What is Blood?
➢ Blood is a specialized connective tissue.
➢ Fluid in nature
➢ Circulates in a closed system of vessels.
➢ The total volume of blood in the human body is about 6 liters.
➢ Blood is slightly alkaline with a pH value of 7.4
➢ Specific Gravity: about 1.055.
Functions of Blood
➢ Blood Transports Oxygen and nutrients to various tissues.
➢ Transports waste products to the organ of excretion.
➢ Carries hormones from endocrine glands to various tissues.
➢ Redistributes water from one part of the body to the other.
➢ Contains antibodies and white blood cells which protect the body from diseases.
➢ Clotting of blood protects against hemorrhage.
Composition of Blood
Blood is composed of Plasma ( nearly 55% ) and Cellular elements.
Plasma :
➢ The fluid component of blood in which the cellular elements are suspended.
➢ Plasma occupies 55% of blood volume.
➢ Composition of Plasma :
1. Water (91%)
2. Non-diffusible constituents: Albumin, globulin, fibrinogen, and enzymes.
3. Diffusible constituents :
i) Hormones and vitamins
ii) Anabolic constituents like glucose, amino acids, fatty acids, and triglycerides.
iii) Electrolytes like sodium, potassium, calcium, and magnesium.
iv) catabolic products like urea, uric acid, and creatinine.
The cellular elements of Blood
1. Red Blood cells (Erythrocytes)
2. White Blood cells (Leucocytes)
3. Platelets (Thrombocytes)