Immune Response and External Defences (Lecture Notes)

Vocabulary flashcards covering key concepts from the lecture notes on immune responses, fever, and external defences.

Primary immune response

The initial, slower immune response to a first exposure to a pathogen, lacking memory B and T cells.

Secondary immune response

A faster, more effective response upon re-exposure due to memory B and T cells.

Memory B cells

Long-lasting B cells that remember a pathogen and rapidly produce antibodies on re-exposure.

Memory T cells

Long-lived T cells that enable quicker cellular immune responses upon re-exposure.

Bordetella pertussis

The bacterium that causes whooping cough.

Immunisation (vaccination)

Introduction of antigens to stimulate memory B and T cells and provide protection.

Fever

Elevation of body temperature in response to pyrogens to help fight infection.

Pyrogens

Substances (e.g., cytokines) that raise the hypothalamic set point to induce fever.

Interleukin-1

A cytokine that acts as a pyrogen released by macrophages.

Hypothalamic set point

The body’s temperature set point raised by pyrogens to induce fever.

Shivering

Muscle activity that generates heat to raise body temperature during fever.

Vasoconstriction

Narrowing of blood vessels to conserve heat during fever.

Inhibition of pathogen replication

Higher body temperatures hinder replication of many pathogens.

Enhanced leukocyte activity

Fever increases immune cell activity and speeds up the immune response.

Mucous membranes

Lined surfaces in the respiratory tract that trap pathogens.

Cilia

Hair-like structures that move mucus and trapped pathogens out of the airways.

Nasal hairs

Filter large particles from inhaled air before reaching the lungs.

Sneezing

Reflex that expels irritants and pathogens from the nasal passages.

Histamine

Mediator released by mast cells during inflammation causing vasodilation and increased permeability.

Mast cells

Immune cells that release histamine in response to infection or injury.

Vasodilation

Widening of blood vessels to increase blood flow to a tissue.

Increased vascular permeability

Blood vessels become leakier to allow immune cells to reach tissue.

Heparin

Anticoagulant that prevents clotting, aiding immune cell access to tissue.

Antibodies (immunoglobulins)

Proteins produced by B cells that bind specific antigens to neutralise pathogens.

B cells

Lymphocytes that produce antibodies against antigens.

Antigen

Molecule or part of a molecule recognized as foreign by the immune system.

Neutralisation by antibodies

Antibodies block pathogens’ function to prevent infection.

Agglutination

Antibodies cause clumping of pathogens to facilitate clearance.

Opsonization

Antibodies tag pathogens for phagocytosis by macrophages.

Macrophages

Phagocytic cells that ingest pathogens and present antigens to activate others.

Phagocytosis

Process by which macrophages engulf and digest pathogens.

Antigen presentation

Macrophages display pathogen-derived antigens to activate T cells.

Stomach acid (HCl)

Chemical defence; stomach acid kills pathogens by denaturing proteins.

Hydrochloric acid (HCl)

Acid in the stomach that reduces pH and kills microbes.

Good bacteria (beneficial microbiota)

Biological defence; compete with harmful microbes to limit their growth.

Mucus

Liquid lining that traps pathogens and contains antimicrobial enzymes like lysozyme.

Lysozyme

Enzyme in mucus that helps break down bacterial cell walls.