Exam 3 Hematologic Slide Set 1 Flashcards
Hematopoesis from the start of life
- Stem cells in the yolk sac at 3rd week of development
- Cells migrate to the developing liver at 3 months
- Blood islands migrate from yolk sac to bone marrow at 4 months
- ALL the bone marrow is active in producing blood cells at birth
- Production is isolated to specific marrow sites by puberty
Red Marrow sites in adulthood
Where blood cells are being produced…
- vertebrae
- ribs
- skull
- pelvis
- proximal epiphyseal portions of the humerus & femur
Process of hematopoesis
-Pluripotent stem cells give rise to the full line of blood cells, which includes: RBCs, WBCs (neutrophils, lymphocytes, eosinophils, monocytes, & macrophages), platelets, plasma cells, mast cells, NK cells, B cells & T cells.
RBC facts
- They transport O2 with hemoglobin! :D
- They consist of 90% hemoglobin! (That’s why they’re red!)
- Their normal life span is 90-120 days!
Anemia defined
Decreased amounts of RBCs (size, numbers, or both), decreased hematocrit, decreased hemoglobin.
Characterized by low O2 transport capacity of the blood.
Polycythemia defined
INCREASED amounts of RBCs!
Anemia is due to what??
- Blood loss
- Impaired RBC production
- Increased RBC destruction
- A combination of the above
Examples of Anemias
- Blood loss
- G6PD
- Iron-deficiency anemia
- Hereditary spherocytosis
- Pernicious anemia
- Thalassemia
- Sickle-cell anemia
Sx of Anemia
- Pallor
- Increased rate/weak pulse
- dyspnea
- palpitations
- dizziness
- fatigue
- headaches
- faintness/syncope
The simplest breakdown of anemia classifications
Loss or Decreased Production
I.e.:
Excessive blood turnover (Hemorrhage or Hemolysis)
or
Failure of blood production
Blood Loss
- Can be massive & acute or slow & chronic (GI, Gyn, or GU)
- Sx vary with degree of anemia & rate of development
- A rapid drop is not tolerated as well, and thus is more symptomatic than a similar loss that is slow over time
Normal Response to Acute Blood Loss
- Lose too much = death
- Otherwise, volume rapidly restored as water is shifted from interstitial fluid compartment into the blood
- Hemo-dilution lowers hematocrit
- Decreased oxygenation (of renal JGA cells) triggers EPO production
- Reticulocytes (young RBCs, just lost nucleus) start to appear in the peripheral blood, can climb from 1.5% to 15% within a week of the event
Polychromasia
A disorder, high # of immature red blood cells found in the bloodstream. Cells stain grayish blue/purplish instead of normal red/pink. Usually an indication of bone marrow stress.
Normal lab value for reticulocytes
0.5%-1.5% in circulating blood
When does chronic blood loss cause anemia?
1- if the rate of loss exceeds bone marrow’s capacity to restore it
2- if the iron sotres are inadequate
These organ systems are usually involved with chronic hemorrhage…
“Gee, why am I anemic??”
GI - ulcer, colitis, cancer
Gynecologic - excessive menstrual flow, cancer
Genitourinary - cancer or stone
Hemolytic Anemias - Characterization
Characterized by: shortened RBC life span, Hgb breakdown products accumulating, marked increase in erythropoiesis in BM.
Characterized as Extravascular/Intravascular and/or Extrinsic/Intrinsic
Hemolytic Anemias - Extravascular v. Intravascular
- Extravascular hemolysis: Spleen (mononuclear phagocytic cells) normally destroy RBCs, can contribute to hemolytic anemias! Also sickle cell anemia & hereditary spherocytisis
- Intravascular hemolysis: destruction of RBCs in the vascular compartment - mechanical trauma (heart valves, marathons & bongo drums), antibody fixation (mismatched blood transfusion), toxic injury to RBCs (malaria, septic shock). Peripheral smear would show multiple fragmented RBCs - helmet cells & schistocytes
Hemolytic Anemias - Intrinsic v. Extrinsic
- Intrinsic: genetic & hereditary RBC diseases (sickle cell, hereditary spherocytosis). May see schistocytes or spherocytes. Can include disorders of rBC membrane, RBC enzyme deficiencies, disorders of hemoglobin synthesis. Often have a + family hx. Can be FURTHER divided into: Abnormal hemoglobin, abnormal RBC metabolism, or abnormal hemoglobin SYNthesis.
- Extrinsic: cause is extrinsic TO THE RBC - heart valve prosthesis/AV shunts, malarial infection, lead poisoning or snake venom, hypersplenism (abnormal sequestration of RBCs in spleen), acquired hemolytic anemias (autoimmune - IgG against RBCs)
Autoimmune causes of Extrinsic Hemolytic Anemias
Can be Primary/Idiopathic or Secondary to…
-lymphoma, carcinoma, sarcoidosis, collagen vascular dz (lupus or RA)
Immune hemolysis is caused by…
Bad blood transfusions
Fetal/Maternal incompatibility… ?? What the hell even is this card? Ugh.
What’s Hemoglobin?
- metallo-proteins made of 2 identical pairs of chains
- Hb F during fetal/neonatal period is made of 2 alpha & 2 gamma chains
- After 1 year, the adult profile is present: over 95% adult hemoglobin (Hb A, 2 alpha chains, 2beta chains) & 2-3.5% of hemoglobin A2
Sickle Cells
- *A single point mutation in the beta-globulin creates hemoglobin S.
- Autosomal recessive inheritance of the dz
- RBCs sickle at low pH & low O2, sickling is initially reversible. Low pH reduces oxygen’s affinity for hemoglobin!
- Shorter life span! 20 days**
Sickle Cell Disease prevalence in US & Africa
- ~8% of American blacks are heterozygous for Hb S = carriers or “sickle cell trait” = 40% Hb S, 60% HbA?
- Homozygous = almost 100% Hb S
- 2 million Americans have trait
- 1 in 500 African-Americans develops sickle cell anemia
- In Africa 1/100 develop dz
- Newborns have several months of protection from fetal hemoglobin
