Podcast
Questions and Answers
What is the term given to the cells that are regulated by certain hormones or substances to proliferate and undergo maturation?
What is the term given to the cells that are regulated by certain hormones or substances to proliferate and undergo maturation?
- Erythrocyte
- Haemopoietic stem cells
- Normoblasts
- Progenitor cells (correct)
What is the term given to the formation or genesis of red blood cells?
What is the term given to the formation or genesis of red blood cells?
- RBC Development
- Haemopoiesis
- CFU-E Formation
- Erythropoiesis (correct)
What is the regulator of BFU-E, which gives rise to thousands of nucleated erythroid precursor cells?
What is the regulator of BFU-E, which gives rise to thousands of nucleated erythroid precursor cells?
- Colony Stimulating Factor
- Erythropoietin
- Haemopoietic factor
- Burst Promoting Activity (BPA) (correct)
At which stage of erythropoiesis does the nucleus condense and Hb appears?
At which stage of erythropoiesis does the nucleus condense and Hb appears?
What is the size of a mature red blood cell?
What is the size of a mature red blood cell?
At which stage of erythropoiesis does the nucleus become pyknotic and Hb is maximum?
At which stage of erythropoiesis does the nucleus become pyknotic and Hb is maximum?
What percentage of cells in the bone marrow belong to the myeloid series?
What percentage of cells in the bone marrow belong to the myeloid series?
What is the characteristic of stem cells that allows them to differentiate into any blood cell lines?
What is the characteristic of stem cells that allows them to differentiate into any blood cell lines?
What is the term for the supporting system formed by the bone marrow and spleen?
What is the term for the supporting system formed by the bone marrow and spleen?
What type of stem cells can convert into any tissue type?
What type of stem cells can convert into any tissue type?
What is the term for the process by which stem cells give rise to new stem cells?
What is the term for the process by which stem cells give rise to new stem cells?
What is the term for the process by which stem cells differentiate into specific blood cell lines?
What is the term for the process by which stem cells differentiate into specific blood cell lines?
What is the term for the precursor cells that give rise to megakaryocytes, lymphocytes, erythrocytes, eosinophils, and basophils?
What is the term for the precursor cells that give rise to megakaryocytes, lymphocytes, erythrocytes, eosinophils, and basophils?
What happens to committed stem cells as they lose their capacity for self-renewal?
What happens to committed stem cells as they lose their capacity for self-renewal?
What is the characteristic feature of a Pronormoblast?
What is the characteristic feature of a Pronormoblast?
What is the distinctive feature of a Polychromatophilic normoblast?
What is the distinctive feature of a Polychromatophilic normoblast?
What is the characteristic feature of an Orthochromatic normoblast?
What is the characteristic feature of an Orthochromatic normoblast?
What is the characteristic feature of a Reticulocyte?
What is the characteristic feature of a Reticulocyte?
What is the duration of the differentiation phase from a Pronormoblast to a Reticulocyte?
What is the duration of the differentiation phase from a Pronormoblast to a Reticulocyte?
What is the feature of maturation phase from Reticulocyte to RBC?
What is the feature of maturation phase from Reticulocyte to RBC?
What is the percentage of Reticulocytes in total red cells?
What is the percentage of Reticulocytes in total red cells?
What is the characteristic feature of Erythrocytes?
What is the characteristic feature of Erythrocytes?
What is the primary site of erythropoietin production?
What is the primary site of erythropoietin production?
What is the primary function of erythropoietin?
What is the primary function of erythropoietin?
What is the effect of hypoxia on erythropoiesis?
What is the effect of hypoxia on erythropoiesis?
What is the role of vitamin B12 in erythropoiesis?
What is the role of vitamin B12 in erythropoiesis?
What is the effect of vitamin B12 deficiency on red blood cells?
What is the effect of vitamin B12 deficiency on red blood cells?
What is the role of intrinsic factor in erythropoiesis?
What is the role of intrinsic factor in erythropoiesis?
What is the effect of iron deficiency on erythropoiesis?
What is the effect of iron deficiency on erythropoiesis?
What is the role of catecholamines in erythropoiesis?
What is the role of catecholamines in erythropoiesis?
What is the result of hypothyroidism on erythropoiesis?
What is the result of hypothyroidism on erythropoiesis?
What is the function of the liver in erythropoiesis?
What is the function of the liver in erythropoiesis?
What is the effect of androgens on erythropoiesis?
What is the effect of androgens on erythropoiesis?
What is the result of bone marrow destruction on erythropoiesis?
What is the result of bone marrow destruction on erythropoiesis?
What is the function of haematopoietic growth factors in erythropoiesis?
What is the function of haematopoietic growth factors in erythropoiesis?
What is the result of hypoxia on erythropoiesis?
What is the result of hypoxia on erythropoiesis?
What is the result of Cushing's disease on erythropoiesis?
What is the result of Cushing's disease on erythropoiesis?
What is erythrocytosis?
What is erythrocytosis?
Study Notes
Hematopoiesis
- Normally, 75% of bone marrow cells belong to the myeloid series, which produces white blood cells, while 25% are maturing red cells
- Despite this, there are over 500 times more red cells in the circulation than white cells
Stem Cells
- Hematopoietic stem cells (HSCs) have extensive proliferative capacity and the ability to:
- Give rise to new stem cells (self-renewal)
- Differentiate into any blood cell lines (pluripotency)
- HSCs differentiate into committed stem cells (progenitor cells), which in turn form various types of blood cells
Clonal Hemopoiesis
- Pluripotent stem cells multiply and commit to specific cell lines, forming progenitor cells
- Progenitor cells regulate the proliferation and maturation of specific blood cells
Progenitor Cells
- Committed stem cells lose their capacity for self-renewal and become irreversibly committed to specific cell lines
- Progenitor cells are regulated by hormones or substances, allowing them to:
- Proliferate
- Undergo maturation
Erythropoiesis
- Erythropoiesis is the process of red blood cell formation
- Stages of RBC development:
- Pluripotential hematopoietic stem cell
- Committed stem cell
- Proerythroblast
- Early, intermediate, and late normoblasts
- Reticulocytes
- Erythrocytes
Stages of RBC Maturation
- Pronormoblast:
- 15-20µm in size
- Basophilic cytoplasm
- Nucleus with nucleoli
- No hemoglobin
- Basophilic normoblast:
- Large nucleus
- Basophilic cytoplasm
- Active mitosis
- Slightly reduced in size
- Polychromatophilic normoblast:
- Chromatin lumps
- Hb starts appearing
- Reduced mitoses
- Orthochromatic normoblast:
- Small and pyknotic nucleus
- Eosinophilic cytoplasm
- Mitoses absent
- Reticulocyte:
- Reticular nuclear fragments
- Nucleus extruded
- Slightly larger than RBCs
Erythrocytes Production
- Process of erythropoiesis takes 5 days from pronormoblast to reticulocyte phase
- Maturation phase from reticulocyte to RBC takes 2 days
- Features of RBC maturation:
- Reduction in size
- Disappearance of the nucleus
- Acquisition of hemoglobin
Control of Erythropoiesis
- Erythropoiesis is stimulated by erythropoietin hormone
- Stimulated by:
- Hypoxia (low oxygen)
- Anemia
- Hemorrhage
- High altitude
- Lung disease
- Heart failure
Erythropoietin
- Glycoprotein hormone produced mainly by the kidneys (90%) and liver (10%)
- Stimulates erythropoiesis by acting on committed stem cells to induce proliferation and differentiation of erythrocytes in bone marrow
- Site of action: bone marrow
Factors Affecting Erythropoiesis
- Hormonal factors:
- Androgens
- Thyroid hormones
- Glucocorticoids
- Pituitary gland
- Haematopoietic growth factors
- Nutritional requirements:
- Amino acids
- Iron
- Vitamin B12 and Folic acid
- Vitamin C
- Proteins
Clinical Aspects
- Anemias: reduced RBC count or reduced Hb concentration
- Polycythemia: increased RBC count
- Erythrocytosis: increased RBC count due to hypoxia
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Description
This quiz covers the process of blood cell formation and the characteristics of stem cells, including their ability to self-renew and differentiate into various blood cell lines.