Blood is specialized connective tissue which circulates in closed system blood vessels. Blood temperature-38°C Blood pH-7.4 (Slightly alkaline)

Blood makes up 6–8% of our total body weight i.e.5600 ml in adult man. Normal adult blood volume is 5 L.


Blood is responsible for…..

  • Transporting gases (oxygen & carbon dioxide)
  • Transporting waste products
  • Transporting nutrients, hormones, vitamins
  • Helping remove toxins from the body
  • Transports metabolites
  • Regulation of pH
  • Regulate water balance
  • Maintain acid-base balance
  • Maintenance of body temperature
  • Protection against infection (foreign substances)
  • Clot formation


Hemopoiesis is the process of development of the blood cells (WBCs, RBCs, Platelets) in bone marrow.


Blood Plasma- the normal plasma volume is about 8 % of body weight.

it is made up of 3 Basic components –

  1. Water,
  2. Dissolved organic & inorganic component
Electrolytes             Gases Nutrients Waste products
Sodium Ions, Potassium Ions, Calcium Ions, Magnesium Ions, Chloride Ions, Bicarbonate Ions, Phosphate Ions. Carbon Dioxide, Oxygen, Nitrogen. Glucose, Carbohydrate, Amino Acids, Lipids, Cholesterol, Vitamins, Trace Elements. Urea, Uric Acid, Creatinine, Bilirubin.

3. plasma protein

Albumins (54%) Globulins (38%) Fibrinogen (7%) Immunoglobulins (1%)
Buffer action Blood clotting Protective (Antibodies)


red bloodcells on white surface
Structure Biconcave disc like
Components Hemoglobin,  lipids, ATP,  Carbonic Anhydrase
Function Transport oxygen from lungs to tissues and carbon dioxide from tissues to lungs
Life span About 120 days Hemoglobin (iron protein)is found in the RBC
Production Formed in the bone marrow


Hemoglobin (Haeme-Non protein part & Globin- Protein part)

4 globin molecules: Transport carbon dioxide (carbonic anhydrase involved), nitric oxide Nitric oxide (NO) binds to hemoglobin Releases NO causing vasodilation to improve blood flow and oxygen delivery 4 heme molecules: Transport oxygen —Iron is required for oxygen transport.

Each RBCs contain—280 million Hb molecules.

Molecular weight of Hb is about 68,000 The iron content of haem imparts Red color to Hb (RBCs)


Structure Largest sized blood cells
Components Contain nuclei with DNA,
Function -Protect body against microorganisms and remove dead cells and debris -Primary cells of the immune system -Fights disease and foreign invaders
Production Formed in the bone marrow and some in lymph glands
Life span is from 24 hours to several years
Size is 8-20 micrometers in diameter

PLATELETS (Thrombocytes)

Production Formed in the bone marrow
Structure Smallest of the blood cells
Size 1-4 micrometers in diameter
Shape round, oval, or appear spiky
Life span around 8-12 days
Functions Involved in the clotting process Seal wounds and prevent blood loss Helps repair damaged vessels
Platelets stain bluish with reddish or purple granules 

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