Rbse Class 10 Science Chapter 4 - Immunity and Blood Groups Notes PDF
Immunity:
The ability of our body to fight with diseases is called immunity.
Immunology:
The branch of science which deals with the system and functions in the body to fight with germs is called immunology.
Numerous lymphocytes, lymph, blood, liver, bone marrow and thymus are providing immunity to the body.
There are two types of immunity in the body:
A. Innate Immunity or Innate Defence Mechanism:
This type of immunity is inborn. This is also called general or natural immunity. This type of immunity does not give any special protection against any specific germ rather works against all the antigens in the same way. Hence, it is called general immunity.
Following factors facilitate working of innate immunity:-
Physical Barriers: Physical barriers prevent the entry of germs physically. For example; skin and cilia etc.
Chemical Barriers: Some germs are warded off by means of chemical barriers. For example; hydrochloric acid in stomach kills any germ in food.
Cellular Barriers: Many special cells eat away germs, e.g. macrophages, neutrophils, etc.
Inflammation: Inflammation and fever also work against germ. The high temperature during fever and inflammation kills the germs.
B. Acquired Immunity or Acquired Defence Mechanism:
This type of immunity is acquired by the body in response to a specific germ and learns to fight that antigen. It remembers and can fight any future onslaught of a specific germ.
There are two types of acquired immunity which are as follows:-
Active Immunity: When body proactively prepares an antibody against a specific antigen.
Passive Immunity: In this case, the body does not make any antibody. The antibody is specially inoculated in the body from outside e.g. vaccination.
Antigen:
The germ or foreign material which enters the body and converts B-lymphocytes into antibodies producing plasma cells and specifically interacts with that antibody is called an antigen. It is also called immunoglobulin.
Antigens are generally those external substances which have molecular weight more than 6000 Dalton. Sometimes, antigens can be produced inside the body, e.g. in case of viral infection or by cancerous cells.
Antigenic Determinant:
The whole molecule of antigen does not interact with antibodies, rather some specific parts interact with antibodies. These parts are called antigenic determinants or epitopes.
Valency of Antigen:
A chain of about 6 to 8 amino acids in a protein work as an antigenic determinant. Number of antigenic determinants in a protein is called the valency of antigen. In most of the bacteria, the antigenic valency can be 100 or even more.
Destruction Of Antigen:
Differentiation between internal and external antigens.
Formation of plasma cells by B-lymphocyte cells according to the antigenic determinant present on external antigen.
Formation of specific antibodies by plasma cells.
Destruction of antigen by antigen-antibody reaction and by cell mediated immunity (CMI).
Antibody / Immunoglobulin
Antibodies are Gamma Globulin proteins which are synthesized by the Plasma cells and are found in the blood and other body fluids. Antibodies identify and interact with the antigen to make it ineffective. The portion of the antibody which interacts with the antigen is called Paratope
Or
The protein which is produced by B-lymphocytes in response to an antigen and can specifically interact with the antigen.
Structure
Antibody is in the shape of Y and is made up of 4 structural units, two heavier units (H) and two lighter units (L).
There are two heavy and large and two light and small polypeptide chains. One heavy and one light chain together forms HL dimer. Two such dimers together form an antibody.
Antibody molecule is made up of two homogeneous halves. Both these are joined with each other through disulfide bonds. Each of the half is made up of one H and one L polypeptide chain.
Each heavy chain is made up of 440 amino acids while each light chain is made up of 220 amino acids.
Each heavier and lighter chain is divided into two parts:
Variable Portion: This part reacts with antigen and is present towards NH2 part of the chain. This is also called Fab portion.
Constant Portion: This part is towards COOH part of the chain and is called Fc portion.
In most of the antigen, the arms of Y-shape have flexible origins which are called hinge. Due to flexibility of hinge, the variable portion is able to react with molecules in antigen.
Types of Anybody
Five different types of heavy polypeptide chains are found among the antibodies
On the basis of the present of heavy chain present, antibodies can be divided into five types-
Blood
Blood is a fluidic living tissue which is thick, sticky and red colored and flows in blood vessels.
This is made up of Plasma (non living liquid medium) and blood corpuscles (living cell)). Plasma function to transport the nutrient absorbed by the intestine to various body organs and carry the harmful substances from different organs to the excretory organ.
Three different type of blood capsules are found in the blood -
Red blood corpuscles - transport and exchange gases.
White blood cells - protect the body from pathogens.
Platelets - protect the body vessels and help to prevent bleeding.
Blood Group
An Australian scientist Karl landsteiner classified the blood into four different blood groups on the basis of the presence or absence of various antigen on the surface of red blood corpuscles.
Normally these antigens are made up of protein glycoproteins carbohydrates or glycolipids. These antigens are synthesized from both mother and father.
Two types of antigens (Antigen a and Antigen B') are found on the surface of the Red Blood Corpuscles. Based upon the presence of these two Antigens, four blood groups are found - A, B, AB, and O. This classification is called ABO blood grouping.
'A' type blood has 'A'antigen on the surface of Red Blood Corpuscles while 'B' type blood has 'B'antigen on the surface of Red Blood Corpuscles. AB type blood has both 'A' and 'B'Antigens on the surface of Red Blood Corpuscles. Red Blood Corpuscles of 'O' type blood is devoid of both 'A' and 'B'Antigens.
Apart from 'A' and 'B' Antigens, another Antigen named Rh can also be found on the surface of the Red Blood Corpuscles. If Rh antigen is present on the surface of the Red Blood Corpuscles, blood is called Rh positive (Rh+). The blood in which Red Blood Corpuscles are devoid of Rh Antigen is called Rh negative (Rh-). This classification system is called Rh Grouping.
Persons having 'A' type blood group have IgM type Anti B antibody in their body. In the same way Anti A Antibody is found in persons having type B blood and Anti A and Anti B antibodies in the blood of the persons with O blood group. The persons with AB blood group have neitherAnti AnorAnti B antibodies. If a person with 'A' blood group is transfused with Type B blood, Anti B antibodies present in his blood will destroy the B type Red Blood Corpuscles. This is the case with every mismatch blood transfusion. Hence, before blood transfusion it should always be taken into consideration that the blood group of the donor and the recipient belongs to the same group. A person with 'O' type blood group is called Universal Donor because he can donate blood to all while a person with 'AB' blood group is called Universal recipient he can accept blood from all.
Rh Factor
This factor is a protein which is composed of about 417 amino acids. There are five types of Rh factor in humans, viz. Rh D, Rh E, Rh e, Rh C, and Rh c. The most important Rh factor is Rh D because it is the most immunogenic.
Rh Incompatibility:
If Rh positive blood is transfused to an Rh negative person then the recipient's body produces IgG antibodies. These antibodies destroy RBCs by agglutination. As a result, the person dies due to renal failure.
Erythroblastosis Foetalis:
During the first pregnancy of Rh negative mother with Rh positive child, the mother’s body develops IgG antibodies because mother’s blood gets mixed up with foetal blood during childbirth. The birth of the first child is normal. Complications develop if the second child is also Rh positive. The Rh antibodies in mother’s blood react with Rh factor in foetal blood. This results in destruction of RBCs in foetus and may result in death of the child or the child is very weak and suffers from hepatitis. This condition is called erythroblastosis foetalis. To prevent this, the mother is given a vaccine of anti IgG antibody (anti Rh. D) within 24 hours of the birth of the first child. These are called Rhogam antibodies.
Requirement for Blood transformation
1. At the time of injury or excessive bleeding
2. Serious blood deficiency
3. During Surgery
4. In the condition of deficiency of platelets in the blood
5. Patients of Hemophilia
6. Patients of Sickle Cell Anemia.
Blood Transfusion
Blood Transfusion is a scientific process which is accomplished as follows:
(A) Blood Collection
(1) Before the process of blood collection, the donor is examined medically.
(2) After medical examination, blood from the donor is collected in special sterilized pouches containing anticoagulants.
(3) The collected blood is kept in a refrigerator. This prevents the bacterial growth and down regulates the cellular metabolism in the blood.
(4) The stored blood is subjected to different tests like Blood group, Rh factor, Hepatitis B, Hepatitis C, HIV etc.
(5) After blood collection, the donor is kept under medical surveillance for some time
Note: In humans, plasma is replenished in 2-3 days after the blood donation while after 36 days, blood cells are restored in the blood circulation.
(B) Transfusion
(1) Before transfusion, the patient's blood is matched with the blood of the donor.
(2) The collected blood is brought out of the storage area just 30 minutes before the start of the transfusion process.
(3) Blood is transfused only through intravenous mode. This is a four hour long procedure which is mediated by the help of a cannula.
(4) Medicines are given by the doctor to prevent the transfusion related reactions like fever, chill, pain, cyanosis, irregularity of the heart beat and others.
On the basis of source of blood, transfusion can be of two types
(1) Allogeneic transfusion - Such a Transfusion in which blood collected from other persons is used.
(2) Autogenic transfusion - Such a Transfusion in which blood collected from the person itself is used.
Note: After processing the donated blood can also be segregated into various components like Red Blood Cells, Plasma and Platelets. .
Precautions to be taken during Blood Transfusion
1. Matching ABO Antigen in the blood of the patient and the donor.
2. Testing donor's blood for the absence of any pathogen or harmful substance.
3. Matching the Rh factor (especially Rh.D.) in the blood of the donor and the patient.
4. Storage of the collected blood in refrigerated conditions
5. In every circumstance, protecting the collected blood from contamination.
6. Blood collection and transfusion must essentially be carried out in the presence of a physician.
The following diseases or infections can occur due to the carelessness observed during the transfusion (i) Infection of HIV-1 and HIV-2 (HIV-Human Immuno deficiency Virus) (ii) Infection of HTLV 1 and HTLV-2 (HTLV - Human T-Lymphotropic Virus) (iii)
Significance of Blood Group Heredity:
The following table shows the genotype of different blood groups:
Blood group in the child obeys Mendel’s laws of inheritance. Inheritance of blood groups has many uses, like in settling disputes related to parentage of a child, in blood transfusion, in treating
The diagram shows possible blood groups in child from each couple
Organ Donation and Body Donation:
Organs from a live donor or from a dead donor can be successfully transplanted in a needy patient.
A live donor can donate kidney, liver and bone marrow, Many organs can be used for transplantation from a dead body.
Organs of a brain dead person can be harvested for transplantation. Now-a-days, organs from road accident victims are utilized for this purpose. For this, consent of the dead person’s relatives is mandatory.
In our country, there is a huge waiting list of patients who need organs from donors. But this demand is only partially fulfilled. Government and many NGOs are carrying out sustained campaigns to increase awareness about organ donation
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