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HUBS192 > 17 > Flashcards

17 Flashcards

1
Q
A
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2
Q

Gas will move form ____ pressure to ____ pressure

A

High
Low

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3
Q

Right before a breath, pressure outside the body and inside the lungs is…

A

Equal

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4
Q

How do you create a pressure gradient

A
  • as u inhale, your diaphragm drop as while your rib cage expands
  • this increases the volume in your chest, which lowers the pressure
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5
Q

Boyes law and what needs to be kept constant for it to apply

A
  • the pressure of gas is inversely related to its volume
  • P= 1/V
  • provided temperature and amount of gas molecules are kept constant

(IN A CLOSED CHAMBER the product of PXV MUST STAY THE SAME)

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6
Q

Creating a pressure gradient in inhalation

A

• Lung volume is increasing
• Pressure inside the lungs is
decreasing
• Pressure outside the lung is now
greater than inside, so air rushes in

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7
Q

Creating a pressure gradient in exhalation

A

• Lung volume is decreasing
• Pressure inside the lungs is
increasing
• Pressure outside the lung is now
lower than inside, so air rushes out

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8
Q

What is the direction of airflow determined by?

A

difference between atmospheric pressure and intrapulmonary pressure

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9
Q

What is intrapulmonary pressure?

A

Pressure inside the lungs

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10
Q

What are the two opposing forces that must be overcome to take a breath

A
  1. Stiffness of the lungs
    • Lungs must expand to take in air
    • How compliant are the lungs?
    • Surface tension holds lungs in place
  2. Resistance of the airways to the lungs
    • Need to move the air from outside to the
    alveoli
    • How much resistance is the respiratory tract
    putting on the movement of air?
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11
Q

What makes lungs stiff/ not stiff

A
  • elastic tissue makes it stretchy
  • low compliance means not very stretchy
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12
Q

What is compliance (lungs)

A

Defined as the magnitude of the change in the lung volume (^V) produced by the given change in pressure (^P)

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13
Q

Compliance equation and graph - lungs

A
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14
Q

Vital capacity =

A

Lung volume

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15
Q

Low compliance - ‘stiff lungs’ =

A

Need more work to expand

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16
Q

What is pulmonary fibrosis and was causes it and what happens to compliance?

A
  • thickening and scaring of the alveolar membranes
  • can arise from chronic inflammation or exposure to industrial chemicals
  • needs a high pressure to clause a same change in volume
  • shallow rapid breaths
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17
Q

What is surface tension

A
  • tendency of a fluid to occupy the smallest possible surface area
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18
Q

Fluids surrounding the lungs exerting surface tension on alveoli

A
  • Alveoli are lined with fluid that exert surface tension
  • walls of alveoli are very thin, enhancing this effect
  • makes alveoli want to collapse
  • must overcome surface tension to expand the lungs
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19
Q

What does surfactant do?

A

Reduces surface tension in alveoli making them easier to expand

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20
Q

What is surfactant produced by?

A

Alveolar type 2 pneumocystis

21
Q

What is a major constituent of surfacent ?

A

Phospholipids

22
Q

Function of surfactant in alveoli

A
  • lowers surface tension
23
Q

How does surfactant lower surface tension

A
  • reduces attractive forces between fluid molecules lining alveoli
  • easier to increase lung size I.e. increased compliance
24
Q

Diagram of with and without surfactant

A
25
Q

Lack of surfactant/ failure to produce adequate surfactant —->

A

‘Stiff’ lungs
(Compliance is reduced)

26
Q

Why do premature infants result in respiratory distress syndrome (RDS)

A

Premature infants do not produce surfactant

27
Q

Airway resistance through the respiratory tract

A
  • need to ,more air from outside to the alveoli
  • air is conducted through the bronchi and bronchioles
  • exert force (fiction) on the air (through the airways) that must be overcome
28
Q

Resistance to airflow and bronchial radius

A
29
Q

Where is the resistance to airflow primarily (yap)

A
  • resistance to airflow primary occurs in the first 6 branchings of the respiratory tree
30
Q

What is the main airway of resistance

A

Bronchi

31
Q

Most of the resistance to airflow arises in the

A

Bronchi

32
Q

Do the small airways contribute to airway resistance? Why?

A

Thesmall airways(terminal and respiratory bronchioles) contribute very little to airways resistance
(Due to high crosssectional area)

33
Q

What does a spirometer measure

A

Volume inspired / exhaled

  • how much and how fast you breathe
  • the speed is indicative of resistance of airways
34
Q

Spirometer is

A

The pulmonary function test

35
Q

Diagram of a spirometer

A
36
Q

Tidal volume

A

Restful breathing
- half a litre

37
Q

Spirometer trace

A
38
Q

At the end of breathing out..

A

Will always be some air left
- RESIDUAL VOLUME

39
Q
A
  • top one that is unlabelled in inspiration capacity
40
Q

Vital capacity

A

Inspiratory reserve + Expiratory reserve + Tidal volume Volume of air that can be moved in and out of your lungs

41
Q

Total lung capacity

A

Vital capacity + Residual volume
Total volume in lungs when it is filled to max

42
Q

Inspiratory capacity

A

Inspiratory reserve + Tidal volume
Total volume of air that can be inspired from rest

43
Q

Functional residual capacity

A

Expiratory reserve + Residual volume
Volume remaining in lungs after normal exhalation

44
Q

How to to determine airway resistance

A

Forced exiratory volume in one second (FEV)
- ie how much of the forced vital capacity (FVC) comes out in the first second
- reduced with diseases causing resistance to airflow (e.g asthma)

45
Q

FEV/FVC ratio

A
  • normal ~ 80%
  • less then 0.7 indicates airways obstruction = increased airway resistance
46
Q

FEV and FVC on graph - forced expiration measurement from a spirometer

A
47
Q

What can discern the difference between obstructive and restirctive issues?

A

Spirometry

48
Q

features if RESTRICTIVE issues

A

Reduced lung capacity:
- reduced lung compliance (e.g fibrosis)
- insufficient surfactant release

49
Q

Features if OBSTRUCTIVE issues

A

Resistance to airflow:
- asthma
- chronic bronchitis
- emphysema

HUBS192 (39 decks)

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