Intro to Heme Flashcards
1
Q
4 Compartments Where Blood Exists in the Body
A
- bone marrow
- blood
- lymphatic system
- tissues
2
Q
Blood Compositioin
A
- formed elements: RBCs, WBCs, platelets
- plasma: water, dissolved ions, proteins
3
Q
Where does fetal/neonatal hematopoiesis occur?
A
- primitive hematopoietic cells at 4-5 wks gestation
- liver at 5 weeks
- bone marrow and thymus at 8 weeks
- spleen 12 weeks
4
Q
What is the primary hematopoietic organ in adults?
A
- bone marrow
- first the long bones (until 20 years or so)
- then vertebrae and pelvis are active most of our lives
5
Q
Bone Marrow Composition
A
- stroma: sinuses lined with endothelial cells and fibroblasts
- hematopoietic cells: stem cells become mature blood cells; must be in contact or near stroma
6
Q
What is the normal hematopoietic process? (Think about the diagram/flow chart of blood cells)
A
- 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)
7
Q
What is required for hematopoiesis to occur?
A
- healthy bone marrow
- hormones/cytokines (erythropoietin, thrombopoietin, etc)
- nutritional factors: iron, folate, B12
8
Q
Erythropoiesis
A
- RBCs originate from myeloid stem cell
- maturation involves synthesis and accumulation of Hgb
- nucleus is extruded before RBC is released from marrow
9
Q
Leukopoiesis
A
- WBCs (except lymphocytes) originate from myeloid stem cell
- condensation and segmentation of nucleus
- formation of granules
10
Q
Lymphopoiesis
A
- lymphocytes originate from lymphoid stem cell
- B cells mature in bone marrow
- T cells mature in thymus
11
Q
Thrombopoiesis
A
- 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
12
Q
What are some causes of bone marrow failure?
A
- 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
13
Q
What will the MCV level be in iron deficiency?
A
MCV is low b/c RBCs are small (microcytic)
14
Q
What will the MCV level be in B12/folate deficiency?
A
MCV is high b/c RBCs are big (macrocytic)
15
Q
Cellularity of Bone Marrow
A
- ratio btw fat and tissue in marrow
- 5% cellular has very little blood making ability
- 95% cellular may actually be too many malignant cells
