Chapter 8- The Immune System Flashcards
2 divisions of immune system
- innate (nonspecific)- always active
- adaptive (specific)- defenses that target a specific pathogen, slower to act but has memory of infections and can fight them off faster if exposed again
spleen
location of blood storage and activation of B-cells, which turn into plasma cells to produce antibodies as part of adaptive immunity
humoral immunity
antibodies dissolve and act in blood instead of within cells
T-cells
agents of cell-mediated immunity b/c they coordinate the immune system and directly kill virally infected cells
lymph nodes
provide a place for immune cells to communicate and mount an attack. B-cells can be activated here as well.
gut-associated lymphoid tissue (GALT)
immune tissue found close to digestive system (site of potential invasion-ex: mouth). this tissue includes tonsils and adenoids in the head, peyer’s patches in small intestine, and lymphoid aggregates in the appendix.
4 organs of immune system
- lymph nodes (filter lymph and where immune responses can be mounted)
- bone marrow (site of immune cell production)
- thymus (site of T-cell maturation)
- spleen (storage for blood and lymph, immune response can also be mounted here)
granules
contain toxic enzymes and chemicals which can be released by exocytosis (particularly effective against bacterial, fungal, and parasitic pathogens)
hematopoietic stem cells
stem cells that create pretty much any cell in blood (red/white/platelets)
lymphocytes
antibody production/ immune modulation/ targeted killing of infected cells
2 types of specific (adaptive) immunity
- humoral (B-cells and antibodies)
2. cell-mediated (T-cells)
integument
skin, first line of defense
defensins
antibacterial enzymes found on skin
lysozyme
nonspecific bacterial enzyme secreted in tears and saliva
how does the GI-tract help with nonspecific immunity?
- stomach- secretes acid that usually kills most pathogens
2. gut- colonized by bacteria
complement system
many proteins in blood that act as nonspecific defense against bacteria. these punch holes in cell walls of bacteria
2 pathways to activate complement system?
- classical- binding of antibody to pathogen
2. alternative- no antibody required
interferons
produced by cells that have been infected with viruses. these are proteins that prevent viral replication and dispersion.
when bacteria enters a tissue, what gets activated?
macrophages (first phagocytize then digests invader)
major histocompatibility complex (MHC)
macrophages show little proteins of pathogen to this, so it can bind to it and brings it to the cells surface where it can be recognized by the adaptive immune system.
what do macrophages release?
cytokines- chemical substances that stimulate inflammation and recruit additional immune cells to the area.
2 classes of MHCs
Class I: in all nucleated cells and presents endogenous antigens
Class II: in antigen-presenting cells and presents exogenous antigens
what happens to cells that have been invaded by intracellular pathogens?
can be killed by a certain group of T-cells (cytotoxic T-lymphocytes) to prevent infection of other cells
antigen
substance (usually a pathogenic protein) that can be targeted by an antibody
examples of professional antigen-presenting cells
macrophages, dendritic cells, some B-cells, and some activated epithelial cells.
Pattern Recognition Receptors (PRR)
special receptors on macrophages and dendritic cells (ex: toll-like receptors-TLR) able to recognize category of invader which allows for appropriate cytokines to recruit the right type of immune cells.
Natural killer cells
- destroys the body’s own cells that have become infected with pathogens
- goes after cancer cells
- monitor expression of MHC molecules on surface of cells
3 types of granulocytes
- neutrophils
- eosinophils
- basophils
neutrophils
short-lived. phagocytic and target bacteria. follow bacteria using chemotaxis and can follow opsonized (marked with antibody from B-cell) bacteria
pus formation
dead neutrophil collections
eosinophils
bright red-orange granules. allergic reactions and invasive parasitic infections. release large amounts of histamine (inflammatory mediator) once activated which results in vasodilation.
basophils
large purple granules. allergic responses. mast cells are closely related, but have smaller granules and exist in the tissues, mucosa, and epithelium. both release histamine
dendritic cell
presents antigens-fragments of protein or other molecules from pathogens or cancer cells- to adaptive immune cells, inducing the cells to attack bearers of displayed antigens
B-cell
antigens stimulate this cell to divide and produce antibodies that neutralize invaders or tag them for killing
T-cell
killer T-cell destroys an infected cell in which it detects the presence of antigens. other T-cells- such as helper and regulatory types- coordinate the immune response
what activates natural killer cells?
cells that do not present MHC (virally infected and cancer cells)
B and T-cell creation and maturity and activation locations
B-cells (bone marrow, bone marrow, spleen/ lymph nodes)
T-cells (bone marrow, thymus, N/A)
humoral immunity
production of antibodies. may take up to a week to become fully effective after initial infection. antibodies are produced by B-cells
antibodies and the 5 subtypes
aka. immunoglobulins. (IgM, IgD, IgG, IgE, and IgA). Cells change whch they produce when stimulated by specific cytokines which is called isotype switching.
Opsonization
When an antibody binds to an antigen and the antibody attracts other leukocytes to phagocytize those antigens immediately
antibody molecule structure
Y-shaped made up of 2 identical heavy and 2 identical light chains.
Name one thing an antibody can you do after binding to an antigen
The antibodies can block the ability of a pathogen to invade tissues. essentially neutralizing it
Degranulation
This occurs when an antigen binds to an anti-body on the surface of a mast cell and it allows for the release of histamine and causing an inflammatory allergic reaction
degranulation
exocytosis of granule contents
antibody molecule structure
Y-shaped made up of 2 identical heavy and 2 identical light chains
antigen-binding region
at the end of each variable region (domain), at the tips of the Y. this is the site where one specific antigenic sequence can bind. each B-cell undergoes hypermutation of this region trying to find the best match for the antigen.
clonal selection
only B-cells that can bind the antigen with high affinity survive, generates specificity
constant region (domain)
cells such as NKC, macrophages, monocytes, and eosinophils have receptors for this region and can initiate the complement cascade.
naive B-cells
B-cells that have not been exposed to an antigen yet wait in the lymph nodes for their particular antigen
Plasma cells
produce large amounts of antibodies. will eventually die
3 types of T-cells
- Helper T-cells (CD4+)
- Cytotoxic T-cells (CD8+)
- Suppressor/ regulatory T-cells
lymphokines
capable of recruiting other immune cells (plasma, cytotoxic, and macrophages) and increasing their activity. these are lost in HIV/AIDS
what happens to T-cells as they mature in the thymus
- positive selection (maturing only cells that can respond to the presentation of the antigen on MHC)
- negative selection (causing apoptosis in cells that do not respond to presentation of MHC antigen)
thymosin
facilitates maturation of T-cells. a peptide hormone secreted by thymic cells.
3 types of T-cells
- Helper T-cells aka. CD4+ T-cells (coordinate the immune response by secreting chemicals known as lymphokines)
lymphokines
capable of recruiting other immune cells (plasma, cytotoxic, and macrophages) and increasing their activity
Helper T-cells
aka. CD4+ T-cells. coordinate the immune response by secreting chemicals known as lymphokines. respond to antigens presented on MHC-II molecules. most effective against bacterial, fungal, and parasitic infections.
5 types of infectious pathogens
bacteria, viruses, fungi, parasites, and prions (no immune defense for prions)
Suppressor/ Regulatory T-cells
express CD4 but also have Foxp3 protein. help tone down immune response once infection has been contained. self-tolerance
self-tolerance
turn off self-reactive lymphocytes to prevent autoimmune diseases
self-antigens
proteins and carbohydrates on the surface of every cell of the body.
5 types of infectious pathogens
bacteria, viruses, fungi, parasites, and prions
viral infections are…
intracellular pathogens
bacterial infections are…
extracelluar pathogens
self-antigens
proteins and carbohydrates on the surface of every cell of the body.
allergies
when immune system misidentifies a foreign antigen as dangerous when its not so its hypersensitive to these antigens and becomes overactive in their presence.
lymphatic system function
equalizing fluid distribution, transportation of biomolecules (chylomicrons from small intestine to circulatory system), and immunity (B-cells proliferate and mature in lymph nodes in collections called germinal centers)
active immunity
immune system is stimulated to produce antibodies against a specific pathogen
passive immunity
transfer of antibodies to an individual (ex: fetus)
structure of lymphatic system
type of circulatory system. one-way vessels that become larger as they move toward the center of the body. vessels carry lymph and join to comprise a large thoracic duct in the posterior chest (delivers fluid into the left subclavian vein near the heart)
lymph nodes: contain lymphatic channel/ artery/ vein. provide a space for the cells of the immune system to be exposed to possible pathogens.
lymphatic system function
equalizing fluid distribution, transportation of biomolecules
edema
swelling due to fluid collecting in tissue. occurs when lymphatics are overwhelmed
what structure is responsible for returning materials from lymphatic circulation to the cardiovascular system?
thoracic duct carries lymphatic fluid into left subclavian vein
platelet
fragments of megakaryocytes
