Lecture 2, 3 and 4: Anemia I-II and RBC
cases
what changes do the nucleus and cell undergo overall during erythropoiesis -
ANS --> nucleus becomes smaller (more pyknotic) to fit more hemoglobin in the
cell
--> cell becomes more hemoglobin-ized (pinker cytoplasm)
where is erythropoietin produced and what stimulates its production - ANS
produced in the kidney and is stimulated by low oxygen tension in the blood (and
also dehydration)
describe the shape and lifespan of the normal RBC
what is the function of its shape - ANS Shape: biconcave disk
--> increases surface area for O2 exchange, increases distensibility
Lifespan: 120 days
which organ is responsible for the removal of RBCs from the circulation - ANS
the spleen
describe the structure of hemoglobin - ANS four globin polypeptides with four
heme groups.
These combine to make 2 alpha chains and two beta chains
what is heme made from - ANS 1) iron
2) porphyrin ring
list the main types of hemoglobin in the body, and the subunit composition of
each
,what is the main type in adults and the main type in newborns - ANS hemoglobin
A = 2 alpha, 2 beta
hemoglobin A1C = 2 alpha, 2 beta
hemoglobin A2 = 2 alpha, 2 delta
hemoglobin F = 2 alpha, 2 gamma
ADULTS = Hemoglobin A
NEWBORNS = hemoglobin F
what are the defining structural characteristics of RBCs and how do these
structures relate to the RBCs function - ANS 1) contains hemoglobin: allows
transport of oxygen
2) no nucleus: can carry more Hb
3) circular biconcave shape: increased surface area to carry more oxygen
what percentage of RBCs are removed from the circulation each day
by how much can EPO stimulate the bone marrow to increase RBC production in
adults - ANS 1%
5-fold
what are the 2 main "skeletal supports" of the RBC membrane
what is their function - ANS ankyrin and spectrin are proteins that cross-link in
the cytoskeleton of an RBC
--> to provide distensibility
how do flow rates through vasculature affect RBC shape
how would different flow rates affect RBC if ankyrin and spectrin were abnormal -
ANS slower flow == more symmetric RBC shape
,faster flow == more asymmetric shape
without normal ankyrin and spectrin, the cell is more rigid --> when subjected to
different flow rates, the cell will break (like glass instead of a balloon)
what is anemia - ANS decreased oxygen delivered in the blood due to
1) Reduction in total number of RBCs
2) Decrease in circulating RBC mass
3) Decrease in Hb
what are the general causes of Anemia - ANS 1) decreased RBC production
2) Increased RBC Destruction
3) Blood loss
what are the clinical signs of anemia - ANS signs and symptoms of Hypoxia
1) weakness/fatigue
2) pale conjunctiva and skin (pallor)
3) headache/lightheadedness/fainting
4) angina (insufficient O2 delivery to heart muscle)
5) SOB
if a patient is anemic and their RBCs are too SMALL, what could this be due to -
ANS 1) can't make heme
- iron deficiency
- sideroblastic anemia
2) can't make globin
- thalassemia
- sickle cell disease (can be normocytic or microcytic)
- other hemoglobinopathies
, if a patient is anemic and their RBCs are NORMAL sized, what could this be due
to - ANS 1) acute blood loss
2) hemolysis due to autoimmune or other issue
3) anemia of chronic disease (can be microcytic or normocytic)
what are the different classes of anemia and give the mean corpuscular volume
(MCV) that defines each - ANS 1) Microcytic and Hypochromic (MCV <70um³)
2) Normocytic and Normochromic (MCV=80-100um³)
3) Macrocytic (MCV>100um³)
what laboratory tests can be used to diagnose anemia - ANS 1) CBC (focusing on
Hg and HCT)
2) RBC indices (MCW, RDW)
3) peripheral blood smear
4) reticulocyte count
5) specific tests (iron, B12, folate, ferritin, TIBC)
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