BODY FLUIDS AND CIRCULATION

POINTS TO REMEMBER :

• Blood: A special connective tissue that circulates in principal vascular system of man and other vertebrates consisting of fluid matrix, plasma and formed elements.

Plasma :

• The liquid part of blood or lymph which is straw coloured, viscous fluid constituting nearly 55 per cent of blood.
• 90-92 percent of plasma is water and 6-8% proteins.
• Fibrinogen, globulin and albumins are the major protein found in plasma.
• Fibrinogen is required in blood clotting or coagulation of blood.
• Globulins involved in defense mechanism of the body.
• Albumin helps in osmotic balance of blood.
• Plasma also contains small amounts of minerals, glucose, amino acids, lipids etc.
• Plasma without the clotting factors is called serum.

Formed elements :

Erythrocytes :

• Also known as RBC (red blood cells) is the most abundant of all the cells of blood.
• 5 – 5.5 million RBC found per mm-3 of the blood.
• Produced from the red bone marrow in the adult.
• RBCs devoid of nucleus in most of mammals.
• Biconcave in shape
• Red in color due presence of complex conjugated protein called haemoglobin.
• 12-16 gm of haemoglobin present per 100 ml of blood in a healthy adult.
• RBCs have average life span of 120 days after which is destroyed in the spleen.
• Spleen is commonly known as the graveyard of RBCs.

Leukocytes :

• Also known as white blood cells (WBC).
• They are colorless due to lack of haemoglobin.
• They are nucleated and relatively lesser in number which averages 6000-8000 mm-3 of blood.
• We have two main category of WBC;
• Granulocytes
  • Neutrophils
  • Basophils
  • Eosinophils
  
  
• Agranulocytes.
  • Lymphocytes
  • Monocytes.
  
  
• Neutrophils (60-65%) of the total WBCs are phogocytic in nature.
• Basophils (0.5-1 %), secretes histamine, serotonin and heparin and also involved in inflammatory reactions.
• Eosinophils (2-3 %) resist infection and also associated with allergic reaction.
• Lymphocytes (T cells and B cells) constitute 20-25 percent and involved in the immune response of the body.
• Monocytes (10-15%), becomes macrophages.

Thrombocytes :

• Also known as blood platelets.
• Produced from fragmentation of megakaryocytes.
• Blood normally contain 1, 500, 00 – 3, 500, 00 platelets mm-3.
• Involved in releasing thromboplastin required to initiate blood coagulation.

BLOOD GROUPS :

• Two blood grouping mechanisms ABO and Rh system.

ABO grouping :

• ABO grouping is based on the presence or absence of two surface antigens on the RBCs namely A and B.
• Plasma of different individuals contains two natural antibodies, anti ‘A’ and ‘B’.

• In a mismatched transfusion the antigen of the donor reacts with antibody of the recipient to cause a reaction called clumping of agglutination.
• Person with blood group ‘O’ has no antigen hence can donate blood anybody, called universal donor.
• Person with blood group ‘AB’ has no antibody in his plasma hence can receive blood from anybody, called universal recipient.

CBSE Biology (Chapter Wise) Class XI ( By Mr. Hare Krushna Giri ) 
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