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BLOOD 1. COMPOSITION, FUNCTIONS, RBC.

BLOOD 1. COMPOSITION, FUNCTIONS, RBC. OBJECTIVES: BLOOD COMPOSITION. Describe the components of blood (cells, ions, proteins, platelets) giving their normal values. Describe the physico -chemical properties of the plasma .

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BLOOD 1. COMPOSITION, FUNCTIONS, RBC.

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  1. BLOOD 1.COMPOSITION, FUNCTIONS, RBC.

  2. OBJECTIVES: BLOOD COMPOSITION • Describe the components of blood (cells, ions, proteins, platelets) giving their normal values. Describe the physico-chemical properties of the plasma. • Define the term hematocrit, state its normal values. Explain the importance of maintaining normal hematocrit level. List the factors that affect the hematocrit value. Understand how dehydration, excessive water intake, RBC count and size affect Htc. Be able to calculate plasma volume for given Htc and total blood volume for given Htc and plasma volume. • Describe the functions of plasma electrolytes. • List the main fractions of plasma proteins and describe their properties and functions. Describe the reasons and consequences of hypoproteinemia. Understand why liver diseases with decreased synthesis of albumins cause edema formation. What is the meaning of the term ‘non-protein nitrogen’?

  3. BLOOD FUNCTIONS • Transportation • Dissolved or chemically bound matter (O2, CO2, nutrients, metabolites) • Heat for heating and cooling (maintenance of the body temperature) • Regulation • Transmission of signals (hormones) • Maintenance of the homeostasis • Concentration of dissolved substances • Osmotic and oncotic pressure • Acid-base balance - buffering the body fluids (maintenance of pH) • Protection • Defense against foreign agents (specific and non-specific immunity) • Prevention of hemorrhage - hemostasis

  4. BLOOD VOLUME AND COMPOSITION Blood volume Males: 5000 – 6000 mL Females: 4000 – 5000 mL 6 - 8% of the total body mass 20% of the ECF. Composition • Blood plasma - non-cellular portion of the blood - 55% 2. Formed elements (45 %): a. Red blood cells, RBC (erythrocytes) -99% of formd. Elmts. b. Platelets (thrombocytes) c. White blood cells, WBC (leukocytes)

  5. HEMATOCRIT (Htc)-ImportantDiagnostic Measurement • Is the fraction of the blood volume made up of the formed elements (mainly RBC) • Is determined by the centrifuging heparinised/anticoagulatedblood in a standard calibrated tube of a small diameter • When blood is allowed to clot or coagulate, the suspending • medium is referred to as serum

  6. HEMATOCRIT Determination of hematocrit values is a simple and important screening diagnostic procedure in the evaluation of hematological disease • Values • Males: 40 – 54 vol% (mean – 47%; 0.47) • Females: 38 – 46 vol% (mean – 42%, 0.42) • ↑ in persons leaving at high altitudes, in dehydrated state, polycythemia, etc. • ↓ in anemia, leukemia, bone marrow failure • Importance • Determines blood viscosity • ↑ Htc → ↑ resistance to blood flow, load on the heart & BP

  7. BLOOD PLASMA Physico-chemical properties • Temperature: 38oC • pH: 7.35 (venous) – 7.45 (arterial) • Relative whole blood viscosity - the internal friction of the blood (viscosity of water is 1.0): 3.5 – 5.4 • Relative plasma viscosity: 1.9 – 2.6 • Erythrocyte sedimentation rate- 2 to 8 mm/hr. Composition • Water: 90-92% • Functions • Solvent & suspending medium for blood components • Absorbs, transports and release heat • Electrolytes(Na+, K+, Ca2+, Fe3+, Mg2+, Cl-, HCO3-, HPO42-, SO42-etc.) dissolved in water: 1% • Functions • Create & maintain plasma osmotic pressure - 290 mOsm/L • Essential role in cell functioning (i.e., electrical properties of the blood cells) • Maintenance of the acid-base homeostasis*- • is a steady state that provides an optimal internal environment for cell function

  8. BLOOD PLASMA: COMPOSITION (cont.) • Organic substances (plasma proteins, nutrients, metabolites and waste products, regulatory substances, etc.) – 7-9% • Plasma proteins – proteins confined to the blood • Nutrients - products of digestion (AA, glucose, FA, glycerol, vitamins, minerals) • Are transported by the blood for distribution in the body • Waste products – breakdown products of protein metabolism (i.e., urea, uric acid, creatine, creatinine, bilirubin and ammonia) • Are transported by the blood for excretion from the body • Regulatory substances (i.e., hormones, enzymes, vitamins) • Dissolvedgases: O2, CO2, N2

  9. Composition of Blood Figure 16-1 (1 of 2)

  10. PLASMA PROTEINS The most charged proteins • 7-9% of the plasma, 65-90 g/L • Are synthesized by the liver (with the exception of γ-globulins) • Fractions • Albumins – plasma concentration – 45 g/L • Globulins (α, β, γ) – 27 g/L • Fibrinogen – 3 g/L • Albumins have the smallest molecular mass whereas fibrinogen is the largest The least negatively-charged serum proteins

  11. GENERAL FUNCTIONS OF PLASMA PROTEINS • Create colloid osmotic pressure (25 mmHg) →retaining water within the capillaries • Binding and transport of hormones, enzymes, lipids, vitamins, metals, bilirubin, drugs, etc. • Contribution to the blood viscosity • Buffer properties – capability of accepting both H+ and base ions • Protection of body against microorganisms and toxic substances • Mediate blood coagulation • Precursors of some hormones (angiotensinogen, erythropoietin) • Protein reserve – source of AA for tissues in case of starvation

  12. PROPERTIES & FUNCTIONS OF VARIOUS FRACTIONS OF PLASMA PROTEINS • Albumins • 60% of the total plasma protein • High concentration and small size → 80% of the total colloid osmotic P of the plasma • 1 globulins (glycoproteins) • Transport of glucose and lipids • Include anti-protease • 2 globulins • Carriers for different substances(high affinity, low binding capacity) • Ceruloplasmin – copper • Thyroxin-binding protein • Transcobalamin – Vit B12 • Bilirubin binding globulin • Transcortin – cortisol, etc.

  13. PROPERTIES & FUNCTIONS OF VARIOUS FRACTIONS OF PLASMA PROTEINS (cont.) • -globulins • Carriers for lipids (lipoproteins), polysaccharides and metals (i.e., transferrin – iron and cupper) • -globulins • Are immunoglobulins (antibodies) • Quantity and composition fluctuate • ↑ in almost all diseases (inflammation and infections) • Fibrinogen • A dissolved precursor of fibrin – blood clotting • Serum – plasma without fibrinogen (and clotting factors)

  14. HYPOPROTEINEMIA • ↓ blood level of proteins • Results from • Malnutrition • Liver diseases (depression of protein synthesis) • Intestinal disease (malabsorption) • Kidney diseases (lost of albumins in urine) • Results in • ↓ plasma oncotic pressure(especially due to ↓ albumin concentration) and edema formation • Depression of specific functions (i.e., ↓ in globulins – ↓ resistance to infections, ↓ in fibrinogen – defective blood clotting)

  15. NON-PROTEIN NITROGEN OF THE PLASMA • Refers to nitrogen-containing substances other than proteins and AA (urea, uric acid, creatinine) • ↑ in deranged kidney function

  16. Plasma Proteins

  17. Blood composition: summary

  18. II. Blood Cells • red blood cells (erythrocytes) • white blood cells (leucocytes) • platelets (thrombocytes).

  19. RBC: Functions • Transport of O2 from the lungs to the tissues and CO2 in the opposite direction • Hemoglobin • Carbonic anhydrase • Catalyses the reaction H2O + CO2 ↔ H2CO3 • Maintenance of pH homeostasis (globin, phosphate and bicarbonate buffers)-hemoglobin in the cells is an excellent acid-base buffer • Contribution to the blood viscosity • ↓ blood oncotic P (by keeping Hb-protein inside the cells)

  20. RBC COUNT • Normal values • Adult males: 4 600 000 – 6 200 000/mm3 (5.4million/mL) • Adult females: 4 200 000 – 5 400 000/mm3 (4.8million/mL) • Abnormally high count – polycythemia • Abnormally low count – anemia

  21. STRUCTURE OF THE MATURE RBC Small size Excess of the plasma membrane & specific shape RBC - biconcave discs with central depression on each side High surface-to-volume ratio Deformation of the cells without stretching the plasma membrane Rapid diffusion of respiratory gases to and from the cell Easy passage through the small capillaries

  22. Red Blood Cells Figure 16-5

  23. STRUCTURE OF THE MATURE RBC (cont.) • Membrane contains special proteins and polysaccharides that differ from person to person – blood groups • Lack of the nucleus and organelles • Cannot undergo mitosis • Generate ATP anaerobically → do not use oxygen they transport • Can not synthesize new cellular components to replace damaged ones Life span - 120 days • Contain a red pigment, hemoglobin(red color of the blood) • Occupies 1/3 of cellular volume • 280 million Hb molecules/RBC

  24. MEAN CORPUSCULAR VOLUME MCV: 82-99 fL • Mean volume of a RBC • Values • Normal range 82 – 99 femtolitre (fL) • Low volume in microcytic anemia • High volume in macrocytic anemia • Calculation of the MCV Hematocrit x 10 RBC count (in millions/mL blood) • Sample calculation: Htc = 40, RBC count = 5 (x 106/mL) MCV = (40 x 10)/5 = 80 fl fL= 10-15 L

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