Resp 2 Flashcards

1
Q
“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.”
A

4 to 5

0.75

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2
Q

pulmonary circulation sequence

A
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
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3
Q

Pulmonary circulation has
(4) than the
systemic circulation.

A

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

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4
Q

Pulmonary Arteries & Arterioles (2)

A

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

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5
Q

Pulmonary Capillaries (2)

A

– More distensible than systemic capillaries

– There is a population that is closed at rest

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6
Q

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

A

potential surface area for

gas exchange estimated to be 50 to 100 m2.

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7
Q

Pulmonary Veins (1)

A

– Much shorter than systemic veins

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8
Q
Bronchial Circulation (Part of Systemic Circuit)
Supplies
A

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

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9
Q

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

A

2

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10
Q

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

This means that blood in the
LA has slightly

A
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.
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11
Q

Structures in the Respiratory Zone receive

oxygen directly by — and receive —

A

diffusion from the
alveolar air

nutrients from the
mixed venous blood in pulmonary
circulation.

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12
Q

The Pulmonary Circulation has Low

2

A

Pressure & Resistance

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13
Q

Pulmonary capillary pressure: ~–mmHg

A

7

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14
Q

Pulmonary venous/Left Atrial pressure: ~–mmHg

A

2

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15
Q

Pulmonary blood volume accounts for ~—% of blood volume

(450ml) but is is highly —.

A

9

variable

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16
Q

Pulmonary blood volume accounts for ~9% of blood volume

450ml) but is is highly variable. (3

A

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

17
Q

Pulmonary vessels are far more

A

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

18
Q

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

A

– 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.

19
Q

The Pulmonary Circulation is not as Prone to

— as the Systemic Circulation.

A

Hypertension

20
Q
During exercise, CO (flow) may 
increase 7-fold...but MAP in the 
pulmonary circulation will only 
increase 1-2 mmHg. 
How is that possible?
21
Q

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

A
  1. Recruitment of pulmonary
    capillaries
  2. Distension of pulmonary
    capillaries
22
Q
An increase in blood flow 
leads to a decrease in 
pulmonary vascular 
resistance. What is the 
mechanism that 
produces this response?
23
Q
When PAO2 (Alveolar concentration of O2) drops 70% below 
normal,
A

adjacent blood vessels constrict. The resistance can

increase more than 5X.

24
Q

If instead PAO2 is high, adjacent vessels will dilate.

A

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).

25
What then would happen throughout the pulmonary | circulation at a high altitude where PAO2 is reduced?
26
Does the same response happen in the systemic circulation | when PaO2 levels drop?
27
Vasoactive Substances for the Pulmonary Arterioles: | Vasodilators (7)
* High O2 in alveoli * Dopamine * Bradykinin * Prostacyclin * Nitric Oxide * Histamine (H2) * Acetylcholine
28
Vasoactive Substances for the Pulmonary Arterioles: | Vasoconstrictors (7)
* Low O2 in alveoli * High CO2 in alveoli * Norepinephrine * Angiotensin II * Endothelin * Vasopressin * Thromboxane A2
29
--- response than what is produced in systemic | arterioles with the same changes in gas concentration.
Opposite
30
Lung Volumes have a --- Effect on | Pulmonary Vascular Resistance (PVR)
Passive
31
Alveolar Vessels:
Pulmonary capillaries, smallest arterioles & | venules
32
Extra-alveolar Vessels:
All other vessels
33
PVR is the the total of
Alveolar Vessels + Extra-alveolar Vessel Resistance
34
When the alveoli expand | during INSPIRATION..... (2)
``` (1) Alveolar vessels are compressed/elongated and their resistance increases (2) Extra-alveolar vessels have decreased resistance ```
35
Resistance in the pulmonary circulation is | lowest when lung volume is equal to ---
FRC
36
``` At low lung volumes, extraalveolar vessel resistance ---, which --- total PVR. ```
increases | increases
37
``` At high lung volumes, alveolar vessel resistance --- which --- total PVR. ```
increases | increases
38
FRC (Functional | Residual Capacity):
The volume of air in the lungs after a normal (TV) expiration.