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Flashcards in pulmonary Deck (29)
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1
Q

air-blood barrier

A

alveolar epithelium
capillary epithelium
basement membrane

very thin for easy diffusion

2
Q

ventilation definition/equation

A

Transport of gas from the atmosphere to the alveolar surface

minute ventilation (ml/min) = respiratory rate (breaths/min) x tidal volume (ml/breath)

3
Q

anatomic dead space

A

volume of conducting airways

~30% of tidal volume

4
Q

physiologic dead space

A

volume of alveoli that are ventilated but are not perfused with blood

low in healthy lungs. May be high in lung diseases

5
Q

collapsing tendency of lungs comes from

A

1/3 from elastic fibers in lung CT

2/3 from alveolar surface tension

6
Q

pressure is function of:

A

1) surface tension of the fluid
2) radius of the sphere

Small alveoli need more pressure to keep it open

7
Q

surfactant

A

Lowers surface tension by disrupting water-water interactions.

Secreted by type II alveolar cells

Detergent: dipalmitoyl phosphatidylcholine

8
Q

common problem with premature infant lungs

A

Lack surfactant –> cyanotic

Tx: inhaler with surfactant

9
Q

compliance of lung

A

Refers to change in volume as transmural pressure is changed

10
Q

[high or low] compliance at low lung volumes?

A

Low compliance at low lung volumes bc of high alveolar surface tension

11
Q

lung compliance in inflation vs deflation

A

Different slopes.

A greater pressure is needed to open a previously closed airway than to keep an open airway from closing.

12
Q

2 mechanisms to inflate the lungs

A

1) positive pressure: blowing up from pressure applied to trachea
2) applying negative pressure to the outside surface to suck it against the inner chest wall [* normal mechanism*]

13
Q

transpulmonary pressure

A

P(tp) = P(alv) - P(ip)

Keeps the lungs expanded in thoracic cavity.

14
Q

accessory muscles of inspiration

A

sternocleidomastoid
scalenes
pectoralis minor
serratus anterior

15
Q

accessory muscles of exhalation

A
internal intercostals
transversus thoracis
external oblique
rectus abdominus
internal oblique
16
Q

How does the thoracic cage change during inhalation?

A
Ribcage moves up/out (increases diameter of thoracic cage).
Diaphragm moves down (increases height of thoracic cage).
Lung expands (due to the expansion of the thoracic cage) --> decreased pressure in lungs --> air flows in
17
Q

How does the thoracic cage change during exhalation?

A
Ribcage moves down/in (decreases diameter of thoracic cage).
Diaphragm moves up (decreases height of thoracic cage).
Lung shrinks (due to the decreased volume of thoracic cage) --> increased pressure in lungs --> air flows out
18
Q

effect of airway resistance on ventilation

A

Smaller radius = larger resistance = decreased ventilation

A change in radius changes the resistance by a factor of 4

19
Q

Functional Residual Capacity (FRC)

A

amount of air left in lungs after normal expiration

20
Q

how to determine FRC

A

Helium dilution method

21
Q

residual volume (RV)

A

amount of air left in lungs after maximum expiration

22
Q

total lung capacity (TLC)

A

Total air possible in lung.

Max inspired, including residual volume.

23
Q

vital capacity (VC)

A

maximum inspired + expired

24
Q

tidal volume (VT)

A

normal, resting breath

25
Q

pulmonary arteries have ______ diameter and ________ smooth muscle than systemic arteries

A

Pulmonary arteries have larger diameter and less smooth muscle than systemic arteries

26
Q

An increase in pulmonary pressure results in [increase/decrease?] in resistance and [increase/decrease?] in blood flow

A

An increase in pulmonary pressure results in a decrease in resistance and and increase in blood flow.

Because: (1) previously collapsed vessels open up. (2) individual capillary segments increase their radii

27
Q

How does alveolar size affect alveolar blood vessels?

A

Expanded alveolar sacs compress alveolar vessels, increasing the resistance

Extra-alveolar vessels are pulled open by expansion of attached parenchymal tissue to decrease resistance.

28
Q

hypoxic vasoconstriction

A

pulmonary vessels constrict in response to local hypoxia to divert flow away from poorly ventilated alveoli

29
Q

T/F: pulmonary flow is pulsatile

A

True.

Pulmonary arteries do not damped the pulse generate by the R heart