resp-4 compliance & surfactant

Question 1

what is lung compliance

Answer 1

the measure of the elastic properties of the lungs and a measure of how easily the lungs can expand

Question 2

compliance formula

Answer 2

change in lung volume / change in transpulmonary pressure

Question 3

what is static compliance

Answer 3

lung compliance measued during periods of no gas flow

ins/ exp pause

Question 4

how to determine static compliance of the lung

Answer 4

by P/V slope when measured at FRC (end of exp. effort)

Question 5

when is dynamic compliance measured

Answer 5

during periods of airflow (transpulmonary pressure changes

Question 6

what else does dynamic compliance measure

Answer 6

lung stiffness and airway resistance

Question 7

when does dynamic compliance fall

Answer 7

lung is stiff or airways are resistant

Question 8

dynamic and static compliance relationship

Answer 8

dynamic is always less than or equal to static

Question 9

what is pneumothorax

Answer 9

loss of subatmosphere pressure in PIP so the lungs collapse

Question 10

what is hysteresis

Answer 10

the difference between the inflation and deflation compliance paths

Question 11

why does hysteresis exist

Answer 11

greater pressure difference is required to open a previously closed airway than to keepan open airway from closing

Question 12

what determines lung compliance

Answer 12

elastic components of lungs and airway tissue (elastin, collagen)
surface tension at the air-water interface within the alveoli

Question 13

where is elastic compliance localized

Answer 13

alveolar walls, around vessels and bronchi

Question 14

what is collagen

Answer 14

like a strong twine, high tensile strength, inextensible, low elasticity

Question 15

what is elastin

Answer 15

like a weak spring, low tensile strength, extensible, high elasticity

Question 16

what happens when elastin and collagen decreases

Answer 16

lung compliance increases (floppy lungs)

Question 17

what is emphysema

cause and effects

Answer 17

elastin &alveolar wall destruction
increased compliance
increased time to fill and empty lungs

Question 18

what is pulmonary fibrosis

cause and effects

Answer 18

collagen deposition in alveolar walls
reduced compliance
higher PTP changes are necessary to generate changes in lung volume

Question 19

what does surface tension do to lung compliance

Answer 19

surface tension decreases lung compliance

Question 20

The surface tension at the air‐water interface
accounts for about (fill in the blank) of the elastic recoil
of the lungs

Answer 20

2/3

Question 21

what is surface tension

Answer 21

a measure of the attracting forces acting to pull a liquids surface molecules together at an air-liquid interface

Question 22

how is hysteresis and inflation pressures affected when lungs are inflated with liquid

Answer 22

no hysteresis and much lower inflation pressure

Question 23

how does alveoli surface tension lead to alveoli collapse

Answer 23

because the surface tension creates an inward recoil

Question 24

what is laplaces equation

Answer 24

P=2T/r
t is constant
r is radius

Question 25

small bubble radius does whast to pressure

Answer 25

more pressure required to keep the bubble inflated

Question 26

describe the equilibrium between alvolar surface tension and pressure

Answer 26

At equilibrium, the tendency of increased pressure to expand the alveolus balances the tendency of surface tension to collapse it

Question 27

what does surfactant do to surface tension and compliance

Answer 27

lower it so the alveoli are stable against collapse | raises lung compliance (Easier to expand the lungs)

Question 28

is surfactant hydrophobic or hydrophilic

Answer 28

it is both

Question 29

what are the most important parts of the pulmonary surfactant

Answer 29

``` the phospholipids (DPPC) apoproteins and calcium ions ```

Question 30

does surfactant thickness increase or decrease with an increase in surface area

Answer 30

Thickness of surfactant decreases with | increase of surface area

Question 31

how is pressure equalized between alveoli of different alveoli

Answer 31

thicker layer of surfactant in smaller alveolar (smaller collapse easier) (T/r ratio remains constant)

Question 32

what does surfactant improve

Answer 32

compliance (by reducing surface tension of alveolar fluid) | stabilizes the alveolar

Question 33

what may be the cause of infant respiratory distress syndrome

Answer 33

lack of surfactants in premature infants

Question 34

what is dynamic stabilization (surfactant)

Answer 34

concentration of surfactant aries with inflation and delation, helps make elastic recoil

Question 35

where is ventilation highest? how did they find out?

Answer 35

ventilation is higher at the bottom (most air per volume) | they measured it with xenon tests

Question 36

how does PIP change throughout the lungs

Answer 36

The weight of the lungs increases pressure in regions near bottom (makes PIP less negative) therefore less pressure pulling it open than regions at top of lung.

Question 37

how does PIP explain how the bottom of the lungs receive more air

Answer 37

the alveoli at the bottom start more deflated, so they can expand more (PIP less negative, PTP is smaller)