Mechanics of Breathing I

Question 1

muscles of inspiration

Answer 1

diaphragm

external intercostals

Question 2

accessory muscles of inspiration?

Answer 2

scalenus
sternomastoids
pectoralis

Question 3

expiration muscles?

Answer 3

passive during rest

forced:
internal intercostals
abdominal muscles

Question 4

external intercostals?

Answer 4

inspiration

Question 5

internal intercostals?

Answer 5

expiration

Question 6

chest wall?

Answer 6

wants to spring outward

Question 7

lung?

Answer 7

wants to collapse inward

Question 8

chest wall and lung create?

Answer 8

negative intrapleural pressure

Question 9

pneumothorax?

Answer 9

intrapleural and atmospheric pressure are equal

Question 10

pressure-volume curve of isolated lung

Answer 10

volume never zero

-can’t get all out of lung

Question 11

compliance

Answer 11

compliance = deltaV / deltaP

slope of pressure-volume curve

Question 12

compliance determined by?

Answer 12

elastic recoil

surface tension

Question 13

emphysema

Answer 13

increased slope, more compliant

Question 14

fibrosis

Answer 14

decreased slope, less compliant

Question 15

what determines elastic recoil?

Answer 15

elastic tissue

-elastin and collagen

Question 16

surface tension?

Answer 16

reduced by surfactants

Question 17

functions of surfactant?

Answer 17

lower surface tension
increase alveolar stability
keep alveoli dry

Question 18

surfactant graph?

Answer 18

mimics the shape of prssure-volume curve

Question 19

without surfactant production?

Answer 19

complete 38 weeks (before 32 weeks bad)

• surface tension is increased, therefore the compliance is reduced
• alveoli would collapse
• alveoli would not be dry

Question 20

high surface tension and low compliance

Answer 20

at low pressure and volume

• as volume and pressure increase
• increase in elastic recoil of lung

Question 21

ventilation at apex

Answer 21

intrapleural pressure more negative at apex

greater transmural pressure gradient

alveoli larger, less compliant

less ventilation at apex

Question 22

perfusion at apex

Answer 22

lower intravascular pressures

less recruitment, distention

higher resistance

less blood flow

Question 23

support of base of lung?

Answer 23

higher pressure required

Question 24

resting chest wall

Answer 24

at airway pressure = 0

Question 25

resting respiratory level

Answer 25

at functional residual capacity (FRC)

-lung and chest movements balanced

Question 26

at volumes above minimal volume for lung?

Answer 26

lung wants to retract

Question 27

volumes above FRC?

Answer 27

net force inward

Question 28

volumes below FRC?

Answer 28

net force outward

Question 29

volumes at FRC?

Answer 29

zero net force

Question 30

kyphoscoliosis?

Answer 30

moves the pressure-volume down

-bc of change in chest wall compliance decrease

Question 31

obese patients

Answer 31

decreased expiratory reserve volume alot

weight on chest restricting movement
-therefore global decrease in all lung volumes with significant decrease in ERV

shift in curve to right