Immunity Lecture Notes

Flashcards covering key vocabulary and concepts related to immunity, adaptive immunity, and the immune response.

Innate Immunity

Inborn immunity.

Adaptive Immunity

Acquired immunity; can be cell-mediated or antibody-mediated.

Antigens (Ag)

Substances recognized as foreign that provoke an immune response.

Adaptive Immunity

The body's ability to adapt defenses against specific antigens of bacteria, viruses, foreign tissues, and toxins.

Specificity (Adaptive Immunity)

Foreign molecules are specifically targeted, distinguishing self from non-self.

Memory (Adaptive Immunity)

The ability to remember previously encountered antigens.

Characteristics of Antigenic Molecules

Organic, structurally complex, and large.

Lymphocyte Recognition

Lymphocytes (B and T cells) recognize antigens.

Clonal Selection

Lymphocyte rapidly reproduces and differentiates when activated by its specific antigen.

Effector Cells

Produce the immune response and die after the antigen is removed.

Memory Cells

Do not participate in the initial immune response but rapidly respond to subsequent exposures.

Antigen-Presenting Cells (APCs)

Initiate the adaptive immune response through nonspecific phagocytosis.

Antigen-Presenting Cells (APCs)

Dendritic cells and macrophages – link innate and adaptive immune systems.

APC Function

Engulfs and destroys foreign invaders, isolates antigens, and presents them to helper T cells.

T Lymphocyte Presented to by APC

Helper T cells (CD4 cells)

Activated Helper T Cell Function

Activate cytotoxic T cells (CD8 cells) and B cells.

Cell-Mediated Immunity

Directly attack infected or damaged cells; also produce suppressor and memory T cells.

Antibody-Mediated Immunity

Produce antibodies (Abs); also produce B memory cells.

MHC Molecules

Proteins that are used as cell-markers to ‘flag’ self from non-self.

Major Histocompatibility Complex (MHC)

Encoded by a group of diverse genes that vary greatly from individual to individual.

Class I MHC Molecules (MHC-I)

On almost all body cells; present non-self proteins to cytotoxic T cells (with CD8 protein).

Class II MHC Molecules (MHC-II)

Only on APCs; present non-self proteins to helper T cells (with CD4 protein).

APC Function with MHCII

Breaks down foreign antigens and loads them onto MHC-II molecules.

Infected Body Cells

Presents antigens using MHC-1 molecules.

Cytotoxic T Cell Destruction

Destruction of an infected cell by release of perforins, granzymes, and granulysin, leading to apoptosis.

B-Cell Activation

B-cells can be activated by direct recognition of antigen through B-cell receptors or T-helper cell activation.

Activated B-cells undergo clonal selection to become antibody producing _.

plasma cells

Antibodies

Also called immunoglobulins or Igs; produced by plasma cells through antibody-mediated immunity; composed of 4 peptide chains (two heavy, two light).

Variable Region (Antigen-binding region)

Gives an antibody its specificity.

Antibody Effects

Neutralizing, Activating complement, Opsonization

Complement System

Series of blood proteins that work in conjunction with antibodies; encourages vasodilation, inflammation, antigen opsonization, and antigen destruction.

Immunological Memory

Thousands of memory cells exist after initial encounter with an antigen.

Active Immunity

Body makes antibodies after exposure to a pathogen (antigen).

Passive Immunity

Body receives antibodies but not the ability to produce more in response.

Natural Active Immunity

Contracting hepatitis A and production of anti-hepatitis A antibodies.

Natural Passive Immunity

Baby receives antibodies from its mother through the placenta and breast milk.

Artificial Active Immunity

A person receives a vaccine of an attenuated (changed/weakened) pathogen that stimulates the body to form an antibody.

Artificial Passive Immunity

An injection of prepared antibody

Threats to the immune system

Viruses, Bacteria/Protists/Fungi, Tumors, Toxins