Structure of the respiratory system, Lung volumes and capacities

Question 1

What are the conducting airways of the respiratory system?

Answer 1

1. trachea
2. bronchi
3. bronchioles
4. terminal bronchioles

Question 2

What are the functions of the conducting system of the lungs?

Answer 2

1. Bring air in/out
2. Warm air
3. Humidify air
4. filter air

Question 3

What do the walls of all conducting airways contain?

Answer 3

SMooth muscle

Question 4

What impact do sympathetic adrenergic neurons have on the conducting system?

Answer 4

They stimulate relaxation and dilation of the airways via B₂ receptors

Question 5

What do parasympathetic cholinergic neurons do to the conducting system?

Answer 5

activate muscarinic receptors which leads to contraction and constriction of airways

Question 6

What are the components of the respiratory zone of the lungs?

Answer 6

1. Respiratory bronchioles
2. Alveolar Ducts
3. Alveolar Sacs
4. Alveoli

Question 7

The respiratory bronchioles are transitional structures. In what way are they like the conducting zone? In what way are they like the respiratory zone?

Answer 7

They are like the conducting system because they have cilia and smooth muscle.

They are like the respiratory zone because they occasionally have alveoli branching off their walls and participate in gas exchange.

Question 8

Describe alveolar ducts. What do they terminate into?

Answer 8

They are completely lined with alveoli, have NO cilia and little smooth muscle.

They terminate into alveolar sacs.

Question 9

Alveolar Sacs are lined with?

Answer 9

Alveoli

Question 10

Alveolar walls are rimmed with elastic fibers and lined with epithelial cells. What types of epithelial cells will we find here?

Answer 10

Type I and Type II pneumocytes

Question 11

What is important about Type II pneumocytes?

Answer 11

1. They synthesize surfactant
2. have regenerative capacity for type I AND II pneumocytes

Question 12

Where do we find Dust cells?

What do they do?

Answer 12

Dust cells, AKA alveolar macrophages are found in the alveoli.

They keep alveoli free of dust/debris since alveoli have no cilia to perform this function.

Question 13

Pulmonary arteries travel with? They divide into?

Answer 13

The bronchi.

Divide into increasingly smaller arteries until the pulmonary capillaries.

Question 14

What impact does gravity have on blood flow in the lungs?

Answer 14

It prevents even distribution of blood in the lungs, when standing the apex of the lung will recieve less blood than the base. Laying supine, we see the effects of gravity dissapear.

Question 15

How is regulation of pulmonary blood flow accomplished?

Answer 15

Through alteration of the resistance of the pulmonary arterioles

Question 16

What is inspiratory capacity composed of?

Answer 16

Tidal volume plus inspiratory reserve volume

Question 17

Functional residual capacity is composed of?

What is it?

Answer 17

FRC = Expiratory reserve volume + Residual volume

The volume remaining in the lungs after a normal tidal volume is expired. (can be considered the equilibrium volume of the lungs)

Question 18

What is vital capacity? What is it composed of?

Answer 18

The volume that can be expired after maximal inspiration.

VC = Inspiratory capacity + expiratory reserve volume

Question 19

What are the two methods used to measure FRC?

Answer 19

Helium dilution

Full body plethysmography

Question 20

What is Pa_O2?

Answer 20

Partial pressure of O₂ in arterial blood

Question 21

What is Pa_CO2?

Answer 21

Partial pressure of CO₂ in arterial blood

Question 22

What is PI_O2?

Answer 22

Partial pressure of O₂ in dry inspired air

Question 23

What is PI_CO2?

Answer 23

Partial pressure of CO₂ in dry inspired air

Question 24

What is PA_O2?

Answer 24

Partial pressure of O₂ in alveolar air

Question 25

What is dead space?

Answer 25

The volume of the airways that does not participate in gas exchange

Question 26

hat is the anatomic dead space?

Answer 26

The volume of the conducting airways (usually 150 ml for a 150 lb person)

Question 27

What is functional dead space? What is the most important cause of this?

Answer 27

Ventilated alveoli that do not participate in gas exchange. Most imp.: is mismatch of ventilation and perfusion (or ventilation/perfusion defect), where ventilated alveoli are not perfused by capillary blood.

Question 28

What is physiologic dead space? What volume of phsyiologic dead space should you (ideally) see in a healthy person?

Answer 28

This is the sum of the anatomic dead space (conducting zone volume) and the functional dead space (non-perfused alveoli). In normal persons, the physiologic dead space should be nearly equal to the anatomic dead space.

Question 29

What is the formula for the ratio of physiologic dead space to tidal volume? V_D/V_T = ?

Answer 29

VD/VT = (Pa_CO2 - Pe_CO2)/Pa_CO2

Question 30

What is minute ventilation? What is the formula for it?

Answer 30

The total rate of air movement into and out of the lungs Minute ventilation - V_T x breaths/min

Question 31

What is alveolar ventilation? What is the formula?

Answer 31

Minute ventilation corrected for the physiologic dead space Alveolar Ventilation (V_A) = (V_T - V_D) x breaths/min

Question 32

If CO₂ production is constant, then what is PA_CO2 determined by?

Answer 32

Determined by alreolar ventilation

Question 33

because CO2 always equilibrates between pulmonary capillary blood and alveolar gas, the arterial P_CO2 always equals... This is important because...

Answer 33

The alveolar P_CO2 This allows us to use Pa_CO2 which can be measured, in calculations

Question 34

When alveolar ventilation is halved, what happens to P_CO2? Why?

Answer 34

P_CO2 doubles. Because less CO2 is being removed from the alveoli

Question 35

What is forced vital capacity?

Answer 35

FVC - the total volume of air that can be forcibly expired after a maximal inspiration.

Question 36

What is FEV₁?

Answer 36

The amount of air that can be forcibly expired in one second. (can also be FEV_{2 or 3}, but no 4 is needed since normally full volume can be exhaled in 3 seconds)

Question 37

What would you expect to see in the ratio of FEV₁/FVC for a patient with an obstructive disease such as asthma?

Answer 37

Reduced ratio

Question 38

What would you expect to see in the ratio of FEV1/FVC for a patient with an restrictive disease such as fibrosis?

Answer 38

Increased ratio, due to more substantial decrease in FVC than the decrease in FEV₁