Body Defenses Flashcards
Lysis?
cell membrane is attacked in some way so cell loses control of its contents and ruptures
Phagocytosis?
engulfment by neutrophil/macrophage then goes under intracellular digestion by lysosomes
Adaptive Defense Systems?
Specific, develop after birth upon exposure to foreign antigens
What are surface barriers and what do the include?
first line of defense
physical and chemical barriers
What are all WBC formed from and where?
Red bone marrow stem cells(hemocytoblasts)
What are characteristics of physical barriers?
Intact skin, keratin resists abrasion, tearing, weak acids and bases and bacterial toxins
intact mucosal membranes protect internal orgs/cavities
What are the two mechs in which foreign orgs are destroyed?
Phagocytosis
Lysis
Innate Defense System?
Nonspecific, born with, activate against any invader
Leukocytosis?
inducing factors from damaged cells stimulate
Chemical barrier characteristics? Skin: Stomach: Saliva and Tears: Mucus:
Skins acidic secretions which inhibit bacterial growth
stomach has hcl and protein digesting enzymes
saliva and tears - lysozymes defensins
Mucus traps organisms
What are internal defense?
Second line
What types of WBC can phagocytosize?
Macrophages
Neutrophils
Eosinophils
What do macrophages develop from?
What are characteristics of them?
What are example of free/fixed?
Monocytes
can phagocytize lots without damage
kill also by releasing a respiratory burst of oxidizing chems/ acids
Heavy hitters
Free - dendritic cells in epidermis and alveolar in lungs
fixed - kupffer cells in liver
Whats the most common WBC?
What is there role?
When do they migrate from blood to tissues?
What are they considered?
Neutrophil
first responders @ infection
Upon chemical clues
suicide killers
What kind of granules do eosinophils contain?
What kind of phaocytes are they considered?
How do they attack large paracites
pink cytoplasmic granules
weak
release hydrolytic enzymes externally
How to phagocytosis occur?
ahattach to pathogen engulf into phaosome fusion with lysosome --> phagolysosome Hydrolysis by enzymes killing by burst of free radicals/oxidizing chems killing by defensins Exocytosis of residual body
Margination?
WBCs move along caps and cling to CAMs on cap walls`
CAMS?
Cell adhesion molecules mark the sites of damage or infections
Diapedesis?
WBC squeeze between endothelial cells toward injurt by amoeboid motion
Positive Chemotaxis?
WBC follow increasing concentration gradient of inflamm chems to site of injury
What is the order of WBC into response of infection?
Neutrophils
monocytes which then convert to macrophages
Pus?
evidence of phagocytosis
Abscess?
Infection not completely cleared, walled of by collagen fibers
Lysis by natural killer cells? What are NK? Where are the found? How to they work? How do they kill cancer and virus cells?
Large type if granular T lymphocyte, involved in non specific defense
Blood, lymph vessels, and other tissues
crawl over surface of cells looking for abnorm marker proteins
perforin and granzymes
Anitmicrobial Proteins?
Enhance defense, attack microorganisms directly, hinder MO’s ability to reproduce
How do perforins work?
insert into membrane of target cells, polymerize and form pores
how do granzymes work?
Enter through pores and attack membranes destroy nucleus and cell undergoes apoptosis
What does inflammation triggered by?
What does it prevent?
what does it prepare for?
What are the four cardinal Signs?
when body tissues are injured or infected
prevents spread of infection, disposes of debris and pathogen
Repair
Red Heat Swelling Pus
What are stimulus’ that trigger inflamm responses?
Histamines - released by mast cells in loose CT
Toll like Receptors - on macrophages and in boundary epithelial tissues recognize specific classes of microbes which trigger release of cytokines
Kinins, Prostglandins, Leukotrienes, complement - released by injured tissue, phagocyte, lymphocyte and basophils
What is the process of inflammation?
Chems released into extracellular fluids–> arteriole dilation–> increased Blood flow –>red/heat–>permeability of caps increase –> exudate leaks out–>pressure –>swelling/pain –>walls off damaged area providing framework for tissue repair –>foreign material into lymphatics –> more pain –> damage to mucosa(secretion of defensins increases)
Two types of antimicrobial proteins?
Interferons
Complement
Interferons are produced by what? What do they act against? What do they do? What do they activate? What do they reduce?
cells infected by viruses
a range of viruses
macrp[hages & NK cells
inflammation
What is complemet?
What does it assist in?
what is it a major mechanism for?
20+ inactive plasma proteins
specific and no defense
destroying antigens
What is complement activated by?`
.
What is complements classical PW?
complement fixation - c1 binds to antigen-antibody complex
What is complements alt pw?
Exposure of factors to bacterial cell wall
What dies cleavage of C3 into C3a and C3b cause?
causes cell lysis, enhanced phagocytosis and inflammation, production c reactive protein
Fever?
In response to pyrogens
Too high=denature of enzymes
Moderate increase inhibits bacterial growth
Also speeds up metabolism increasing repair
What does the third line of defense do?
It recognizes, immobilizes, neutralizes and destroyed specific antigens
Protects against pathogens and abnormal cells
Amplifies inflamm
Carries out complement fixation
What do both classical and alt pws of complement lead to?
Formation of C3
Characteristics of the third line of defense?
Systemic
Specific
Memory
Humoral and cellular component
Humoral component?
B cells release antibodies which immobilize bacteria, toxins and free viruses
mark destruction by phagocytes and complemement
Cellular Component?
t Lymphocytes act directly against infected cancerous or foreign cells lyse cells(direct) release chemicals (indirect)
What is the difference between complete antigens and incomplete antigens?
Complete antigens are antigenic and reactive
Incomplete antigens are not antigenic
What are antigenic Determinants?`
part of molecule that cause antibody formation or activation of lymphocytes
most natural are large proteins
many diff lymphocytes react to it
What are self antigens? MHC
major histocompatibility complex proteins
What characteristics of MHC?
glycoproteins on surface
normally not attacked by immune system
coded by our genes
display peptides
Class 1 Self Antigens?
on most body cells
Class 2 MHC where found?
some cells in immune response
Crucial Cells Of Adaptive Immune System?
B Lymphocytes
T lymphocytes
Antigen Presenting Cells
B Lymphocytes in adaptive immune system role?
What type of defense?
Produce antibodies
Humoral Defense
T lymphocytes role in adaptive immune system?
What type of Defense
kill directly, cell mediated defense
What do antigen presenting Cells do?
Alert other defense cells to presence of foreign antigens
Where are lymphocytes Formed?
Where Mature?
Red bone marrow
Tcells mature in thymus
Bcells Mature in Mone Marrow
What is T cell processing controlled by?
Thymosin and thymopoietin
What process do T cells go under?
lymphocytes divide and are exposed to antigen, undergo positive and negative selection and self tolerance and immunocompetence are both acquire
What is positive selection?
ones that tolerate self but recognizing nonself are kept
What is negative selection?
unsuitable T cells sorted and destroyed
Where do B cells process? and at the end what is acquired?(2)
Red Bone Marrow
Self tolerance and ummunocompetence
What is immunocompetence?
how is it determined?
What does it allow cells to do?
What are cells still after being processed? Which then where do they go??
What happens if cells encounter their antigen?
Ability to respond to foreign invaders
genetics
Respond to foreign invaders in environment
niave and immature
secondary lymph orgs
they bind to it to complete development to functional
How do B cells and T cells differ?
B cells can react directly with antigens where T cells need APC to first process antigen & present it before they can react
What are the 3 typoe of antigen presenting cells?
Dendritic Cells
Macrophages
Activated B cells
What are the steps of an APC processing an antigen?
APC phagacytogize foreign antigen
hydrolyzes then presents antigen fragment on surface attached to MHC protein
lymphocyte immune response initiated
chems secreted to activate T cells which in tirn secrete more chems to speed up maturation of APCs and more macrophages
What is the antigen challenge?
first contact b/w naive B and its antigen causes
How are B cells activated?
antigen binds (antigen-receptor complex) endocytosis interaction with helper T cell
B cell then grows/multiplies
What do most activated B cells become?
plasma cells which secrete antibodies
after destruction of antigen in humoral response what remains in body?
B memory cells
What is the primary response to antigen exposure?
antibodies produce for 4-5 days the suicide
antibodies have same receptors as parent therefore same antigen react too
travel through fluids to bind free antigens and mark for destruction
What happens with second exposure?
Memory B cells provide fast response
2-3 days after [antibody] higher than 1st and lasts higher
plasma cells live longer this time
Natural Active Humoral Immunity?
B cells exposed to natural antigen, clone and antibody production, memory cell produced .. LT immunity
Artificial Active Humoral Immunity?
Vaccine, dead weakened pathogen or component
stims antibody/memory production
Passivel Humoral immunity?
antibodies made elsewhere introduced to body
fast, ST protection
Natural = placenta /milk Artificial= Injected , immed/ protection but not long
What are characteristics of antibodies?
immunoglobins
monomer
4 polypeptide chains - 2 heavy, two light, held together by disulfide bridge
variable regions where antigens bind
What does stem of antibody have? What does it determine?
constant region antibody class cells and chems that can bind to how function in antigen elimination
Class of antibody : Igm?
found in primary response, released by plasma cells
agglutinator, many binding sites
fixes and activates complement
IgA antibody class,
where found in small amounts?
Where mainly found? What does it prevent?
In plasma
body surface secretions
attach of pathogens to epithelial cells
IdB Antibody Class?
Where found?
What does it do?
bound to B cell
Binds to Antigen receptors and activates B Cells
IgG antibody Class?
What does it react with and where is it found?
What it is the main antibody for?
Viruses, bacteria and toxins
circulating
1&2 Response
IgE class of Antibody: What is it secreted by? When do its levels rise? What do its stems bind to and what does that trigger the release of? What does it trigger?
Plasma Cells
Allergic rxn
Stem cells bind to mast and basophil receptors which triggers release of histamine
inflamm and allergic responses
What four ways can antibodies destroy/ disarm invaders?
Stimulation complement fixation and activation
neutralization
Agglutination
Precipitation
What happens when antibodies stimulate complement fixation and activation?
What is it effective against
antibody-antigen complex triggers complment fixation –> lysis occurs –> inflamm and phagocytosis
effective against cellular antigens
What happens with the simplest mechanism, neutralization? (antibodies)
Antibody blocks sites -virus can reach target
antibody binds on bacterial ecotoxin inactivating it
complexes eventually destroyed by phagocytosis
Aggultination of antibodies?
bind to groups of antigens causing clumpage then phagocytotized –> may cause transfusion Rxn
Precipitation of Antibodies?
soluble molecules cross linked, precipitate out and phagocytized
What are monoclonial antibodies prepared from?
What will the react with?
What are they used for?
Descendants of single B Cell
Single Antigen
Dx, Tx
How do humoral and cell mediated targets compare?
Humoral: Bacteria and molecules in extracellular environments - body secretions, tissue fluid, blood, lymph, free antigens.
Mediated: Body cells infected by viruses or bacteria, abnorm/cancerous cells, foreign cells
What do T cells do in cell mediated response?
attack infected foreign cells
Can only recognize foreign antigens when attached to self MHC
Must bind to foreign antigen and self MHC protein before activation
crawl over body cells looking for antigens
Response only initiated by cekks with foreign and self antigens
What do Helper T cells do?
What kind of protein do they contain?what do they bind to?
what Defenses do they stimulate?
Have CD4 recognition protein
foreign antigen attached to MHC 2
Specific and Non Specific Defnses
Cytotoxic Killer T Cells -t8 cells:
What kind of protein do they have?
What do they bind to?
What do they do?
CD8 Protein
foreign antigen attached to MHC 1
Destroy invaders by lysing
What cells provide strong fast response to second exposure?
Memory Helper, cytoxic T Cells
Regulatory T cells?
inhibit actions of other T cells to end immune response
Delayed Hypersensitivity Helper T cells role?
allergic responses
Gamma Delta T Cells location and function?
intestine and fight cancer
What proteins are found on the surface of T cells?
TCR CD4 Cd8 Costimulant Receptors Other Receptors
What to TCR proteins do on T cells?
Antigen receptors
What do TCR on T cells variable region bind too?
foreign antigen fragment
What does TCR on T Cells constant region bind to?
appropriate MHC proteins (1 for killer and 2 for helper)
What do CD4 and CD8 proteins on T cells do?
adhesion molecules
help T cells stick to other cells during protein recognition
What do costimulant Receptors on T cells do?
bing msgr chems like cytokines, interleukins or other cells
Ex. CD28 on helper T binds with B7 protein produced by macrophages
What is Costimulation?
3 signals required to activate T cell Response
act as fail safe
Prevent unecessary immune activation
What are types on costimulation?
T cell binds to apecific proteins on B7 protein on macrophage
T Cell bind to chemical signal molecules
T cell binds to other Cells
Without ci-stimulation what would happen?
T cells would become tolerant to that antigen, unable to divide and not secrete cytokines
What are cytokines?
Chemical msngr in immune systen allows cells to communicate with others stimulate or inhibit immune rsponse Some roles? Costimulants of T cells Cell toxins Enhance killing by macrophages Enhance inflammation
What 3 stimuli needed for T cell antigen recognition and clonal selection?
binding of appropriate foreign antigen
binding to self antigen (MHC)
bind to costimulant
How are helper to killer T cells Activated?
APC display frags of foreign antigen on MHC protein
T Cells Bind to foreign antigen and MHC protein
CD4 and CD8 help T cell adhere to target cell during recognition
costimulants bind to T cell and complete activation
activated T cell enlarge multiply to form clone
carry out activities according to their class
What are Special roles of helper T cells?
stimulate and regulate whole defense(innate and adaptive)
Stim other T cells to multiply and differentiate
Costimulate activated B cells to clone and multiply
stim B cell antibody production and release
stimulates macrophages and NK cells to kill
attract other WBC to area and strengthen non specific defenses
How Helper T cells Act?
binds to macrophage and stimulates macrophage to produxe IL-1, which then stimulates the bound T cell to release IL-2
Which then stimulates:
B Cells to multiply and produce antibodies
other helper T cells to multiply
activation of NK cells
which sets up positive FB speeding division of activated killer T cells
Cytotoxic T Cell Rolls?
directly attacks and kills other cekks
activated killer cell travels searching out cell with their antigen
tearget virus infected cells and some bacteria infected cells, parasites in body, cancer and foreign cells
any kind of cell can be attacked if displaying both MHC 1 and foreign antigen and costimuluis us present
How are Cytotoxic T Cells Activated?
bind to target containing both MHC and antigen frag
CD8 Protein helps T cell bind to target
costimulate produced by target binds to T cell activating it and enlarging it forming a clone
then clones search out and attack target cells with same foeign antigen
die after aweek by apoptosis
memory cells remain and mediate fast secondary response
Mechanism for killing of cytoxic T cells?
Lysis of target cell, cytotoxic binds to target, releases perforin and granzyme which causes lysis
cell then binds and secretes lymphotoxin, and releases tumour necrosis factor which triggers apoptosis in cancer cells
cytotoxic secrete gamma interferon stimulating activity of macrophages
