Biology Chapter 8: The Immune System (2 Stars) Flashcards
The immune system can be divided into ____ and adaptive immunity.
innate.
Innate immunity is composed of defenses that are always active, but that cannot target a specific invader and cannot maintain immunologic memory; also called _________
nonspecific immunity.
__________ is composed of defenses that take time to activate, but that target a specific invader and can maintain immunologic memory; also called specific immunity.
Adaptive immunity
Immune cells come from the _______
bone marrow.
The spleen and lymph nodes are sites where immune responses can be mounted, and in which ____ are activated.
B-cells
The _____ is the site of T-cell maturation.
thymus
Gut-associated lymphoid tissue (GALT) includes the tonsils and _____
adenoids.
______ or white blood cells, are involved in immune defenses.
Leukocytes
Many of the nonspecific defenses are ______
noncellular.
The ____ acts as a physical barrier and secretes antimicrobial compounds, like defensins.
skin
____ on mucous membranes traps pathogens; in the respiratory system, the mucus is propelled upward by cilia and can be swallowed or expelled.
Mucus
Tears and saliva contain _____, an antibacterial compound.
lysozyme
The stomach produces acid, killing most pathogens. Colonization of the gut helps prevent overgrowth by pathogenic bacteria through ______
competition.
The complement system can punch holes in the cell walls of bacteria, making them osmotically _____
unstable.
_____ are given off by virally infected cells and help prevent viral replication and dispersion to nearby cells.
Interferons
Many of the nonspecific defenses are also ____
cellular.
_____ ingest pathogens and present them on major histocompatibility complex (MHC) molecules. They also secrete cytokines.
Macrophages
MHC class I (MHC-I) is present in all nucleated cells and displays _____ antigen (proteins from within the cell) to cytotoxic T-cells (CD8+ cells).
endogenous
MHC class II (MHC-II) is present in professional antigen-presenting cells (macrophages, dendritic cells, some B-cells, and certain activated epithelial and displays exogenous antigen (proteins from outside the cell) to ______
helper T-cells (CD4+ cells).
_____ include neutrophils, eosinophils, and basophils.
Granulocytes
______ ingest bacteria, particularly opsonized bacteria (those marked with antibodies). They can follow bacteria using chemotaxis.
Neutrophils
_____ are used in allergic reactions and invasive parasitic infections. They release histamine, causing an inflammatory response.
Eosinophils
_______ are used in allergic reactions. Mast cells are related cells found in the skin.
Basophils
Antibodies target a particular antigen. They contain two heavy chains and ______. They have a constant region and a variable region; the tip of the variable region is the antigen-binding region.
two light chains
______ lie in wait for a second exposure to a pathogen and can then mount a more rapid and vigorous immune response (secondary response).
Memory B-cells
Cell-mediated (cytotoxic) immunity is centered on the functions of _____
T-cells.
T-cells undergo maturation in the ____ through positive selection (only selecting for T-cells that can react to antigen presented on MHC) and negative selection (causing apoptosis in self-reactive T-cells). The peptide hormone thymosin promotes T-cell development.
thymus
Helper T-cells(Th or CD4+ ) respond to antigen on MHC-II and coordinate the rest of the immune system, secreting lymphokines to activate various arms of immune defense. Th1 cells secrete interferon gamma, which activates macrophages. Th2 cells activate _____, primarily in parasitic infections.
B-cells
Suppressor (regulatory) T-cells (Treg) tone down the immune response ____ an infection and promote self-tolerance.
after
______ serve a similar function to memory B-cells.
Memory T-cells
