week 11 lecture 1 and 2 Flashcards
IS = immune system, WBC = white blood cells
what is innate immunity
- first line of defense
- offers resistance to any microbe or foreign material
- includes general mechanisms - skin, mucus, and antimicrobial chemical
what is adaptive immune response?
- activated by chemicals of innate immunity
- tailored to a particular foreign agent
- has memory effectiveness increases on repeated exposure to foriegn agent
two types of adaptive immunity cells?
T cells
B cells
what are antigens?
- any substance recognized by the immune system
- immune system differentiates between self-antigen and no-self (foreign)
- enables IS to rid host of foriegn invaders (and cancer cells)
- when discrimination goes awry, it is the basis for allergic responses and autoimmune disease
what is the first line of defense?
- barriers
how does the skin act as a barrier? type?
- mechanical barrier
- associated microbiota prevent colonization of pathogens
what do mucosal membranes serve as?
- protective covering - resists and traps microbial invaders
- mucosal secretions are toxic to microorganisms
what are the functions of the complement system?
- triggers inflammation and recruits WBCs (leukocytes)
- lyising microbial cell membranes
- promoting phagocytosis of microbial invaders via opsonization (protein coating - tags microbes for destruction )
what are the two ways the complement system will kill a microbe?
- phagocytosis - cell envlopes and digests
- membrane attack complex (MAC) - destroys the target cell by inserting a series of proteins into the membrane, creates pores and cell looses cohesion/control - death
what happens in primary organs and tissues?
- stem cells differentiate into immune cells
what happens in secondary organs and tissues?
- where lymphocytes are activated by antigen interactions
(lymph nodes, tissues, and spleen)
what are B-cells?
- bone marrow (orginates here)
- enter bloodstream and migrate to lymph nodes and spleen to await introduction to the antigen to which they will make targeted antibody
- differentate into plasma cells and form antibodies
what are T-Cells?
- thymus (matures here)
- mature T-Cells and enter the bloodstream where they await activation by innate immune cells
- does cellular immune response
what are the two types of WBC?
- mast cells - triggers inflammatory reactions and responsible for allergic symptoms (early warning system)
- dendritic cells - processes foreign matter and presents to lymphocytes (typically invaded)
what are the two categories of of wbc?
- granulocytes
- Agranulocytes
what are the three types of granulocytes?
- eosinophils - worm and fungal infections, allergy, and inflammatory reactions
- basophils - functions in inflammatory events and allergies
- neutrophilis - essential blood phagocytes, active engulfurs and killers of bacteria
what are the two cargoies of agranulocytes?
- monocytes-produce in bone marrow and enter the blood, mature into macrophages and dendritic cells
- lymphocytes - immune reaction to foreign matter
what are macrophages?
- largest phagocytes that ingest and kill foreign cells
- resides in specific tissues
what is the general function of common lymphoid progenitors? two types?
- do not express antigen-specific receptors, innate response and has no memory
1. NK cells
2. inate lymphoic cells
what is the function of NK cells?
. NK cells - kill tumor cells and cells with intracellular infections
what is the function of innate lymphoic cells?
- secrete cytokines that assist both innate and adaptive cells, not antigen scpeifc, supports lymphoid tissue development
how does the microbe recognized by the phagocyte?
- opsonin-dependent recognition - protein coat
- opsonin independent recognition - microbe-associated molecular patterns
what is the defense reaction to tissue injury?
- can be caused by pathogen or wond
- can trigger complement system
- acute inflammation is the immediate response of body to injury or cell death
what are cardinal signs of the body in response to inflammation?
- reddness
- warmth
- pain
- swelling
- altered function
what is a granuloma? response to ?
- when phagocytic cells can not destroy pathogen and mass of cells formed in attempt to call off site
- inflammation
what are the three major functions of immune system?
- recognize anything foreign to the body
- defend the host from this foreign material
- remember the foreign invader
what are the 5 characteristics of adaptive immunity?
- discrimination - between self and non-self
- specificity - activated t and B lymphocytes respond to specific (non-self) antigens
- diversity - generates enormous diversity of cellular receptors and antibodies that recognize the foreign substance
- timing - turned on after activation by innate response
- memory - response to a second exposure is so rapid that there is ususlally no noticeable illness
what are the two types of adaptive immunity?
- humoral - antibody-mediated immunity (B)
- cellular - cell-mediated immunity (T)
what function do T cells have in cell-mediated immunity?
- cytotoxic T cells (CTL or CD8+ cells) - attack target cells infected with intracellular pathogens
- T helper (CD4+ cells) - direct CTL to target cell lysis
what are the two types of recognitions of foreignness?
- endogenous antigen protein
- exogenous antigen processing
what is class I and class II?
- I - on all human cells with nucelus (self)
- II - on cells that can process and present antigens to T lymphocytes
what is endogenous antigen protein ?
- class I binds to peptides by sampling the proteins in the cytoplasm
- enables host cells to present peptide antigen to CD8+ cytotoxic T cells
what is exogenous antigen processing?
- class 2 binds fragments that come from atigens outside the cell abd present to CD4+ T helper cells
what will happen when T cells are stimulated?
- differentiate to become
- effector cells - carry out specific functions to protect hosts against foreign antigens (put to work)
- memory cells - mature, educated cells that can be quickly reactivated by antigen (sleep)
what are B-Cell receptors made of?
membrane-bound antibodies
out of the 5 classes of antibodies which is the most common?
- IgG
describe the structure for immunoglobulins?
- 4 polypeptide chains - 2 heavy and two light chains
- constant (C) region - sequences does not vary
- variable (V) regions- forms antigen-binding sites
what contributes to antibodies?
- combination of variable regions of H and L cahins generated by recombination of chromsomes
what are 5 actions of antibodies that will help kill them?
- perciptation - makes soluble antigen insoluble
- aggultation - lnks cell bound antigens together forming clumps
- . neutralization -masks dangerous parts of pathogen
- inflammation - triggers histodine release
- complement - lysis
PANIC
what are the two mechanisms for B-cell activation?
- T-Cell-independent B-cell activation
- T-Cell-dependent B-cell activation
What is T-cell-independent B-cell activation?
- directly triggered B-Cells to produce antibodies
- antibodies produced have a low affinity for antigen
- less effective than T-dependent-B cell activation but more rapid
What is T-cell-dependent B-cell activation?
- activation of T and B cells with the same antigen
- needs antigen-B cells specific interaction and R-cell cytokines
- B cells differentiate into plasma cells and memory cells
What is clonal selection theory?
- A genetically unique B cell is activated by a specific antigen, reproducing to form a clone of cells with identical specificity
- Lymphocytes can bind a wide range of epitopes, but only B cells that recognize the antigen are stimulated to clone.
How can immunity be acquired?
- naturally - active (infection) and passive (breast milk)
- artificial - active (vaccination) and passive (therapy)
What is a primary antibody response?
- relatively slow upon first antigen encounter
secondary antibody response?
- after subsequent exposure to same antigen it will be faster, more efficent at preventing the illness
- shows how adaptive immune system will remember a pathogen and is the basis for vaccination
how can extreme immune response cause hypersensitivity?
- type 1 - peanut allergy
- type 2: blood transfusion incompatibility
- type 3: arthritis
- type 4: autoimmune disorder
Two types of transplant rejection?
- host v graft - host cells does not recognize graft as self and attacks
- graft v host - graft will attack host
microbiota
all the mocrogoranginsm that live and on an organism
microbiome
all the genes found in ones microbiota
holobiont
hosts and microbes live together and evolve together
when does oure microbiome develop? what are ways we can increase our microbiome?
- at birth and changes as we age
- birth mode (vaginal better), siblings, smoking, vacinations
what should be free of microorganism? what should be constantly changing?
- interanl organs and tissues (brain and cerebrospinal fluid)
- surface tissue (skin) since in contact with enciornmnet and colonized by various organisms
characteristics of skin microbiome?
- slightly acidic pH
- high concentration salt
- staphylococcus epidermis - nonpathogenic that inhibits growth of other pathogens (bacterial interfrence)
what happens to micorbes in stomach?
- killed by acidic conditions but some survive
- if pass through stomach quickly or if ingested with food particles and are resistant to gastric pH
what did the Germ free mice reveal?
- eat more but weigh less (less absorption)
- fecal transplant and made the mice fat
- have limited devlopment of WBC that mature in bine marrow
- had an effect on behavioral traits (stressed)
what are three ways microbiome can influences CNS?
- microbiome impacts the immune system
- direct pathway from gut to brain through nervs in GI tract which transmits signals to brain by vagus nerve
- soluble microbial products cross the blood brain barrier
how does cardiovasular disease happen?
- lot of red meat
- prmotes grth of “meat eating” microbial population that produces TMA and is oxidized by liver into TMAO
- TMAO (toxic) causes atherosclerosis
3 features of cancer?
- heliobacter pylori disregulates host cell cycling
- bacteria can be involved in metastasis of tumors o distant sites
- cancers linked to microorgansims driven by inflammatory state associated with dysbiosis
infection
a microbe growing and multiplying on or within a host
pathogencity
ability of a pathogen to cause disease (when damage is caused)
virulence
degree of harm inflected on its host
signs v symptoms
- signs: objctive changes that can be directly observed and measure (fever)
- symptoms - subjective chnages (pain)
what is the course of an infectious disease?
- initial exposure - time between pathogen entry and development of signs/symptoms
- incubation period - mild, non specific signs and symptoms
- illness - most sever
- recovery stage or death
two ways disease can be transmitted?
- indirect or direct
what are the three factors that influence whether an infection will happen?
- virulence of organism
- number of invading organisms
- presence of adhesion and invasion factors
infectious v lethal dose
- infectious dose 50(ID50) - number of microbes required to cause disease in 50% of inoculated hosts (varies among pathogens)
- lethal dose 50(LD50) - dose that kills 50% of a group of experimental hosts within a specific period (influenced by host susceptibility)
how does adherence work?
- adherence> entry > colonization
- adherence structures have specificity to targets
infectivity
ability to create discrete points of infection
invasiveness
ability to spread to adjacent tissues
What are the six ways that microorganisms can evade a host?
- survive and replicate inside host cells
- secrete exopolysaccharides to form a biofilm
- excrete specialized proteins to selectively kill host cells
- produce proteins to inactivate or distract innate resistance
- make capsules to avoid phagocytosis
- mutate/reduce cell surface proteins
two types of toxins
- endo: fragments of cell- can be shed, typically released after death
- factor 12 triggers shock and death - exo - secreted from cell
- superantigens: T helper cells will be bound and will overexpress cytokines and release pro-inflammatory molecules
