Course Introduction and Overview of Hematology

Question 1

1.Define:hematopoiesis,erythropoiesis,anemia,hemolysis,hemostasis,andthrombosis.

Answer 1

• Hematopoiesis:
• Process of making all the blood cells from a hematopoietic stem cell –>then they differentiate along different lines of development.
• Erythropoiesis:
• process that makes RBCs (stimulated by EPO from kidneys).
• RBCs have nuclei early on, but eventually those get pinched out as the RB matures.
• RBCs are rapidly dividing cells, so need lots of iron, folic acid and B12.

*Anemia:
-when you have less RBC’s or Hgb content in the blood.
Causes are as follows.
-decreased RBC mass (inadequate O2 delivery to tissues)
-decreased RBC production
-marrow damage chronic disease
-lots of bleeding
-and hemolysis

• Hemostasis:
• arrest of bleeding –> blood clots due to platelet activity (which arise from megakaryocytes).
• Platelets regulated by inhibitory factors + fibrinolytic system.
• If clotting happens uncontrollably –> pathologic clots called thrombosis.

Question 2

2. Describethebasicshapeandcompositionofanerythrocyte.

Answer 2

• Erythrocytes have no nuclei or mitochondria (cannot generate new RNA when damaged/stressed so they die)
• do have lots of Hgb.
• HbA = dominant form in adult = alpha2beta2 tetramer with each chain attached to a heme prosthetic group that reversibly binds O2.
• Mutations can change binding affinity, properties (sickle cell), chain composition (thalassemia), etc.
• Shape = biconcave disk –> 40% more surface area for gas exchange and allows it to easily deform so RBC can squeeze through small capillaries. (Due to special membrane proteins)
• Undergo anaerobic metabolism; produces ROS so depend on NADPH to help produce GSH (via pentose phosphate shunt).
• Aided by G6PD  deficiency causes ‘bite cells.’

Question 3

3. Listthefivetypesofwhitebloodcellsintheblood.

Answer 3

Lymphocytes –> adaptive immune response and development of memory. t and b
Myeloid cell types comprise the innate immune system –> neutrophil (phagocytic), monocytes, eosinophils, and basophils.

Question 4

4.Compareandcontrastleukemiavs.lymphoma,acuteleukemiavs.chronicleukemiaandlymphoidleukemiavs.myeloid leukemia.

Answer 4

-Malignancies are clonal, neoplastic conditions with altered differentiation/proliferative capacity.

Leukemia:
-from the bone marrow, in the blood stream.

Lymphomas: -“extramedullary” (outside marrow), involving lymph nodes and other lymph organs.

Acute leukemia:
-cells are of immature differentiation; clinical course is rapidly progressive without intervention.

Chronic leukemia:
-cells are maturely differentiated; disease follows slower clinical course.

Lymphoid leukemia:
-from lymphocytic lineage.

Myeloid leukemia:
-from one of the other WBC cell types.

Question 5

5.Explainwhatplateletsare,wheretheycomefrom,andtheirbasicfunction

Answer 5

Platelets:

• thrombocytes –> aid with blood clotting.
• Produced as smaller fragments from large, polyploidy cells (megakaryocytes;
• 1 megakaryocyte –>~5000 platelets).
• Hemostasis process counterbalanced by inhibitory factors and fibrinolytic system (if not –> can get pathologic clots).