RBC and erythropoiesis

ERYTHROCYTES
- Major function - carry O2 , CO2, buffer
- Contain Haemoglobin (Fe atoms)
- 14 gms/100ml
- Biconcave disc
- High surface to volume ratio
Plasma membrane contain special polysaccharide & proteins - spectrin
- Differ from person to person - blood type/group
Normal count 4.5 - 5 million/cumm

1. RBC &
Erythropoiesi
s
Dr. K. Ambareesha., PhD (Med. Physio)
Assit. Professor, Department of Physiology
MNR Medical College & Hospital, Sangareddy, Telangana, India.

2. CONTENTS
•INTRODUCTION TO RBC –
•Structure, Functions, Normal count, Variations in size, shape
and structure.
•HAEMOPOIESIS
•ERYTHROPOIESIS-
•Stages and its Regulation

3. ERYTHROCYTES
Surface area is 120 µ2.
Normal volume is 80-
94 µ3.
Normal life span of an
RBC is 120 days.

4. ERYTHROCYTES
Normal Erythrocyte Count
Males 5-5.5 million
cells/mm3
Females 4.5-5 million
cells/mm3
Infants6 –7 million
cells/mm3

5. STRUCTURE OF RBC
•Lipids:Cholesterol,
phospholipid, and
glycolipids
•Proteins:Spectrin,
actin, ankyrin.
•The glycolipids:
constitute the ABO blood
group substances
(agglutinogens).

6. Metabolism Of RBC
It is met by the glucose
metabolism through the
anaerobic Embden-
Meyerhof (EMF) pathway
(90%) and the pentose
phosphate shunt (10%).

7. FUNCTIONS OF RBC
•Transport of oxygen
from lungs to tissues.
•Transport of Co2 from
tissues to lungs.
•Regulation of acid-base
balance.

8. ERYTHROPOIESIS
Erythropoiesis is the process of
formation of RBCs.
Till 3rd week of intrauterine life in the
mesoderm of the yolk sac.
From the third month erythropoiesis takes place
in the liver and spleen.
After the fifth intrauterine life, the fetal bone
marrow starts producing RBCs.

9. BONE MARROW
Red bone marrow
1.Atbirth,itispresentinallthebones.
2. In adults, it is present in flat bones
(membranous bones) like cranial
bones, vertebrae, pelvic bones, ribs,
sternum, and upper ends of long
bones like femur and humerus.
Yellow bone marrow
1.is mainly made up of adipose
(fat) tissue

10. STAGES OF
ERYTHROPOIESIS

12. PLURIPOTENT STEM
CELLS
This differentiates to
form the committed
stem cell.
The committed stem
cell of the myeloid
series gives rise to all
blood cells except the
lymphocytes.
*The committed stem cells for the erythrocyte
give rise to the progenitor cells.

13. PROGENITOR CELLS
BFU-E (burst-forming units)
The development of Large
colonies requires the
presence of factors called
burst-promoting activity
(BPA).
The cells are immature blast
cells oval in shape with
moderately basophilic
cytoplasm, occasional
pseudopods, fine chromatin,
and nucleoli.
CFU-E (colony-forming units)
They form small colonies.
They do not require BPA but
require other factors like
erythropoietin. CFU-E cells
give rise blast cells.
CFU-E cells are more mature
than BFU-E cells.
Morphologically, they are
similar to BFU-E cells.

14. ERYTHROPOIESIS -
PROERYTHROBLAST
These cells develop from CFU-E.
They are large cells, 15-20 µ in
diameter.
The nucleus is large containing
basophilic nucleoli.
It occupies 80% of the cells.
Cytoplasm is scanty and basophilic.
These cells actively divide by
mitosis.
They do not have hemoglobin.

15. ERYTHROPOIESIS -EARLY
NORMOBLAST
•10-16 µ in diameter.
•They also show active
mitosis.
•The nucleus is large, the
cytoplasm is basophilic,
and hemoglobin
•begins to appear.
•The nucleoli disappear and
condensation of chromatin
begins in the stage.

16. ERYTHROPOIESIS -INTERMEDIATE
NORMOBLAST
•10-14 µ in diameter.
•The nucleus becomes
small.
•Mitosis stops at this stage.
•Hemoglobin concentration
increases and cells become
acidophilic due to Hb.
•The condensation of
nuclear chromatin increase
in this stage.

17. ERYTHROPOIESIS -LATE
NORMOBLAST
8-10 µ in diameter.
The cytoplasm is
acidophilic.
The nucleus is very small,
becomes pyknotic (small),
and is lost by extrusion.

18. ERYTHROPOIESIS -
RETICULOCYTE
•It is slightly basophilic.
•Hbcontent increases to
reach the level of the mature cell.
•The chromatin is organized in the
form of a network (reticulum);
hence, it is called a
reticulocyte.
•RBC attains maturity in 1-2 days
after the loss of the basophilic
material.

19. ERYTHROPOIESIS -ERYTHROCYTES
This is a mature cell, 7-2 µ in diameter, eosinophil, non-nucleated; it resembles a biconcave disk.
The process of erythropoiesis takes 7 days.

20. FACTORS AFFECTING ERYTHROPOIESIS -
Erythropoietin
•Glycoprotein hormone that stimulates
erythropoiesis. It increases RBC production.
•It has a molecular weight of 46,000. It is
made up of 74% protein and 26%
carbohydrate.
•Formation:It is mainly formed in the kidney
and partly in the liver. In the kidney it is
produced by the endothelial cells of the
peritubular capillaries.

21. Erythropoietin -Functions
•Increases RBC production.
Enhances synthesis of Hb.
Hastens maturation of RBC.
•The basic stimulus for erythropoietin production is hypoxia.
Androgens increase erythropoietin production.
Estrogens depress erythropoietin production.
Products of RBC destruction increase erythropoietin production.
Vasoconstrictors produce renal hypoxia. They cause formation of
erythropoietin.
Erythropoietin is inactivated in the liver and is excreted through the kidneys.

22. Stimulus for Erythropoietin
Androgens: Stimulate erythropoiesis. Therefore, men have a higher RBC
count compared to women. Androgens stimulate the production of
erythropoietin. In addition, they directly stimulate erythropoiesis.
Estrogens:They have inhibitory effect on the erythropoiesis by
suppression of erythropoietin production.
Hormones: Thyroxin, cortisol, and growth hormone are necessary for
RBC production. Interleukin 1,5, and 3, granulocyte macrophage colony-
stimulating factor (GM-CSF), and BPA all act as local hormones and
help in the conversion of stem cells to progenitor cells.

23. Stimulus for Erythropoietin

24. Stimulus for Erythropoietin
Dietary Factors: Iron is necessary for Hbsynthesis. The
deficiency of iron leads to hypochromiaand decrease in the size of
RBC.
Vitamin B12and folic acid are necessary for maturation of RBC.
Vitamin B6 vitamin C, copper, and cobalt act as cofactors.

25. Applied Physiology

26. Conditions decrease RBC count
Physiological:

27. Conditions decrease RBC count
Anemia
This is a clinical condition wherein RBC count or
Hb% or both are decreased. In anemia, O2
carrying capacity of blood is reduced.
Pathological:

29. Conditions increase RBC count
Physiological:

30. Conditions increase RBC count
Pathological:

31. Conditions increase RBC count
Pathological:

32. Conditions increase RBC count
Pathological:

33. UNIVERSITY ASKED QUESTIONS
•Define erythropoiesis. Describe the stages of erythropoiesis and
identify the factors influencing it 10m [1+7+2]
•Outline the steps of erythropoiesis. Explain the essential factors
for it? [july-aug-2014].4m
•Erythropoiesis 4m [July; 2012]
•Erythropoietin 2m [july-2010]

34. Thank you