BLOOD & BLOOD CIRCULATION
PART 1
BLOOD
• It transports substances like digested food from the small intestine to the other parts of the body. It carries oxygen from the lungs to the cells of the body. It also transports waste for removal from the body.
• Blood is a liquid, which has cells of various kinds suspended in it. The fluid part of the blood is called plasma.
• One type of cells are the red blood cells (RBC) which contain a red pigment called haemoglobin.
• Haemoglobin bind with oxygen and transports it to all the parts of the body and ultimately to all the cells. The presence of haemoglobin makes blood appear red.
• The blood also has white blood cells (WBC) which fight against germs that may enter our body.
• The clot is formed because of the presence of another type of cells in the blood, called platelets.
BLOOD VESSELS
• They are two types of blood vessels namely arteries and veins.
• Veins are the blood vessels that carry carbon dioxide-rich blood [impure blood] from all parts of the body back to the heart. Pulmonary vein is an exception as it carries oxygen-rich blood [pure blood] from lungs to heart. The veins have thin walls.
• Arteries are the blood vessels that carry oxygen-rich blood from heart to all parts of the body. Pulmonary artery is an exception as it carries carbon dioxide-rich blood from heart to lungs. The arteries have thick walls as the pressure acting on then is high.
Blood FROM Heart → Artery
Blood TO Heart → Vein
• Arteries divide into smaller vessels. On reaching the tissues, they divide further into extremely thin tubes called capillaries. The capillaries join up to form veins which empty into the heart.
BODY FLUIDS AND CIRCULATION
• Blood is a special connective tissue consisting of a fluid matrix, plasma, and formed elements.
PLASMA
• Plasma is a straw coloured, viscous fluid constituting nearly 55 per cent of the blood.
• 90-92 per cent of plasma is water and proteins contribute 6-8 per cent of it.
• Fibrinogen, globulins and albumins are the major proteins.
• Fibrinogens are needed for clotting or coagulation of blood.
• Globulins primarily are involved in defense mechanisms of the body
• Albumins help in osmotic balance.
• Plasma also contains small amounts of minerals like Na+, Ca++, Mg++, HCO3-, Cl-, etc. Glucose, amino acids, lipids, etc., are also present in the plasma as they are always in transit in the body.
• Factors for coagulation or clotting of blood are also present in the plasma in an inactive form. Plasma without the clotting factors is called serum.
Formed Elements
• Erythrocytes, leucocytes and platelets are collectively called formed elements and they constitute nearly 45 per cent of the blood.
1. Red Blood Cells (RBC)
• Erythrocytes or red blood cells (RBC) are the most abundant of all the cells in blood.
• A healthy adult man has, on an average, 5 million to 5.5 million of RBCs mm-3 of blood.
• RBCs are formed in the red bone marrow in the adults. RBCs are devoid of nucleus in most of the mammals and are biconcave in shape.
• They have a red coloured, iron containing complex protein called haemoglobin, hence the colour and name of these cells.
• RBCs have an average life span of 120 days after which they are destroyed in the spleen (graveyard of RBCs).
2. White Blood Cells (WBC)
• Leucocytes are also known as white blood cells (WBC) as they are colorless due to the lack of haemoglobin. They are nucleated and are relatively lesser in number which averages 6000-8000 mm-3 of blood. Leucocytes are generally short lived. We have two main categories of WBCs – granulocytes and agranulocytes.
• Neutrophils, eosinophils and basophils are different types of granulocytes, while lymphocytes and monocytes are the agranulocytes.
• Neutrophils are the most abundant cells (60-65 per cent) of the total WBCs and basophils are the least (0.5-1 per cent) among them.
• Neutrophils and monocytes (6-8 per cent) are phagocytic cells which destroy foreign organisms entering the body.
• Basophils secrete histamine, serotonin, heparin, etc., and are involved in inflammatory reactions.
• Eosinophils (2-3 per cent) resist infections and are also associated with allergic reactions.
• Lymphocytes (20-25 per cent) are of two major types – ‘B’ and ‘T’ forms. Both B and T lymphocytes are responsible for immune responses of the body.
3. Platelets
• Platelets also called thrombocytes, are cell fragments produced from megakaryocytes (special cells in the bone marrow).
• Blood normally contains 1,500,00-3,500,00 platelets mm-3.
• Platelets can release a variety of substances most of which are involved in the coagulation or clotting of blood.
• It transports substances like digested food from the small intestine to the other parts of the body. It carries oxygen from the lungs to the cells of the body. It also transports waste for removal from the body.
• Blood is a liquid, which has cells of various kinds suspended in it. The fluid part of the blood is called plasma.
• One type of cells are the red blood cells (RBC) which contain a red pigment called haemoglobin.
• Haemoglobin bind with oxygen and transports it to all the parts of the body and ultimately to all the cells. The presence of haemoglobin makes blood appear red.
• The blood also has white blood cells (WBC) which fight against germs that may enter our body.
• The clot is formed because of the presence of another type of cells in the blood, called platelets.
BLOOD VESSELS
• They are two types of blood vessels namely arteries and veins.
• Veins are the blood vessels that carry carbon dioxide-rich blood [impure blood] from all parts of the body back to the heart. Pulmonary vein is an exception as it carries oxygen-rich blood [pure blood] from lungs to heart. The veins have thin walls.
• Arteries are the blood vessels that carry oxygen-rich blood from heart to all parts of the body. Pulmonary artery is an exception as it carries carbon dioxide-rich blood from heart to lungs. The arteries have thick walls as the pressure acting on then is high.
Blood FROM Heart → Artery
Blood TO Heart → Vein
• Arteries divide into smaller vessels. On reaching the tissues, they divide further into extremely thin tubes called capillaries. The capillaries join up to form veins which empty into the heart.
BODY FLUIDS AND CIRCULATION
• Blood is a special connective tissue consisting of a fluid matrix, plasma, and formed elements.
PLASMA
• Plasma is a straw coloured, viscous fluid constituting nearly 55 per cent of the blood.
• 90-92 per cent of plasma is water and proteins contribute 6-8 per cent of it.
• Fibrinogen, globulins and albumins are the major proteins.
• Fibrinogens are needed for clotting or coagulation of blood.
• Globulins primarily are involved in defense mechanisms of the body
• Albumins help in osmotic balance.
• Plasma also contains small amounts of minerals like Na+, Ca++, Mg++, HCO3-, Cl-, etc. Glucose, amino acids, lipids, etc., are also present in the plasma as they are always in transit in the body.
• Factors for coagulation or clotting of blood are also present in the plasma in an inactive form. Plasma without the clotting factors is called serum.
Formed Elements
• Erythrocytes, leucocytes and platelets are collectively called formed elements and they constitute nearly 45 per cent of the blood.
1. Red Blood Cells (RBC)
• Erythrocytes or red blood cells (RBC) are the most abundant of all the cells in blood.
• A healthy adult man has, on an average, 5 million to 5.5 million of RBCs mm-3 of blood.
• RBCs are formed in the red bone marrow in the adults. RBCs are devoid of nucleus in most of the mammals and are biconcave in shape.
• They have a red coloured, iron containing complex protein called haemoglobin, hence the colour and name of these cells.
• RBCs have an average life span of 120 days after which they are destroyed in the spleen (graveyard of RBCs).
2. White Blood Cells (WBC)
• Leucocytes are also known as white blood cells (WBC) as they are colorless due to the lack of haemoglobin. They are nucleated and are relatively lesser in number which averages 6000-8000 mm-3 of blood. Leucocytes are generally short lived. We have two main categories of WBCs – granulocytes and agranulocytes.
• Neutrophils, eosinophils and basophils are different types of granulocytes, while lymphocytes and monocytes are the agranulocytes.
• Neutrophils are the most abundant cells (60-65 per cent) of the total WBCs and basophils are the least (0.5-1 per cent) among them.
• Neutrophils and monocytes (6-8 per cent) are phagocytic cells which destroy foreign organisms entering the body.
• Basophils secrete histamine, serotonin, heparin, etc., and are involved in inflammatory reactions.
• Eosinophils (2-3 per cent) resist infections and are also associated with allergic reactions.
• Lymphocytes (20-25 per cent) are of two major types – ‘B’ and ‘T’ forms. Both B and T lymphocytes are responsible for immune responses of the body.
3. Platelets
• Platelets also called thrombocytes, are cell fragments produced from megakaryocytes (special cells in the bone marrow).
• Blood normally contains 1,500,00-3,500,00 platelets mm-3.
• Platelets can release a variety of substances most of which are involved in the coagulation or clotting of blood.
To be Continued in Part 2
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