Module 4, section 1: Disease and the immune response

What diseases are caused by bacterial pathogens?

TB and ringrot.

What diseases are caused by viruses?

HIV/AIDS, influenza and TMV

What diseases are caused by fungi?

black sigatoka, athletes foot.

What diseases are caused by protoctista?

Malaria, potato/tomato blight.

What are some social factors that can affect the rate of transmission?

Overcrowding, bad education on healthcare, poor living conditions, lack of contraceptive access.

What are some non-specific (innate) aspects of the human immune system? Explain how these parts can help fight disease.

1. The skin (physical barrier and secretes antimicrobial substances)

2. Mucous membranes. Trap pathogens to prevent them from reaching the lungs.

3. Blood clotting. Plugs wounds and prevents pathogens from entering open wound.

4. Inflammation. Heats up the area to make a non-favourable environment for pathogens, and cuts off the affected area to prevent spread of pathogens to the rest of the body.

5. Expulsive reflexes, like sneezing/coughing. Causes foreign pathogens to be expunged from the body, preventing infection.

What are some non-specific aspects of the plant immune system?

1. Physical barriers like the waxy cuticle. Prevents pathogens from entering the plant. The casparian strip also contributes to this effect.

2. Callose deposits. These block substances from moving through the plasmodesmata, thus reducing the rate of transmission.

3. Secreting antimicrobial substances like antibiotics that kill pathogens.

Describe the stages of phagocytosis.

1. Neutrophils identify pathogen (made easier by opsonins).

2. Phagolysosome is formed between lysosome and pathogen.

3. Phagocyte presents antigens on cell surface to become a APC.

How do opsonins aid phagocytosis?

they coat the pathogen in a substance that makes it more easily identifiable to the phagocyte.

How do neutrophils know where to move?

Through the release of cytokines at the wound site.

Describe the action of T-lymphocyte activation.

1. Receptors on the T-lymphocyte bind to the antigens on the APC. This process triggers clonal selection.

2. Activated t-lymphocyte undergoes clonal expansion, and produces clones of itself.

What are the two types of t-lymphocytes, and what are their individual functions?

1. T-helper cells release substances to activate B-lymphocytes.

2. T-Killer cells attach to and kill cells infected with the pathogen.

What are B-lymphocytes,

White blood cell that is covered in antibodies, and releases them when binding to a complementary antigen.

What do b-lymphocytes divide into, and what do they do?

Plasma cells and memory cells, plasma cells produce loads of the antibody to fight the disease.