Intro to Heme Flashcards
(26 cards)
4 Compartments Where Blood Exists in the Body
- bone marrow
- blood
- lymphatic system
- tissues
Blood Compositioin
- formed elements: RBCs, WBCs, platelets
- plasma: water, dissolved ions, proteins
Where does fetal/neonatal hematopoiesis occur?
- primitive hematopoietic cells at 4-5 wks gestation
- liver at 5 weeks
- bone marrow and thymus at 8 weeks
- spleen 12 weeks
What is the primary hematopoietic organ in adults?
- bone marrow
- first the long bones (until 20 years or so)
- then vertebrae and pelvis are active most of our lives
Bone Marrow Composition
- stroma: sinuses lined with endothelial cells and fibroblasts
- hematopoietic cells: stem cells become mature blood cells; must be in contact or near stroma
What is the normal hematopoietic process? (Think about the diagram/flow chart of blood cells)
- a pluripotent stem cell becomes a myeloid or lymphoid stem cell
- myeloid stem cell can become RBCs, platelets, WBCs, or monocytes
- lymphoid stem cell can become T cells and B lymphocytes (plasma cells)
What is required for hematopoiesis to occur?
- healthy bone marrow
- hormones/cytokines (erythropoietin, thrombopoietin, etc)
- nutritional factors: iron, folate, B12
Erythropoiesis
- RBCs originate from myeloid stem cell
- maturation involves synthesis and accumulation of Hgb
- nucleus is extruded before RBC is released from marrow
Leukopoiesis
- WBCs (except lymphocytes) originate from myeloid stem cell
- condensation and segmentation of nucleus
- formation of granules
Lymphopoiesis
- lymphocytes originate from lymphoid stem cell
- B cells mature in bone marrow
- T cells mature in thymus
Thrombopoiesis
- platelets are derived from megakaryocytes, which originate from myeloid stem cell
- megakaryocyte nucleus divides, but cell does not
- cell grows then cytoplasm falls apart –> shedded fragments are platelets
What are some causes of bone marrow failure?
- Nutritional deficiency: B12, folate, iron
- Marrow toxins: drugs, chemo, radiation
- Infections: HIV, HBV, HCV, EBV, CMV
- Marrow replacement: infections, leukemia, lymphoma
- Autoimmune diseases
- Primary bone marrow diseases
What will the MCV level be in iron deficiency?
MCV is low b/c RBCs are small (microcytic)
What will the MCV level be in B12/folate deficiency?
MCV is high b/c RBCs are big (macrocytic)
Cellularity of Bone Marrow
- ratio btw fat and tissue in marrow
- 5% cellular has very little blood making ability
- 95% cellular may actually be too many malignant cells
What does pyruvate kinase do for blood cells?
-maintain RBC shape and deformability
What does glucose-6-phosphate-dehydrogenase do for blood?
-prevent excessive oxidation of Hgb
What does the reticulocyte count tell you?
-will tell difference btw decreased RBC production and increased RBC destruction
What are some examples of microcytic anemias?
- iron deficiency
- anemia of chronic dz
- thalassemia
- sideroblastic anemia
What are some examples of macrocytic anemias?
- folate/B12 deficiency
- liver dz
- hypothyroidism
- drugs
- myelodysplastic syndrome
Sxs of Anemia
- fatigue
- dyspnea
- palpitations, tachycardia, angina
- dizziness, lightheadedness, faintness
- HA
- claudication
How is anemia classified?
- decreased production
- increased destruction
What will the retic count be if there is decreased production of RBCs? What else might be found?
- low retic count
- abnormalities of WBCs or platelets
What will the retic count be if there is increased destruction of RBCs? What else might be found?
- high retic count
- jaundice/icterus
- elevated bili and LD
- low haptoglobin
