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Spr2015_Week5 > Lung Microanatomy > Flashcards

Lung Microanatomy Flashcards

1
Q

Inspiration carried out by ___

A

contraction of the inspiratory muscles

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2
Q

what is the mechanism of inspriation

A

1) contraction of inspiratory muscles

force abdominal contents down and forward

upper ribs inward

lower ribs elev and rotate

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3
Q

what is most important inspiratory muscle

what innervates it

A

diaphragm

innerv by phrenic nerve

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4
Q

function of diaphragm

A

contracts during inspiration and diaphragm descend

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5
Q

muscles of respiration

A

1) diaphragm
2) external intercostals
3) sternocleidomastoids
4) scalenes

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6
Q

what happens to external intercostals with inspiration

A

pulls rib forward and outward

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7
Q

role of sternomastoids and scalenes in respiration

A

silent during normal breathing

elevate rib cage with ventilation and incr respiratory load

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8
Q

mechanism of expiration

A

abdominal muscles contract

push diaphragm up

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9
Q

when does active expiration become necessary

A

volumes >40 L/min

or significant expiratory resistance

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10
Q

most important expiratory muscles

when are they active

A

abdominal wall muscles

active in upright position
silent during supine position

push diaphragm down during active expiration

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11
Q

during active expiration, the abdominal muscles ___

A

push diaphragm down

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12
Q

function of internal intercostals

A

pull ribs inward and down

decr thoracic volume

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13
Q

during active expiration, the intenral intercostals ___

A

pull ribs in and down

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14
Q

force generated by muscle is a function of its ___

A

length

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15
Q

___ generated by muscle is a function of its length

A

force

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16
Q

maximal tension (force) for diaphragm achieved at ___ of resting length

A

130% of resting length

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17
Q

mechanical disadvantages of diaphragm

A

1) diaphragm is more contracted, reduced length

2) @ high lung volumes, greater radius of curvature (decr pressure generated by muscle)

18
Q

diseases assoc with diaphragm being more contracted

A

1) asthma
2) chronic bronchitis
3) emphysema

19
Q

define intrapleural pressure (P IP)

A

movement of thoracic cavity into expansion of lung based on pressure outsdie of lung

20
Q

what is source of P IP

A

intrinsic elastic properties of lung + chest wall

lung and chest wall deviate from equilibrium

21
Q

lung is more __ than its intrinsic equilibrium position

this causes

A

more inflated

–> force to make lung DEFLATE

22
Q

chest wall is more ___ than its intrinsic equilibrium position

this causes

A

more deflated

–> force to make chest expand

23
Q

two opposing forces from lung and chest wall make —> ___

A

negative P IP (vacuum)

to glue lung to chest cavity

24
Q

how does negative P IP affect during inspiration

A

expanding chest cavity pulls lung open to expand volume

25
Q

what happens when expansion of chest cavity fails?

what disease

A

chest wall spring out

lung collapse

–> pneumothorax

26
Q

define transpulmonary pressure

A

P TP = P L(lung) - P IP (intrapleural

27
Q

how do you measure P IP

A

needle into pleural cavity and connect to water manometer

difference in atmospheric pressure (cm H2O)

28
Q

how does P IP vary during breathing cycle

A
  • 5 cm H2O at end of expiration

- 30 cm H2O at end of inspiration

29
Q

why is P IP greater at end of inspiration

A

tendency of lung to recoil toward equilibrium position

30
Q

a

A

a

31
Q

a

A

a

32
Q

what happens to pressures during inspiration

A

P L (lung)

33
Q

what happens to pressure during expiration

A

P L (lung) > P (mouth)

34
Q

what happens after expiration and before inspiration

A

no air flow because lung pressure = 0

35
Q

function of P TP

A

driving force for changing lung volume during breathing

36
Q

based on P TP why does P L get more negative with inspiration

A

P L = P TP + P IP

both P TP and P IP become more negative
PIP more quickly negative than P TP

37
Q

why does P L achieve negative values during inspiration

A

increase in negativity of P IP due to lung inflating

38
Q

what happens to chest wall and lungs during expiration

A

chest wall contract

releases lung from more inflated state

lungs recoil back to intrinsic equilibrium –> push air out

39
Q

what happens to pressure when lungs recoil back to intrinsic equilibrium

A

transient positive pressure inside lung (elastic recoil pressure)

40
Q

define compliance equation

A

compliance = change in volume

Spr2015_Week5 (19 decks)

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