LEC 15 pathogens, antigens, and antibodies

Define Pathogen

Something that causes disease.

What are examples of biological pathogens?

Bacteria, viruses, fungi, yeast, protozoa, and worms.

What are examples of non-biological pathogens?

Toxic chemicals and asbestos.

How many bacteria can fit inside a white blood cell?

Hundreds

Where do bacteria live in the body?

Between body cells, where they use nutrients from the body.

How do bacteria cause harm?

By secreting toxins.

How many viruses can fit inside the nucleus of one white blood cell?

Thousands.

How many viruses can fit inside the nucleus area of a bacterium?

Hundreds.

Where do viruses live in the body and why?

Inside body cells because they need the host cell's DNA or RNA to replicate.

What happens when a body cell has been invaded by a virus?

The entire infected host cell must be killed by a white blood cell.

What is an antigen?

Anything that can trigger an immune response, not necessarily a biological pathogen.

What are examples of non-biological antigens?

Pollen, dust, grass, and other allergens.

What are antibodies also known as?

Immunoglobulins (Ig).

What are antibodies made by?

Plasma cells.

What are antibodies made of?

Two heavy chains and two light chains.

What shape does an antibody have?

A Y shape.

What are the tips of the "Y"?

Antigen-binding receptors specific to a particular antigen.

What does the stem of the "Y" do?

It can be grasped by a phagocyte.

What is the hypervariable region?

A small region at the tip of an antibody that forms the antigen-binding site, allowing millions of different antibodies to exist.

What is the advantage of the hypervariable region?

It allows the immune system to recognize a wide variety of different antigens.

Why are people sick more often as children than in their 20s and 30s?

memory lymphocytes build up during childhood

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→ provides immunity to more antigens in adulthood.