Immunity Important Notes
1. Types of immunity
- Innate immunity
- Acquired immunity
- Types
- Active immunity
- Natural active
- Artificial active
- Passive immunity
- Natural passive
- Artificial passive
- Active immunity
- Types
2. Antigens
- Heterophile antigen
- These are the same or closely related antigens present in different tissues of more than one species
- Haptens
- These are substances unable to induce antibody formation on its own but can be immunogenic when linked to carrier proteins
- It is a partial/incomplete antigen
3. Immunoglobulin
- These are substances which are formed in serum in response to an antigen
- It consists of two heavy chains and two light chains held together by disulphide bonds
Immunoglobulin Classes
Read And Learn More: Microbiology Question and Answers
4. Types of antigen-antibody reactions
5. Complement
- It refers to a system of factors which occurs in normal serum and are activated by antigen-antibody reaction
- It is triggered by two parallel pathway
- Classical pathway
- Alternate pathway
6. Interleukins (IL)
7. Hypersensitivity reactions
8. Vaccines
Immunity Long Essays
Question 1. Define and classify immunity. Discuss acquired immunity.
Answer:
Definition:
1. Immunity:
- It is defined as resistance exhibited by the host against any foreign antigen including micro-organisms.
Immunity Classification:
- Immunity may be classified into different types as follows.
2. Acquired immunity:
Definition:
- It is the resistance acquired by an individual during life.
Acquired immunity Types:
1. Active Immunity:
- It is subdivided into two types.
- Natural active immunity.
- Acquired by natural subclinical or clinical infections.
- It is long-lasting.
- Example: A person recovering from smallpox develop natural active immunity.
- Artificial active immunity.
- Induced by vaccination.
- Natural active immunity.
Mechanism:
- Active immunity stimulates both humoral and cell-mediated immunity.
2. Passive Immunity:
- It is subdivided into two types:
- Natural
- Immunity is transferred from mother to fetus transplacentally.
- Artificial
- Occurs through the parenteral administration of antibodies.
- Natural
Mechanism:
- It is induced in an individual by preformed vaccines against infective agents.
- It is short lasting.
- It is used when immunity is required immediately.
Uses:
- To provide immediate short-term protection
- For suppression of active immunity.
- For treatment of serious infection
Immunity Short Essays
Question 1. Innate immunity.
Answer:
Innate immunity Definition:
- It is the resistance which individual possesses by birth.
Innate Immunity Types:
- Factors influencing it:
1. Age:
- Infants have immature immunity, while during old age there is gradual decreases in immunity.
- This increases susceptibility to infections.
2. Hormones:
- Hormonal disorders may lead to increased susceptibility to infections.
3. Nutrition:
- Malnutrition predisposes to infections.
Innate immunity Mechanism:
1. Epithelial surfaces:
- Skin.
- Act as a mechanical barrier to micro-organisms
- Provides bacteriocidal secretions.
- The resident bacterial flora prevents colonization by pathogens.
- Respiratory tract.
- Nasal passages arrest the inhaled particles.
- The mucous secretions of the respiratory tract act as a trapping mechanism.
- Cilia help to propel the particles toward the pharynx.
- Intestinal tract.
- Mouth – inhibits micro-organisms.
- Acidic gastric pH – destroys bacteria.
- Intestine – prevents colonization of bacteria,
- Conjunctiva.
- Tears flushes away bacteria and dust particles.
- Lysozyme present in tears has bacteriocidal actions.
- Genitourinary tract.
- Urine eliminates bacteria.
- Vaginal secretions destroy pathogens.
- Semen contains antibacterial substances.
2. Antibacterial substances:
- It includes properdin, complement, lysozyme, beta-lysin, basic polypeptides, and interferons.
3. Cellular factors:
- Phagocytic cells ingest pathogenic organisms and de¬stroy them.
4. Inflammation:
- It is a non-specific defense mechanism.
- It phagocytoses and destroys micro-organism.
5. Fever:
- Stimulates production of interferon
6. Acute phase proteins:
- Activate alternate pathways of complement.
Immunity Short Question And Answers
Question 1. Types of active immunity with examples.
Answer:
Types of active immunity with examples
Question 2. Difference between active and passive immunity
Answer:
Difference between active and passive immunity
Question 3. List two examples of Passive immunity.
Answer:
Two examples of Passive immunity
Question 4. Define and classify antigens.
Answer:
Antigen Definition:
- The antigen is a substance which, when introduced into a body evokes an immune response to produce a specific antibody with which it reacts in an observable manner.
Antigen Types:
1. Complete antigen.
- These can induced antibody formation by themselves.
2. Complete antigen.
- These can induced antibody formation by themselves.
3. Incomplete antigen/haptens.
- These are unable to induce antibody formation on their own.
- But can become immunogenic when they are covalently linked to carrier proteins.