1. Lung anatomy and physiology

Question 1

What is the conducting zone of the lungs?

Answer 1

The conducting zone of the lungs is the upper and lower respiratory tract, which is also known as dead space.

Question 2

What is the respiratory zone of the lungs?

Answer 2

The respiratory zone of the lungs is the lung parenchyma, where gas exchange occurs.

Question 3

How many lobes and segments are in the right lung?

Answer 3

The right lung has three lobes (upper, middle, lower) and 10 bronchopulmonary segments, which help in ventilation and gas exchange.

Question 4

What is the difference between the right and left main bronchus?

Answer 4

The right main bronchus divides into three lobar bronchi, while the left main bronchus divides into two lobar bronchi and is longer than the right.

Question 5

Where do the bronchial veins empty into on the right side?

Answer 5

They empty into the azygos vein.

Question 6

Where do the bronchial veins empty into on the left side?

Answer 6

They empty into the accessory hemiazygos vein.

Question 7

What are the layers covering the lungs?

Answer 7

Endothoracic fascia, parietal layer, pleural fluid, and visceral layer.

Question 8

What is ventilation?

Answer 8

Movement of air through the respiratory tract into (inspiration) and out of (expiration) the respiratory zone to facilitate gas exchange (O2 and CO2).

Question 9

What is the anatomical dead space?

Answer 9

The conducting zone of the respiratory tree, which includes the nose, pharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles.

Question 10

What is the site of gas exchange in the respiratory tree?

Answer 10

The respiratory zones, which include respiratory bronchioles, alveolar ducts, and alveoli.

Question 11

What is the difference between dynamic and static lung volumes?

Answer 11

Dynamic lung volumes are related to the rate at which air flows in/out of the lungs, while static lung volumes are not affected by the rate of airflow into/out of the lungs.

Question 12

What is tidal volume?

Answer 12

The amount of air entering/leaving the lung without extra effort, which is approximately 500mL.

Question 13

What is inspiratory reserve volume?

Answer 13

The maximum inspiration above tidal volume, which is approximately 3100mL in men and 1900mL in women

Question 14

What is expiratory reserve volume?

Answer 14

The volume exhaled besides tidal volume, which is approximately 1200mL in men and 800mL in women

Question 15

What is Residual Volume (RV)?

Answer 15

It is the amount of air remaining in the lungs after complete exhalation (1200mL in men, 1000mL in women)

Question 16

What is Inspiratory Capacity (IC)?

Answer 16

It is the sum of IRV and tidal volume, which is the largest amount of air that can be inhaled (3600mL / 2400mL)

Question 17

What is Functional Residual Capacity (FRC)?

Answer 17

It is the sum of RV and ERV, which is the volume of air remaining in the lungs after normal exhalation (2400mL / 1800mL)

Question 18

What is Vital Capacity (VC)?

Answer 18

It is the entire volume of air that can be maximally inhaled and exhaled (4800mL / 3200mL)

Question 19

What is Total Lung Capacity (TLC)?

Answer 19

It is the sum of VC and RV, which is the total volume of all lung volumes (6000mL / 4200mL)

Question 20

What is the distribution of blood flow in the lungs dependent on?

Answer 20

It depends on the position of the body and is precisely regulated in relation to the ventilation to optimize gas exchange.

Question 21

What is the ventilation-perfusion ratio (V/Q ratio)?

Answer 21

It is the volumetric ratio of air that reaches the alveoli (ventilation) to alveolar blood supply (perfusion) per minute.

Question 22

What happens if a lung section is perfused but not ventilated?

Answer 22

There is a drop in the O2 concentration in the blood, leading to hypoxic vasoconstriction and blood shift from poorly ventilated to better-ventilated areas.

Question 23

What is the purpose of hypoxic vasoconstriction in the lungs?

Answer 23

The vessels of the lungs react to hypoxia with vasoconstriction to keep the V/Q ratio constant.

Question 24

What is ventilation-perfusion mismatch (V/Q mismatch)?

Answer 24

It is an imbalance between total lung ventilation and total lung perfusion that occurs when either ventilation or perfusion, or both, change in a way that the two parameters no longer match.

Question 25

What causes an increased V/Q ratio (dead space)?

Answer 25

Ventilation of poorly perfused alveoli, which can be caused by blood flow obstruction (e.g., pulmonary embolism, cardiovascular shock) or exercise (CO increased, leading to vasodilation of apical capillaries).

Question 26

What causes a decreased V/Q ratio (shunt)?

Answer 26

Perfusion of poorly ventilated alveoli, which can be caused by airway obstruction (e.g., foreign body aspiration) or conditions such as pneumonia, atelectasis, CF, or pulmonary edema.

Question 27

What is the formula for diffusion?

Answer 27

Vgas = A x D x (P1-P2) / T

Question 28

What is the diffusion capacity of the lung?

Answer 28

DL, which is a product of A and D/T.

Question 29

Why is the diffusion capacity different for O2 and CO2?

Answer 29

Although the pressure gradient is 10 times larger for O2, CO2 is about 20x more soluble than O2 in water, resulting in a much larger DL for CO2.

Question 30

What is perfusion-limited gas exchange?

Answer 30

Gas exchange limited by the rate of blood flow through the pulmonary capillaries, where gases can diffuse freely across the blood-air barrier and the concentration of gases in the plasma will become equal to the concentration in the alveoli before the blood reaches the end of the capillary.

Question 31

What is diffusion-limited gas exchange?

Answer 31

It is when gas exchange is limited by the diffusion rate of the gas (e.g. O2, CO) across the blood-air barrier.

Question 32

When does diffusion-limited gas exchange occur?

Answer 32

It occurs during strenuous exercise or in lung diseases (emphysema, lung fibrosis).

Question 33

What is the pressure gradient for pO2 between the alveolus and the capillary?

Answer 33

The pressure gradient for pO2 is 60 mmHg.

Question 34

What is the pressure gradient for pCO2 between the alveolus and the capillary?

Answer 34

The pressure gradient for pCO2 is 6 mmHg.