Topic 11: Human Health and Physiology

11.1 Defense Against Infectious Diseases

11.1.1 Describe the process of blood

clotting

11.1.2 Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity

11.1.3 Define active and passive

immunity

11.1.4 Explain antibody production

11.1.5 Describe the production of monoclonal antibodies and their use in diagnosis and treatment

11.1.6 Explain the principles of

vaccination

11.1.7 Discuss the benefits and dangers of

vaccinations

11.1.1 Describe the process of blood clotting

When human tissues and organs are injured, so are blood vessels

The body reacts in a non-specific response called clotting

• Non-specific – the body does not produce substances for a specific pathogen or disease (for example - antibodies)

Equally important, it does not clot when there isn’t an injury which would prevent blood flow

11.1.1 Describe the process of blood clotting

The process:Blood reacts with: • the air • damaged cells• platelets

Step 1: Damaged cells and platelets release an enzyme called thrombokinase

Step 2: The combination thrombokinase, and clotting factors (X and VII) and Ca2+ ions will change prothrombin (inactive form) into thrombin.

11.1.1 Describe the process of blood clotting

Step 3: Thrombin will change soluble fibrinogen into smaller insoluble fibrin molecules.

This forms a net that catches platelets and erythrocytes (RBC) and forms a plug or clot.

11.1.2 Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity

11.1.4 Explain antibody production

• Blood contains red blood cells (erythrocytes) and white blood cells (leukocytes).

• It is the leukocytes that play a major role in the immune system • There are many different types of leukocytes

11.1.2 Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity

11.1.4 Explain antibody production

Immunity – the body’s ability to recognize self and distinguish self from non-self substances (any non-self substance is called an antigen)

Antibody – a special type of protein constructed in the shape of a “Y”

The top part of the “Y” is the antigen binding site

This binding site is what gives the antibody its specificity

11.1.2 Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity

11.1.4 Explain antibody production Challenge and response” – when a pathogen invades an organism, the organism is challenged and must respond

11.1.2 Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity

11.1.4 Explain antibody production

Step 1: The macrophages ingests the pathogen (phagocytosis)

Step 2: Part of the bacterial cell wall and cell membrane is displayed on the outside of the macrophage (on MHC protein)

11.1.2 Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity

11.1.4 Explain antibody production Step 3: The macrophage travels to the lymph node

• The lymph node contains cells called lymphocytes

• When the macrophage is in the lymph node it will select a helper T- cell which has receptors that are complimentary to the antigen that the macrophage is carrying

Step 4: The T-cell is activated and will divide by mitosis creating a clone

The cloned T-cells will activate B-cells which also have surface receptors that are complementary to the antigen.

This is called clonal selection (the process when the macrophage selects which T-cells and B-cells have required surface receptors)

11.1.2 Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity

11.1.4 Explain antibody production Step 5: B-cells also form clones.

• B-cells produce memory cells that create a faster and stronger response to an antigen that has infected the body before

• B-cells also become plasma cells which will make large amounts of antibodies

• This is called clonal expansion

Clonal expansion – is the process in which T-cell and B-cells form clones through mitosis. This results in a large number of cells to deal with the infection.

11.1.2 Outline the principle of challenge and response, clonal selection and memory cells as the basis of immunity

11.1.4 Explain antibody production

11.1.3 Define active and passive immunity

Active immunity – production of antibodies by the organism itself after the body's defense mechanisms have been stimulated by antigens. This can be from a previous infection or injection of antigens.

Passive immunity – the immunity that is due to the acquisition of antibodies from another organism in which active immunity has been stimulated (placenta, colostrum, injection of antibodies)

11.1.5 Describe the production of monoclonal antibodies and their use in diagnosis and treatment

Monoclonal antibodies can be used to determine someone's blood type or vaccinate a patient.

They are obtained from a single B-cell clone that is fused with an immortal tumor cell.

11.1.5 Describe the production of monoclonal antibodies and their use in diagnosis and treatment

Example: Using Monoclonal Antibodies to Determine Blood Type

• A mouse is injected with an antigen (for example, human red blood cell type A)

• Mouse plasma cells will produce antibodies in response to the human red blood cells

• The plasma cells are extracted and fused with B-cell tumor cells.

• These hybrid cells are grown in culture and will produce identical antibodies (anti-A)

• Now, if you add human blood to the antibodies produced by the hybrid cells.

• If you see clotting than you know that the blood sample contains type A blood.

11.1.6 Explain the principles of vaccination

Vaccination uses the same principles as memory cells in creating a fast secondary response to an antigen.

Vaccination is the deliberate exposure of a patient to the antigens (epitopes) of a dead or a weakened pathogen.

The patient develops memory cells against the antigen. Recovery is therefore rapid perhaps showing little or any sign of infection with these serious diseases because:• high antibody levels• rapid response

Used for serious disease (polio, tetanus, measles, etc...)

11.1.7 Discuss the benefits and dangers of vaccinations

Keyword

11.1.7 Discuss the benefits and dangers of vaccinations