immunity

the resistance to or protection against disease-causing pathogens

immunization

the conferring of immunity to a particular disease

vaccination

-the introduction of a weakened or altered pathogen to prime the body's immune system, so it fights later infections effectively

innate immunity

cells that are always ready 

-cells involved are nonspecific in response to antigens

-respond in same way to all antigens

adaptive immunity

-cells that are selectively activated to eliminate a specific pathogen

-cells respond in an extremely specific way to each antigen

antigen

-any foreign molecule that can initiate an immune system response

-most are proteins or glycoporteins from bacteria/viruses/other invaders

-can be carbohydrates nucleic acids and lipids

Characteristics the allow SKIN to act as a barrier

-tough physical barrier

-chemical deterrent

-oil secreted by skin cells=coverted to fatty acids by bacterial cells that live on surface

-->fatty acids LOWER pH of skin-creat dry acidic enviro and prevents growth of most bacter

cuticle

-tough layer

(exoskeletal type)

usually accompained w/a layer of wax

How are Eyes protected

-blinking wipes tears across eyes

-->contain lysozyme (antibacterial enzyme)

Lysozyme

-antibacterial enzyme

-acts as antibiotic by digesting bacterial cell walls

How are Ears protected?

-hair/earwax trap pathogens in the passageway of external ear

How is the nose protected?

-nasal passages are lined w/muscus secretions and hairs that rap pathogens

How is the digestive tract protected?

-pathogens are trapped in saliva and mucus then swallowed

-->destroyed by acidic pH in stomach

mucus

-solution secreted by cells w/in the epithelium

-rich in proteoglycans

proteoclycans

-molecules that consist of large polysaccharides bonded to proteins

innate immune response

-body's nonspecific response to pathogens

leukocytes

WBC

-macrophages

-neurophils

-mast cells

innate/adaptive immunity

Mast Cells

-secrete signals that constrict blood vessels to dec blood flow and therefore less blood loss

-release histamine

Neutrophils

 -move out of dilated blood vesssels and migrate to site of infection

-ingest (via phagocytosis) and kill pathogens

-kill invading cells w/a complex array of toxic compounts

Macrophages

-recruit other cells and ingest to inject and kill pathogens

-secret singaling proteines chemokines

(cytokines-cells that will mature into macrophages)

pattern recognition receptors

-proteins that when activated by molecules from pathogens, the cell responds

inflamatory response

-multi-step innate immune response 

inflamatory response 

step 1

-break in skin allows bacteria to enter body

-blood leaves if capillaries/other small blood vessels are broken

inflamatory response 

step 2

platelets release proteins to form clots and lessen bleeding

-other clotting proteins in blood form cross-linked structure that help wall wound and reduce blood loss

platelets

-release proteins to form clots and lessen bleeding

inflamatory response 

step 3

wounded tissue and leukocytes (particularly macrophages) secrete signaling protens-chemokines-from gradent that marks a path to wounded site

chemokines

-produced by injured tissue and macrophages in the tissue

-recieved by neutrophils and macrophages

-"signaling" protein

-creates a gradient that marks a path to the wound site

-also INC permeability of blood vessels

inflamatory response 

step 4

-mast cells release chem messengers that constrict blood vessels near wound (DEC blood loss by reducing blood flow)

-mast cells release histamine and other singaling molecules that induce blood vesses slightly farther from the wound to dilate and become more permable

histamine

 produced by mast cells

recieved by blood vessels

High [ ] next to wound-constricts blood vessels

Low [ ] farther from wound dilates (more permeable)

inflamatory response 

step 5

-dilate blood vessels and chemokine gradient provides specific directions

-neutrophils move out of dilated blook vessels and migrate to site of infection

inflamatory response 

step 6

-cells that will mature into macrophages arrive

->phagocytize bacteria @ wound and secrete cytokines

cytokines

-produced by macrophages

-recieved by lekocytes (mark path to wound)

-bone marrow (INC production of macrophages and neutrophils)

-CNC-induce fever by INC set point for control of body temp

-Local tisue-stimulate cells involved in wound repair

toxic cells secreted by mast cells

lysozyme

free radical

nitric oxide

reactive oxygen intermediate (ROIs)

why does site of inflamation become swollen

-due to INC # of cells/fuids in the area

red and warm due to INC blood flow

innate immunity in invertebrates

-cells respond by sythesizing and secreting peptides w/potent antibacterial antifungal properties

adaptive immune response

-aquired immune response

-based on interactions btwn specific immune system cells and a specific antigen

antibodies

-proteins produced/secreted by certain lymphocytes

-bind to specific part of specific antigen

-immune system can produce almost limitless array 

4 characteristics of antibodies

 1-specify-bind to specific sites on specific antigens in ADAPTIVE immune system

lymphocytes

-cells that carry out the major features of the adaptive immune response

lymphocyte origin

-produced in bond marrow (tissue that fills internal cavities in bone)

-can also be produced in spleen

lymphocyte maturation

Bcells mature in bone marrow

T cells matrue in thymus

lymphocyte activation

-recognize antigens and become activated in spleen/lymph nodes

Secondary Organs of immune system

-lymph nodes (filter lymph)

-spleen (destroys old Blood cell)

-lymphatic dutcs-transport lymph

lymph = fluid and lymphocytes

Mucosal-associate lymphoid tissue

(MALT)

-immune system cells found in gut & respiratory organs

-MALT + leukocytes in skin-->guard

inactive lymphocytes

-large nucleus, little cytoplasm, few mitochondria, ruffled membrain

-if does not encounter antigen will eventually undergo aptosois

activated B cells

-massive amnts of rough ER and large # mitochondria

B Cells

(bursa)

-produce antibodies

-mature in bone marrow

T Cells

(thymus)

-involved in array of functions

-->recognizing

-->killing infected host cells

Clonal Selection Theory

1-antigens are recognized by receptors on B/T cells

2-Lymphocytes activated by antigen-receptor binding

3-Activate lymphocytes are cloned (/and make identical copies)

4-activated lymphocytes endure

B cell Receptor

-protein has same structure as antibodies in blood produced by C cells

(1)light chain-protein

(2)heavy chain

(3)transmembrane domain

-BCR and bcell antibodies (both produced by B cells) identical except for transmembrane domains

immunoglobulins

-family of proteins

-critically important to adaptive immune system

-each class is distinguished by a unique a.a. sequence in the heave chain region and each has distinct function

IgG

-monomer

-most abundant type of secreted antibody

-circulated blood and interstitial fluid

-protects against bacteria/viruses/toxins

IgD

-monomer

-present on membranes of immature B cells

-rarely secreted

-serves as BCR

IgE

-monomer

-secreted in minute amnts

-involved in response to parasitic worms

-responsible for hypersensitive rxn that causes allergies

IgA

-dimer

-most common antibody in breast milk, tears, saliva and mucus lining of respiratory/digestive tracts

-prevents bacteria and viruses from attaching to mucos membranes

-helps immunize breastfed newborns

IgM

-pentamer

-1st type of secreted anibody to appear during an infection

-binds many antigens @ once

-effective @ clumping viruses and bacteria so that it can be killed

T Cell Receptors

-bind only to antigens that have been modified by other cells and presented/displayed on the plasma membranes of this cells

antigen presentation has to occur for TCR to bind to antigen

-composed of alpha and beta chains

epitopes

-selected region of antigen in which antibodies/BCR/TCR attach

-each is recognized by a particular antibody

-antigens normally have mlultiple

Variable Regions

V regions of BCR/TCR are adjacent and face away from plasma membrane

-unique a.a. sequences therefore bind to diff epitopes

light chain-40 possible V segments

heavy chain-51 pssible V segment

joining segments

-light chain has 5 possible segments

-heavy chain has 6 possible segments

diversity segments

-found only in heavy chain DNA

27 possible segments

self molecules

-molecules that belong to the host

autoimmunity

-autoimmune rxn that lead to immne system cells destroying part os host's own body

if receptors respond to self molecule nd trigger immune response

anticell receptors

-cause the destruction of maturing B/T cells

T Cell Activation

-begins when antigens are taken up by a specific type of leukocyte or infected cell

-cut into pieces

-packed w/specific cell proteins

-transfered to cell surface

Types of T cells

CD4+ and CD8+

depends on presence of CD4 or CD8 proteins

dendritic cells

 -leukocytes

-ingest antigens present

-antigen enters membrane bound compartment (either ER or endosome)

-enzymes break antigen into pieces that bind to MHC prteins

-MHC proteins present antigen on surface of cell membrane 

MHC protein

-antigen presenting proteins taht have a groove where small peptide fragments bind

-transport cell to surface

-MHC protein peptide complex is displayed on cell surface

2 types of MHC proteins

-class I bind to antigens inside ER

-class II bidn to antigens inside endosomes

-distinct proteins on each

-polymorphic - many diff alleles exist in population

which T cells interact with MHC proteins

-CD8+ interacts with MHC class 1

-CD4+ interacts with MHC class 2

how are cytotoxic T cells and helper T cells created

-after CD8+ and CD4+ undergo clonal expansion

daughter cells give rise to these types of cells

effector T cells

helper T cells and cytotoxic cells

Helper T cells

-CD4+ differentiate into these types of cells

-assist w/activation of other lymphocytes

Th1-help activate cytotoxic T cells

Th2-help activate B cells

-interact w/antigens presented on class II MHC protein molecules (found only on surfaces of dendritic cells/B cells/other leukocytes that presnet antigens)

Cytotoxic T cells

-activated by CD8+ cells

-killer T cells

-interact w/cells that display antigens presented on class I MHC proteins

B Cell Activation steps

1-B cells recognize invader; binds to foreign protein in lymph node or spleen; protein internalized, processed and presented on surface by an MHC class II 

2-B cell activates Helper T cell; MHC peptide complex interacts w/complementary receptors on a helper T cell, activating it

3-B cell is activated by helper T cell cytokines from the activated helper T cell activate B cell

4-B cell /s; some daughter ells differentiate into plasma cells-produce large quantities of antibodies

plasma cells

-produce and secrete large quantities of antibodies

What happends if activated Th1 cell binds to antigen-laden macrophages

(1) phagocytic activity of macrophages is enhanced

(2) Th1 cells secrete cytokines that recruit additional phagocytic cells to site

(INC inflammatory response)

Agglutination

-clumping of cells

-antibodies from plasma cells begin coating bacteria fungi/etc

-each antibody has at least 2 binding (can bind epitopes on foreign cells and link them-form clumps)

complement sytem

-group of lethal proteins

-complement proteins circulate in blood steam and assemble @antigen-antibodie complexes

-when activated punch deadly holes in plasma mems of invading cells

2 ways in which viruses are destroyed

1-cell-mediated response

2-humoral response

cell mediated response

-involve cytotoxic T cells (activated CD8+ cells)

-takes place on suface of infected cells

-cells express MHC I class protein-hav ability to signal they are infected

-activated CD8+ cells migrate it area, recognize and bind to antigens epitopes and MHC protien displaced on infected cell

-->CD8+ then secretes molecules that assemble on surface of infected cells 

-->release chem and activate self destruct response

Humoral Response

-involves antibodies and takes place in blood and lymph

-antibodies coate free virus particles

-viruses cannot bind to host cell plasma membrane

-antibody coated virus is recgonized, phagocytized, and destroyed by neutrophil or macrophage

A/B molecules

-RBC have membrane glycoporteins -A and B

-->act as antigens if introduced into person who lack A/B glycoproteins

type a-you have antigen A

-antigenic molecuels in foreign organs are the MHC proteins found on the surface of their cells

memory cells

-activated B and T cell's daughter cells

-do not participate in initial adaptive response (primary immue response)

-->provide surveillance service after original infection cleared

-remain in spleen/lymph nodes

secondary immune response

-memory cells recognize if same antigen enters bodie 2nd time

-recognize antigens epitopes

immunological memory

-launching seconday immune response by means of memory cells

germinal center

-sepcialized area in lymph nodes

-DNA sequences that code for the variable region of immunoglobuline gene undergo rapid mutations that modify the receptors produced by memory cells

somatic hypermutation

mutations that occur in immunoglobulin genes of immune system's memory cells (variati in the receptors tha bind to antigens)

-->antibodies bind to antigen more tightly than antibodies produced by plasma cells during primary immune response

-->as 2ndary immune response porceeds, this continues (better fitting antibodies produced)