CHAPTER 43 IMMUNE SYSTEM

What are pathogens?

Disease-causing agents (bacteria, viruses, fungi).

Two types of immunity in vertebrates?

Innate and adaptive.

What is innate immunity?

Immediate, nonspecific defense present in all animals. (targets everything)

What is adaptive immunity?

An adaptive immune response activated after the innate response and develops more slowly

First line of defense includes what?

skin and mucous membranes.

Key innate defenses in vertebrates?

Barriers, phagocytes, NK cells, interferons, inflammation.

What do barrier defenses do?

Block pathogen entry.

Role of mucus?

Traps and removes microbes.

What are TLRs?

Receptors recognizing common pathogen molecules.

Main phagocytic cells?

Neutrophils and macrophages.

Function of dendritic cells?

Activate adaptive immunity.

Function of eosinophils?

Attack parasites with enzymes.

What do natural killer cells do?

Kill infected or cancer cells.

What triggers inflammation?

Injury or infection signals.

Role of histamine?

Dilates blood vessels.

What is pus?

Dead cells, pathogens, debris.

Function of lymphatic system?

Transports lymph and filters pathogens.

What is systemic inflammation?

Body-wide immune response.

What causes fever?

Reset body temperature from immune signals.

What is septic shock?

Severe, life-threatening inflammation.

Function of interferons?

Block viral replication.

What does the complement system do?

Lyses pathogens and aids immunity.

How do pathogens evade immunity?

Capsules or resisting breakdown.

What makes adaptive immunity unique?

Specificity and memory.

Two main lymphocytes?

B cells and T cells.

What are antigens?

Molecules that trigger immune response.

What is an epitope?

Specific part of antigen recognized.

What do B cells produce?

Antibodies.

Structure of antibodies?

Y-shaped proteins.

How do T cells recognize antigens?

Via MHC-presented fragments.

What is MHC?

Protein displaying antigen fragments.

APC or dendritic cells have what type of MHC?

Class II MHC

MHC class I bind to what?

Cytotoxin T cell receptors (CD8)

What 5 different forms of immunoglobulin can B cells express?

IgD IgA IgE IgG IgM

Which form of immunoglobulin is membrane bound?

IgD

Which form of immunoglobulin is most common and crosses the placenta from mother to fetus

IgG

Which form of immunoglobulin passes from mother to infant in breast milk?

IgA

Which form of immunoglobulin occurs during the first infection the body?

IgM

What form of immunoglobulin releases antibodies from plasma cells?

IgE

Four traits of adaptive immunity?

Diversity, self-tolerance, proliferation, memory.

What is clonal selection?

Rapid division of activated lymphocytes.

Primary vs secondary response?

Primary = slow; second = faster/stronger.

Humoral response?

B cells + antibodies in fluids.

Cell-mediated response?

T cells kill infected cells.

Role of helper T cells?

Activate B and T cells.

What do cytotoxic T cells do?

Kill infected cells.

What is neutralization?

Antibodies block pathogen entry.

What is opsonization?

Antibodies enhance phagocytosis.

What is immunization?

Artificial activation of immune memory.

Active immunity?

self response, develops naturally when a pathogen invades the body

Passive immunity?

borrowed antibodies, immediate short-term protection

What are monoclonal antibodies?

Identical antibodies from one clone.

Why do transplants get rejected?

Immune response to foreign MHC.

What are allergies?

Overactive immune responses.

What is anaphylactic shock?

Severe, rapid allergic reaction.

What are autoimmune diseases?

Immune attack on self.

What is HIV?

Virus that destroys helper T cells → AIDS.