Exam 2, L1

Question 1

Why is the right lung larger than the left lung?

Answer 1

Because the heart occupies space on the left side.

Question 2

How far can the lungs extend superiorly?

Answer 2

Past the first rib and sometimes above the clavicle.

Question 3

What defines the thorax as a ‘sealed unit’?

Answer 3

The thorax is a closed negative pressure system where all structures are interdependent.

Question 4

What are the two pleural linings of the lungs?

Answer 4

Visceral pleura (on the lung surface) and parietal pleura (lining the chest wall).

Question 5

What is the purpose of pleural fluid?

Answer 5

Reduces friction and allows smooth movement of lungs within the chest cavity.

Question 6

What is the main muscle of inspiration?

Answer 6

The diaphragm.

Question 7

What nerves innervate the diaphragm?

Answer 7

Phrenic nerves (C3–C5).

Question 8

What are the three diaphragm openings?

Answer 8

IVC, esophagus, and aorta.

Question 9

What is the central tendon of the diaphragm?

Answer 9

A connective tissue platform that supports the heart.

Question 10

What risk is associated with regional anesthesia near the cervical plexus?

Answer 10

Accidental phrenic nerve block, which can impair breathing.

Question 11

Name three accessory respiratory muscles.

Answer 11

Scalene, intercostals, and abdominal muscles.

Question 12

When are accessory muscles used?

Answer 12

During respiratory distress, exercise, or forced breathing.

Question 13

How many airway generations are in the respiratory tree?

Answer 13

24 generations.

Question 14

What generation is the trachea?

Answer 14

Generation 0.

Question 15

Where does gas exchange occur?

Answer 15

In the respiratory zone: alveoli, alveolar ducts, and respiratory bronchioles.

Question 16

What are conducting vs. respiratory zones?

Answer 16

Conducting zone moves air; respiratory zone performs gas exchange.

Question 17

What are respiratory bronchioles considered?

Answer 17

Transitional zones — some gas exchange occurs.

Question 18

What does eupnea mean?

Answer 18

Normal breathing.

Question 19

What is dyspnea?

Answer 19

Subjective shortness of breath or respiratory distress.

Question 20

What is orthopnea?

Answer 20

Difficulty breathing while lying flat.

Question 21

Define hypoxia vs. hypoxemia.

Answer 21

Hypoxia: low O₂ in tissues; Hypoxemia: low O₂ in arterial blood.

Question 22

What is cyanosis?

Answer 22

Bluish discoloration due to ≥5 g/dL deoxyhemoglobin.

Question 23

What unit is used for thoracic pressures?

Answer 23

cm H₂O — greater resolution than mmHg for low pressures.

Question 24

What is normal pleural pressure between breaths?

Answer 24

−5 cm H₂O

Question 25

What does transpulmonary pressure represent?

Answer 25

The difference between alveolar and pleural pressure — drives lung inflation.

Question 26

What is the alveolar pressure at rest?

Answer 26

0 cm H₂O, equal to atmospheric pressure.

Question 27

What is a normal tidal volume (VT)?

Answer 27

500 mL

Question 28

What is total lung capacity (TLC)?

Answer 28

6 liters in a healthy adult

Question 29

What is functional residual capacity (FRC)?

Answer 29

3 liters — the volume left in the lungs after normal expiration.

Question 30

What are the components of FRC?

Answer 30

Expiratory reserve volume (ERV) + Residual volume (RV)

Question 31

How much is the ERV and RV each?

Answer 31

1.5 L each

Question 32

What is inspiratory reserve volume (IRV)?

Answer 32

2.5 L — volume that can be inhaled above tidal volume.

Question 33

What is inspiratory capacity (IC)?

Answer 33

VT + IRV = 3 L

Question 34

What is vital capacity (VC)?

Answer 34

Total air that can be forcibly exhaled after maximal inspiration — VC = IRV + VT + ERV = 4.5 L

Question 35

What is the normal respiratory rate?

Answer 35

12 breaths per minute

Question 36

What are the time phases of a normal breath cycle?

Answer 36

2 sec inspiration → 2 sec expiration → 1 sec pause

Question 37

When does peak inspiratory flow occur?

Answer 37

1 second into inspiration, when alveolar pressure is most negative.

Question 38

What is transpulmonary pressure during inspiration?

Answer 38

+5 cm H₂O (alveolar 0, pleural −5)

Question 39

What mechanism allows for passive expiration?

Answer 39

Elastic recoil of stretched alveoli.

Question 40

What determines airflow direction in the lungs?

Answer 40

ΔP = alveolar − atmospheric pressure

Question 41

When alveolar pressure < atmospheric, what occurs?

Answer 41

Inspiration

Question 42

When alveolar pressure > atmospheric, what occurs?

Answer 42

Expiration

Question 43

What defines Zone 1?

Answer 43

No blood flow: PA > Pa > Pv (alveolar pressure compresses capillaries)

Question 44

What defines Zone 2?

Answer 44

Intermittent flow: Pa > PA > Pv ('waterfall zone')

Question 45

What defines Zone 3?

Answer 45

Continuous flow: Pa > Pv > PA — most perfused zone

Question 46

What is Zone 4?

Answer 46

At the very base of the lung: continuous but reduced flow due to compression

Question 47

What increases the risk of creating a Zone 1?

Answer 47

Positive pressure ventilation — raises alveolar pressure above vascular pressures.