West Pulmonary Book (end of chapter summary notes)

Question 1

What two zones are the airways divided into?

Answer 1

• conducting zone

- respiratory zone

Question 2

The volume of the anatomic dead space is about how much?

Answer 2

150 mL

Question 3

The volume of the alveolar region is about how many liters?

Answer 3

2.5 - 3 L

Question 4

Gas movement in the alveolar region is done chiefly by ______.

Answer 4

diffusion

Question 5

The approximate surface area of the alveoli is about how much?

Answer 5

50 - 100 meters squared

Question 6

In the alveolar ducts, the predominant mode of gas flow is _______ rather than _______.

Answer 6

• diffusion

- convection

Question 7

When you take a maximal inspiration followed by a maximal expiration, the exhaled volume is called what?

Answer 7

vital capacity

Question 8

The gas that remains in the lungs after maximal expiration is known as what?

Answer 8

residual volume

Question 9

The volume of gas in the lung after a normal expiration is known as what?

Answer 9

functional residual capacity

Question 10

The amount inspired and expired during normal ventilation is called what?

Answer 10

tidal volume

Question 11

How do you calculate total ventilation?

Answer 11

tidal volume x respiratory frequency

Question 12

With normal ventilation, which areas ventilate better, the upper or lower areas?

Answer 12

the lower areas ventilate better than the upper areas

(regardless of what position the patient is in (supine, lateral, etc) the dependent part of the lung will have better ventilation, d/t the effects of gravity)

Question 13

Which lung volumes cannot be measured with a simple spirometer?

Answer 13

• total lung capacity
• functional residual capacity
• residual volume

Question 14

Is the concentration of CO2 (and therefore its partial pressure) in alveolar gas and arterial blood directly or inversely related to the alveolar ventilation?

Answer 14

inversely related

Question 15

Fick’s Law of diffusion states that the diffusion rate of a gas is directly proportional to what (3 things), and inversely proportional to what (1 thing)?

Answer 15

directly proportional:

1. partial pressure gradient
2. membrane area
3. solubility of the gas

inversely proportional:
1. membrane thickness

Question 16

The rate of transfer of a gas is proportional to a diffusion constant, which depends on the properties of the tissue and the particular gas. What is directly and inversely proportional to this constant?

Answer 16

• directly proportional to the solubility of the gas

- inversely proportional to the square root of the molecular weight

Question 17

The diffusion process can be challenged by what 3 things?

Answer 17

• exercise (d/t increased blood transit time through the pulm capillaries and less time for exchange)
• alveolar hypoxia (not enough O2 hopping on the RBCs)
• thickening membrane (can’t get through)

Question 18

In normal lungs, when pulmonary vascular pressures are increased (ie with exercise), the pulmonary vascular resistance is decreased by what two mechanisms?

Answer 18

• recruitment (opening of previously closed vessels)

- distention (increased in caliber of the vessels)

Question 19

Define hypoxic pulmonary vasoconstriction.

Answer 19

the contraction of smooth muscle in the walls of the small pulmonary arterioles in hypoxic regions of the lungs

Question 20

At what point in one’s life is the release of hypoxic pulmonary vasoconstriction critical?

Answer 20

at birth in the transition from placental to air breathing

for knowledge!

Question 21

What is the approx. ratio of the pressures in the pulmonary circulation to that of the systemic circulation?

Answer 21

1:10

pulm ~ 10 mmHg, systemic ~ 100 mmHg

Question 22

If capillary pressure is less than alveolar pressure at the top of the lung, what happens to the capillaries?

Answer 22

they collapse

Question 23

Fluid movement across the capillary endothelium is governed by what concept?

Answer 23

the Starling equilibrium

basically has to do with the differences in hydrostatic and osmotic pressures in the vasculature and the interstitium

Question 24

In zone 2 of the lung, blood flow is determined by _______ _______ minus _______ _______.

Answer 24

arterial pressure minus alveolar pressure

Question 25

Define hypoxemia.

Answer 25

abnormally low PO2 in arterial blood

Question 26

What is the partial pressure of O2 in the atmosphere? What is the partial pressure of O2 in the alveoli?

Answer 26

atmosphere - 150 mmHg

alveoli - 100 mmHg

(the lower value in the alveoli is due to the removal of O2 by pulmonary capillary blood and its continual replenishment by alveolar ventilation)

Question 27

What are the 4 causes of hypoxemia?

Answer 27

• hypoventilation
• diffusion limitation
• shunt
• ventilation-perfusion inequality

Question 28

Fun facts about hypoventilation. (3)

Answer 28

• always increases the alveolar and arterial PCO2
• decreases the PO2 unless additional O2 is inspired
• hypoxemia is easy to reverse by adding O2 to the inspired gas

Question 29

Fun facts about shunts. (3)

Answer 29

• hypoxemia responds poorly to added inspired O2 **
• when 100% O2 is inspired, the arterial PO2 does not rise to the expected level (a useful diagnostic test) **
• if the shunt is caused by mixed venous blood, its size can be calculated from the shunt equation

Question 30

What does the ventilation-perfusion ratio determine?

Answer 30

the gas exchange

Question 31

What does a ventilation-perfusion inequality impair?

Answer 31

the uptake and elimination of all gases by the lung

Question 32

The elimination of CO2 is impaired by V/Q inequality, but can this be corrected with increased ventilation?

Answer 32

yes. yes it can.

Question 33

The uptake of O2 is impaired by V/Q inequality, but can this be corrected with increased ventilation?

Answer 33

no. no it can’t.

Question 34

What are two causes of hypercapnia?

Answer 34

• hypoventilation

- V/Q inequality

Question 35

The different behaviors of O2 and CO2 is attributable to what?

Answer 35

the differences between their dissociation curves

Question 36

A shift to the right of the oxygen dissociation curve is cause by what 4 things?

Answer 36

• increase in H+
• increase in PCO2
• increase in temp
• increase in 2,3-DPG

Question 37

CO2 is carried in the blood in three forms:

Answer 37

• as bicarbonate
• combined with proteins
• dissolved

Question 38

What is the Haldane effect?

Answer 38

This describes how oxygen concentrations determine hemoglobin’s affinity for carbon dioxide.

(For example, high oxygen concentrations enhance the unloading of carbon dioxide. The converse is also true: low oxygen concentations promote loading of carbon dioxide onto hemoglobin. In both situations, it is oxygen that causes the change in carbon dioxide levels.)

Question 39

What is the Bohr effect?

Answer 39

This describes how carbon dioxide and H+ affect the affinity of hemoglobin for oxygen.

(High CO2 and H+ concentrations cause decreases in affinity for oxygen, while low concentrations cause high affinity for oxygen.)

Question 40

The maximum amount of oxygen that can be bound to hemoglobin is known as what?

Answer 40

O2 capacity

Question 41

The amount of oxygen combined with hemoglobin divided by the capacity is known as what?

Answer 41

O2 saturation