Immunity System

What is immunity

The process that protects the body from injury and pathogens

What is the immune system composed of

Proteins and cells- it does not contain its own organs or tissues

What are the three lines of immune defense

1. Surface barriers

2. Cells and proteins of innate immunity

3. Cells and proteins of adaptive immunity

What are the two main types of immunity

Innate and adaptive immunity

What is innate immunity

A nonspecific defense that responds to pathogens in the same way

What is adaptive immunity

A specific defense that responds to pathogens in the same general way

Which type of immunity provides the dominant initial response

Innate

Which type of immunity takes longer to become the dominant response

Adaptive

What is immunological memory

The ability to remember antigens for a quicker, more efficient response to later exposures

What are the two branches of adaptive immunity

Cell-mediated immunity (T cells) and antibody-mediated immunity (B cells and antibodies)

What are the main components of innate immunity

Surface barriers

Innate immune cells

Antimicrobial proteins

Inflammatory responses

What are the main components of adaptive immunity

T lymphocytes

B lymphocytes

Antibodies

Memory cells

How do innate and adaptive immunity work together

Innate defenses respond first. Antigen-presenting cells activate T cells, and T cell cytokines help activate B cells and other immune cells

What are surface barriers

Physical barriers

Mucus membranes

Protective secretions

Substances that deter pathogen growth

How does the skin help defend the body

It acts as an external physical barrier

How do mucus membranes protect the body

They provide surface protection against pathogens

How does stomach acid contribute to immunity

It is a protective secretion that helps defend against pathogens

What is sebum and how does it help

A secretion from sebaceous glands that deters pathogen growth

How do protective substances help prevent infection

They kill or deter the growth of other bacteria

What are phagocytes

Cells that ingest foreign, infected, or damaged cells

What are the major phagocytes

Neutrophils

Eosinophils

Macrophages

Dendritic cells

What do neutrophils do

Respond rapidly, especially to bacterial infections

Phagocytize pathogens

What do eosinophils do

Respond to parasitic infections

Cytotoxic

What do macrophages do

Phagocytize pathogens

Specialized monocyte

Activated first

Cytotoxic and APC

What is a monocyte

A circulating cell that can mature in a macrophage

Where are macrophages found compared to monocytes

Macrophages are found in the tissue

Monocytes are circulating in the blood

What do dendritic cells do

Ingest material

Display pathogen antigens

Active T cells as APC

Specialized monocyte

What is an antigen-presenting cell (APC)

A cell that displays a portion of an ingested pathogens antigen on its membrane

Why are APC important

They help activate T cells and initiate adaptive immune response

What are non phagocytes

Immune cells that defend without ingesting pathogens

What are the non phagocytes

Basophils
Mast cells
Natural Killer (NK) cells

What do mast cells do

Release inflammatory mediators involved in inflammation and allergic responses

Recruit neutrophils and macrophages

What do basophils do

Participate in inflammation and allergic responses

What do NK cells target

Cancerous and virus-infected cells

How do NK cells destroy target cells

They release cytotoxic substances that damage and destroy target cells

Activate macrophages

What is the role of NK cells in innate immunity

They provide a rapid defense against cancerous and virus-infected cells

What are antimicrobial proteins

Proteins that help defend the body against pathogens and coordinate immune responses

What is the complement system

A system of proteins that circulate in an inactive form and are activated by enzymes

What are the functions of complement proteins

Enhance inflammation and phagocytosis

Neutralize targets

Clear immune complexes

What are cytokines

Chemical messengers that coordinate and regulate immune responses

How do cytokines support immunity

They help activate, attract, and regulate immune cells

How do interferons help defend against viruses

They inhibit viral replication and help protect neighboring cells

What symptoms can cytokines induce

Flu-like symptoms

What is an inflammatory response

A coordinated reaction to tissue damage or infection involving inflammatory mediators and immune cells

Which cells release inflammatory mediators

Mast cells

What are the main effect of inflammatory mediators

Vasodilation

Increased capillary permeability

Phagocyte recruitment

What are the four classic signs of inflammation

Redness

Swelling

Heat

Pain

What causes redness and heat during inflammation

Vasodilation increases blood flow to the affected area

What causes swelling during inflammation

Increased capillary permeability allows fluid to enter surrounding tissues

What happens to phagocytes during inflammation

They are recruited to the affected area to help remove pathogens and damaged material

Which cells are recruited during an inflammatory response

Neutrophils

Monocytes

Which phagocytes increase rapidly during acute inflammation

Neutrophils

How do macrophages develop

Monocytes enter tissues and mature into macrophages

How do macrophages compare with neutrophils

Macrophages develop from monocytes, live longer, and are slower but more effective

What are lymphocytes

Immune cells that include T cells and B cells and provide adaptive immunity

Where are T cells produced and where do they mature

They are produced in bone marrow and mature in the thymus

Where are B cells produced and where do they mature

They are produced and mature in bone marrow

What happens to self-reactive T cells

Self-reactive and non-immunocompetent cells are destroyed in the thymus

What happens to self-reactive B cells

Self-reactive cells are destroyed in bone marrow

What is a naive lymphocyte

A lymphocyte that has not yet been activated by its specific antigen

Where do naive lymphocytes circulate and reside

They circulate in blood and reside in lymphoid tissue and organs

What activates a naive lymphocyte

Binding to its specific antigen

What is a clonal selection

Selection and activation of lymphocytes with receptors specific to an antigen

What is clonal expansion

The multiplication of activated lymphocytes with the same antigen specificity

What is differentiation in adaptive immunity

Activated lymphocytes develop into specialized effector cells and memory cells

What are the the helper TH cells

T cells that activate and coordinate immune responses

How are helper T cells activated

A naive helper T cell recognizes its specific antigen presented by an antigen-presenting cell

What happens after helper T cell activation

Clonal selection and differentiation produce effector helper T cells and memory helper T cells

What do effector helper T cells secrete

Cytokines

How do helper T cells affect macrophages

Their cytokines stimulate macrophages, macrophage cytokines can also activate helper T cells

How do helper T cells support B cells

They help active B cells and stimulate their proliferation

How do helper T cells support cytotoxic T cells

They help activate and stimulate the proliferation of cytotoxic T cells

Do effector helper T cells directly destroy target cells

No

They are not phagocytic or cytotoxic, they coordinate immune response

What are cytotoxic T (TC) cells

T cells that use cytotoxic effects to destroy cancerous, foreign, and infected cells

How are cytotoxic T cells activated

Through antigen-specific activation, clonal selection, and differentiation

What are effector cytotoxic T cells

Short lived, active cells that destroy target cells

What are memory cytotoxic T cells

Longer lasting cells that support a quicker response to subsequent exposures

What is cell-mediated immunity

Adaptive immunity involving T cells, including cytotoxic T cells that destroy target cells

What are B lymphocytes responsible for

Antibody-mediated adaptive immunity

How are B cells activated

A B cell receptor binds a specific antigen, and the B cell interacts with a helper T cell

What determines a B cell’s antigen specificity

Its receptor binds a specific antigen

What happens after B cell clonal selection

Selected B cells proliferate and differentiate into plasma cells and memory B cells

What do plasma cells do

Secrete antibodies that bind the same antigen recognized by the B cell receptor

What do memory B cells do

Help produce antibodies more quickly after subsequent exposure to the same antigen

What is antibody-mediated immunity

Adaptive immunity in which B cells produce antibodies against specific antigens

What is the main similarity between T-cell and B-cell functions

Both involve:

Antigen recognition

Clonal selection

Proliferation

Differentiation

What is the main difference between T-cell and B-cell activation

T cells coordinate immune responses or destroy target cells

B cells differentiate into antibody-secreting plasma cells and memory cells

What are immunoglobulins

Antibodies that bind specific antigens

Which immunoglobulin can cross the placenta

IgG

Which immunoglobulin is associated with a secondary immune response

IgG

Which immunoglobulin is found in breast milk

IgA

What type of immunity can antibodies in breast milk provide

Passive immunity

Which immunoglobulin is secreted first

IgM

Which immunoglobulin is associated with parasitic and allergic reactions

IgE

What is agglutination

Clumping of cells or particles caused by antibody binding

Which immunoglobulins are associated with agglutination

IgM

IgA

What is precipitation

Clumping of soluble antigens caused by antibody binding

Which immunoglobulin is associated with precipitation

IgA

What is opsonization

Antibodies bind pathogens and promote phagocytosis

Which immunoglobulin is associated with opsonization

IgG