Blood Physiology
Professor A.M.A Abdel Gader
MD, PhD, FRCP (Lond., Edin), FRSH (London)
Professor of Physiology, College of Medicine &
The Blood Bank, King Khalid University Hospital
King Saud University
Riyadh
BLOOD
Lecture # 1 & 2
Topic: Red Blood Cells (RBCs)
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Composition & functions of the Blood
Morphological Features of RBCs.
Production of RBCs
Regulation of production of RBCs
Nutritional substances need for RBC production
Haemoglobin
(Iron metabolism)
Sites of blood formation
• Adults…………..
• Children ………….
Bone Marrow
(Flat bones)
Bone Marrow
(Flat & long bones)
• Before Birth: ….
Bone Marrow
Liver & spleen,lymph nodes
• Fetus 1st 4 months …Yalk Sac
Production of RBC-cont.
Monophyletic theory of cell formation
Red blood cells
Genesis of RBC
Hematopoiesis
(17.9)
Erythropoiesis, (Formation/genesis of RBC)
Growth factors (inducers):
Control growth and maturation
of stem cells:
– Interleukin-3
– Erythropoeitin
– Granulocyte stimulating factor
(GSF)
Production of Erythrocytes:
Erythropoiesis
Figure 17.5
Erythropoiesis, (Formation/genesis of RBC)
– Stages of RBC development
Pluripotential haemopoietic STEM CELL
Committed Stem cell
Proerthroblast
early, intermediate and late normoblast
Reticulocytes
Erythrocytes
Maturation
Sequence
Stages of differentiation of RBC
Features of the maturation process
of RBC
1. Reduction in size
2. Disappearance of the nucleus
3. Acquisition of haemoglobin
Lecture # 1 & 2
Topic: Red Blood Cells (RBCs)
•
•
•
•
•
•
•
Composition & functions of the Blood
Morphological Features of RBCs.
Production of RBCs
Regulation of production of RBCs
Nutritional substances need for RBC production
Haemoglobin
(Iron metabolism)
Control of Erythropoiesis •
Control of Erythropoiesis
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Erythropoiesis is stimulated by
erythropoietin hormone
Stimulated by:
Hypoxia (low oxygen)
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Anaemia
Hemorrhage
High altitude
Lung disease
Heart failure
Role of the kidneys in RBC
formation
Tissue oxygenation and RBC
formation
Control of erythropoiesis
Cont.
• Erythropoietin
• glycoprotein
• 90% from kidneys 10% liver
• Stimulates the growth of:
early RBC-committed stem cells
• Can be measured in plasma & urine
• High level of erythropoietin
– anemia
– High altitude
– Heart failure
Maturation
Times
Control of erythropoiesis
cont.
Other hormones
– Androgens, Thyroid, cortisol &
growth hormones are essential for
red cell formation
– Deficiencies of any one of these
hormones results in anaemia
Control of erythropoiesis
ErythropoiteinMechanism of production of
Hypoxia, (blood loss)
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 Blood O2 levels
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Tissue (kidney) hypoxia
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 Production of erythropoietin
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 plasma erythropoietin
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Stimulation of erythrocytes production
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 Erythrocyte production
Lecture # 1 & 2
Topic: Red Blood Cells (RBCs)
•
•
•
•
•
•
•
Composition & functions of the Blood
Morphological Features of RBCs.
Production of RBCs
Regulation of production of RBCs
Nutritional substances need for RBC production
Haemoglobin
(Iron metabolism)
Nutritional requirements for
RBC formation
1. Amino acid
– HemoGlobin
2. Iron
– HemoGlobin
– Deficiency  small cells
(microcytic anaemia )
Nutritional requirements for
RBC formation cont.
3. Vitamins
• Vit B12 and Folic acid
– Synthesis of nucleoprotein
DNA
– Deficiency  macrocytes
megaloblastic (large) anemia
• Vit C
– Iron absorption
Production of Erythrocytes:
Erythropoiesis
Figure 17.5
Vitamin B12 & Folic acid
• Important for cell division and
maturation
• Deficiency of Vit. B12 > Red cells are
abnormally large (macrocytes)
• Deficiency leads:
– Macrocytic (megaloblastic) anaemia
• Dietary source: meat, milk, liver, fat,
green vegetables
Vitamin B12
• Absorption of VB12 needs intrinsic
factor secreted by parietal cells of
stomach
• VB12 + intrinsic factor is absorbed in
the terminal ileum
• Deficiency arise from
– Inadequate intake
– Deficient intrinsic factors
• Pernicious anaemia
Nutritional requirements for RBC formation cont.
– Essential elements
• Copper, Cobalt, zinc, manganese,
nickel
• Cobalt  Erythropoietin
ANAEMIAS
– Definiation
• Decrease number of RBC
• Decrease Hb
– Symptoms:
Tired, Fatigue, short of breath,
(pallor, tachycardia)
Causes of anaemia
1. Blood Loss
– acute accident
– Chronic  ulcer, worm
2. Decrease RBC production
– Nutritional causes
• Iron  microcytic anaemia
• VB12 & Folic acid  megaloblastic anaemia
– Bone marrow destruction by cancer, radiation,
drugs  Aplastic anaemia.
3. Haemolytic  excessive destruction
– Abnormal Hb (sickle cells)
– Incompatible blood transfusion
The most common cause for a hypochromic •
microcytic anemia is iron deficiency. The most
common nutritional deficiency is lack of dietary
iron. Thus, iron deficiency anemia is common.
Persons most at risk are children and women in
reproductive years (from menstrual blood loss
and from pregnancy).
The most common cause for a hypochromic
microcytic anemia is iron deficiency. The
most common nutritional deficiency is lack of
dietary iron. Thus, iron deficiency anemia is
common. Persons most at risk are children
and women in reproductive years (from
menstrual blood loss and from pregnancy)
Macrocytic anemia
The RBC are almost as large as the lymphocyte. Note
the hypersegmented neurotrophil. There are fewer
RBCs.
The RBC's here are smaller than normal and have an
increased zone of central pallor. This is indicative of a
hypochromic (less hemoglobin in each RBC) microcytic
(smaller size of each RBC) anemia.
There is also increased anisocytosis (variation in size) and
poikilocytosis (variation in shape).
Macrocytic anemia
Note the
hypersegmented
neurotrophil and also
that the RBC are
almost as large as
the lymphocyte.
Finally, note that
there are fewer
RBCs.
Polycythemia
– Increased number of RBC
– Types:
• True or absolute
– Primary (polycythemia rubra vera):
uncontrolled RBC production
– Secondary to hypoxia: high altitude,
chronic respiratory or cardiac disease
• Relative
– Haemoconcentration:
» loss of body fluid in vomiting, diarrhea,
sweating