Blood

Blood Plasma (55%) Colour: red Cells (45%) ( hemoglobin) - Erythrocytes (red blood cells) Leukocytes (white blood cells) Thrombocytes (platelets) Colour: red ( hemoglobin) pH: 7.4 (7.35-7.45) Osmotic pressure: 5100-5500 mmHg = 0.9% gm NaCl ( Saline).

Plasma Water about 90% Plasma proteins 7.1-7.4% Inorganic constituents 0.9% Other solutes 2% (Nutrients, hormones, waste products & enzymes

Plasma Proteins Albumin Globulin - Value: 3.5-5 gm% - M.W: 70.000 Liver - Synthesis: Liver - Main function: Transporter, Osmotic pressure regulation Globulin - Value: 2.3-3.5 gm% - M.W : 150.000 - Synthesis: Liver  1, 2, 1 2 types B- lymphocte   type - Main function:- Transporter & defensive function

Fibrinogen Prothrombin - Value: 200-400mg % - M.W: 340.000 Liver - Synthesis: Liver - Main function: Viscosity, Blood Clotting (factor I) Prothrombin - Value: 10-15 mg % - M.W: 69.000 - Synthesis: Liver - Main function: Act as clotting (factor II)

Functions of plasma proteins 1) Blood clotting (haemostasis) 2) Defensive: gamma globulins 3) Transport function 4) Osmotic pressure regulation : albumin 5) Buffer functions 6) Nutritional functions 7) CO2 carriage

Hypoproteinemia It is marked decrease in plasma proteins. Causes: 1- Prolonged starvation 2- Malabsorption. 3- Decrease synthesis as in liver diseases (cirrhosis). 4- Increase loss as in kidney diseases (nephrosis). Effect: - Decrease albumin  decrease osmotic pressure  oedema. - Decrease globulin  decrease immunity. - Decrease fibrinogen & clotting factors  bleeding tendency.

Albumin/globulin ratio (A/G ratio) - It is about 1.2 - 1.7 - It decreases in: (1) Liver diseases (2) Kidney failure or nephrosis (3) Infections

Differences between plasma and serum Obtained by centrifugation of blood sample after adding anticoagulant. - Contains plasma proteins and clotting factors - Clot on standing - Normal serotonin level Serum: Obtained by centrifugation of clotted blood sample - Contains plasma proteins but no clotting factors I, II, V & VIII (consumed in blood clotting) - Not clot on standing - Serotonin from broken platelets with blood coagulation

THE RED BLOOD CELL Erythrocytes - RBCs

RED BLOOD CELL - Biconcave, non-nucleated discs - 90 cubic microns in volume. - The center appears paler than periphery due to the biconcavity - Red cell membrane is flexible plastic (not elastic) to allow RBCs passage in narrow capillaries.

Contents of RBCs A - Haemoglobin: give the RBCs Its red appearance and carry oxygen. B - Carbonic anhydrase enzyme: which catalyze reactions of CO2 transport. C - glucose-6-phosphate dehydrogenase & pyruvate kinase required for cell metabolism D - Ions: K+, Na+, Mg++, Cl-, HCO3- & phosphate. E - Normal cellular organelles: RBCs don’t contain organelles.

Functions of RBCs: 1) Function related to cell membrane: a- The great surface area of the biconcave discs facilitate gas exchange, deformation in narrow capillaries. b- Ion channels  ion transport. c- It contains blood groups antigens. d- It keeps Hb and enzymes inside RBCs.

2) Functions related to contents: - O2 carriage - Co2 carriage - Acid – base buffer - RBCs & plasma proteins are responsible for blood viscosity and blood pressure regulation.

Formation of RBCs (Erythropoiesis) (A) Sites of formation: 1- In the foetus : - Yolk sac: in the first few weeks of pregnancy - Liver & spleen: from 6 weeks to 6 months. - Bone marrow: from the 6th. month. 2- In infancy & childhood: From red bone marrow of all bones. 3- In adult life: - From red bone marrow restricted to vertebrae , ribs and proximal ends of long bones as humerus, femur & tibia.

(B) Factors affecting erythropoiesis: I) Oxygen supply to tissue: (hypoxia): - Occurs in anemia, high altitude, heart or lung diseases - Hypoxia is the main stimulus for erythropoietin formation - Hypoxia stimulates the secretion of erythropoietin hormone (from the kidney 85% and 15 % from the liver).

Hypoxia and erythropoietin (-ve feedback)

II) - Dietary factors A - Proteins of high biological value as animal proteins (contain essential amino acid) to form globin part of Hb b- Iron: Importance: for synthesis of haem part of Hb Sources meat, liver, green vegetables (it must be added to infant diet as the mother milk is not sufficient in iron).

Requirements adult male require 10 mg/day adult female require 15 mg/day pregnant require 20 mg/day infant require 10 mg/day Loss In faeces, sweat, exfoliated skin (about 1mg/day) and very little amount in urine and in lactating milk Women loss in menstruation: 0.5 mg/day (3.5 mg/period)

Absorption of iron (about 10% of dietary intake) 1- Iron is fed as ferric changed into ferrous by gastric HCl , vit. C and duodenal lumen reductase enzyme  Ferrous is transported into the duodenal cell via special transporter  ferrous is trapped as ferritin and stored in this form to be under need.

2- When iron content of blood decreases  ferrous is released from ferritin  transported out to the blood  carried by transferrin  bone marrow where iron is taken from transferrin to be used in the synthesis of haem part of hemoglobin. 3- In the liver and other tissue, iron is taken from transferrin to be stored as tissue ferritin

Intestinal iron uptake lumen Blood Intestinal iron uptake Fe2+ Fe3+ Transferrin Fe2+ Fe3+ e- Ferritin Fe2+

c- Vitamins 1-Vitamin B12: Importance: maturation of RBCs, DNA synthesis and cell division. Absorption: - combines with the intrinsic factor (glycoprotein secreted from gastric parietal cells) to prevent its digestion by enzymes - absorption of B12 occurs in the terminal ileum  blood  carried by transcobalamin  bone marrow. Storage: in liver (storage in liver is very high = 1-5 mg) Requirement: 1-2 g/day Deficiency: Due to malabsorption  pernicious anemia.

Vitamin B12 Absorption B12 Stomach terminal Ileum - B12 IF IF B12+IF Parietal cells - produce IF (intrinsic factor Stomach IF terminal Ileum - IF receptors IF B12+IF B12 IF B12

2- Folic acid It is water soluble vitamin , present in green vegetables, some fruits, liver and meat It is absorbed easily from all small intestine and changed into active folinic acid which is essential for DNA formation and cell maturation Its deficiency leads to megaloblastic anaemia

III ) Hormonal factors: - Androgens - Thyroid hormone - Pituitary hormones - Glucocorticoids