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Question 1

Describe the mechanism of breathing

Answer 1

Air flows in when Palv

Question 2

distending pressure

Answer 2

transpulmonary pressure (Ptp)

Like a transmural pressure, it is the different between the inside and outside pressure

Ptp = Palv – Ppl

Question 3

why do the lungs want to be smaller

Answer 3

The lungs want to be smaller
Lung tissue is elastic. Higher elastic recoil = more difficult
to inflate the lungs. Elastic recoil is a measure of how
stretchy or stiff the alveoli and connective tissue are.

Question 4

why does the chest wall want to be smaller

Answer 4

The chest wall wants to be bigger
Chest wall has elastic properties too, but also acts as a spring.
At nearly all lung volumes the chest wall wants to expand
outwards.

Question 5

what is intrapleural pressure

Answer 5

Inward force of the lungs on visceral pleura + outward force of chest on parietal pleura .

Question 6

how is Ptp generated

Answer 6

Via inspiratory muscle: diaphragm, external intercostal scavene and sternocleidomastoid

Question 7

What properties of the diaphragm help breathing

Answer 7

Larger radius- lower force needed to be generated for breath

Patients with emphysema have a weaker and flatter diaphragm

Question 8

ppl is average of pleural pressure- any other info

Answer 8

Ppl becomes less negative
Ptp is bigger at top of chest wall and exerts more pressure at top- therefore alveoli are larger at top and less compliant so inflate less

Question 9

what is compliance

Answer 9

the dispensability of a chamber object due to changes in trans mural pressure

Question 10

what is the compliance of the lung

Answer 10

Relationship between changes in lung volumes and Ptp

Question 11

what is chest wall compliance

Answer 11

Relationship between changes in lung volumes and trans mural pressure

Question 12

For total compliance

Answer 12

Add both chestwall and lung compliance

Question 13

what is the total lung capacity

Answer 13

volume of gas in the lungs at maximal inhalation

Question 14

FRC: functional residual capacity-

Answer 14

amount f air at end of expiration

Question 15

Rv

Answer 15

residual volume- amount of air remaining in lung & forced exhalation to lowest lung volume

Question 16

VC

Answer 16

Vital capacity- largest possible breath

Question 17

Compliance in fibrosis and emphysema

Answer 17

fibrosis- low

Emphysema- high

Question 18

what do type 2 alveoli produce

Answer 18

Pulmonary surfactant (Phosphlipoproteins)- reduce surface tension and increase lung compliance

Question 19

what happens to premature babies in relation to Surfactant

Answer 19

Don’t make enough and at risk of respiratory distress syndrome

Question 20

surfactant also

Answer 20

decreases pressure and equalizes it, preventing atelectasis -lung collapsing

Question 21

Breathing overcomes

Answer 21

Recoil pressures-(elastic and tension) &

Airway resistance during airflow

Question 22

Type of gas flow in lungs

Answer 22

Laminar
Turbulent-@ higher resistances to exhaling & higher velocities
Transitional

Question 23

what is Reynold number

Answer 23

It predicts turbulent flow

Question 24

flow=

Answer 24

1/R

Question 25

Alveolar pressure =

Answer 25

sum of elastic recoil pressure and pleural pressure

Question 26

Radius is very important determinant for

Answer 26

resistance

Question 27

when airways are narrow what increases

Answer 27

Resistance and pressure-needed to create same flow

Question 28

When airways are narrow what decreases

Answer 28

Air Flow

Question 29

Look at summary on slide 6 of lecture

Answer 29

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