Formation of Blood Flashcards
Hemopoiesis: Erythropoiesis and Leucopoiesis
Hemopoiesis
What is hemopoiesis?
It is the production and development of all blood cells
Hemopoiesis
When does hemopoiesis begin?
In the 20th week of life in fetal liver and spleen.
Hemopoiesis
What is the site of hemopoiesis in fetus?
- 0-2 months: Yolk sac
- 2-7 months: Liver and spleen
- 5-9 months: Bone marrow
Hemopoiesis
What is the site of hemopoiesis in infants?
Bone marrow
Hemopoiesis
What is the site of hemopoiesis in adults?
- The axial skeleton
- Appendicular skeleton: Skull, sternum, vertebrae, ribs, sacrum, pelvis and proximal ends of femur and humerus.
Hemopoiesis
What factors affect hemopoiesis?
- Hemapoietic Pluripotential Stem cells
- Growth inducers
- Differentiation inducers
Hemopoiesis
How do growth inducers/ factors work in helping with hemopoiesis?
- Stimulate proliferation of cells
- Stimulate differentiation of lineage-committed progenitor cells
- Suppress apoptosis
- Stimulate cell maturation
- Activate function
Erythropoiesis
What is erythropoiesis?
It is the process of production of RBCs in the bone marrow.
Erythropoiesis
What are the steps of erythropiesis?
- Pluripotential Stem Cell (Hemocytoblast)
- Myeloid Stem Cell
- Colony Forming Units- Erythrocyte (CFU-E)
- Proerythroblast: Committed Cell
- Early Erythroblast (Basophilic Erythroblast): Ribosome synthesis
- Late Erythroblast (Polychromatophil Erythroblast): Hemoglobin accumulation
- Normoblast (Orthochromatic Erythroblast): Nucleus Ejection
- Reticulocyte: Nucleus Ejection
- Erythrocyte
Erythropoiesis
What is the fate of a reticulocyte?
- Reticulocytes have a few remnants of nucleus left.
- They are ejected out of the bone marrow through diapedesis.
- They mature into erythrocytes in 1-2 days in the blood.
- Their concentration in the blood is less than 1%.
Erythrpoiesis
How long does a reticulocyte take to mature?
1-2 days
Erythrpoiesis
What does a high reticulocyte count in the blood indicate?
Low oxygen concentration. To help with this, the bone marrow tries to produce more RBCs, and it does this by releasing more reticulocytes in the blood.
Erythrpoiesis
What is erythropoietin?
It is a glycoprotein (165 aminoacids) that regulates erythropoiesis.
Erythrpoiesis
Where is erythropoietin produced?
90%- Kidneys
10%- Liver
Erythrpoiesis
When is erythropoietin produced in the body?
In case of tissue hypoxia due to:
1. Anemia
2. Hemorrhage
3. Lung diseases
4. Heart Failure
5. High altitude
Erythrpoiesis
How does erythropoietin regulate erythropoiesis?
- It acts on CFU-E
- It increases the number of nucleated precursors in the bone marrow.
- It increases reticulocytes in the blood.
- It increases RBCs in the blood.
Erythrpoiesis
Why is erythropoietin supplied as synthetic epoietin?
Because our body can degrade the natural erythropoietin.
Erythrpoiesis
How do androgens regulate erythropoiesis?
- Directly stimulate bone marrow cells.
- Indirectly stimulate erythropoietin release.
Erythrpoiesis
Which hormones meant for general metabolism of all the body cells stimulate erythropiesis?
- Thyroid hormones (T3 and T4)
- Glucocorticoids
Erythrpoiesis
Why can patients with chronic gastritis also suffer from anemia?
Patients with chronic gastritis lack intrinsic factor which is required for the absorption of B12 and folic acid in the small intestine.
Erythrpoiesis
Why is B12 and folic acid important in our body?
- Important for DNA synthesis
- Stmulates erythropoiesis
- Important to maintain the structure of RBCs
Erythrpoiesis
Which other nutrients are important for stimulating erythropoiesis?
*Nutrients other than B12 and Folic Acid
- Amino acids (synthesis of hemoglobin)
- Vitamin C (Iron absorption)
- Cobalt
- Zinc
- Manganese
- Copper
Leucopoiesis
What is Leucopoiesis?
The development and maturation of leucocytes is called leucopoiesis.
Leucopoiesis
What are the two types of leucopoiesis?
- Myelopoiesis: The development of all WBCs except lymphocytes.
- Lymphopoiesis: The development of lymphocytes.
