Physiology

Question 1

Laplace’s law

Answer 1

Pressure required to keep open alveoli = 2T/r

smaller alveoli collapse first, surfactant helps by reducing surface tension

Question 2

What does inhalation and exhalation do to lung vascular resistance?

Answer 2

1) Inhalation stretches alveoli vessels and causes increased resistance.
2) Exhalation pushes on extra-alveolar vessels and increases resistance.

Least vascular resistance is at FRC
Also, least airway resistance is at FRC (air has no tendency to move in or out of lung)

Question 3

Furthest you can find mucociliary clearance in lung?

Answer 3

URI clear 10-15 micron particles.
2.5-10 micron - Trachea to large bronchioles - mucociliary clearance. Afterwards club cells are secretory cell. Club cells produce glycosaminoglycans to trap and use P450 in smooth ER to detoxify.
Under 2 micron - Alveolar macrophages

Question 4

What part of bronchial tree has most resistance?

Answer 4

1. Medium sized bronchi

2. Trachea

Question 5

Normal A-a gradient hypoxemia

Answer 5

Hypoventilation (OSA, obesity, opiods) and high altitude

Question 6

Receptors that drive respiratory rate

Answer 6

Healthy people - PaCO2 in medulla (central chemo receptor)

COPD - PaO2 in carotid body (CN9) and aortic arch (CN10)

Question 7

Alveolar ventillation

Answer 7

= Tidal volume x RR - dead spacex RR rate

= minute ventillation - dead space x RR rate

Question 8

How does Interstitial lung disease cause increased FEV1/FVC?

Answer 8

Increased flow due to radial traction on airway walls from fibrosis. Both FEV1 and FVC decreased but flow per volume is higher b/c airways opened up

Question 9

CFTR

Answer 9

CFTR = ATP-gated chloride channel, allows chloride out to hydrate lung and pancreas secretions. Also allows Cl- back into cells in eccrine sweat glands. Sodium follows wherever Cl- goes because ofENaC.

deletion of Phe on chromosome 7

Question 10

PE ABG values

Answer 10

Respiratory alkalosis with low PO2

Question 11

Cheyne stokes breathing

Answer 11

Increasing, then decreasing tidal volume –> apnea

= CHF

Question 12

Pleuritic chest pain nerve distribution

Answer 12

Parietal pleura
- Mediastinum, diaphragm (heart and lower lobe pneumonias) –> C3-C5 distribution phrenic nerve

• Rest of parietal pleura = intercostal nerves

Question 13

Smoking addiction receptor

Answer 13

alpha4beta2 NICOTINIC ACETYLCHOLINE receptor in CNS

- Varenecline is partial agonist of this

Question 14

HiB vaccine

Answer 14

HiB capsule (polysaccharide capsule w/polyribosylribitol phosphate - PRP that protects from phagocytosis)

+ tetanus toxoid

Question 15

Secondary bacterial pneumonia after influenza infection

Answer 15

1. Strep pneumo
2. Staph
3. Hib

Question 16

Why are Mycoplasma infections (Ureaplasma, etc) resistant to penicillins?

Answer 16

Have no cell wall - need anti-ribosomal (tetracyclines, macrolides)

Question 17

What do you see in acute heart failure vs chronic?

Answer 17

Chronic heart failure = heart failure cells (hemosidern laden macrophages)
Acute heart failure = transudate

Question 18

Abscess vs. granuloma formation

Answer 18

Granuloma: Neutrophil releases IL12 –> Th1 releases IFN-gamma –> Macrophages cause granuloma

Abscess: Neutrophils/Macrophages release lysosomal enzymes

Question 19

Lobar pneumonia stages

Answer 19

1 day - Congestion: reg, boggy, bacteria
1 week - Red/Grey hepatization
      - early: Red: Neutrophils w/RBCs
      - late: Gray: Neutrophils w/fibrin
After 1 week: Normal

Question 20

Selective IgA deficiency

Answer 20

Anaphylaxis with transfusion

• GI/Sinus infections
• autoimmune disease

Question 21

Proteases/Antiproteases

Answer 21

Proteases: Elastase, cathepsin G, MMPs
Antiproteases: alpha1-antitrypsin, alpha2 macroglobulin, TIMPS

Question 22

Retinopathy of prematurity

Answer 22

O2 treatment for premie –> increased VEGF/neovascularization –> retinal detachment/blindness

Question 23

Aging lung PFTs

Answer 23

INCREASED RESIDUAL VOLUME, decreased FVC, normal TLC

Question 24

CF clinical characteristics

Answer 24

Confirmed with sweat testing. High NaCl in sweat (can lead to hyponatremia if kid exercises). Salt supplementation recommended.

Question 25

Central chemoreceptors vs peripheral receptor

Answer 25

Central - sense pH (via CO2 diffusion)

Peripheral - sense pO2