Studied by 5 people
Pathogens definition
agents that cause disease, infect a wide range of animals, including humans
Which animals have innate immunity
All animals
Which animals have adaptive immunity
vertebrates
1st line of defense in body
skin, mucous membranes and their secretions
2nd line of defense in body (3)
antimicrobial substances, inflammation and fever, phagocytic white blood cells
3rd line of defense
Specialized lymphocytes (B cells and T cells)
which type of immunity is present before any exposure to pathogens and is effective from the time of birth?
Innate
What does innate immunity consist of? (2)
external barriers, internal cellular and chemical defenses
What immunity develops after exposure to agents such as microbes, toxins, or other foreign substances
Adaptive
In innate immunity what does recognition and response rely on?
Traits common to groups of pathogens
Is innate immunity present in vertebrates?
Yes
What do barrier defenses include? (what, of what tracts?)
Skin and mucous membranes of the respiratory, urinary and reproductive tracts
Examples of body fluids which are hostile to many microbes?
Saliva, mucous, tears
What feature of the pH of skin and the digestive system prevents growth of many bacteria?
It is low
TLRs definition
Toll-like receptors
What do cellular innate defences include? (4)
Phagocytic cells, (in verebrates) Natural Killer cells, Lymphatic system
How do phagocytic cells recognize groups of pathogens
By TLRs
4 types of Phagocytic cells
Neutrophils, Macrophages, Dendritic cells, Eosinophils
neutrophils description (where they are found, how they are activated, what they do)
Circulate in blood and are affected by signals from infected tissues, engulf and destroy pathogens
macrophages description (where they are found, alternative name)
Found throughout the body (especially lymphatic system and spleen), also called “big eaters”
Dendritic cells description (where they are found, what they do)
Found in the skin, stimulate the development of adaptive immunity
Eosinophils description (where they are found, what they do, who do they target)
Found beneath mucosal surfaces, discharge destructive enzymes against multicellular invaders (e.g. parasitic worms)
Natural Killer cells description (where they are found, what they do, who do they target?)
Circulate throughout the body and detect abnormal cells, release chemicals leading the cell death, inhibiting the spread of virally infected or cancerous cells
What does the lymphatic system consist of? What are their functions? (2)
Lymphatic vessels through which lymph (fluid in the lymphatic system) travels, structures (nodes and organs) that trap foreign substances
Lymphoid organs (6)
Spleen, thymus, appendix, Peyler’s patches, adenoid, tonsils
Examples of peptides and proteins of the innate immune system (2)
Interferon and proteins of the immune system
How do peptides and proteins function in the innate immune system? (2)
By attacking pathogens or impeding their reproduction
Interferon- what is it, what types of organisms is it found in, function?
protein unique to vertebrates, induces nearby uninfected cells to produce substances that inhibit viral reproduction
What is interferon produced by?
Virus-infected body cells
How many proteins make up the complement system?
About 30
Where can you find proteins of the complement system and in what state?
They circulate in the blood plasma in an inactive state
Who are the proteins of the complement system activated by and what do they do?
Activated by microbes, causes lysis of invading cells and helps trigger inflammation
What is a mast cell?
A type of cell of the connective tissue which releases histamine
What does histamine do?
triggers blood vessels to dilate and become more permeable
Local inflammatory response- what is it brought about by, what does it include (5 signs)? (general)
brought about by molecules released upon injury of infection, includes redness, swelling, heat, pain and loss of function
Cytokines in the inflammatory response- what are they released by, what are its effects, what do the effects cause?
Released by activated macrophages and neutrophils, it signals molecules that promote blood flow to the site of injury, causing redness and increase of skin temperature
Examples of what can trigger acute inflammation (2)
cell or tissue damage, presence of dead cells or noxious agents such as bacteria
What is the first phase of wound healing?
Acute inflammation
What does the acute immune response aim to do?
remove the injury causing agent and limiting the extent of tissue damage
Acute inflammatory response step 1 (2 things)
Mast cells release histamines, macrophages release cytokines that cause capillaries to dilate
Acute inflammatory response step 2 (2 things)
Capillaries are now more permeable and allow fluid containing antimicrobial peptides to enter the tissue, neutrophils are attracted.
Acute inflammatory response step 3 (1)
Neutrophils digest pathogens and cell debris
Pus definition
A fluid rich in white blood cells, dead pathogens, and cell debris from damaged tissues
Septic shock definition
A life-threatening condition caused by an overwhelming inflammatory response
Fever- what is it, what is it triggered by
Systemic inflammatory response triggered by pyrogens (e.g. interleukin 1)
What releases pyrogens
Macrophages and toxins from pathogens
Fever phase 1
Pathogen or toxin- most common cause is infection from bacteria/viruses, macrophage ingesting that will start the process
Fever phase 2 (4 ish sub-steps)
Macrophages respond- by ingesting, they destroy the pathogen, releasing endotoxins, which induce the production and release of interleukin-1 into the bloodstream
Fever phase 3- interleukin 1
Interleukin-1 travels to the brain, induces the hypothalamus to produce more prostaglandins which resets the bodys “thermostat” to a higher temperature, producing fever
Hypothalamus function
Controls the bodys temperature settings
Prostaglandins function
Resetting the bodys thermostat to a higher temperature, producing fever
Fever phase 4 (+ 3 results) (after interleukin 1 in brain)
Fever onset- body raises temperature resulting in: blood vessel constriction, increased metabolic rate, shivering
Fever phase 5 (after fever onset)
Chill phase- skin remains cold, shivering occurs, this stops once the body reaches the setting of the thermostat
Fever phase 6 (final phase)
Crisis phase- increased body temperature remains until the interleukin-1 is eliminated, heat reducing methods (sweating, vasolidation (widening of blood vessels)) cause the person to feel warm, it indicates the bodys temperature falling`
Examples of how some pathogens avoid destruction
Modifying their surface to prevent recognition, resisting breakdown following phagocytosis
Two types of aquired immunity
Naturally aquired, artificially aquired
Two types of naturally aquired immunity (+ brief explanations)
Active (getting the disease, even when no symptoms), passive (from mother to fetus through placenta or milk)
Two types of artificially aquired immunity (+ brief explanations)
Active (vaccines), passive (immune serum, eg antivenom, no antibodies produced)
Lymphocytes that mature in the thymus
T-cells
Lymphocytes that mature in the bone marrow
B-cells
Two types of lymphocytes
B-cells and T-cells
Antigen definition (in relation to B cells and T cells)
A substance that can elicit a response from a B or T cell
Epitope definition
The small, accessible part of an antigen that binds to an antigen receptor
A feature unique to the adaptive immune system with lymphocytes
Each individual lymphocyte is specialized to recognize a specific type of molecule
How can B or T cells bind to foreign molecules?
With receptor proteins
B cell antigen receptor structure
A Y-shaped molecule with two identical heavy chains and two identical light chains, connected by disulphide bridges, heavy chains go through plasma membrane into cytoplasm- has a transmembrane region
What varies in B-cell antigen structure?
The variable regions, at the tips of the light and heavy chains
What do the variable regions in B-cells provide
Antigen specificity
What is the difference between antibodies and B cell receptors?
Antibodies lack transmembrane regions that anchor receptors in the plasma membrane
What does the binding of a B cell antigen receptor to an antigen give rise to?
Cells that secrete a soluble form of the protein called an antibody or immunoglobin (Ig)
T-cell receptor structure
Two different polypeptide chains (alpha and beta)
What do T-cells bind to?
Antigen fragments presented on a host cell
MHC definition
Major histocompatibility complex, are host proteins that display the antigen fragments on the cell surface
Antigen presentation description
In infected cells, MHC molecules bind and transport antigen fragments to the cell surface
What can a T cell bind to?
Both the antigen fragment that is displayed and the MHC molecule
What interaction is necessary for the T cell to participate in the adaptive immune response?
T cell binding to the antigen fragment displayed and the MHC molecule
How are lymphocytes activated once an antigen is found?
In the lymph nodes, the antigen is exposed to a steady stream of lymphocytes until a match is made, the binding initates the activation
Clonal selection definition
Proliferation of lymphocytes, the cell divisions that B and T cells undergo
Two types of clones produced during clonal selection & brief descriptions?
Effector cells (short lived, act immediately against an antigen) and memory cells (long lived, can give rise to effector cells if the same antigen is encountered again)
Effector cells in B cells name
Plasma cells
What is immunological memory responsible for?
Long-term protection against diseases due to either a prior infection or vaccination
What is the first exposure to a specific antigen called? + Brief description
Primary immune response, selected B and T cells give rise to their effector forms
What is special about the secondary immune response?
Memory cells facilitate a faster, more efficient response
ELISA test description
A type of analytic biochemistry assay that uses a solid phase enzyme to detect the presence of an antigen, in a wet sample
ELISA example procedure steps (3)
Virus sample on surface, antibody with enzyme conjugate attached to viral antigen, substrate and enzyme interaction create color change for detection
Two branches of aquired immunity
Humoral and cell-mediated
Humoral immune response simple explanation
Antibodies help neutralize or eliminate toxins and pathogens in the blood and lymph
Cell-mediated immune response simple explanation
Specialized T cells destroy affected host cells
Look at and explain this graph and then type done
Done
Cell-mediated immune response part description of diagram (from 1st exposure to antigen) (maybe draw on paper if available to make it easier?)
Antigen 1st exposure - engulfed by antigen presenting cell - stimulates BOTH cytotoxic T cell and helper T cell - Cytotoxic T-cell gives rise to - BOTH memory T cells and active cytotoxic T cells - Helper T cells give rise to memory helper T cells which stimulate - memory cytotoxic T cells
Antigen 2nd exposure - stimulates memory helper T cells AND memory cytotoxic T cells
Humoral (antibody-mediated) immune response part description of diagram (maybe draw on paper if available to make it easier?)
Antigen 1st exposure - that AND Helper T cell - stimulates B cell which gives rise to - Plasma cells and Memory B cells - Plasma cells secrete antibodies - Memory B cells also give rise to Plasma cells
Antigen 2nd exposure - stimulates memory B cells together with Memory helper T cells
Helper T cells function
Signals from them: initiate production of antibodies that neutralize pathogens AND activate T cells that kill infected cells
What types of cells have class I and II MHC molecules on their surface
Antigen-presenting cells
What molecules are the basis upon which antigen-presenting cells are recognized?
Class II MHC molecules
What happens when a helper T cell binds to an antigen and the class II MHC molecule? (three main ideas)
Signals are exchanged then the helper T cell is activated, proliferates, forms a clone of helper T cells which then activate the appropriate B cells
Effector cell in cell mediated immune response name
Cytotoxic T cell
Cytotoxic T cell function
Recognizes fragments of foreign proteins on infected cells, possess an accessory protein that binds to class I MHC molecules, then activated cytotoxic T cell secretes proteins that disrupt cell membranes of target cells and trigger apoptosis
Apoptosis definition
Programmed cell death
What is the humoral immune response characterized by?
The secretion of antibodies by B cells
Activation of B cells description
In response to cytokines from BOTH helper T cells and an antigen, a B cell proliferates and differentiates into memory B cells and antibody-secreting effector cells (plasma cells)
Note 
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