BLOOD

BLOODLearning objectives:Composition of blood. Functions of blood. How plasma is separated from the blood cells. Hematocrit /PCV and its clinical significanceESR and its clinical significance Plasma proteins types , functionsFunctions of lymph

Study of components and functions of blood is known as HEMATOLOGY.

Blood is a homogenous fluid connective tissue which is in constant circulation throughout the body.

In a normal adult, the volume of blood is about 70 ml/kg body weight and in an infant it is about 90 ml/kg body weight.

On an average in a normal adult weighing about 70 kg, the volume of blood present is about 5 liters.The functions of blood :RespiratoryExcretoryNutritiveProtectiveRegulation of body temperaturepH regulation.

Packed Cell Volume(PCV)/ hematocrit:Definition PrincipleNormal valueSignificance

Erythrocyte Sedimentation Rate(ESR):Definition PrincipleNormal values Significance

Rouleaux formation Westergrens tube Plasma Is the fluid part of blood in which formed elements (cellular components) are suspended.

The normal proportion of plasma in blood is about 55%.

About 91 93% of plasma is made up of water.

The remaining 7 9% is contributed by organic and inorganic constituents.

Inorganic constituents of plasma positively charged ions Sodium normal sodium level of plasma is about 150 mEq/L of water

Potassium normal potassium level of plasma is about 5 mEq/L of water.

Calcium its concentration is about 9 to 11 mg%.

Negatively charged ions in plasma:Chloride Normal level is about 110 mEq/L of water.

Bicarbonate normal level is about 24 mEq/L of water .

Plasma reflects the overall inorganic composition of extra cellular fluid (ECF) in the body.

The organic constituents arePlasma proteins- 6 8 g%Glucose- 60 90 mg% (fasting)Urea- 15 40 mg%Cholesterol - about 150 to 250 mg%Creatinine- about 0.3 -1.3 mg%

Plasma proteins and their functions:Albumin-4.2 to4.8 grams%Globulins-2.3 grams%Fibrinogen-300 to 400 mgs%Prothrombin-15 to 40 mgs%Total-6 to 8 grams%Normal albumin globulin ratio is 2:1

Globulin type can be further sub divided into 1

2

1

2

globulin. This protein is also known as immunoglobulins

14Synthesis:Albumin, fibrinogen and Prothrombin exclusively by the LiverGlobulins 80% by the liver, the rest from the cells belonging to the Reticulo Endothelial System.Concentration of the plasma protein falls markedly in Liver diseases-Cirrhosis of the liver

FUNCTIONS OF PLASMA PROTEINS1. Blood coagulation-Fibrinogen and Prothrombin in coagulation.

2. Colloidal osmotic pressure and its role in fluid exchange, across the capillaries.

3. Maintains viscosity of the blood, its role in maintenance of BP.Blood is about 5-6 times more viscous than water. For viscosity of blood both the plasma proteins and formed elements contribute equally.

Among the plasma proteins it is fibrinogen which contributes most. It is because fibrinogen has irregular shape unlike albumin and many of the globulin fractions.

Viscosity of blood has to be maintained in order to maintain peripheral resistance. Peripheral resistance in turn helps to maintain blood pressure.

4. Regulation of body fluid pH -The plasma proteins have amino (NH2) and carboxyl terminals (COOH). These terminals either can accept hydrogen ion (NH2) or can donate hydrogen ion (COOH).When pH of blood falls below 7.4 (acidosis) plasma proteins accept hydrogen ion.When the pH blood is above 7.4 (alkalosis), plasma proteins donate hydrogen ions.5. Protective role-Gamma globulins are immunoglobulins.

6. Transport function-transport of Hormones and metals.Hormones like thyroxine, cortisol, growth hormone etc.Metals like iron, copper etc.Gas like carbon dioxide.

Applied aspects:Decrease in plasma proteins-Decreased synthesis :Cirrhosis of liver HepatitisMalnutrition - proteinIncreased excretion :Nephrotic syndromeGlomerulonephritis

Edema 4. Regulation of body fluid pH -The plasma proteins have amino (NH2) and carboxyl terminals (COOH). These terminals either can accept hydrogen ion (NH2) or can donate hydrogen ion (COOH).When pH of blood falls below 7.4 (acidosis) plasma proteins accept hydrogen ion.When the pH blood is above 7.4 (alkalosis), plasma proteins donate hydrogen ions.5. Protective role-Gamma globulins are immunoglobulins.

6. Transport function-transport of Hormones and metals.Hormones like thyroxine, cortisol, growth hormone etc.Metals like iron, copper etc.Gas like carbon dioxide.

Applied aspects:Decrease in plasma proteins-Decreased synthesis :Cirrhosis of liver HepatitisMalnutrition - proteinIncreased excretion :Nephrotic syndromeGlomerulonephritis

Edema