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CPR Test 2 > Respiratory cycle and mechanics > Flashcards

Respiratory cycle and mechanics Flashcards

1
Q

what is Boyle’s law?

A

P1V1=P2V2

pressure of gas is inversely proportional to its volume

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2
Q

what happens when there is an increase in lung volume?

A

pressure decreases- air enters

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3
Q

what happens when there is an decrease in lung volume?

A

pressure increases- air exits

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4
Q

what happens when inspiratory muscles (external intercostal muscles) contract?

A

it increases thoracic volume

causes an interplay between the chest wall wanting to expand and the lungs wanting to collapse

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5
Q

is intrapleural pressure (PPL) more or less than atmospheric pressure?

A

less (negative)

*think of it like intrathoracic pressure

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6
Q

what is the PPL at rest?

during inspiration?

A
  • 5 cm H20
  • 8 cm H20 (decreases)… lungs expand (increase volume) as thorax does because of coupling
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7
Q

what is alveolar pressure at rest?

what is PA at mid- inspiration? what does this cause?

A

0 cm H20 (equal to PB)

-1 cm H20 (decreases as alveolar size increases)

causes air to enter lungs

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8
Q

what is transpulmonary pressure?

A

pressure between alveoli and pleura (PTP=Palv-PPL)

5 cm H20 at rest

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9
Q

at end inspiration, what is the volume in the lungs?

A

peak volume in lungs– 0.5 liters (500 mL)

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10
Q

at end inspiration, what is happening to alveolar pressure?

A

returns to 0 cm h20

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11
Q

at end inspiration, what is happening to the PPL?

A

at its lowest: -8 cm H20

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12
Q

at end inspiration, what is happening to air flow?

A

stops

(at 0 L/sec)

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13
Q

what is happening during mid-expiration for volume?

A

decreasing

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14
Q

what is happening during mid-expiration for PAlv?

A

increasing (peaks at 1 cm H20)

due to recoil of alveoli

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15
Q

what is happening during mid-expiration for PPL?

A

increasing

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16
Q

what is happening during mid-expiration for air flow?

A

exiting lungs (at about 1 L/sec)

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17
Q

what is happening at end expiration for volume?

A

return to rest

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18
Q

what is happening at end expiration for Palv?

A

decreases to 0

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19
Q

what is happening at end expiration for PPL?

A

returns to rest

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20
Q

what is happening at end expiration for air flow?

A

has exited the lungs

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21
Q

at rest, what is the volume in the lungs?

A

0 L

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22
Q

at rest, what is air flow in lungs?

A

0 L/sec

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23
Q

during mid-inspiration, what is happening to volume?

A

increasing

24
Q

during mid-inspiration, what is happening to Palv?

A

decreasing (hits about -1 cm H20)

25
Q

during mid-inspiration, what is happening to PPL?

A

decreasing

26
Q

during mid-inspiration, what is happening to air flow?

A

entering lungs

27
Q

what is PTP at rest?

A

+5 cm H20

28
Q

what is PTP at mid-inspiration?

A

+5.5 cm H20

29
Q

what is PTP at end-inspiration/start of expiration?

A

+8 cm H20

30
Q

what is PTP at mid-expiration?

A

+7.5 cm H20

31
Q

what is tidal volume?

A

air inhaled and exhaled in single breath

32
Q

what is minute ventilation? what is the equation? what is the normal value?

A

volume of air inhaled every minute

VE=VT*frequency

7 L/min (for 14 breaths per min)

33
Q

what is dead space? what are the two types?

A

regions of lungs that recieve air but no blood so no gas exchange

  1. anatomic dead space- space in respiratory system other than alveoli
  2. physiological- alveoli (should be zero!!)
34
Q

what air is left in lungs at end-expiration?

A

alveolar air from previous breath

35
Q

what air is in lungs at end-inspiration?

A
  1. alveolar air from previous breath (bottom)
  2. inspired air that does gas exchange (350 mL)
  3. inspired air that fills conducting pathways (anatomic dead space)

** 2 and 3 make up tidal volume

36
Q

how do we calculate minute alveolar ventilation?

A

Valv= VT- VDS(dead space)

Vdot alv= Valv * f

37
Q

when the lungs have low volume, is it hard or easy to get more volume into them?

A

hard- small increase in volume because it’s harder to stretch them

38
Q

is it easy or hard to add more volume to lungs during quiet breathing?

A

easy- it becomes easier to stretch the lungs and they will have a big increase in volume

39
Q

is it easy or hard to add more volume to lungs at high lung volume (total lung capacity)?

A

hard- they become difficult to stretch again and experience small increase in volume

40
Q

in a controlled system, the lungs inflate and deflate the same way. why is it not like this in real life?

A
  1. surfactant- reduces tension in smallest alveoli more than larger alveoli
  2. LaPlace’s law- contributes to hysteresis (difference between inspiration and expiration)
41
Q

what is compliance in the lungs? (fml it’s back)

A

how easy it is to stretch the lungs (change in volume/ change in pressure)…. reduces work lungs have to do

42
Q

when is lung compliance highest?

A

during normal breathing/ normal VT

43
Q

when is lung compliance low?

A

when there is either too little or too much pressure around the lungs (at either extreme of the graph)… lungs have to work harder

44
Q

how is compliance different than elasticity?

A

elasticity is actually how easy it is to recoil, while compliance is how easy it is to stretch

45
Q

when baby is born and before its first breath, what is the volume, compliance, effort?

A

volume= very low

compliance= low

effort= high

46
Q

in fibrosis and obesity, what are the changes of volume, compliance, effort?

A

volume= lower (because they take shallower breaths)… pressure must increase

compliance= lower

47
Q

in aging, what are the changes in volume, compliance, effort?

A

volume= ?

compliance= increases (elasticity decreases because of loss of elastin and collagen)

48
Q

in emphysema, what are the changes in volume, compliance, effort?

A

volume= increase?

compliance= increases (destroys alveolar septal tissue that normally opposes lung expansion)

49
Q

when lung is at relaxation, what is its volume?

A

volume= low (at residual volume)

** lungs want to shrink to an even smaller volume than this and is known as minimal volume (below residual volume) because lungs have a lot of elastic fibers

50
Q

when chest wall is relaxed, how does its pressure compare to the lungs? its volume?

** I think this concept is using chest wall synynomly with intrapleaural pressre

A

lower than lung

volume= high volume (because of joint arrangement)

** PPL wants to have as much volume as possible which is why lungs want to collapse and chest wall expand

51
Q

when are the recoil of the lungs and chest wall balanced with each other?

A

functional residual capacity (FRC)–> amount of air that remains in lungs following normal expiration (ERV+RV)

*kinda like lungs are at rest

in other words, where they exactly counter each other

52
Q

what happens to the pressure-volume curve in a pneumothorax?

A

shifts to the left

lungs collapse, chest maximally expands

they both get what they want!

53
Q

what is the equation for airway resistance?

A

R= 8hL/r4

h= viscosity

L=length

54
Q

what is interdependence?

how does it influence airway resistance?

what happens if we lose it (thru smoking, aging, etc)?

A

structural stability of small airways and alveoli depends on their connectivity

the elastic recoil in one alveolus is countered by the recoil in an adjacent alveolus

if we lose these shared walls then the alveoli will collapse during expiration

55
Q

when airway resistance increases, what compensation must take place?

A

increase pressure to change volume of air in lungs (allow air flow into lungs)

56
Q

what 2 forces does breathing overcome?

A
  1. 0AECD0- elastic forces
  2. ABCEA- resistive forces
57
Q

does increase VT increase or decrease work?

A

increase

CPR Test 2 (14 decks)

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