Immune System Defences and Medical Interventions

15 Question-and-Answer flashcards covering the first, second, and third lines of defence, types of immunity, and medical interventions.

What type of barriers constitute the first line of defence against pathogens?

Physcial and Chemical Barriers.

Which physical barrier blocks the entry of most pathogens into the body?

Intact skin.

Give one example of a chemical barrier and explain how it prevents infection.

Stomach acid; it’s low pH kills many ingested pathogens.

How do mucous membranes help prevent infection?

They trap pathogens in sticky mucus, which can then be expelled or destroyed.

What are the four key signs of inflammation?

Redness, heat, pain and swelling

List the four key steps that lead to inflammation in the second line of defence.

(1) Tissue injury, (2) Release of chemical signals from Mast Cells. (3) Vasodilation & increased permeability of the capillaries. (4) Phagocytes move to site and destroy pathogens.

What is the primary purpose of fever during infection?

To raise body temperature, inhibiting pathogen growth and enhancing immune reactions.

What role do neutrophils and macrophages play in immunity?

They are phagocytes that engulf and digest invading pathogens during the second line of defence.

What is the main job of B cells in the third line of defence?

To produce antibodies that bind to pathogens, marking them for destruction.

How do Killer T cells contribute to immunity?

They directly destroy infected or abnormal cells harbouring pathogens.

Why are memory cells important after an infection?

They store information about the pathogen, enabling a faster and stronger response upon reinfection.

How does active immunity differ from passive immunity in terms of memory cells?

Active immunity produces memory cells; passive immunity does not.

What distinguishes natural immunity from artificial immunity?

Natural immunity is acquired through everyday exposure or maternal transfer, whereas artificial immunity is gained through medical procedures such as vaccination or antibody injection.

Define passive immunity and give an example.

Immunity gained by receiving ready-made antibodies, e.g., antibodies passed from mother to baby via breast milk.

What are antibiotics and antivirals used for in medical treatment?

Antibiotics treat bacterial infections; antivirals inhibit viral replication.

What consequence can arise from the misuse of antibiotics?

The development of multidrug-resistant bacteria.

Define the term antigen.

A protein on the surface of a pathogen, that causes an immune response.