29 Pulmonary Mechanics

Question 1

What are the primary muscles of inspiration?

Answer 1

Diaphram

External intercostal mm

Question 2

What are some examples of secondary expiratory muscles?

Answer 2

Internal intercostal mm

abdominal mm

Question 3

what is the equation for compliance?

Answer 3

compliance= V/P (delta volume over delta pressure)

Question 4

where is the transpulmonary pressure greatest in the lungs?

Answer 4

at the apex, this is due to gravity.

Question 5

what is the equation of transpulmonary pressure?

Answer 5

Transpulmonary pressure= alveolar pressure minus pleural pressure

Question 6

What is the most important determinant of airway resistance?

Answer 6

airway radius

Question 7

Where is flow turbulent in the lungs? what about laminar flow?

Answer 7

It is turbulent in the trachia, and bronchi

It is laminar in the smaller airways

Question 8

what is the Bernoulli effect?

Answer 8

A fast moving air current has a lower pressure because of a drop in potential energy.

Question 9

what percentage of oxygen consumption goes toward breathing during health?

Answer 9

less than 5 %

Question 10

If you removed a lung from the thoracic cavity, how much would it collapse?

Answer 10

It would collapse to about 10% of the TLC

Question 11

what makes a lung want to collapse down?

Answer 11

surface tension in the alveoli

elastic and collagen fibers in the lung

Question 12

what produces surfactant?

Answer 12

Type II alveolar cells

Question 13

In health, the chest wall wants to expand during normal tidal breathing and at lung volumes below what percent?

Answer 13

Below 70% of TLC the chest wants to expand. Above 70% TLC the chest wall actually wants to recoil. Note: the lungs always want to recoil while in the body.

Question 14

What effect does abdomen expansion have on breathing?

Answer 14

since the diaphragm expands into the abdominal cavity, the abdomen can be considered part of the chest wall. An expanded abdomen makes it more difficult to inspire.

Question 15

When is the inward recoil of the lungs and the outward recoil of the chest wall perfectly matched?

Answer 15

At FRC (Functional residual capacity)

Question 16

What is FRC?

Answer 16

ERV + RV

Expiratory reserve volume + residual volume

Question 17

which muscles can be activated during exercise and disease?

Answer 17

secondary accessory muscles of inspiration include the scalene muscles, sternocleidomastoid muscles, neck and back muscles, and upper airway dilatory muscles.

Question 18

Which muscles are considered the primary muscles of expiration?

Answer 18

None because it is passive.

Question 19

Which muscles are considered the secondary muscles of expiration?

Answer 19

abdominal muscles and internal intercostal mm.

Question 20

What is the elastance equation?

Answer 20

elastance=P/V (delta P over delta V)

Note: this is the inverse of compliance.

Question 21

A stiff balloon would be considered to have low or high compliance?

Answer 21

Low compliance.

Question 22

pulmonary fibrosis and pulmonary edema have what effect on the lungs?

Answer 22

They reduce lung compliance

Question 23

kyphosis, scoliosis, distended abdomen have what effect on breathing?

Answer 23

They reduce chest wall compliance

Question 24

What does emphysema do to the lungs?

Answer 24

Increases compliance resulting in a barrel chest.

This is bad because it reduces the elastic recoil.

Question 25

what is hysteresis?

Answer 25

The fact that the lung is less compliant during inflation than during deflation.

Question 26

What is the inflection point in the compliance graph?

Answer 26

It is the horizontal part of the curve at the very beginning of inspiration. It is horizontal because the inspired air has to recruit a large population of collapsed alveoli to open before filling.

Question 27

which alveoli are better ventilated in the lungs, the ones at the apex or at the base?

Answer 27

base

Question 28

What is Poiseulle’s law?

Answer 28

The equation states:
Resistance= 8nL/ (pie R to the 4th)

It says that resistance is mainly based off of radius.

Question 29

Where is airway resistance the greatest in the lungs?

Answer 29

in the trachea

Question 30

What is the reynolds number?

Answer 30

it tells you if the flow is turbulent of not. If above 2000, the flow is considered turbulent.

Question 31

how do you calculate Reynolds number?

Answer 31

Reynolds number= 2(radius)x velocity x density / viscosity

Question 32

Where do you find transitional flow?

Answer 32

in turbulent eddies formed at airway branching points.

Question 33

What kind of flow do you hear with the stethoscope?

Answer 33

turbulent and transitional flow.

Question 34

what is the equation for flow?

Answer 34

flow = P/R (delta P over delta R)

Question 35

which factors provoke the collapse of alveoli and small passageways in the lungs?

Answer 35

small areas
floppier tubes

This is important in diseases such as emphysema because with high velocities the pressure decreases and promotes the collapse of the already weakened passageways.

Question 36

what is FEV1?

Answer 36

The forced expiratory volume in 1 second.

Question 37

What is FVC?

Answer 37

Forced vital capacity. Its a maneuver to test you lung capacities.

Question 38

What would happen to the FEV1 in a patient with emphysema? FRC?

Answer 38

FEV1 would be reduced.

FRC would be increased

Question 39

What is the equation for work of breathing?

Answer 39

Work of breathing= PxV

delta P times delta V

Question 40

what are some signs of increased work of breathing?

Answer 40

tachypnea (rapid breathing)
tachycardia
hypertension
anxiety
use of accessory muscles