Anatomy Flashcards

0
Q

What is the diaphragm innervated by?

A

Phrenic nerve (C3, 4, 5)

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1
Q

What structures perforate the diaphragm at T8? T10? T12?

A

T8: IVC
T10: esophagus
T12: aorta, thoracic duct, azygos vein

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2
Q

What favors the taut/low affinity form of Hb over the relaxed/high affinity form?

A

increased Cl-, H+, CO2, 2,3-BPG and temperature
all shift dissociation curve to the right, increasing the unloading of O2
(decreases affinity for O2)

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3
Q

What is methemoglobin? What causes methemoglobinemia? What is the treatment?

A

Methemeglobin - oxidized form of Hb (ferric, Fe3+) that does not bind O2 as readily, but has a high affinity for cyanide
Iron is normally in a reduced ferrous, Fe2+ state

Caused by nitrites (poisoning causes oxidation of Fe2+ to Fe3+)
Treated with methylene blue

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4
Q

Why is cyanide toxic? What is the treatment and mechanism?

A

CN binds to iron-containing enzymes (most important is the cytochrome a-a3 complex critical for e- transport during ox-phos in mitochondria - inhibits aerobic metabolism in minute amounts!)

Treatment is nitrates and sodium thiosulfate.

Nitrates - oxidize Hb into methemoglobin which binds CN with high affinity (binds and sequesters CN in blood and away from mito)
Sodium thiosulfate - combines with CN to form less toxic thiocyanate (excreted in urine)

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5
Q

What are the perfusion-limited gases? What are the diffusion-limited gases?

A

Perfusion-limited: O2 in normal people, CO2, N2O

Diffusion-limited: CO, O2 in pts with emphysema or fibrosis

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6
Q

Where in the lung is ventilation greatest? Perfusion? What is the V/Q ratio at the apex vs. base of the lung?

A

Ventilation and perfusion is greatest at the base of the lung vs. apex.

apex V/Q = 3 (wasted ventilation; low ventilation/very low perfusion)
base V/Q = 0.6 (wasted perfusion; high ventilation/very high perfusion)

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7
Q

What are the 3 forms in which CO2 is transported from tissues to the lungs?

A
  • HCO3- (90%)
  • Carbaminohemoglobin / HbCO2 (5%)
    CO2 bound to N-terminus of globin (not heme) and favors taut Hb
  • dissolved CO2 (5%)
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8
Q

What is pulmonary surfactant comprised of? Which is the most important?

A

Pulmonary surfactant is a complex mix of lecithins,

the most important of which is dipalmitoylphosphatidylcholine.

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9
Q

How is fetal lung maturity measured?

A

Lecithin to sphingomyelin ratio > 2.0 in amniotic fluid indicates fetal lung maturity

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10
Q

What type of organisms are responsible for aspiration pneumonia? What species are common?

A

most often due to anaerobic bacteria in the oropharynx

  • Bacteroides
  • Fusobacterium
  • Peptococcus
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11
Q

What kind of pneumonia is Legionella associated with? What is the best way to visualize it?

A

Atypical/interstitial pneumonia

Intracellular organism, best visualized by silver stain

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