RBC 2 Flashcards
Red Cell Indices
The red cell indices defined below are calculated taking normal values of the RBC count 5 million/μL, PCV 45% and Hb level of 15 g/dL.
Mean Corpuscular Volume (MCV)
=Average volume of a single RBC
Mean Cell Haemoglobin (MCH)
=Average weight of the haemoglobin contained in each RBC
Mean Cell Haemoglobin Concentration (MCHC)
=Amount of Hb expressed as a percentage of the volume of RBC
Mean Corpuscular Volume (MCV)
Average volume of a single RBC
Normal value = 90 μm3 (range 78–94 μm3)
Decreased MCV occurs in microcytosis.
Increased MCV occurs in macrocytosis
Mean Cell Haemoglobin (MCH)
It is calculated by dividing the amount of Hb in 1 L of blood by the red cell count in 1 L of blood
-Normal value of MCH is 30 (range 27–33) pg.
-Increased MCH occur in the spherocytosis and megaloblastic anaemia.
Mean Cell Haemoglobin Concentration (MCHC)
Amount of Hb expressed as a percentage of the volume of RBC
Normal value of MCHC is 33.3% (range 30–38%).
RBCs normal MCHC - normochromic.
RBCs < normal MCHC - hypochromic [seen in iron deficiency anaemia].
RBCs > normal Hyperchromia
Haemopoiesis
-Development of blood cells
Erythropoiesis- Development of RBCs
Leucopoiesis- Development of WBCs
Thrombopoiessi-Development of platelets
Site of Haemopoiesis
3rd week of intrauterine life-Mesoderm of the Yolk Sac
3rd month of intrauterine life-Liver and Spleen
5th month of intrauterine life-Fetal Bone Marrow & Liver
After birth to adult-Red Bone Marrow
Monophyletic Theory of Haemopoiesis
All blood cells originate from the pluripotent or multipotent stem cell.
Describe Stages of Erythropoiesis(very important)
look at slide RBC2 PG 10
Regulation of Erythropoiesis
RBC or Hb remains relative constant through life, because destruction of old red cells is balanced by the production of new ones from the bone marrow .
factors
General Factor
- Erythropoietin
Maturation of cells
* Vitamin B12
*folic acid
*Intrinsic factor
Hemoglobinization
-Factors necessary for haemoglobin formation
Erythropoietin
❖Hormone ( glycoprotein)
❖Produced by interstitial fibroblasts in
the kidney in close association with the peritubular capillary and proximal convoluted tubule ( 85%) and liver
❖Stimulation factors: Hypoxia or decrease in number of RBC
❖Hypoxia stimulate increase RBC count (polycythaemia in high altitude
Roles of Erythropoietin
- increases erythropoiesis by acting at the site of erythropoiesis( yolk sac,liver,spleen and bone marrow)
- stem cells differentiation in proerythroblasts
-promotes haemoglobin synthesis - promotes every stage of maturation
Roles of Erythropoietin
- increases erythropoiesis by acting at the site of erythropoiesis( yolk sac,liver,spleen and bone marrow)
- stem cells differentiation in proerythroblasts
-promotes haemoglobin synthesis - promotes every stage of maturation
Factors Influence Erythropoiesis
Dietary Factors
Intrinsic Factors
Other hormones
Other factors
Dietary Factors
Iron
Necessary for the synthesis of Hb
Dietary Factors
Vitamin B12
* Necessary for maturation of RBC.
* Required for the synthesis of DNA and maturation of nucleus and cell
Deficiency
➢ Failure of maturation of nucleus. ➢ Cells remain large (megaloblasts)
and become more fragile.
➢ There occurs a reduction in cell division
Folic acid
* Necessary for maturation of RBC.
* Is required for the synthesis of DNA and maturation of nucleus and cell.
Intrinsic Factors
Produced from the parietal cells of the gastric mucosa.
✓ Helps in the absorption of vitamin B12.
✓ Combines with dietary vitamin B12 in stomach to form the intrinsic factor (cyanocobalamin)
