unit 4 immunity

Self Cell

A cell that belongs to the body and is recognized by the immune system as not being foreign.

Non-self Cell

A cell or particle that is foreign to the body and triggers an immune response.

Surface Protein/Glycoprotein

Markers used by the immune system to determine if a cell is a self cell or a non-self cell.

Antigen

A substance used to define and identify self and non-self cells to the immune system.

First Line of Defense

A component of innate immunity that prevents pathogens from entering the body; the skin is responsible for keeping over $99\%$ of encountered pathogens out.

Mast Cells

Cells in the innate immune system involved in the inflammatory response and the release of histamines.

Neutrophils

A type of innate immune cell that responds to pathogens during the initial stages of infection.

Dendritic Cells

Innate immune cells that can become antigen-presenting cells (APCs) to link the second and third lines of defense.

Macrophages

Phagocytic cells of the innate immune system that can become antigen-presenting cells (APCs).

Antigen-Presenting Cell (APC)

A cell, such as a Dendritic Cell or Macrophage, that displays foreign antigens on its surface to activate the third line of defense (acquired immunity).

Inflammatory Response

A reaction that aids in the identification and destruction of pathogens during the second line of defense.

Histamines

Chemicals released during the inflammatory response to aid in the immune system's defense mechanisms.

Helper T Cells

Cells in acquired immunity that play a central role in coordinating the immune response and activating other cells.

Cytotoxic T Cells

Cells in acquired immunity that identify and destroy pathogens or infected body cells.

B Cells

Cells in acquired immunity responsible for the production of antibodies.

Two-step Activation Process

The specific procedure required to activate Cytotoxic T Cells and B Cells in the acquired immune system.

Effector (Active) Population

The group of immune cells actively engaged in fighting a pathogen during an current infection.

Memory Population

A group of long-lived immune cells that increase the speed and strength of the response during a second encounter with a specific pathogen.

Antibody

Proteins produced by B cells that identify and help neutralize pathogens in the immune system.

Jenner’s Experiment

A historical experiment that led to the development of modern vaccination procedures.

Humoral (antibody-mediated) immune response

An immune response where B cells give rise to plasma cells that secrete antibodies to defend against extracellular pathogens by binding to antigens.

Cell-mediated immune response

An immune response involving cytotoxic T cells that defend against intracellular pathogens and cancer by initiating apoptosis in infected or cancer cells.

Antigen-presenting cell

A cell that engulfs an antigen and presents it to help stimulate helper T cells, B cells, and cytotoxic T cells.

Plasma cells

Cells derived from B cells that secrete antibodies into the body to neutralize pathogens or mark them for phagocytes.

Secondary immune response

An immune response triggered by a second exposure to an antigen that is both faster and larger than the primary immune response due to memory populations.

Edward Jenner

A country doctor in Gloucestershire ($1749$-$1823$) who developed the first vaccination by testing the relationship between cowpox and smallpox.

Smallpox

An acute contagious disease caused by the variola virus, which historically killed around $30 \%$ of those infected and claimed $300$ million lives globally in the $20\text{th}$ century.

Variola virus

The specific virus that causes smallpox, which gets its name from the Latin word for "spotted."

James Phipps

The boy Jenner used in his experiment, whom he first infected with cowpox from Sarah Nelmes and later repeatedly exposed to smallpox.

Sarah Nelmes

The milkmaid who had developed cowpox blisters from a cow named Blossom; these blisters provided the source material for Jenner's experiment on James Phipps.

Vaccination

The injection of a deactivated virus, dead bacteria, or antigens to trigger a natural immune response and generate memory populations for future protection.

Memory B cells

A population of cells generated during the primary immune response that allows for a much quicker antibody production upon subsequent exposure to the same pathogen.

Helper T cell

A type of T cell that, when stimulated by an antigen-presenting cell, stimulates both the humoral and cell-mediated immune responses.

Innate Immunity

Cells and body features that are always ready to respond to invaders to confer immunity.

Acquired Immunity

Also known as Adaptive Immunity, these are cells selectively activated to eliminate a specific pathogen.

First Line of Defense

A passive, non-specific line of defense consisting of the skin, mucous membranes, and cilia.

Skin

A component of the first line of defense characterized by a dry environment and low pH where many harmless bacteria are adapted to live.

MALT

An acronym for Mucosal-associated lymphoid tissue found in mucous membranes.

Cilia

Structures responsible for trapping pathogens and keeping out over $99\%$ of all pathogens encountered.

Second Line of Defense

An active, non-specific line of defense featuring neutrophils, macrophages, and inflammatory responses.

Third Line of Defense

An active, specific line of defense comprising cell-mediated responses (Cytotoxic T Cells) and humoral responses (B Cells).

Mast Cells

Cells that secrete histamines to regulate blood flow, specifically constricting blood flow at the site of a wound while increasing it nearby.

Neutrophils

Phagocytes that arrive at a wound site to engulf and kill invading cells.

Macrophages

Phagocytes that engulf pathogens, secrete chemokines to recruit other cells, and can become Antigen Presenting Cells (APC).

Dendritic Cells

Cells that can become Antigen Presenting Cells (APC) to provide a link to the third line of defense.

Histamine

A signaling molecule produced by mast cells that acts on blood vessels to regulate flow and constriction at a wound site.

Chemokines

A subset of cytokines that mark the path to a wound and promote dilation and increased permeability of blood vessels.

Cytokines

Signaling molecules secreted by macrophages that increase leukocyte production and induce fever by raising the body temperature set point in the CNS.

Antigen Presenting Cell (APC)

A cell, such as a macrophage or dendritic cell, that engulfs a bacterium and presents its antigens on the cell surface with MHC II molecules.

MHC II

A molecule on the surface of an APC that presents antigens from a digested bacterium to lymphocytes of the adaptive immune response.

Platelets

Cells that participate in the inflammatory response by clotting the wound.

Leucocytes

Cells that arrive at a wound site and mature into macrophages; they also secrete cytokines to increase production of more leucocytes.

Immunity

The resistance to or protection against disease-causing pathogens.

Antigen

A protein or glycoprotein not on the body's approved list that is capable of stimulating an immune response.

Epitopes

Distinct surface features on an antigen that result in specific immune responses.

Self Cell

A cell lacking foreign antigens that is considered an acceptable cell to be in the body.

Non-self Cell

A cell with foreign antigens that will generate an immune response and will generally be killed.

Proteins and Glycoproteins

Molecules produced on the outer surface of cell plasma membranes used by the immune system to identify self and non-self cells.

ABO Blood Types

Blood classifications determined by specific antigens presented on red blood cells.