Lecture 31: Respiraton 2, 3, and 4

Question 1

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

Answer 1

compliance

Question 2

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

Answer 2

elasticity

Question 3

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

Answer 3

surface tension forces

Question 4

Compliance/distensibility

Answer 4

The ease with which the lungs can expand under pressure

Question 5

Lung compliance can be measured as

Answer 5

change in lung volume

Question 6

A given transpulmonary pressure will cause

Answer 6

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

Question 7

Compliance of lungs is reduced by factors that

Answer 7

produce a resistance to distension

Question 8

Pulmonary fibrosis

Answer 8

Infiltration of lung tissue with connective tissue

Decreases lung compliance

Question 9

Elasticity

Answer 9

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

Question 10

Why are the lungs elastic?

Answer 10

High content of elastin proteins

Question 11

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

Answer 11

elastic tension

Question 12

The elastic tension ____ during inspiration

Answer 12

increases

Question 13

Elastic tension is reduced by ____ ____ during expiration

Answer 13

elastic recoil

Question 14

Tidal volume

Answer 14

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

Question 15

Forces that act to reduce distension include

Answer 15

• Elastic resistance

- Surface tension exerted by fluid in the alveoli

Question 16

The most important determinant of lung compliance is

Answer 16

Surface tension at the air-water interphases in the alveoli

Question 17

Surface tension

Answer 17

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

Question 18

Surface tension is responsible for a two fold effect

Answer 18

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

Question 19

Conclusions of surface tension

Answer 19

1. Reduces size of alveolus

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

Question 20

Pulmonary surfactant

Answer 20

• 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

Question 21

Two benefits of pulmonary surfactant

Answer 21

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

Question 22

Inadequate production of pulmonary surfactant results in

Answer 22

Difficulty breathing due to low lung compliance

Question 23

When does cortisol production increase

Answer 23

during pregnancy

Question 24

Restrictive lung diseases

Answer 24

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

Question 25

Pulmonary fibrosis is an example of a

Answer 25

restrictive lung disease

Question 26

Obstructive pulmonary diseases

Answer 26

Respiration is more difficult and takes longer

Question 27

Asthma

Answer 27

• Obstructive pulmonary disease

- Airways are narrowed by bronchoconstriction

Question 28

Chronic bronchitis

Answer 28

• Obstructive pulmonary disease

- Plugs of mucus and inflammatory swelling of bronchial mucosa obstructs the airways

Question 29

Anatomic dead space

Answer 29

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

Question 30

Tidal volume components

Answer 30

• 450 mL enter alveoli
• 150 mL is old air from dead space
• 300 mL fresh air from atmosphere

Question 31

Ventilation rate

Answer 31

Volume of air moved into and out of the lungs per unit time

Question 32

Ventilation rate can be expressed as

Answer 32

1. Minute ventilation - total rate of air movement in and out of lungs
2. Alveolar ventilation - corrects for anatomic dead space

Question 33

Minute ventilation equation

Answer 33

Tidal volume x respiratory rate

Question 34

Alveolar ventilation equation

Answer 34

(tidal volume - dead space volume) x respiratory rate

Question 35

4 factors affecting the diffusion across the respiratory membrane

Answer 35

1. Thickness of membrane
2. SA of membrane
3. Diffusion coefficient
4. Partial pressure gradients of o2 and co2

Question 36

Thickness of membrane normally remains

Answer 36

constant

Question 37

Thickness of membrane increases with pathological conditions such as

Answer 37

• Pulmonary edema
• Pulmonary fibrosis
• Pneumonia

Question 38

Surface area of membrane changes

Answer 38

• Increases during exercise
• Normally remains constant
• Decreases during diseases like emphysema

Question 39

Rate of transfer increases as the diffusion coefficient ____

Answer 39

increase

Question 40

Diffusion coefficient for CO2 is ____ times that of O2

Answer 40

30

Question 41

Partial pressure gradients of O2 and CO2 - rate of transfer increases as diffusion partial pressure gradient _______

Answer 41

increases