Question

Short Answer Questions
1. Explain the difference between innate and adaptive immunity.
2. What is an antigen and how does it relate to antibodies?
3. Why is inflammation important in fighting infections?
4. How do vaccines help the immune system?
5. Give one example of an autoimmune disease and describe what happens in the body

Answer 1

1. Innate vs adaptive immunity
- Innate immunity is the body’s first line of defense: fast, non‑specific, and present from birth. It includes physical barriers (skin, mucous), chemical defenses, phagocytes (neutrophils, macrophages), natural killer cells, and complement.
- Adaptive immunity is slower to develop on first exposure but is highly specific and has memory. It relies on lymphocytes (B cells that make antibodies, and T cells that kill infected cells or help other immune cells). Adaptive responses improve on repeated exposure to the same pathogen.

2. Antigen and its relation to antibodies
- An antigen is any molecule (often a protein or polysaccharide) that the immune system recognizes as foreign and can trigger an immune response. Specific parts of an antigen that are recognized are called epitopes.
- Antibodies are proteins produced by B cells that specifically bind an antigen’s epitopes. Binding can neutralize the pathogen, mark it for destruction (opsonization), or activate complement.

3. Why inflammation is important
- Inflammation is a controlled tissue response that increases blood flow and vessel permeability at a site of injury or infection. This:
- Delivers immune cells and soluble defense molecules to the area,
- Helps contain and isolate pathogens,
- Removes damaged cells and debris,
- Promotes tissue repair.
- Acute inflammation is protective; chronic inflammation can cause tissue damage.

4. How vaccines help the immune system
- Vaccines expose the immune system to a safe form of an antigen (live-attenuated, inactivated, subunit, toxoid, mRNA, etc.) so the adaptive immune system mounts a response and forms memory B and T cells without causing the disease. On later exposure to the real pathogen, the immune system responds faster and more effectively, often preventing illness.

5. Example of an autoimmune disease — Type 1 diabetes
- In type 1 diabetes the immune system (primarily T cells, with some autoantibodies) mistakenly attacks and destroys insulin-producing beta cells in the pancreatic islets. As beta cells are lost, insulin production falls, blood glucose rises, and patients develop symptoms of hyperglycemia and require insulin replacement therapy.