Disorders of RBCs II Flashcards
Where do RBCs develop during fetal and life development?
Fetal Life:
3 weeks: Yolk sack (derived from mesoderm of aorta gonad mesonephros)
Months 3-8: Stem cells migrate to liver
- Also spleen, thymus, lymph nodes
Birth - Age 18: All marrow
>Age 18: Vetebrae skull, ribs, pelvis (<50% marrow space is active)
What is the average life span of RBCs?
120 days
What are normal values of Hemoglobin for men and women?
Men: 14-18
Women: 12-16
What are signs and symptoms of anemia?
Note: O2 delivery = cardiac output X O2 carrying capacity
With anemia:
- Cardiac output increases
(fast rate, palpitations, murmurs)
- Heart failure from too much output
(dyspnea, nocturia, orthopnea)
- Insufficient O2 delivery
(angina, claudication, mental status changes)
What are three mechanistic causes of anemia?
- Blood Loss (acute and chronic)
- Increased rate of RBC destruction
- Impaired RBC production
What are signs and symptoms of acute blood loss?
- Effect depends on amount and rate
- Shock, CV collapse, death ultimately occur
- FIRST changes seen: Leukocytosis
- Hgb and Hct don’t change
- Plasma wanter increases from interstitium (will eventually cause Hgb to fall)
- Reticulocyte count rises around day 7
What are signs and symptoms of chronic blood loss?
- Hgb an Hct will depend on rate of loss and ability of marrow to replenish
- Marrow can increase production 10 fold
- Anemia arises when rate of production can’t be sustained (depletion, infection, etc) or if the RBC survival is short
What are hemolytic anemias?
Premature destruction of RBCs
- Compensatory increase in production; mediated by erythropoietin
- Accumulation of products of hemoglobin catabolism (depletion of haptoglobin, increase bilirubin, jaundice, biliary stone issues)
What are the two location classifications of hemolytic anemias?
Intravascular
Extravascular:
RBCs destroyed because they cannot navigate spaces or bear surface markers targeting them for destruction
