Lecture 17: THE WORK OF BREATHING Flashcards

1
Q

What happens during inhalation?

A

Volume is increasing, pressure inside the lungs is decreasing so that pressure outside is now greater than inside and air rushes in

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2
Q

What happens during exhalation?

A

Volume is decreasing, pressure inside the lungs is increasing and pressure outside is now lower than inside so air rushes out

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3
Q

What is the direction of airflow determined by?

A

Difference between atmospheric pressure and intrapulmonary pressure

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4
Q

What must be overcome to take a breath?

A

Stiffness of the lungs and resistance of the airways to the lungs

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5
Q

What must the lungs do to take in air?

A

Expand

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6
Q

What holds the lungs in place?

A

Surface tension

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7
Q

Where does air need to move?

A

From outside to the alveoli

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8
Q

What is compliance?

A

The magnitude of the change in lung volume produced by the given change in pressure

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9
Q

What does low compliance of lungs mean?

A

Stiff lungs so lungs have to do more work to expand

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10
Q

What is pulmonary fibrosis?

A

Thickening and scarring of the alveolar membranes

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11
Q

What does pulmonary fibrosis do?

A

Makes the lungs too elastic and hard to expand

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12
Q

What can pulmonary fibrosis arise from?

A

Chronic inflammation or exposure to industrial chemicals

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13
Q

What are alveoli lined with?

A

Fluid that exerts surface tension

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14
Q

The wall of the alveoli is…

A

very thin, enhancing the effect of surface tension and making the lungs less compliant

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15
Q

What must be overcome to expand the lungs?

A

Surface tension

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16
Q

What does surfactant do?

A

Reduces surface tension in alveoli and makes them easier to expand

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17
Q

What is surfactant produced by?

A

Alveolar Type 2 pneumocytes

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18
Q

What is the major constituent of surfactant?

A

Phospholipids

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19
Q

How does surfactant reduce surface tension?

A

It reduces the attractive forces between fluid molecules lining alveoli by inserting phospholipids between. This increases compliance and makes the lungs easier to expand

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20
Q

What can lack of surfactant/failure to produce surfactant do?

A

Lead to stiff lungs

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21
Q

What do premature infants do?

A

Dont produce surfactant (until 28 weeks) which results in respiratory distress syndrome (RDS)

22
Q

Where is air conducted?

A

Through the bronchi and bronchioles which exert force (friction) on the air that must be overcome

23
Q

Where is most of the resistance to airflow?

A

In the bronchi

24
Q

DO the small airways contribute much resistance?

A

The small airways (terminal and respiratory bronchiole) contribute very little to airways resistance (due to high cross sectional area)

25
Q

What does a spirometer measure?

A

Volume inspired/exhaled

26
Q

What type of test is spirometer?

A

Common, simple

27
Q

What can a spirometer do?

A

Measure how much and how fast you breather and test response to therapy

28
Q

What is tidal volume?

A

The volume air moved in and out during a normal quiet breath

29
Q

What is normal tidal volume?

A

About 500mL

30
Q

What is inspiratory reserve volume?

A

Extra volume that can be inhaled over and above the tidal volume

31
Q

What is expiratory reserve volume?

A

Extra volume that can be exhaled voluntarily after completion of a normal, quiet respiratory cycle

32
Q

What is residual volume?

A

Volume remaining in lungs after maximal exhalation

33
Q

What is minimal volume?

A

Volume remaining in lungs if they collapsed

34
Q

What is vital capacity made up of?

A

Inspiratory reserve, expiratory reserve and tidal volume

35
Q

What is vital capacity?

A

Volume of air that can be moved in and out of your lungs

36
Q

What is total lung capacity made up of?

A

Vital capacity and residual volume

37
Q

What is total lung capacity?

A

Total volume in lungs when it is filled to maximum

38
Q

What is inspiratory capacity made up of?

A

Inspiratory reserve and tidal volume

39
Q

What is inspiratory capacity?

A

Total volume of air that can be inspired from rest

40
Q

What is functional residual capacity made up of?

A

Expiratory reserve and residual volume

41
Q

What is functional residual capacity?

A

Volume remaining in lungs after normal exhalation

42
Q

What is FEV1?

A

How much of the forced vital capacity (FVC) comes out in the first second

43
Q

What does FEV1 reduce with?

A

Diseases causing increased resistance to outflow such as asthma

44
Q

What is the normal FEV1/FVC ration?

A

80%

45
Q

What does <0.7 FEV1/FVC ratio indicate?

A

Airway obstruction and increased airway resistance

46
Q

What can spirometry discern between?

A

Obstructive and restrictive issues

47
Q

What is obstructive issues?

A

Resistance to airflow

48
Q

What are examples of obstructive issues?

A

Asthma and chronic bronchitis

49
Q

What is restrictive issues?

A

Reduced lung capacity

50
Q

What can restrictive issues be caused by?

A

Reduced lung compliance (fibrosis) and insufficient surfactant release