 is reduced?

Question 26

Does the same response happen in the systemic circulation

when PaO2 levels drop?

Question 27

Vasoactive Substances for the Pulmonary Arterioles:

Vasodilators (7)

Answer 27

• High O2 in alveoli
• Dopamine
• Bradykinin
• Prostacyclin
• Nitric Oxide
• Histamine (H2)
• Acetylcholine

Question 28

Vasoactive Substances for the Pulmonary Arterioles:

Vasoconstrictors (7)

Answer 28

• Low O2 in alveoli
• High CO2 in alveoli
• Norepinephrine
• Angiotensin II
• Endothelin
• Vasopressin
• Thromboxane A2

Question 29

— response than what is produced in systemic

arterioles with the same changes in gas concentration.

Answer 29

Opposite

Question 30

Lung Volumes have a — Effect on

Pulmonary Vascular Resistance (PVR)

Answer 30

Passive

Question 31

Alveolar Vessels:

Answer 31

Pulmonary capillaries, smallest arterioles &

venules

Question 32

Extra-alveolar Vessels:

Answer 32

All other vessels

Question 33

PVR is the the total of

Answer 33

Alveolar Vessels + Extra-alveolar Vessel Resistance

Question 34

When the alveoli expand

during INSPIRATION….. (2)

Answer 34

(1) Alveolar vessels are 
compressed/elongated 
and their resistance 
increases
(2) Extra-alveolar vessels 
have decreased 
resistance

Question 35

Resistance in the pulmonary circulation is

lowest when lung volume is equal to —

Answer 35

FRC

Question 36

At low lung volumes, 
extraalveolar vessel 
resistance ---, 
which --- total 
PVR.

Answer 36

increases

increases

Question 37

At high lung 
volumes, 
alveolar vessel 
resistance 
--- which 
--- total 
PVR.

Answer 37

increases

increases

Question 38

FRC (Functional

Residual Capacity):

Answer 38

The volume of air in
the lungs after a
normal (TV) expiration.