MCAT Biology - The Immune System

Chapter 8

Innate Immunity

Composed of defenses that are always active against infection, but lack the ability to target specific invaders

Adaptive Immunity

Refers to the defenses that target a specific pathogen adaptive system is slwoer to act, but can maintain immunological memory of an infection to amount a faster attack in subseqent infections

Bone Marrow

Produces all of the leukocytes

Spleen

Location of blood storage adn activation of B cells

B cells

Turn into plasma cells to produce antibodies as part of adaptive immunity

T Cells

Agents of cell mediated immunity, coordinate immune system and directly kill virally infected cells

Lymph Nodes

Provide a place for immune cells to communicate and mount an attack

What are gut associated lymphoid tissue

Tonsils, adenoids, peyeris paten, appendix

Lymphocytes

Responsible for antibody production, immune system modulation and targeted killing of infected cells

Monocytes

phagocytic cells in the blood stream become macrophages

First method of defense for immune system

The skin

Defensins

antibacterial enzymes found on skin

Compleiment System

Consists of a number of proteins in the blood that act as a nonspecific defense against bacteria

Classical Pathway

Requires the binding of an antibody to a pathogen

Alternative Pathway

Does not require antibodies

Interferons

Proteins that prevent viral replicationa dn dispersion

Macrophages

A type of agranulocyte, reside within the tissue

Major Histocompatibility Complex (MHC)

Protein binds to a pathogenic peptide adn carries it to the cell surface where it can be reconized by cells of the adaptive immune system and releases cytokines

Cytokines

Chemical substances that stimulate inflammation and recruit additional immune cells to area

MCH I

All nucleated cells in the body

MCH II

displayed by professional antigen presenting cells

Antigen

Substance that can be targeted by an antibody

..

Able to recgonize the category of the inbvador

Natural Killer Cells

Nonspecific lymphocyte are able to detect down regulation of MHC and induce apoptosis in virally infected cells

Neutrophils

Populous leukocyte in blood, short live phagocytic and target bacteria

Opsonized

Marked with an antibody from a B cell

Eosinophils

Contain bright red range granules and are primarily involved in allergic reactions and invasive parasitic infections

Basophils

Contain large purple granules and involved in allergic response

Mast cells

closely related to basophils have smallre granules and exist in tissues, muscosa and epithelium

Isotope Switching

Cells can change which isotope of antibody they produce when stimulated by specific cytokines in a process

Naive B cells

Those not yet exposed to an antigen

Plasma cells

Produce large amount antibodies

Memory B cells

Stay in lymph node awaiting re-exposure to same antigen

Primary Response

Initial activation

Secondary Response

If same microbe encountered again memory cells rapidly proliferate and differentiate into plasma cells to produce antibodies specific to the pathogen

Positive Selection

Allowing only maturation of cells that can respond to the presentation of antigen of MHC

Negative Selection

Causing apoptosis in cells that are self reactive

Thymosin

Peptide hormone secreted by thymic cells that facilitate maturation of T cells

Helper T cells/CD4+ T Cells

coordinate immune response by secreting lymphokines, most effective against bacterial fungal and parasitic infections.

Cytotoxic T Cells CD8+ Tcells

Capable of directly killing virally infected cells by injecting toxic cehmicals that promote apoptosis into infected cell. Most fight against viral infections

Supressor/Regulatory T Cells

Express CD4, but can be differentated also express protein Foxp3

Help tone down immune response once infection been adequeately contained

self tolerance

Memory T Cells

cells lie in wait unti next exposure to same antigen, when activated carry out a more robust and rapid response

Lymphokines

Capable recruiting other immune cells and increasing their activity

Self tolerance

Turn off reactive lymphocytes to prevent autoimmune disease

Self antigens

Proteins and carbohydrates present on the surface of every cell of the body

Autoimmunity

When immune system fails to mate distinction between self and foreign, it may attack cells expressing particular self antigens

Active immunity

The immune system is stimulated to produce antibodies against a specific pathogen

Passive immunity

Results from transfer of antibodies to an individual