Lecture 31: Respiraton 2, 3, and 4 Flashcards

1
Q

In order for inspiration to occur, the lungs must be able to expand when stretched, thus have high

A

compliance

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2
Q

In order for expiration to occur, lungs must get smaller when stretching force is released, thus have

A

elasticity

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3
Q

The tendency to get smaller is aided by what within the alveoli

A

surface tension forces

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4
Q

Compliance/distensibility

A

The ease with which the lungs can expand under pressure

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5
Q

Lung compliance can be measured as

A

change in lung volume

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6
Q

A given transpulmonary pressure will cause

A

greater or lesser expansion, depending on the compliance of the lungs

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7
Q

Compliance of lungs is reduced by factors that

A

produce a resistance to distension

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8
Q

Pulmonary fibrosis

A

Infiltration of lung tissue with connective tissue

Decreases lung compliance

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9
Q

Elasticity

A

Refers to the tendency of a structure to return to it’s initial size after being distended

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10
Q

Why are the lungs elastic?

A

High content of elastin proteins

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11
Q

Since the lungs are normally stuck to the chest wall, they are always in a state of

A

elastic tension

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12
Q

The elastic tension ____ during inspiration

A

increases

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13
Q

Elastic tension is reduced by ____ ____ during expiration

A

elastic recoil

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14
Q

Tidal volume

A

the amount of air moved into and out of the lungs during a single respiratory cycle

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15
Q

Forces that act to reduce distension include

A
  • Elastic resistance

- Surface tension exerted by fluid in the alveoli

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16
Q

The most important determinant of lung compliance is

A

Surface tension at the air-water interphases in the alveoli

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17
Q

Surface tension

A

the attractive forces between the water molecules in the lipid film that lines each alveolus

18
Q

Surface tension is responsible for a two fold effect

A
  1. Liquid layer opposes expansion of alveolus because the surface water molecules are being pulled apart
  2. Liquid sa tends to become as small as possible because surface water molecules try to get as close together as possible
19
Q

Conclusions of surface tension

A
  1. Reduces size of alveolus

2. Would be so great that the lungs would collapse if the alveolus were lined with water alone

20
Q

Pulmonary surfactant

A
  • A complex mixture of lipids and proteins secreted by type II alveolar cells
  • Counteracts surface tension of the liquid lining alveoli by interspersing between water molecules
21
Q

Two benefits of pulmonary surfactant

A
  1. Increases pulmonary compliance, reducing the work of the inflating lungs
  2. Reduces tendency of lungs to recoil, so they don’t collapse as readily
22
Q

Inadequate production of pulmonary surfactant results in

A

Difficulty breathing due to low lung compliance

23
Q

When does cortisol production increase

A

during pregnancy

24
Q

Restrictive lung diseases

A

Alveoli are stiff, expansion is restricted, all volumes and capacities are less than normal

25
Pulmonary fibrosis is an example of a
restrictive lung disease
26
Obstructive pulmonary diseases
Respiration is more difficult and takes longer
27
Asthma
- Obstructive pulmonary disease | - Airways are narrowed by bronchoconstriction
28
Chronic bronchitis
- Obstructive pulmonary disease | - Plugs of mucus and inflammatory swelling of bronchial mucosa obstructs the airways
29
Anatomic dead space
Where inspired gas that does not get down to the site of gas exchange in the alveoli and remains in the conducting airways, not available for gas exhange
30
Tidal volume components
- 450 mL enter alveoli - 150 mL is old air from dead space - 300 mL fresh air from atmosphere
31
Ventilation rate
Volume of air moved into and out of the lungs per unit time
32
Ventilation rate can be expressed as
1. Minute ventilation - total rate of air movement in and out of lungs 2. Alveolar ventilation - corrects for anatomic dead space
33
Minute ventilation equation
Tidal volume x respiratory rate
34
Alveolar ventilation equation
(tidal volume - dead space volume) x respiratory rate
35
4 factors affecting the diffusion across the respiratory membrane
1. Thickness of membrane 2. SA of membrane 3. Diffusion coefficient 4. Partial pressure gradients of o2 and co2
36
Thickness of membrane normally remains
constant
37
Thickness of membrane increases with pathological conditions such as
- Pulmonary edema - Pulmonary fibrosis - Pneumonia
38
Surface area of membrane changes
- Increases during exercise - Normally remains constant - Decreases during diseases like emphysema
39
Rate of transfer increases as the diffusion coefficient ____
increase
40
Diffusion coefficient for CO2 is ____ times that of O2
30
41
Partial pressure gradients of O2 and CO2 - rate of transfer increases as diffusion partial pressure gradient _______
increases