Immunity

What are the types of immunity

1. Innate immune system - natural and unspecific immunity targeting all pathogens

2. Adaptive immune system - specific response to antigens

• Humoral nervous response in the blood - B lymphocytes

• Cell-mediated response - T lymphocytes

Explain the parts of the innate immune system

1. Skin - vitamin C for string connective tissue barrier and microflora to outcompete pathogens on surface

2. Phagocytes

3. Stomach acid

4. Lysozymes - in tears which hydrolyse peptidoglycan cell walls for lysis

5. Inflammation - localises damage and diverts blood for phagocytes and increases temp - non optimal for their growth

6. Blood clotting - prevent entry of pathogens and sealing wound

7. Ciliated columnar epithelium - mucus to trap bacteria and move up trachea

Explain the humoral immune response as a part of the adaptive immune system

1. B lymphocytes are produced in the bone marrow as stem cells but mature in the spleen and lymph nodes.

2. They are then secreted into the blood where they travel round with a specific complementary receptor to an antigen

3. When that specific antigen binds to the receptor (clonal selection) it triggers proliferation by mitosis to produce more BL - clonal expansion

4. They then differentiate into plasma cells which are antibody secreting cells and memory cells which travel dormant in the blood with the specific receptor ready for secondary immune response

Explain the cell-mediated immune response as a part of the adaptive immune system

1. T lymphocytes are produced from bone marrow as stem cells and then mature in the thymus gland

2. Phagocytes like macrophages in the blood have receptors complementary to the antigens of pathogens so when they bind to receptors they engulf and digest by phagocytosis and lysosomes in the cell destroy the pathogen.

3. The macrophages then present the antigen

4. The T-lymphocytes then detect this - clonal selection with their complementary receptor, proliferate by mitosis - clonal expansion and differentiate to form

• T-killer cells which lyse cells

• T-helper which produce cytokines which stimulate antibody response, B L and phagocytes

• memory cells

Explain the primary vs secondary immune response in terms of antibodies concentration

The pathogens first initial contact creates a lag in the primary response because it takes time for phagocytosis and lymphocytes clonal selection and expansion and so symptoms are already displayed when the antibodies are secreted

The antibodies concentration then increases and the primary response kills the pathogens

Subsequent exposure to the pathogens trigger fast secondary immune response with no lag before symptoms as memory cells remember the antigens and have a complementary receptor so can stimulate plasma cells and specific antibodies even with low levels of pathogen

Draw and label an antibody

Explain the 4 types of immunity and examples from each

1. Natural - There is no medical intervention in causing an immune response

2. Artificial - There is medical intervention in provoking an immune response

3. Active The body makes it’s own antibodies and memory cells for secondary response

4. Passive - medically made antibodies are transferred ready made so no memory cells for 2ndary response

Examples

1. Natural active - catching disease, primary and then secondary response

2. natural passive - vaccine

3. Artificial active - transfer of milk/ placenta antibodies

4. Artificial passive - transfer of antibodies - no memory cells and used in Rabies

What is a vaccination

It is a type of artificial active immunity to stimulate a primary response within the body without symptoms but to create memory cells so that secondary exposure and response is quick with no symptoms

What are the 4 types of vaccine

1. Killed - killed through chemicals or heat eg. Flu

2. Attenuated - live micro-organisms cultured under specific conditions so they aren’t pathoegenic eg. TB

3. Toxoid - Toxics from pathogen are inserted

4. Subunits - parts of the pathogens eg. antigens which will provoke primary response

What are the features of vaccines

• Long last immunity

• Few side effects

• Can provide immunity - immunogenic from a disease

• Even if lots of antigenic types so less long term immunity, yearly immunization programes can create ‘herd immunity’ where enough of a population has been vaccinated so that there is a low human reservoir so that it protects those who can’t be vaccinated

List some ethical issues with vaccines

1. Cost

2. side effects

3. Right to refuse vs compulsory