BIOCHEMISTRY285 PHLIntroduction Blood Glucose

BloodBlood

Blood is a connective tissue that circulates in the closed system of blood vessels

Functions:• Transportation • Regulation of acid-base balance• Regulation of body temperature • Immunity• Coagulation

Blood: CompositionBlood: Composition

Blood

Plasma

Cellular Elements

RBCs

WBCs

Platelets

Water

Solids :Diffusible - Anabolic - CatabolicNon-diffusible

Types of SamplesTypes of Samples

• Whole bloodWater (plasma) + cells (RBCs, WBCs, platelets)

• Plasma Water + solids (e.g. glucose, urea, albumin, fibrinogen)No cells

• Serum Serum = plasma – clotting factors

Centrifuging tubes

Centrifugator

Preparation of sample: PlasmaPreparation of sample: Plasma

Cent. tube

anticoagulant

Add venous blood

Mix then centrifuge

Transfer theclear

supernatantto specimen

tube

cells

Preparation of sample: SerumPreparation of sample: Serum

Venous Blood

Cent. tube

Allow blood to clot(20min.)

Remove the clotand centrifuge

Transfer theclear

supernatantto specimen

tube

cells

ComparisonComparison

Plasma Serum- Anticoagulant - Contains clotting factors- Advantage: time saving

- No anticoagulant- Contains no clotting factors- Advantage: less interference

plasma serum

AnticoagulantsAnticoagulants

Definition:Anticoagulants are chemicals which prevent blood

clottingTypes :

1- Heparin MOA:

Prothrombin thrombin

Advantage: less interference with chemical tests Disadvantage: high cost

Anticoagulants:Anticoagulants: cont. cont.2-EDTA (ethylene diamine tetraacetic acid):

MOA: Binds to calcium

Advantage: prevents platelets clumping 3-Oxalates: (Na, K, Li, or NH4 salts)

MOA:Form insoluble complex with calcium

Disadvantage: interfere with lactate dehydrogenase

N.B Na, K salts should not be used in electrolytes determination

Anticoagulants:Anticoagulants: cont. cont.

4-Citrate: e.g. trisodium citrate Used in ESR

5-Na fluoride: (enzyme poison)Used in blood sugar determination b/c it inhibits

glycolysis

N.B: it inhibits urease enzyme., therefore it should not be used in urea determination

DeproteinizationDeproteinization

Purposes:

1- Proteins have UV absorption

2- Proteins make the solution turbid & difficult to read

3- Determination of non-protein nitrogen & glucose

4- Use the precipitate in plasma protein determination e.g. albumin

Deproteinization Agents Deproteinization Agents Acids

1- Trichloroacetic acid2- Tungestic acid

MOA: – ↓ pH– proteins become cations – ppt as insoluble salts of acids

Bases 1- Zinc hydroxide 2- Cu, Ba, Cd hydroxide

MOA: -↑ pH,- proteins become anions - ppt as insoluble salts of heavy metals

Deproteinization AgentsDeproteinization Agents

Organic substances e.g. ethanol or ether

MOA:

remove water from protein mol.