chapter 43: The Immune System Flashcards
what is innate immunity
defense mechanism an animal is born with
what is adaptive immunity
the response is enhanced by previous exposure to the pathogen
what is a pathogen
agents that cause disease
what do first lines defense help with
prevent pathogens from gaining entry to the body
within the body what are the 2 types of molecular recognition
detection of nonself molecules, particles and cells
what animals have what immunity
innate
- includes barrier defenses
what immunity do vertebrates have
adaptive
when is adaptive immune response activated
after the innate response and develops more slowly
what are the barrier defenses for innate immunuty
skin
mucous membranes
secretions
what are some innate internal defenses
- phagocytic cells
- natural killer cells
- antimicrobial proteins
- inflammatory response
what is adaptive immunity
recognition of traits specific to particular pathogens
what is the humoral response for adaptive immunity
antibodies defend against infection in body fluids
what is the cell-mediated response for adaptive immunity
cytotoxic cells defend against infection in the body cells
benefit of the exoskeleton in insects
forms the first barrier to pathogens
what is the digestive system protected by
chitin-based barrier and lysozyme
what is a lysozyme
an enzyme that breaks down bacterial cell walls
what is hemocyctes
circulated within the hemolymph and carry out hemolymph
what is phagocytosis
ingestion and digestion of large foreign substances
what do hemocytes secrete
antimicrobial peptides
what do antimicrobial peptides do
disrupt the plasma membranes of the fungi and bacteria
what does the immune system recognize
bacteria and fungi structures on their cell walls
what nucleic acid do the viruses that infect insects have
genome consisting of single-stranded rna
how does the virus invade the host cell
- ## replicates sRNA in the host cell which then results in dsRNA
what rna type is not produced by animals
double stranded
what can double stranded rna do
trigger a specific defense against the invading virus
what is the process of the double stranded rna using its defense mechanism
- host enzyme dicer 2 recognizes dsRNA
- dicer 2 cut the dsRNA into fragments
- host argo complex protein binds to the fragments and blocks the viral mRNA
what are some innate defenses mammals and invertebrates share together
phagocytosis and antimicrobial peptides
what defenses are unique to vertebrates
- natural killer cells
- interferons
- inflammatory response
what are some of the barrier defenses
- skin and mucous membranes
where are mucous membranes found
digestive, respiratory, urinary, and reproductive tracts
what are the function of the skin and mucous membranes
- block entry of pathogens
- mucus traps and allows for the removal of microbes
what body fluids are hostile to many microbes
saliva, mucus, and tears
what is a lysozyme
destroy the cell walls of weak bacteria
how is a low pH benefical to the skin and digestive system
prevents the growth of many bacteria
what pH is the stomach and how is it good
2; kills most of the bacteria before they enter the small intestine
how do the secretions of oil and sweat glands affect the pH
give human love pH of 3-5
what does cilliated epithelia cells do
sweep dust and pathogens trapped preventing infection of the lungs
what are some functions of the innate immune cells in mammals (3 D’s)
- detect
- devour
- destroy invading pathogens
what do innate cells do
recognize groups of pathogens and they use different receptors
what are the receptors the innate cells use
TLR (toll-like receptor)
what do TLR receptors do
recognize and bind to the fragments of molecules characteristic of a set of pathogens
what are the different types of TLR receptors
TLR 3, 4, and 5
what is TLR 3
located in the surface vesicle and it binds to dsRNA
what is TLR 4
located on the plasma membrane
binds to lipopolysaccharide found in some bacteria cell wall
what is TLR 5
located on the plasma membrane
- binds to flagellin
what is flagellin
main protein of bacterial flagella
what are the 2 types of phagocytic cells
-neutrophils and macrophages
what are phagocytic cells
engulf and destroy pathogens in the body
what are neutrophils
circulate in the blood and make up most of while blood cells in humans
what are macrophages
(big eaters) some migrate through the body or reside permanently in organs and tissues
what are the additional types of phagocytic cells
- dentritic cells and esoinophils
what are dendritic cells
stimulate development of adaptive immunity
- found in tissues that have contact with the environment
what are eosinophils
discharge distructive enzymes against multicellular invaders like parasites
- found beneath an epithelium
what are neutrophils attracted to and what is their shape
- infected tissues
- spherical shape at rest but can change shape to fight infection
what receptors do eosinohils have and what group are they apart of
- Fc receptors that bind to antibodies
- part of white blood cells
where do macrophages originate
in bone marrow
what are natural killer cells
circulate through the body and detect abnormal surface proteins on cancerous cells
how can natural kills cells fight against cancer
release chemicals that lead to cell death and inhibit the spread of cancer
what are antimicrobial peptides (AMP)
small peptides that exist in nature and they use pathogen recognition and release peptides to attack pathogens
what are interferons
proteins that provide defense by stopping the replication of viruses
what do virus-infected cells secrete
interferons Proteins that induce nearby cells to stop viral replication
what happens when interferons activate macrophages
cascade of reactions that can lead to lysis (bursting) of the invading cells
what is the inflammatory resposne
pain and swelling is brought by molecules that are released during injury or infection
where can inflammation occur
locally or systematicallt
what is an example of an inflammatory response
fever
what does local inflammatory response involve
- mast cells
- increased blood blow to the site
- accumulation of pus
what are mast cells
immune cells found in the connective tissue that release histamine
what does histamine do
triggers blood vessls to dialte and become more permeable
what do activated complement proteins do
promote further release of hsitamine and they attract more phagocytic cells
what does increased blood flow help with (local)
deliver neutrophils and antimicrobial peptides to the site
what is pus
fluid rich in white blood cell, dead pathogens, and cell debris from damaged tissues
what are 2 types of lymphocytes
t cells and b cells
where do t cells orginate from
thymus
where do b cells orignate from
bone marrow
what are antigens
substances that can cause a response from B or T cell
- large and foreign molecules
what do t cells or b cells bind to
antigens via antigen receptor
what is the epitiope
the small accessible part of an antigen that binds to an antigen receptor
where do b cells live
in the lymph nodes and spleen and also circulate in the blood
what does a b cell antigen receptor look like
y shaped molecule with 2 heavy polypeptde chains and 2 light polypeptide chains
what do the variable regions of b cells provide
antigen specificity
compare the constant c regions with the constant v regions
the c regions of the chains vary little among B cells whereas the variable v regions differ greatly
what is the first step in B cell activation
binding of a B cell antigen receptor (epitope)
what do B cells transform
into plasma cells
what do plasma cells secrete
soluble form of the protein called an antibody or immunoglobulin
what shape do antibodies have
the same Y shape as B cells antigen receptors2
different antibodies can recognize what
different epitopes on the same antigen
antibodies can also recognize what
free antigens as well as antigens on a pathogen surface
what does a t cell receptor consist of
- 2 different polypeptide chains (alpha and beta)
what do t cells bind to
antigen fragments displayed or presented on a host cell
what are antigen fragments bound to
cell-surface proteins called histocompatibility complex molecules
what do MHC molecules bind to in infected cells
mhc molecules bind and transport antigen fragments to the cell surface
what is antigen presentation
mhc molecules bind and transport antigen fragments to the cell surface
what are the 4 major characteristics
- immense diversity of lymphocytes and receptors
- self-tolerance: lack of reactivity against an animals own molecules
- B and T cells proliferate
- immunological memory
what does the immune system do with antigens
assembles millions of different antigen receptors (T and B)
what does the immunoglobin gene encode
light chain of the B cell receptors and secretes antibodies
what are Ig gene rearrangements
are permanent and passed on to daughters cells when the lymphocyte divides
what does the v and j segments encode
the variable region of the receptor chain
what does segment c encode for
constant region
what cells can B cells express
five different forms of immunoglobin IgA, IgE, IgM, IgD
what is self-tolerance
the ability for the immune system to recognize itself and not react or attack
how does the body distinguish self from non-self
- regulate at the stage of immature B and t cells
- lymphocytes tested for self-reactivity
- antigen receptor genes are randomly rearranged
what happens to immature lymphocytes since they are randomly rearranged
produce receptor specific for an epitope on the organisms own molecules
what b and t cells are destroyed by apoptosis
with receptors specific for the body’s own molecules are destroyed
what happens in the lymph nodes
an antigen is exposed to a steady stream of lymphocytes until a match s made
what is clonal selection
b or t cells undergo multiple cell divisions forming a clone of identical cells
what are effector cells
act immediately against the antigen and they are plasma cells that secrete antibodies
where do effector cells form
in t cells and they are helpter t cellls and cytotoxic t cells
what is the function of immunological memory
responsible for long-term protections against disease
what does the first exposure to a specific antigen represent
the primary immune response ( clone of lymphocytes is formed)
what is the secondary immune response
memory cells facilitate a faster, greater, and more prolonged response from a reservoir
what are the defenses provided by B ad T lymphocytes
humoral immune
the cell mediated immune response
what is humoral immune response
protects the blood and lymph
-
what are antibodies
help neutralize or eliminate toxin and pathogens in the blood and lymph
what is cell mediated immune response
specialized t cells destroy infected host cells
what does helper t cell do
activates both the humoral and cell mediated immune response
