Class 9 - Biology
Amazing Facts About Blood
- Human heart pumps the blood 36 thousand liters of blood in the distance of 20 thousand kilometers in a day.
- Blood is a fluid connective tissue.
- Human blood is red in colour due to the presence of red pigment i.e. haemoglobin.
- The blood is always not red in all animals. The cockroach has white blood where as there is blue coloured blood in a snail.
- Normal adult human beings have about 5 litres of blood. A chief component in plasma is water.
- Plasma also contains factors responsible for blood clotting. Herarine helps to prevent blood clotting in blood vessels.
- Cells present in blood are corpuscles. These are three types
3. Blood platelets.
- Red blood cells also known as erythrocytes are red in colour. They have red coloured protein called haemoglobin
- When a human baby is in her mother's womb, RBCs are formed in the liver and spleen. After birth, these RBC are generated from the bone marrow of long bone. All mammals except camel and Ulama have red blood cells without a nucleus.
- WBCs do not have haemoglobin, hence they are colourless cells or leucocytes. There are two types - granulocytes and agranulocytes. There are three types of cells in the granulocytes - Neutrophils, Basophils and Eosinophils. These cells attack and destroy the microorganisms that enter the blood.
- These dead WBC come out of wound. This is generally called 'pus'.
- There are two types of agranulocytes lymphocytes and monocytes. Lymphocytes secret anti-bodies to guard against foreign material that enter into blood. Monocytes move like amoeba and along with granulocytes. They attack the foreign materials and engulf them.
- Blood platelets are a separate group of cells which do not have a nucleus. They are disk like projections. Whenever a blood vessel is injured, platelets accumulate at the site of injury and help in the formation of a blood clot.
- Land Steiner, a German doctor, found a new blood relation among us. He divided human beings into four major groups. They are A, B, AB and O.
- AB group human beings can receive the blood from any other groups. Hence they are called as universal recipients. 'O' group people can donate the blood to any other group. So these people are known as universal donors.
Tissues - Notes
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