Human Blood

Circulatory System of Class 11

It is composed of following two elements:

Plasma : Alkaline (pH 7.35—7.45), viscous aqueous solution (viscosity is due to the presence of various proteins and other cellular materials) constitutes about 55% to total volume of blood, about 30-35% of total extracellular fluids (ECF).


Water about 90%.

Diffusible constituents include electrolytes, anabolic and catabolic substances formed during metabolism, hormones and vitamins.

Non-diffusible constituents include albumins, globulins, fibrinogen and various enzymes.

Proteins and other organic substances, protein about 7 % comprises of globulins, albumins, fibrogen & prothrombin.

Glucose about 1%.

Fats, endocrine secretion, enzymes about 2%.

Inorganic substances (chloride, bicarbonate, phosphate, calcium constitute about 1%).


Carries the digested food materials and endocrine secretions to different parts of body.

Maintains the actual continuity of flow.

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