HL Biology Unit 6.1 - Defense against Infectious Diseases

What is “Innate Immunity”

Non-specific immunity; barriers against infection that prevent entry of any pathogen

What role does skin play in immunity?

it provides non-specific immunity as a physical barrier against pathogens. It also has a chemical barrier: sebum is a waxy/oily substance that is slightly acidic to prevent infection (made in the sebaceous glands).

What are 4 types of pathogens and examples of each?

Viruses (coronavirus, flu), bacteria (e.coli, cholera), fungi (ringworm, athlete’s foot), protists (malaria, amoebas)

What is the role of mucus in immunity?

Mucus membranes line orifices to trap pathogens and contain lysozyme, an anti-bacterial enzyme

What are phagocytes?

White blood cells from the capillaries that find pathogens by amoeboid movement and engulf them

What is the process of blood clot formation?

1. When blood vessels are damaged, platelets bind to the exposed molecules and activate

2. Positive Feedback Loop: These activated platelets encourage activation/binding of more platelets and release clotting factors

3. Ex. of clotting factors:

   1. prothrombin (inactive) → thrombin (active)

   2. Thrombin facilitates: fibrinogen (soluble) → fibrin (insoluble), polymer fibers that hold cells together to form a mesh, stabilizing the clots

What are 4 things associated with specific/adaptive immunity?

Antigens, Antibodies, Macrophages, Lymphocytes

What are antigens?

Proteins (often glycoproteins) that elicit specific immune responses

What are Macrophages?

Phagocytes that begin “learned” immune responses

What are Lymphocytes?

White blood cells that make antibodies, used to target specific pathogens to gain learned immunity. Lymphocytes circulate through the blood and concentrate in the lymph nodes. (ex. T cells)

What are the steps of adaptive immunity?

1. Macrophage identifies and kills pathogen, but presents its antigens to a Helper T cell.

2. T cells produce antibodies and activate certain B cells - we have a lot of B cells, but each one only makes one type of antibody

3. Activated B cells clone by mitosis to form plasma cells that make specific antibodies for the infection

4. Plasma cells that remain in are called memory cells, which provide long-term immunity

Name 4 types of vaccines

antigen, live pathogen, attenuated/weakened pathogen, mRNA

What is Herd Immunity?

The threshold required to stop transmission of a pathogen (ex. Polio was eradicated in the U.S.)