Lecture Quiz 10 Flashcards
What are the three lines of defense in immunity?
surface barriers - nonspecific
inflammation response - nonspecific
specific immune response - specific obv lol
How are skin and mucosae surface barriers?
they are impervious to pathogenic agents
How is keratin a surface barrier?
resistant to weak acids and bases, bacterial enzymes, and toxins
How are epithelial membranes a surface barrier?
produce protective chemicals that destroy microorganimas skin acidity (pH 3-5) inhibits bacterial growth
How is sebum a surface barrier?
contains chemicals toxic to bacteria
How is stomach mucosae a surface barrier?
secrete concentrated HCl and protein-digesting enzymes
How are saliva and lacrimal a surface barrier?
contain lysozye
How is mucus a surface barrier?
traps microorganisms that enter the digestve and respiratory systems
How is the ciliated respiratory tract a surface barrier?
sweep dust and bacteria-laden mucus away from lower respiratory passages
What happens during inflammatory response (vague)?
pathogen is recognized by phagocytes and natural killers
How do natural killers act on pathogens?
the recognize the lack of self-antigen (MHC type I)
react nonspecifically by releasing cytolytic chemicals (perforins)
What do perforins do and what did they develop from?
lyse and kill cancer cells and virus-infected cells
develop from lymphocytes
How are phagocytes involved in the inflammatory response?
They initiate the inflammatory response
macrophages are the chief phagocyte
include variety of cells
most cells bind and ingest a wide range of bacteria
Where are macrophages found?
interstitial spaces of most tissues
What happens to neutrophils when they encounter a bacteria?
become phagocytic cell
What are two examples of fixed macrophages?
kupffer cells - liver
microglia - brain
What is interferon?
produced by virus-infected cells and works to alert healthy cells of possible infection
activate macrophages and lymphocytes
How does interferon act on cells?
when a host cell invades, IFN is synthesized
interferon leaves infected cells and goes to neighboring cells
stimulates neighboring cells to produce PKR - antiviral protein
PKR nonspecifically blocks viral reproduction
What is complement?
a group of ~20 proteins that enhance inflammation and phagocytosis
able to create permanent hole on the cellular membrane resulting in its lysis
enhance effectiveness of other defenses
What type of cells do complement proteins act upon?
bacteria and certain other cell types
What is inflammation?
a normal tissue response to injury
triggered whenever the tissues are injured
What is the purpose of inflammation?
prevent the spread of damging agents to nearby tissues
dispose of cell debris and pathogens
set the stage for the repair process
What are the five cardinal signs of acute inflammation?
redness heat swelling pain loss of function
What is inflammatory response initiated?
when tissue macrophages encounter foreign antigens and release chemical mediators of inflammation
What are some examples of chemical mediators of inflammation
histamine
cytokine
bradykinin
prostaglandins
What does histamine do?
causes arteriolar dilation and increased permeability of capillaries to plasma proteins
primary mediator of inflammatory response
What does bradykinin
causes arteriolar changes
plays an important role in chemotaxis
sensitizes pain receptors
What do prostaglandins do?
lipids
potentiate the effects of histamine and bradykinin
sensitize painr eceptors
apirin inhibits these
What do mediators of inflammation do?
cause small local blood vessels to dilate
results in hyperemia (redness)
What does the permeability of the capillaries do?
increases fluid which contains
proteins
clotting factors
antibodies (exudate)
What does exudate do?
helps dilute harmful substances
brings in large quantities of oxygen and nutrients
clotting proteins prevent spread of bacteria
How is fever initiated in inflammation response?
macrophages release pyrogens, which activate the hypothalamus
this resets the body’s thermostat
What is the purpose of fever?
inhibits reproduction of viruses and bacteria
increase interferon activity
increase metabolic rates, which induce healing
What happens are the stages of neutrophils reacting during inflammatory response?
leukocytosis - increased number released from bone marrow
margination - neutrophils cling to vessel walls
diapedesis - they squeeze through the capillary walls
chemotaxis - mediators chemically attract the neutrophils
Give a vague timeline of the life of neutrophils
They are the first cells to migrate to site of infection
engulf pathogens
they do not survive phagocytosis
die
What is pus?
dead neutrophils
What happens to monocytes during inflammation?
they follow the neutrophils
enter tissues
become macrophages
remove cellular debris
What is the adaptive immune system?
a functional defense system that is specific to the pathogen
acts systematically
can develop “memory” to quickly recognize pathogens previously encountered
What are the three steps in the adaptive immune system?
recognition of foreign antigens by specific immune cells
activation of immune cells
targeted response through two separate but overlapping arms:
humoral - antibody mediated
cellular - cell-mediated
What are antigens?
substances that can mobilize the immune system and provoke an immune response
What are some examples of the complete antigens?
non-self proteins
nucleic acid
some lipids
large polysaccharides
What is the active center on an antigen?
epitope
antigenic determinant
What are the three properties of antigens?
immunogenicity - ability to elicit an immune response
reactivity - ability to react with antibodies
specificity - only react with a specific kind of antibody
What are haptens?
incomplete antigens
small molecules, such as peptides, nucleotides, and many hormones
not immunogenic
What happens when haptens bind to self-proteins?
may be recognized as foreign, causing allergic reaction
Where are haptens found?
poison ivy
dander
some detergents
cosmetics
What do major histocompatibility complex (MHC) glycoproteins do?
hold antigens of the surface of cells so lymphocytes can find them
What are MHC class I molecules?
found on all cells show endogenous (self) antigens interact with CD8 proteins on T-cells
What are MHC class II molecules?
found only on antigen presenting cells
show exogenous antigens (collected from other organism)
interact with CD4 proteins on T-cells
What are antigen-presenting cells (APCs)?
dendritic cells
macrophages
activated B cells
What do APCs do?
do not respond to specific antigens engulf foreign particles and present fragments of antigens on their own surfaces (MHC class II) to be recognized by T and B cells
What do B-lymphocytes do?
produce antibodies and oversee humoral immunity
What do T-lymphocytes do?
non-antibody-producing cells
constitute the cell-mediated arm of immunity
Give an overview of lymphocyte production
produced in red bone marrow from hemocytoblasts into lymphoblast
then mature in primary lymphoid organs
B-lymphocytes mature in bone marrow
T-lymphocytes mature in the thymus
What do lymphocytes gain during maturation?
self-tolerance - ability to recognize and not react to self-antigens
immunocompetence - ability to recognize one type of foreign antigen
seeded in secondary organs - lymph nodes and spleen
What happens during antigen presentation?
APCs first encounter the foreign organ and phagocytize it
bacterium is broken down within the phagosome
fragments are presented on the surface of the macrophage in association with its MHC II receptors
What happens during antigen challenge?
antigen-presenting cells migrate to lymph nodes or spleen
are then recognized by T- or B- lymphocytes
this is the first encounter between an antigen and naive lymphocytes
What happens during clonal selection?
B cells that recognize antigen are activated, grow, and rapidly multiply
What do immune cells proliferate and differentiate into?
plasma cells or memory cells
What are plasma cells?
produce antibodies, which are an immunoglobulin
What do antibodies consist of?
two heavy and two light peptide chains that forms antigen-binding sites and a site recognized by cells of innate response
What are IgM antibodies?
pentamers
secreted in early primary response
activate complement
What are IgG antibodies?
monomers
most common type secreted in late primary response and secondary response
active complement
What are IgE antibodies?
monomers
activate mast cells or basophils
induce inflammation or allergic reaction
What are IgA antibodies?
dimers
secretory antibodies
found in saliva, mucus, sweal, milk
prevent invasion of epithelia
What are IgD antibodies?
monomers
assist B-cells
How do antibodies act on the antigen?
do not destroy them
bind to specific antigens in lock-and-key fashion
form antigen-antibody complex
How is the antigen-antibody complex formed?
precipitation - make soluble molecules insoluble
agglutination - sticking several cells in a clump
neutralization - block the binding sites on bacteria and viruses so they cannot invade host cells
lysis of the pathogen
How does lysis occur during antibody mediation?
other site on antibodies is recognized and activated compliment or NK and T-cytotoxic cells that lyse the pathogen
phagocytic cells activated
pathogens swallowed
What are memory cells?
some B-cells turn into memory cells
these circulate the bloodstream ready to proliferate if they encounter the same pathogen later in life
What is the primary immune response?
first encounter with antigen
antigen presentation, challenge, B-cell cloning takes place before antibodies can be made
peak level of plasma antibodies achieved at day 10
What is the secondary immune response?
re-exposure to same pathogen
memory cells proliferate into plasma cells capable of antibody production
antibody levels peak in 2-3 days at much higher levels than primary response
What is active humoral immunity?
naturally acquired in response to bacterial or viral infection
artificially acquired through vaccines
longer lasting
What is passive humoral immunity?
naturally acquired from mother to fetus
artificially acquired from injection of serum containing gamma globulins against the antigen
B cells are not challenged
protection ends when antigens naturally degrade
What happens during clonal selection of cell-mediated immunity?
T lymphocytes
requires recognition of antigen on MHC II and CD4 or CD8 binding site
What role do helper T cells have in proliferation and differentiation?
release cytokines, like interleukin 2, that activate T-cells, B-lymphocytes, and amplify innate defenses
What do activated cytotoxic T cells do during proliferation and differentiation?
recognize foreign antigen on MHC class I on infected, cancer, or transplanted cells produce perforins and granulozymes which induces apoptosis
What do memory T- cells do?
helper T-cells and cytotoxic T-lymphocytes may develop into memory cells for the next antigen encounter
