Responding to Antigens and Acquiring Immunity – Flashcards

A comprehensive set of Q&A flashcards covering antigens, pathogens, innate and adaptive immunity, immune cells, antibodies, lymphatic system, and types of acquired immunity.

What is an antigen?

Immune trigger

How does a self-antigen differ from a non-self antigen?

Own vs. foreign

Which cell-surface proteins allow immune cells to recognise ‘self’ in humans?

MHC molecules

Where are MHC-I molecules found?

Nucleated cells

Which cells display MHC-II molecules?

APCs

Give two examples of cellular pathogens.

Bacteria, fungi

Name two non-cellular pathogens.

Viruses, prions

What is the main structural difference between Gram-positive and Gram-negative bacteria?

Wall thickness

Define exotoxin.

Secreted toxin

Define endotoxin.

Lysis toxin

What is a prion?

Misfolded protein

List the three broad first-line barriers in animals.

Physical, chemical, microbiological

Give one chemical barrier found in tears and saliva.

Lysozyme

Why is intact skin an effective physical barrier?

Tightly packed

What is the role of cilia in the respiratory tract?

Move mucus

Which innate immune cells are professional phagocytes?

Macrophages, neutrophils

Outline the five basic steps of phagocytosis.

Recognize, engulf, fuse, digest, exocytose

Which innate cell releases histamine during inflammation?

Mast cell

What two major chemicals do natural killer (NK) cells release?

Perforin, granzymes

What are complement proteins?

Immunity enhancers

How do interferons protect against viruses?

Antiviral signals

State two cardinal signs of inflammation.

Redness, swelling

Differentiate innate and adaptive immunity on speed and specificity.

Innate: fast, broad. Adaptive: slow, precise.

Which lymphocytes mediate humoral immunity?

B cells

What do plasma cells secrete?

Antibodies

Define opsonisation.

Coating pathogen

Name the five classes of immunoglobulins.

IgG, IgA, IgM, IgE, IgD

Which antibody class is involved in allergic reactions?

IgE

What two cell types are essential for initiating an adaptive response?

APCs, Helper T

Describe clonal selection.

Selection, proliferation

What is the main function of cytotoxic T cells?

Kill cells

Which cytokine do helper T cells release to activate B and cytotoxic T cells?

Interleukin-2

Explain the role of lymph nodes in immunity.

Immune activation

Distinguish active from passive immunity.

Own vs. received

Provide an example of natural passive immunity.

Maternal antibodies

What type of immunity does vaccination induce?

Artificial active

Why are booster shots sometimes required?

Boost protection

What is an attenuated vaccine?

Weakened pathogen

Define allergen.

Allergic antigen

What immediate treatment is given for severe snakebite and which type of immunity does it provide?

Antivenom; artificial passive

Why do prions evade immune detection?

Misfolded self

What is herd immunity?

Community protection

Which two organs are primary lymphoid organs?

Bone marrow, thymus

What is the main difference between exotoxins and endotoxins regarding heat

Labile/stable