Lung Ventilation & Compliance

Question 1

RDS

Answer 1

Respiratory Distress Syndrome

Question 2

What is the worry about a premature newborn’s respiratory system?

Answer 2

Surfactant deficiency (difficult to breath)

Question 3

Anatomic vs. Alveolar Dead Space

Answer 3

Anatomic: air resides in the conducting airways
Alveolar: amount of wasted ventilation (blood supply blocked; ventilation greater than perfusion)

Question 4

If tidal volume is 500 mL, how much is anatomic dead space

Answer 4

150 mL

Question 5

In healthy lungs, Physiologic Dead Space should be nearly equivalent to…

Answer 5

Anatomic Dead Space (minimal alveolar dead space)

Question 6

What can contribute to Alveolar Dead Space

Answer 6

1. Obstruction to blood flow (embolism)

2. Ventilation is greater than the perfusion can handle

Question 7

What two resistances must be overcome during ventilation?

Answer 7

Chest Wall resistance

Airway resistance

Question 8

Why is positive end expiratory pressure (PEEP) important during lung ventilation?

Answer 8

It is hard to inflate a completely deflated lung, so always ensuring a positive pressure in the lungs helps keep alveoli somewhat open, and thus ease ventilation efforts

Question 9

Elastic recoil assists in (inflation/deflation)

Answer 9

Deflation

Question 10

Compliance assists in (inflation/deflation)

Answer 10

Inflation

Question 11

What two factors help determine how hard/easy it is to fill your lungs with air (Lung Compliance)?

Answer 11

Elastic recoil
Surface tension (surfactant)

Question 12

According to LaPlace’s Law, the smaller the bubble the ________ the pressure has to be to support the surface tension

Answer 12

higher (P= 2T/r)

Question 13

Why is surface tension important for alveoli?

Answer 13

their thin walls and short radii at end-expiration make them susceptible to collapse as a result of surface tension. If large and small alveoli were connected via a common airway, the higher pressure in the smaller alveolus would force air into the larger alveolus, and the small alveolus would collapse

Question 14

Surfactant is a mixture primarily made up of..

Answer 14

phospholipids (90%); majorly DPPC

• other 10% with proteins including surfactant proteins

Question 15

Pulmonary surfactant is made by what cell?

Answer 15

Alveolar Type II cells (cuboidal cells at alveolar septa)

Question 16

Pulmonary surfactant metabolism disorders are treated with surfactant replacement therapy, but not cured by it (True or False)

Answer 16

True; only a lung transplant can cure

Question 17

Interconnecting walls stabilize neighboring alveoli. In effect neighboring alveoli tug on each other to prevent collapse of any single alveolus, and also help each other open up during inspiration

Answer 17

Alveolar Interdependence

Question 18

Lung disease where the breakdown of lung connective tissue causes decreased elastic recoil. These lungs have very high compliance: they are very easy to inflate, but have very little elastic recoil necessary for a passive expiration, thus a large FRC (Emphysema or Fibrosis)

Answer 18

Emphysema

Question 19

Lung disease where the lung connective tissue is thickened by the pathologic deposition of tough fibrotic tissue. The result is a very stiff lung, with a low compliance that is difficult to inflate. (Emphysema or Fibrosis)

Answer 19

Fibrosis

Question 20

puncture of the chest wall and/or visceral pleura allowing entry of air into the pleural space, disrupting the lung-chest coupling and therefore blocks mechanical energy transfer. This increases work of breathing.

Answer 20

Pneumothorax

Question 21

In healthy individuals, total body O2 consumption at rest is about

Answer 21

5% or less

Question 22

What might increase one’s work of breathing

Answer 22

Exercise
Obesity
Pulmonary Fibrosis (reduced compliance)
RDS
Obstructive diseases

Question 23

The total volume of the lungs that does not participate in gas exchange is known as

Answer 23

physiological dead space

Question 24

The ______ the hydrophobicity of the medium in contact with water, the _______ the surface tension

Answer 24

greater; greater

Question 25

Most gases are very _________ than water

Answer 25

hydrophobic

Question 26

What surfactant proteins are essential for formation of the surfactant layer?

Answer 26

SPB and SPC

Question 27

What surfactant proteins are members of the collectin family and are active in lung defense?

Answer 27

SPA & SPD

Question 28

What is the organelle that secretes surfactant in type II alveolar cells?

Answer 28

lamellar bodies

Question 29

In the alveolus, a phospholipid monolayer of surfactant exists at the ________

Answer 29

air-liquid interface

Question 30

Polar lipid heads face towards______, and hydrophobic lipid tails stick into _____

Answer 30

alveolar liquid; gas phase

Question 31

During alveolar expansion (inspiration), what happens to the SA, phospholipid molecules, water molecules, and surface tension?

Answer 31

• SA: increases
• Phospholipid: more separated
• Water molecule: exposed more to air
• Surface tension: increases

Question 32

During alveolar compression (expiration), what happens to the SA, phospholipid molecules, water molecules, and surface tension?

Answer 32

• SA: decreases
• Phospholipid: more complete/closer
• Water molecule: less exposed to air
• Surface tension: decreases

Question 33

Alveolar interdependence increases the compliance of the lung especially during ______

Answer 33

expiration when alveoli becomes smaller

Question 34

What two types of compliance contribute to the work needed for ventilation?

Answer 34

1. Lung Compliance
2. Chest Compliance

• Lung Compliance + Chest Compliance = Total Compliance

Question 35

What factors can decrease chest wall compliance?

Answer 35

1. obesity
2. musculoskeletal disorders affecting rib cage
3. fibrothorax (scarring or fibrosis of the pleural space)

Question 36

The concept in which the efficient transfer of energy from one component to the other component decreases the work of breathing.

• Energy released from the lung and transferred to the ribs/chest wall OR vise versa

Answer 36

See-saw exchange of mechanical energy

Question 37

In emphysema, the lung elastance is ______ due to destruction of lung elastin fibers. FRC is ________

Answer 37

reduced; increased (larger volume of air present in the lungs at the end of passive expiration)

Question 38

Pneumothorax disrupts _______ that decreases the work of breathing in normal lung?

Answer 38

mechanical coupling of the lung and chest wall (mechanical exchange of energy)