Blood Physiology

Professor A.M.A Abdel GaderMD, 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 & 2Topic: 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)

Sites of blood formation

• Adults………….. Bone Marrow(Flat bones)

• Children …………. 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 formationMonophyletic 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 developmentPluripotential haemopoietic STEM CELL

Committed Stem cell

Proerthroblast

early, intermediate and late normoblast

Reticulocytes

Erythrocytes

MaturatioMaturation n

SequenceSequence

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 & 2Topic: 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

• Erythropoiesis is stimulated by erythropoietin hormoneStimulated by:

• Hypoxia (low oxygen)– 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 Maturation TimesTimes

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

Erythropoitein- Mechanism of production of

Hypoxia, (blood loss)

Blood O2 levels

Tissue (kidney) hypoxia

Production of erythropoietin

plasma erythropoietin

Stimulation of erythrocytes production

Erythrocyte production

Lecture # 1 & 2Topic: 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 macrocytesmegaloblastic (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 anaemia1. 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