Physiology

Question 1

Characterisitics of aplastic crisis in a patient with chronic hemolytic anemias

Answer 1

Transient arrest of erythropoiesis due to parvovirus B19 (nonenveloped single-stranded DNA virus).
Seen as anemia only.
Infection of erithroid precursor cells in bone marrow
Reticulocyte count diminished

Question 2

Mechanism of action of apixaban

Answer 2

Anticoagulant that block active site of factor Xa → ↓ conversion of prothrombin to thrombin

Question 3

Molecule synthesized in liver that acts as the central regulator of iron homeostasis. Acute phase reactant. Controls intestinal iron absorption and macrophage iron release

Answer 3

Hepcidin

Question 4

What causes RBC sickling

Answer 4

Low oxygen levels, increased acidity and dehydration

Question 5

Reddish skin discoloration, tachypnea, headache, tachycardia, N/V, confusion, weakness, bitter almond odor, cardiovascular collapse

Answer 5

Cyanide poisoning

Question 6

Why is cyanide poisoning treated with inhaled amyl nitrate?

Answer 6

Because nitrites oxidize Hb → methemoglobin → binds cyanide → cyanomethemoglobin → less toxicity

Question 7

Enzyme involved in Porphyria cutanea tarda

Answer 7

Uroporphyrinogen decarboxylase

Question 8

Carbon monoxide poisoning effect on oxygen content of blood

Answer 8

Normal PaO2, normal metahemoglobinemia, ↑ carboxyhemoglobin, ↓ total O2 content.
Left shift in curve: ↑ affinity for O2, ↓ O2 unloading in tissues

Question 9

Characteristics of cold autoimmune hemolytic anemia

Answer 9

Acute anemia. IgM + complement → RBC agglutination upon exposure to cold .
Seen in CLL, Mycoplasma pneumoniae infections, mononucleosis

Question 10

Signaling pathway of EPO

Answer 10

JAK2/STAT

Question 11

Precursor aminoacid in the synthesis of heme

Answer 11

Glycine

Question 12

Locations in the cell where the heme molecule is sinthesized

Answer 12

Mitochondria and cytoplasm