Explain the absorption and assimilation of nonheme iron into ...

[PhilipSeeMore]

Explain the absorption and assimilation of nonheme iron into hemoglobin in the RBC.
 
  What will be an ideal response?

Question 2

A 55-year-old male consulted his physician because of weakness, lightheadedness, vertigo, and angina. The patient also complained of sores on his tongue. The physical examination revealed jaundice.
 
  The pulse rate was increased, and the spleen and liver were slightly enlarged. The tongue appeared smooth and bright red in color. Family history revealed no clues. Neurological exam revealed quickening of reflex responses. Patient history indicated a total gastrectomy five years earlier for stomach cancer and intermittent heart problems that had not required surgery. The physician ordered the following tests:
 
  TEST RESULTS
  WBC 3.1 x 109/L
  RBC 2.45 x 1012/L
  HGB 10.5 gm/dL
  HCT 29.0
  MCV 118 fl
  MCH 42.8 pg
  MCHC 36.2 gm/dL
  RDW 15.7
  PLT 83 x 109/L
 
  Differential:
  Polys 49
  Stabs 6
  Lymphs 30
  Mono 8
  Eos 5
  Basos 2
  Peripheral blood: macro-ovalocytes, no hypersegmentation noted.
 
  What would be the results of vitamin B12 and/or folate levels in a diagnosis of pernicious anemia?
  a. Increased folate
  b. Increased vitamin B12
  c. Decreased vitamin B12
  d. Decreased folate and vitamin B12

[aruss1303]

Answer to Question 1

Answer: Nonheme iron is usually in the trivalent (ferric) form. Once it comes into contact with the enterocytes, it is reduced to the divalent (ferrous) form by DCytB. DMT1 is responsible for transporting ferrous iron through the apical membrane. Ferroportin then takes ferrous iron from the apical membrane across the basolateral membrane. At the basolateral membrane, hephaestin converts ferrous iron back to the ferric form, which binds to transferrin in the blood and is transported to the bone marrow. It can be used in heme synthesis or stored as ferritin. Some of the iron remains in the enterocyte as ferritin.

Answer to Question 2

Correct Answer: C