Final Lecture; Final Exam Random Loose Ends

Question 1

What enzyme contributes to emphysema by breaking down elastic lung tissue?

Answer 1

Neutrophil elastase, part of the trypsin family of proteases.

Question 2

What is the effect of emphysema on residual volume (RV)?

Answer 2

RV increases due to trapped air in the alveoli.

Question 3

Why does total lung capacity increase in emphysema?

Answer 3

Because RV increases significantly, pushing other volumes to expand TLC.

Question 4

What happens to ERV and IRV in emphysema?

Answer 4

Both ERV and IRV decrease as RV increases.

Question 5

What happens when tidal volume equals total lung capacity?

Answer 5

There is no inspiratory capacity left, indicating severe disease.

Question 6

How do obstructive and restrictive diseases differ in lung volumes?

Answer 6

Obstructive = increased RV and TLC; Restrictive = decreased RV, ERV, IRV, and TLC.

Question 7

How does the nose filter large particles from inhaled air?

Answer 7

Turbinates swirl air and mucus traps larger particles.

Question 8

Why can’t the nose filter very small particles like smoke?

Answer 8

Small particles have low inertia and can make the hairpin turn into the airway without being trapped.

Question 9

What nerve innervates most intrinsic laryngeal muscles?

Answer 9

Inferior laryngeal nerve (from recurrent laryngeal nerve).

Question 10

Which laryngeal muscle is innervated by the superior laryngeal nerve?

Answer 10

Cricothyroid muscle.

Question 11

What is Galen’s anastomosis?

Answer 11

A non-functional anatomical connection between superior and inferior laryngeal nerves.

Question 12

What are the suprahyoid muscles?

Answer 12

Digastric (anterior/posterior), mylohyoid, geniohyoid, stylohyoid.

Question 13

What are the infrahyoid muscles?

Answer 13

Sternohyoid, omohyoid (superior/inferior), sternothyroid, thyrohyoid.

Question 14

What muscle action moves the hyoid bone upward?

Answer 14

Suprahyoid muscle contraction.

Question 15

What muscle action moves the hyoid bone downward?

Answer 15

Infrahyoid muscle contraction.

Question 16

What is Cheyne-Stokes breathing?

Answer 16

Cyclic breathing with increasing then decreasing depth, followed by apnea; often from brain injury.

Question 17

What is Biot’s (Bo) breathing?

Answer 17

Irregular breathing pattern with unpredictable apnea; associated with opioid overdose.

Question 18

What is agonal breathing?

Answer 18

Gasping respirations, typically near death; from brainstem dysfunction.

Question 19

What is the difference between tachypnea and hyperventilation?

Answer 19

Tachypnea is rapid breathing; hyperventilation is excessive ventilation relative to metabolic need.

Question 20

What is Kussmaul breathing?

Answer 20

Deep, rapid breaths seen in metabolic acidosis, like DKA.

Question 21

What causes elevated CO₂ on capnography?

Answer 21

• Hypoventilation
• fever
• bicarb infusion (from increased CO2 production in the blood)
• tourniquet release
• increased cardiac output.

Question 22

What causes decreased CO₂ on capnography?

Answer 22

Hyperventilation, PE, airway obstruction, low cardiac output, extubation, esophageal intubation.

Question 23

What waveform indicates bronchospasm?

Answer 23

“Shark-fin” or sloped expiratory upslope.

Question 24

What does an abrupt drop to zero on capnography indicate?

Answer 24

Disconnection or extubation.

Question 25

What is the earliest sign of malignant hyperthermia?

Answer 25

Rapid rise in end-tidal CO₂.

Question 26

What is the role of capnography in CPR?

Answer 26

Rising ETCO₂ may indicate return of spontaneous circulation.

Question 27

What law governs gas compression in a plethysmography box?

Answer 27

Boyle’s Law (P1V1 = P2V2).

Question 28

What does Dalton’s Law state?

Answer 28

Total pressure = sum of partial pressures of individual gases.

Question 29

What does Graham’s Law say?

Answer 29

Rate of gas diffusion is inversely proportional to the square root of its molecular weight.

Question 30

What does Henry’s Law state?

Answer 30

Gas solubility in liquid is proportional to its partial pressure.

Question 31

What is used to measure RV or FRC besides plethysmography?

Answer 31

Helium dilution.

Question 32

Why does anesthesia reduce lung volumes?

Answer 32

Muscle relaxation, supine position, and abdominal pressure compress lungs.

Question 33

What area is ventilated most when lung volume is very low and the patient is supine?

Answer 33

Anterior lungs.

Question 34

Where is perfusion greatest in a supine patient?

Answer 34

Posterior lungs (gravity dependent).

Question 35

How does PEEP improve V/Q matching?

Answer 35

Increases lung volume, reduces atelectasis, redistributes ventilation toward posterior lung.

Question 36

What is a downside of PEEP?

Answer 36

Increases right heart workload, especially in patients with right heart failure.

Question 37

What are J receptors in the lungs?

Answer 37

Juxtacapillary (J) receptors are stretch receptors that sense lung inflation.

Question 38

What reflex do J receptors mediate?

Answer 38

The Hering-Breuer reflex (inflation reflex) — they inhibit inspiration when lungs are overinflated.

Question 39

What triggers the Hering-Breuer reflex?

Answer 39

Lung inflation activating pulmonary stretch receptors.

Question 40

What is the functional purpose of the Hering-Breuer reflex?

Answer 40

To prevent over-inflation of the lungs by terminating inspiration.

Question 41

What is the effect of overstretched lungs on breathing patterns?

Answer 41

Can lead to inspiratory inhibition and irregular respiratory rhythms.

Question 42

Which cranial nerve provides sensory innervation to the face and nasal mucosa?

Answer 42

The trigeminal nerve (CN V), especially its maxillary (V2) branch.

Question 43

How can lateral inhibition reduce the sneeze reflex?

Answer 43

Stimulating adjacent sensory areas (like pinching the upper lip) can dampen sneeze signals.

Question 44

What are common methods to suppress a sneeze reflex?

Answer 44

Drinking water or pinching the upper lip — both activate V2 sensory pathways.

Question 45

How does a pulmonary embolism affect ETCO₂?

Answer 45

Decreases ETCO₂ due to reduced perfusion and increased dead space.

Question 46

How does increased alveolar dead space affect capnography?

Answer 46

Dilutes alveolar gas with CO₂-free air, lowering ETCO₂.

Question 47

What is the relationship between arterial and alveolar CO₂?

Answer 47

Arterial PCO₂ is always equal to or higher than alveolar PCO₂.

Question 48

What is the alveolar-arterial difference in O₂?

Answer 48

Alveolar PO₂ is always equal to or higher than arterial PO₂.

Question 49

What does helium dilution measure?

Answer 49

Functional residual capacity (FRC) and residual volume (RV).

Question 50

Why is helium used in lung volume testing?

Answer 50

It is inert and doesn’t diffuse across the alveolar-capillary membrane.

Question 51

What principle underlies body plethysmography?

Answer 51

Boyle’s Law — measuring pressure and volume changes in a sealed box.

Question 52

What does Fick’s Law of diffusion state?

Answer 52

Diffusion rate ∝ surface area × gradient / membrane thickness.

Question 53

What does Ohm’s Law analogously describe in the lungs?

Answer 53

Flow = Pressure / Resistance (applies to airways and vasculature).

Question 54

What lung regions receive most ventilation in supine, paralyzed patients?

Answer 54

Anterior (non-dependent) lung regions.

Question 55

Why is V/Q mismatch common during anesthesia?

Answer 55

Low lung volumes favor anterior ventilation while posterior regions remain perfused.

Question 56

How does using 30% FiO₂ help during surgery?

Answer 56

It provides a buffer for oxygenation in case of transient hypoventilation or mismatch.

Question 57

Why might a single-lung transplant cause a split capnography waveform?

Answer 57

Due to uneven alveolar emptying — healthy lung empties faster than diseased lung.