Chapter 31: Immunology: Animal Defense Systems Flashcards
pathogens
harmful organisms and viruses that can cause disease
immunity
the ability to avoid disease when invaded by a pathogen
Innate Immunity
Nonspecific
deployed against/targets a wide variety of invasive organisms
Barriers and phagocytes
Can be there all of the time or just activated by an invasion/injury
Super quick
Most animals have this
Adaptive Immunity
Specific distinguishes between self and nonself involves antibody proteins and other proteins that recognize, bind to, and help destroy specific invaders Slow Long lasting JUST VERTEBRATES
Innate, nonspecific 1st line
barriers (skin and organ lining) Dryness, low pH mucus lysozymes, defensins 1st 4 hours after pathogen infection
Innate, nonspecific (second line)
Inflammation phagocytosis Natural Killer Cells Complement System Interferons 4-96 hours after infection by pathogen
Adaptive, specific
Humoral immunity (B cells, antibodies) Cellular Immunity (T cells) More than 96 hours after infection
self
substances made by organism
nonself
substances that are not part of the organism
T or F: In mammals and other vertebrates, specific and nonspecific mechanisms work together as a coordinated defense system, usually in sequence
True
T or F: The major players in immunity are specific cells and proteins
True
T or F: There are more white blood cells than red blood cells in human blood
False, there are more red than white blood cells
White blood cells
cells in the blood that are specialized for various functions in the immune system
two major kinds
Lymphocytes and Phagocytes
Phagocytes
LARGE CELLS [large font to help remember]
engulf pathogens [p to help remember] and other substances by phagocytosis [cell eating]
Innate and Adaptive Immunity
type of WBC
ex. macrophage
Lymphocytes
type of WBC
ex. B cells and T cells
adaptive immunity
Antibodies
Proteins that bind to specific substances identified as nonself
This can be inactivate and DESTROY microorganisms and toxins
OR
it can function as a tag/marker, making it easier for other immune cells to attack
produced by B cells
Major Histocompatibility Complex (MHC)
proteins found in two classes (I and II)
MHC proteins act as labels and present antigens to T cells
MHC I proteins
found on most cells in mammals
self-identifying labels
present antigens to cytotoxic T cells
MHC II proteins
found on macrophages, B cells, and dendritic cells
self-identifying labels
present antigens to helper T cells
coordinate interactions between lymphocytes and macrophages
T Cell receptores
integral membrane proteins on the surfaces of T cells
Recognize and bind to the substances presented by the MHC proteins on other cells
Cytokines
soluble signaling proteins released by many cell types
bind to surface receptors and alter target cell action
Activate or inactivate B cells, macrophages, and T cells
like an on and off switch for immune cells
Skin
Physical barrier: rarely penetrated by bacteria when INTACT
Saltiness: usually not hospitable to bacteria growth
Presence of Normal Flora: the bacteria and fungi that are normally just chilling out on the skin take up space and nutrients, causing competition
Mucus
slippery secretion by mucous membranes
traps microorganisms that are super duper tiny so that they can be removed by the motion of the cilia
Mucous membranes
line body cavities that are exposed to the external environment
Lysozyme
enzyme made by mucous membranes
breaks the bonds in the cell walls of bacterias, causing them to lyse (break open), hence the name
Defensins
made by (guess what?) Mucous membranes
peptides
Have hydrophobic domains
toxic to a wide range of pathogens, like bacteria, microbial eukaryotes, and enveloped viruses
insert selves into plasma membranes and make the membranes freely permeable to everything, killing the invader
DefenseIN: INsert themselves IN membrane
also made in phagocytes to kill pathogens
Plants also use these
enveloped viruses
membrane-enclosed viruses
Harsh internal conditions
kill pathogens
ex. stomach #gastricjuice
Phagocytes
Recognize pathogens and ingest them by phagocytosis
Once inside the pathogen, the invader is killed by hydrolysis within lysosomes or by defensins
Natural Killer Cells
A class of lymphocytes
can tell the difference between healthy body cells and infected/cancerous cells
Initiate apoptosis in the infected/cancerous cells
also interact with adaptive immune by lysing the cells labeled by antibodies
apoptosis
programmed cell death
Complement Proteins
In blood
more than 20 types
once initiated, proteins function in a cascade
system can be initiated by innate and adaptive immune responses
In adaptive, the bonding of a complement protein to an antibody starts the cascade
Steps in complement Protein sequence
- A protein binds to components on surface of invading cell, helping phagocytes recognize and destroy the invader
- Another protein starts inflammation response and attracts phagocytes
- Other proteins lyse the invading cell
Interferons
Signaling proteins/ class of cytokines
produced by an infected cell
helps increase resistance of nearby cells
induced by various molecules, such as viral RNA bind to receptors on plasma membrane of uninfected cells– creating a signaling pathway that prevents viral reproduction if the cell becomes infected, which is less likely because it stimulates cells to hydrolyze bacteria/viruses, a step in adaptive immunity
Inflammation
The redness, swelling, and localized heat caused by tissue damage due to infection or injury
can become painful
can happen almost anywhere in the body
Why is inflammation important
isolates the infected area to prevent spread of damage
recruits cells and molecules to the area that could be useful in destroying any pathogens that could be there
and promotes healing
Mast Cells
one of the first responders to tissue damage
adhere to skin and linings of organs
Release lots of chemical signals
Tumor Necrosis Factor
a chemical signal produced by mast cells
a cytokine protein that kills target cells and activates immune cells
Prostglandins
chemical signal produced by mast cells
fatty acid DERIVATIVES that play roles in like multiple immune responses, but apparently, the only one worth mentioning is the initiation of inflammation in nearby tissues
gland—>glad—->happy—->heyyy—-> aaaayyyy —> a —-> acid—-> fatty acid
Histamine
chemical signal produced by mast glands
an amino acid DERIVATIVE that increases the permeability of blood vessels to white blood cells and molecules so that they can act in nearby tissues.
What causes the redness and heat of inflammation?
The dilation of blood vessels in the affected/injured area
What molecules/cells are responsible for the healing associated with inflammation?
Phagocytes and Neutrophils
How/why is a fever produced in the inflammatory response?
Phagocytes and neutrophils produce cytokines, which signal the brain to turn up the heat in the body
This heat accelerates lymphocyte production and phagocytosis, accelerating the immune response.
Additionally, some phagocytes are picky about temperate and can have their growth inhibited by fever
What does the pain of inflammation come from?
swelling, the action of leaked enzymes on nerve endingsm and the action of prostglandins, which increase nerve ending sensitivity
Pus
A mixture of leaked fluid and dead cells
normal result of body fighting disease and/or inflammation
removed by marcophages
Platelets
Cell fragments in the blood
go to wound and produce growth factors that stimulate nearby skin cells to divide and heal the wound
Allergic Reaction
harmless nonself molecule binds to mast cells, causing release of histamine and inflammation
autoimmune disease
immune system fails to distinguish between self and nonself
tissues in the organisms body are attacked
inflammation is more general
Sepsis
inflammation caused by bacterial infection is not localized
extends throughout the body, causing blood vessels throughout the body to become dilated
This causes a potentially lethal drop in blood pressure
adaptive immunity
After exposure to a toxin, make a protective factor that was not present before exposure
specific
Passive Immunity
Process of acquiring immunity from antibodies received from another individual
What are the four key features of adaptive immunity?
Specific- allows it to focus its responses on pathogens that are present
Immunological memory-allows it respond more effectively in later exposures to the pathogen
Diverse- enables it to respond to novel pathogens
Distinguishes self from nonself- prevents it from destroying self cells
SIDD
Specificity
B and T lymphocytes are all over this
T cell receptors and antibodies produced by B cells recognize and respond to specific antigens, initiating a specific immune response
Antigen determinants/epitopes
The sites on antigens recognized by the immune system
can be multiple antigenic determinants on an antigen
Antigen
Antibody generating
nonself substances
usually proteins or polysaccharides
can be multiple antigens on an invading pathogen
Why does the immune system need Diversity?
Since there are TONS of different types of pathogens, and each species has tons of slightly different strains, humans need to be able to respond to MANY different antigens specifically
What is the primary way of generating diversity in the immune system?
DNA changes- chromosomal rearrangements and other rearrangements
these occur just after the B and T cells are formed in the bone marrow
T or F: The adaptive immune system is predeveloped
True
All of the machinery available to respond to an immense diversity of antigens is already there, even before the antigens are encountered
What triggers the proliferation of B or T cells
antigen binding
this activates the cells and causes them to divide
clonal selection
the process of producing an immune response by having an antigen bind to a cell, activate it, and then have the cell form a clone of cells, which are all identical and perform the same job
selection occurs because of binding and activation
Distinguishes from Self and Nonself
super important because the human body has tons of different molecules which are capable of generating responses and so the body needs to be tolerant of its own molecules and not generate an immune response
This is ensured primarily through clonal deletion
Clonal Deletion
when B and T cells are differentiating, they encounter self antigens.
Any B or T cells that shows the potential to mount a strong immune response against self-antigens undergo apoptosis
Autoimmunity
caused by a failure of clonal deletion
an immune response within an individual to self-antigens
doesn’t always lead to disease
Systemic Lupus Erythematosis (SLE)
antibodies to many cellular components
can cause serious damage when they bind to normal tissue antigens and form gigantic antigen-antibody complexes
these complexes can get stuck places and cause inflammation
Hashimoto’s thyroiditis
most common autoimmune disease in women over 50
Immune cells attack thyroid
Immunological Memory
After responding to a pathogen once, the immune system remembers that pathogen and can respond more quickly and powerfully in the future
Molecular Mimicry
A possible mechanism for autoimmunity, exposure to an antigen similar to a self antigen provokes an immune response that cross-reacts with the self antigen
Primary Immune Response
adaptive immune response to first exposure to a pathogen
takes several days to produce antibodies and T cells for the antigen
Effector cells
carry out the attack on an antigen
live for a very short time
Plasma cells
Effector B cells, secrete antibodies
Effector T cells
release cytokines and other molecules that begin the reactions that kill the cells
Memory cells
long lived
can divide on short notice to produce more effector and memory cells
can survive for decades, rarely dividing
True or False: Immunological Memory arises from the fact that activated lymphocytes divide and differentiate to produce two types of daughter cells
true
What two types of daughter cells do activated lymphocytes produce?
effector and memory
Secondary Immune Response
the more powerful and fast immune response triggered by subsequent encounters with the antigen due to memory cell proliferation
How does vaccination work?
Produce a primary immune response to prepare the body to have a super duper powerful and fast secondary immune response the second time it encounters the pathogen (which would be in like real life)
What are the three phases of adaptive immunity?
Recognition Phase- organism discriminates between self and nonself PATHOGEN ALERT A PATHOGEN HAS ENTERED THE BUILDING WE HAVE A NONSELF ENTITY
Activation Phase- The recognition event leads to a mobilization of cells and molecules to fight the invader Rally the troops
Effector phase- The mobilized cells and molecules destroy the invader Give me a V Give me an I Give me a C Give me a T Give me an O R Y
Victory victory that’s our cry
Humoral Response
Major players: B cells that make antibodies
Helper T cells
starts with exposure of the antigen to immune system, primarily when an antigen binds to a B cell that has a surface antibody for that antigen
this gets the B cell all ready for division
It internalizes some of the antigen and puts some of the digested fragments on the MHC protein and presenting it on the surface
a T-helper cell then binds to the B cell, causing cloning (#spanishclass)
Cellular Immune Response
Major Players: Cytotoxic T cells
Helper T cells
starts with exposure of the antigen to immune system, primarily when an antigen is inserted into the plasma membrane of an antigen-presenting cell, with its epitopes sticking out
these epitopes are recognized by a T-helper cell with a T cell receptor protein for the antigen
The T-helper cell then release cytokines which makes Cytotoxic T cells with the same T cell receptor to divide
What is the result of activation in the humoral immune response?
A clone of B cells that can produce antibodies specific to the antigen
cells of the B clone produce antibodies that bind to free antigen in the blood, resulting in activation and destruction of the antigen
What is the result of activation in the Cellular Immune Response?
A clone of cytotoxic T cells that express a T cell receptor that can bind to any cell expressing the antigen on its surface
cells of the cytotoxic T cell clone bind to cells with the antigen and destroy them
presentation of the antigen to the immune system
exposure of the antigen to the immune system
What do B cells begin life as?
naive B cells
True or False: A B cell can be stimulated to divide by a T-helper cell binding to the exposed antigen on a B cell surface
True
The T-helper cell releases cytokines
Immunoglobulins
antibodies all have a tetramer with four polypeptide chains two identical light chains two identical heavy chains chains held together by disulfide bonds
constant Region
determines the general structure and function (class) of an immunoglobulin
Variable Region
responsible for antibody specificity
True or false: Antibodies are bivalent because the two antigen-binding sites on each immunoglobulin molecule are identical
True
This allows antibodies to form large complexes with antigens
What are the five classes of immunoglobulins?
IgG secreted by B cells 80% of circulating antibodies
IgD cell surface receptor of B proteins
IgM initial surface and circulating antibody released by B cells
IgA protects mucosa on epithelia exposed to the environment
IgE binds to Mast cells and is involved with inflammation
What are the two things for an antibody to do in the bloodstream?
- some antibodies bind to the antigen that is expressed on the surface of a pathogen, stimulating macrophages to ingest, or natural killer cells to destroy, the pathogen
- The antigen is free in the bloodstream, antibodies may bind to it using the cross-linking function to form large, insoluble antibody-antigen complexes, which get destroyed and ingested by phagocytic cells.
True or False; The T cell receptor is an immunoglobulin
False, it is a glycoprotein made up of two polypeptide chains
What two things do Cytotoxic T cells do to eliminate the antigen-carrying cell?
Produce perforin, which lyses the bound target cell
stimulate apoptosis in the target cell
regulatory T cells (Tregs)
makes sure that the immune response does not go crazy regulates like the system of checks and balances supervisor recognize self antigens
What cytokine do Tregs release when activated?
Interleukin-10, which blocks T cell activation and leads to apoptosis of cytotoxic and helper T cells that bind to self antigen presenting cell
AIDS
Acquired Immune deficiency syndrome
caused by human immunodeficiency virus (HIV)
initially infects helper t cells, macrophages, and antigen-presenting dendritic cells
at first immune repsonse, but then HIV and ctotoxic T cells kill helper T cells (because they are infected)
then there is a dormant period but eventually, helper T cell level goes down to a point where infections they could normally fight off really easily become dangerous
additionally, stimulates Treg cells, downregulating immune response
opportunistic infections
infections occur because of this in HIV infected patients
Pathogens take advantage of the very weak immune system of the host
Lymph vessels
tubes that run parallel to the circulatory vessels and serve as a blood filtration system to remove foreign particles
Lymph nodes
oval shaped organs in the armpits, neck, etc. that are connected to lymph vessels; they collect foreign particles and store B and T cells
Spleen
stores blood cells, removes clumped pathogens coated with antibodies form the blood stream
Adenoids (tonsils)
trap pathogens
Bone Marrow
Stem cells within the bone marrow differentiate into blood cells, locatio nwhere B lymphocytes mature
Thymus
organ in the neck that is used to create and promote maturation of T lymphocytes (T cells)
Leukocytes
phagocytic white blood cells that swallow foreign particles
ex. macrophages
Hypersensitivity response
plants
cells that come in direct contact with pathogen undergo apoptosis and signal other nearby cells to improve defenses in cell wall
antimicrobial peptides
pathogen recognition triggers the production and release of a variety of peptides and proteins that attack pathogens or impede their production
Hemocytes
Immune cells that travel through the body in the hemolymph
Neutrophils
most abundant WBC circulate in blood, are attracted by infected tissue, and self destruct as they destroy invades
digest pathogens and cell debris
short life span
Dendritic cells
Antigen presenting cell. located mainly in lymphatic tissue and skin
presents antigens to Helper T cells initiating primary immune response
Eosinophils
WBC that destroys parasitic organisms and plays a role in allergic reactions
often beneath mucosal surfaces low phagocytic activity discharge destructive enzymes when they encounter parasites
