HUBS192 > 17 > Flashcards

17 Flashcards

(49 cards)

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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?

Study These Flashcards
A

Alveolar type 2 pneumocystis

21
Q

What is a major constituent of surfacent ?

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A

Phospholipids

22
Q

Function of surfactant in alveoli

Study These Flashcards
A
  • lowers surface tension
23
Q

How does surfactant lower surface tension

Study These Flashcards
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

25
Lack of surfactant/ failure to produce adequate surfactant —->
‘Stiff’ lungs (Compliance is reduced)
26
Why do premature infants result in respiratory distress syndrome (RDS)
Premature infants do not produce surfactant
27
Airway resistance through the respiratory tract
- 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
Resistance to airflow and bronchial radius
29
Where is the resistance to airflow primarily (yap)
- resistance to airflow primary occurs in the first 6 branchings of the respiratory tree
30
What is the main airway of resistance
Bronchi
31
Most of the resistance to airflow arises in the
Bronchi
32
Do the small airways contribute to airway resistance? Why?
Thesmall airways(terminal and respiratory bronchioles) contribute very little to airways resistance (Due to high crosssectional area)
33
What does a spirometer measure
Volume inspired / exhaled - how much and how fast you breathe - the speed is indicative of resistance of airways
34
Spirometer is
The pulmonary function test
35
Diagram of a spirometer
36
Tidal volume
Restful breathing - half a litre
37
Spirometer trace
38
At the end of breathing out..
Will always be some air left - RESIDUAL VOLUME
39
- top one that is unlabelled in inspiration capacity
40
Vital capacity
Inspiratory reserve + Expiratory reserve + Tidal volume Volume of air that can be moved in and out of your lungs
41
Total lung capacity
Vital capacity + Residual volume Total volume in lungs when it is filled to max
42
Inspiratory capacity
Inspiratory reserve + Tidal volume Total volume of air that can be inspired from rest
43
Functional residual capacity
Expiratory reserve + Residual volume Volume remaining in lungs after normal exhalation
44
How to to determine airway resistance
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
FEV/FVC ratio
- normal ~ 80% - less then 0.7 indicates airways obstruction = increased airway resistance
46
FEV and FVC on graph - forced expiration measurement from a spirometer
47
What can discern the difference between obstructive and restirctive issues?
Spirometry
48
features if RESTRICTIVE issues
Reduced lung capacity: - reduced lung compliance (e.g fibrosis) - insufficient surfactant release
49
Features if OBSTRUCTIVE issues
Resistance to airflow: - asthma - chronic bronchitis - emphysema
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