Hematolymphoid Flashcards
Lymphoid tissue
Location; role
- Located in the lymphoid tissue and blood (lymphocytes)
- Primary (BM & thymus) vs secondary (lymph node, spleen, MALT)
- Role: Adaptive immunity
Myeloid tissue
Location; role
Location:
- Bone marrow (blood cell precursors)
- Blood (erythrocytes, platelets, granulocytes, monocytes)
Role: transport oxygen (RBCs), clotting (platelets), fight infection (WBCs)
Hematopoiesis
Different cell lines, each undergo differentiation into a committed cell type
Lymphopoeisis
Location and types of cells
- B cells mature in BM
- T cells mature in thymus
Hematopoiesis (Fetal, infant, adult)
- Fetal: HSCs in yolk sac migrate to liver, BM, spleen, LNs and thymus
- Infant: Extramedullary hematopoiesis stops
- Adult: Hematopoiesis occurs in flat bones, ribs, vertebrae, and end of long bones (If BM destroyed, extramedullary hematopoiesis in spleen, liver and lymph nodes)
Components and composition of blood
Blood quantity; components; blood measurements
Quantity: 5L of blood
Components:
- Plasma (water, plasma proteins, solutes)
- RBCs
Measurements:
- Complete blood count (CBC): tests whether components are within normal range
- Hematocrit: ratio of packed RBC to total volume (~40-45%)
Serum
Plasma without coagulation proteins (blood clotting factors: fibrinogen, prothrombin, coagulation factors)
RBC morphology
Normal
Normal: biconcave disk (no nucleus) (abnormal: sickle cell, etc.)
Hemoglobin
Function; structure
Function: carries oxygen
Structure: Consists of 4 globin chains (each globulin chain has a heme containing Fe to carry oxygen; 4 polypeptide chains designatied alpha, beta, delta and gamma - normal adults mostly HbA)
RBC life cycle
- Circulation for 120 days
- Erythropoietin (growth factor) released by kidneys promotes erythropoiesis in BM and release
- Spleen sequesters old RBCs (components reutilized or excreted)
Anemia
Definition; assessment; etiological classification
Definition: Reduction of total circulating red cell mass below normal limits
Assessment: Hemoglobin levels (Hb < 130 males; < 115 females)
Etiological classification: Increased loss, increased destruction, decreased production
Anemia
Morphological classification: RBC size (microcytic, normocytic, macrocytic) and hemoglobin content (hypochromic (pale), normochromic (normal))
Anemia
1) Iron deficiency
2) Massive blood loss
3) Vitamin B12 and/or folic acid deficiency
4) Sickle cell
1) Hypochromic microcytic
2) Normochromic normocytic
3) Macrocytic
4) Abnormal shape
Anemia Etiological Classification
Increased factors
Increased loss (bleeding): acute vs chronic
Increased destruction (hemolytic anemia):
Destruction of abnormal RBCs:
- Inherited: red cell membrane disorders, anzyme deficiencies, abnormal Hb)
- Acquired: PNH
Destruction of normal RBCs:
- Immune mediated
- Mechanical (repetitive trauma)
- Infections
- Chemical/toxic injury
Anemia Etiological Classification
Decreased factors
Decreased RBC production
Nutritional deficiences:
- Deficiency in Hb synthesis (iron deficiency anemia)
- Deficiency affecting DNA synthesis (vitamin B12 or folic acid deficiency)
Bone Marrow failue:
- Aplastic anemia
- Infiltration of BM by malignant cells
Inherited genetic defects:
- Thalassemoa syndromes
Anemia signs and symptoms
Why; signs; symptoms
Due to decreased ability to carry oxygen
Signs: Pale skin, pale mucosa, brittle nails, tachycardia
Symptoms: fatigue, weakness, short of breatj, drowsiness, chest pain, unusual cravings
Important:
Iron deficiency anemia
Where is it absorbed? incorporated? how is it stored? lost?
- Iron is absorbed in SI and tansported to other sites bound to transferrin
- Iron incorporated into hemoglobin in BM
- Iron is stored as ferritin (aggregates form hemosiderin)
- Iron lost primarily in cell loss
- Aging RBCs destroyed in spleen and iron is reutilized
Iron deficiency anemia causes, lab results, treatment
Causes: Decreased intake, decreased absorption, increased loss, increased requirements
Lab results: blood smear, hemoglobin and hematocrit low, serum iron and ferritin low
Treatement: determine/treat underlyinh cause, iron replacement
Important
Aplastic anemia
What? Causes? Diagnosis?
Characterized by loss of multipotent stem cell, resulting in pancytopenia (decreased RBCs, WBC, and platelets)
Causes:
- Primary (idiopathic)
- Secondary (related to BM supression): chemical agents, radiation, viral infection, inhereted
Diagnosis:
- CBC: Pancytopenia
- BM biopsy: few forming blood cells
Important
Megaloblastic anemia
Pathogenesis; diagnosis
Caused by deficiency of B12 vitamin or folic acid
Pathogenesis:
- Deficiencies delay normal maturation of RBCs
- RBC precursors do not mature (for megaloblasts)
- Megaloblasts destroyed in BM or spleen
Diagnosis:
- Peripheral blood smear: oval macrocytes, large segmented neutrophils
- BM biopsy: hypercellular with megaloblasts
Megaloblastic anemia
Vitamin B12 general, absorption, deficiency
Vitmain B12:
- Essential nutrient
- Co-enzyme required for synthesis of DNA
Absorption:
- Dietary B12 achieved from food > binds to intrinsic factor from gastric parietal cells > B12-IF complex transferred to BM
Deficiency:
- Decreased intake
- Impaired absorption (Pernicious anemia)
Megaloblastic anemia
Pernicious anemia pathogenesis; clinical manifestations
Pernicious anemia pathogenesis:
- Atrophic gastritis > results in decrease in gastric parietal cells > insufficient IF > B12 deficiency > megaloblastic anemia
Clinical manifestations:
- Spinal cord lesions > loss of vibration, relfexes
Megaloblastic anemia
Folate deficiency
Folate deficiency:
- Results in megaloblastic anemia similar characteristics to B12 deficiency
Causes folate deficiency:
- Impaired absorption
- Decreased intake
- Increased requirement
Thalassemias
- Genetic defect in synthesis of normal Hb (no abnormal Hb produced or defect in quantity)
- HbA has 4 chains: 2a, 2B (genes affected)
- Thalassemoa classified on basis of type of chain affected (E.x. a thalassemia > defective a chain synthesis)
Thalassemias
a thalassemia (4 genes code):
- Single gene deletion (asymptomatic)
- 2 gene deletion (a thalassemia trait > mild anemia)
- 3 gene deletion (Hemoglobin H disease > moderate to severe anemia)
- 4 gene deletion (Hydrops fetalis > most severe
