Explain the structure and function of human blood.
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[Textbook Question 5b pg no.82]
The Blood is a liquid connective tissue that consists of cells surrounded by a liquid extracellular matrix. It has a slightly alkaline pH ranging from 7.3-7.4. The colour of blood depends upon the amount of oxygen. When the blood is saturated with oxygen, it is bright red and when the amount of oxygen is less then it is dark red.
The blood consists of two components: plasma and blood cells.
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Blood plasma: It is a pale yellow, clear and slightly alkaline liquid. When all the blood cells are removed from the blood, the liquid that we get is called plasma. It is about
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91.5% water and
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8.5% solutes from which 7% are proteins and 1.5% are inorganic salts.
The proteins which are present in blood are known as plasma proteins. These are albumins, globulins and fibrinogens. Albumins help in maintaining osmotic pressure and exchange of fluids. Globulins help in protection against foreign bodies and fibrinogens play an essential role in blood clotting. Besides proteins, other solutes are inorganic salts like Ca2+, K+ and Na+ and they help in other functionings of cells.
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Blood cells: It is composed of three principal components: red blood cells, white blood cells and platelets.
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Red blood cells: These are small, circular, enucleated and biconcave shaped cells. A pigment called haemoglobin is present in these cells which bind with oxygen to give them a bright red colour. A number of these cells vary from 50-60 lakh per cubic millimetre of blood.
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White blood cells: These are large, enucleated and colourless cells. The number of these cells varies from 5000-10000 per cubic millimetre of blood. There are 5 types of WBCs in the blood: basophils, eosinophils, neutrophils, monocytes and lymphocytes.
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Platelets: These are small and disc-shaped fragments. The number of these cells varies from 2.5-4 lakh per cubic millimetre of blood.
The various functions which are performed by blood are:
- It transports oxygen from the lungs to the cells of the body and carbon dioxide from the body cells to the lungs.
- It carries nutrients like glucose, amino acids, fatty acids from the gastrointestinal tract to cells of the body.
- It transports waste products to various organs for its elimination.
- It protects the body from foreign bodies like viruses and bacteria through the action of antibodies.
- Various enzymes and hormones are transported from their site of production to the target site.
- It helps in maintaining blood pH and body temperature.
- Blood also helps in clotting which avoids excessive loss from the body.
The Blood is a liquid connective tissue that consists of cells surrounded by a liquid extracellular matrix. It has a slightly alkaline pH ranging from 7.3-7.4. The colour of blood depends upon the amount of oxygen. When the blood is saturated with oxygen, it is bright red and when the amount of oxygen is less then it is dark red.
The blood consists of two components: plasma and blood cells.
-
Blood plasma: It is a pale yellow, clear and slightly alkaline liquid. When all the blood cells are removed from the blood, the liquid that we get is called plasma. It is about
-
91.5% water and
-
8.5% solutes from which 7% are proteins and 1.5% are inorganic salts.
-
The proteins which are present in blood are known as plasma proteins. These are albumins, globulins and fibrinogens. Albumins help in maintaining osmotic pressure and exchange of fluids. Globulins help in protection against foreign bodies and fibrinogens play an essential role in blood clotting. Besides proteins, other solutes are inorganic salts like Ca2+, K+ and Na+ and they help in other functionings of cells.
-
Blood cells: It is composed of three principal components: red blood cells, white blood cells and platelets.
-
Red blood cells: These are small, circular, enucleated and biconcave shaped cells. A pigment called haemoglobin is present in these cells which bind with oxygen to give them a bright red colour. A number of these cells vary from 50-60 lakh per cubic millimetre of blood.
-
White blood cells: These are large, enucleated and colourless cells. The number of these cells varies from 5000-10000 per cubic millimetre of blood. There are 5 types of WBCs in the blood: basophils, eosinophils, neutrophils, monocytes and lymphocytes.
-
Platelets: These are small and disc-shaped fragments. The number of these cells varies from 2.5-4 lakh per cubic millimetre of blood.
-
The various functions which are performed by blood are:
- It transports oxygen from the lungs to the cells of the body and carbon dioxide from the body cells to the lungs.
- It carries nutrients like glucose, amino acids, fatty acids from the gastrointestinal tract to cells of the body.
- It transports waste products to various organs for its elimination.
- It protects the body from foreign bodies like viruses and bacteria through the action of antibodies.
- Various enzymes and hormones are transported from their site of production to the target site.
- It helps in maintaining blood pH and body temperature.
- Blood also helps in clotting which avoids excessive loss from the body.
