The Lymphatic and Immune Systems

phagocytes

(eg. macrophages, neutrophil) found in nearly every body organ, engulfs foreign material and digests it

surface membrane barriers

1. acidic pH of skin secretions and sebum inhibit bacteria 2. stomach mucosa secretes pathogen-killing hydrochloric acid and protein-digesting enzymes 3. saliva and lacrimal fluid contain lysozyme 4. sticky mucous traps microorganisms

stages of inflammatory response

1. injured cells release inflammatory chemicals (histamine, kinins) 2. histamine and kinins cause blood vessels to dilate and capillaries to become leaky as well as active pain receptors and attract phagocytes and WBCs to area 3. plasma leaks from blood, causing edema which also activates pain receptors (edema may prevent proper functioning of joint, aiding healing) 4. neutrophils enter via diapedesis and phagocytize debris. clotting proteins activated fom fibrin mesh, local heat increases meabolic rate of tissue cells, aiding healing 5. monocytes become macophages, replacing neutrophils and doing most of the rest of the work 6. Third line of defense activated?

functions of inflammatory response

1. prevents the spread of damaging agents to nearby tissues 2. disposes of cell debris and pathogens 3. sets stage for repair

memory cells

B cell clone members that do not become plasma cells become this, capable of responding to the same antigen at later meetings with it. responsible for immunogical memory and creating secondary humoral responses that are faster produced ,more prolonged and more effective. blood levels of antibodies now peak 2 to 3 days

helper T cells

T cells which manage the immune system, circulating through body and recruiting other cells to fight invaders. prod B cells attached to antibody to more rapid division and signaling for antibody formation to begin. also release cytokine chemicals that indirectly rid body of antigesn

primary humoral response

a B cell makes hundreds of clones of itself after encountering its antigen

complement proteins

a group of at least 20 plasma proteins that circulate in the blood in an inactive state. Then, fixate on foreign cells and form membrane attack complexes, amplifies inflammatory response, vasodilators, chemotaxis chemicals, opsonization

inflammatory response

a nonspecific response trigger whenever body tissues are injured (physical trauma, intense heat, irritating chemicals, infection

lymphocytes

a type of white blood cells located in lymph nodes that respond to foreign substances in lymphatic stream

fever

abnormally high blood temperature, a systemic response to invadng microorganisms. initiated by pyrogens, causes liver and spleen to gather up iron and zinc making it less available to bacteria and speeds up metabolic healing of cells

lysozyme

an enzyme that destroys bacteria, found in saliva and lacrimal fluid

monoclonal antibodies

antibodies used for research that are produced by descendants of a single cell, pure antibody preparations that exhibit specificity for only one antigen

IgA antibody

antibody in monomer forms in plasma and dimer forms in secretions such as saliva, tears, intestinal juice and milk. bathes and protects mucosal surfaces from attachment fo pathogens

antigen (Ag)

any substance capable of mobilizing our immune system and provoking an immune response

efferent lymph vessels

branch from hilum of lymph node, carry lymph from node

immunocompetent

capable of responding to a specific antigen by binding to it (only the one antigen). which antigen is determined genetically, not by previous exposure

macrophages

cells in lymph nodes which engulf and destroy bacteria, viruses and other foreign substances in lymph before it is returned to blood. found in lymph node medulla, mostly stationary. arise from monocytes in bone marrow. present fragments of antigens on surfaces where they can be recognized by t cells, secrete cytokines. become killer macrophages after activation from t cells

cytotoxic (killer) T cells

cells that specialize in killing virus-infected, cancer or foreign graft cells. may bind tightly to a foreign cell and release toxic perforins which enter the foreign cell's membrane. pores appear, allowing granzymes (protein-digesting enzymes) to enter and kill the cell. cytotoxic T cell then moves on

B lymphocytes (B cells)

cells which produce antibodies and oversee humoral immunity. become immunocompetent in bone marrow

pyrogens

chemicals secreted by white blood cells and macrophages exposed to foreign substances which cause fever

precipitation

clumped antigen molecules caused by cross-linking processes involving soluble antigenic molecules and antibodies that are so large they settle out of solution

agglutinization

clumping of foreign cells caused by cross-linking of antibodies with cell-bound antigens.allows easier phagocytosis

mucosa-associated lymphatic tissue (MALT)

collection of small lymphoid tissue (including tonsils and Peyer's patches) which acts as a sentinel to protect upper respiratory and digestive tracts from foreign matter

follicles

collections of lymphocytes found in lymph node cortex, containing dark-staining germinal centers

sinuses

compartments of a lymph node marked off by trabeculae

antibodies/immunoglobulins (Igs)

constitute gamma globulin part of blood proteins, secreted by B cells or plasma cells in response to an antigen and capable of binding specifically with that antigen. formed from four amino acid chances linked together bydisulfide bonds (two symmetric long and two symmetric short chains). capable of binding to multiple antigens at a time, forming lattices

thoracic duct

drains lymph from body excluding right arm and right side of head and thorax, empties into left subclavian

right lymphatic duct

drains lymph from right arm and right side of head and thorax, empties into right subclavian

antimicrobial proteins

enhance innate defenses either by attacking microorganisms directly o by hindering their ability to reproduce

germinal centers

enlarge when B cells are generating daughter plasma cells which release antibodies

lymph

excess tissue fluid returned to blood

edema

fluid accumulation in tissue

nonself

foreign intruders, proteins being the strongest

antigen

foreign substance

lymphatics (lymphatic vessels)

form a one-way system directing lymph flow towards heart

membrane attack complexes

formed by fixated complements, produces lesions and holes in membrane of foreign cells, causing water to rush into cell and bursting it

pathogens

harmful or disease-causing microorganisms

lymph nodes

help protect the body by removing foreign material such as bacteria and tumor cells from lymphatic stream, produce lymphocytes. large clusters found in inguinal, axillary and cervical regions of body. fibrous capsule houses trabeculae which divide node into compartments

immunity

highly specific resistance to disease. must be primed by initial exposure to a foreign substance before it can protect the body against it

inflammatory chemicals

histamine, kinins

humoral (antibody-mediated) immunity

immunity provided by antipodes present in the body's fluids

cellular (cell-mediated) immunity

immunity provided by lymphocytes, have cell targets

immunosuppressive therapy

includes corticosteroids to suppress inflammation, antiproliferative drugs, x-ray therapy, immunosuppressor drugs in order to prevent immune rejection of grafts

hilum

indented region of lymph node from which efferent lymphatic vessels branch

important aspects of adaptive defense

it is antigen specific, it is system (not restricted to initial infection site, it has "memory"

lymphatic collecting vessels

larger lymphatic vessels that lymph travels into from lymph capillaries

spleen

located in left side of abdomnial cavity just beneath diaphragm and next to stomach. destroys worn-out red blood cells and returns some of their breakdown products (such as iron) to liver. Also stores platelets, acts as blood reservoir and allows lymphocyte proliferation. Site of lymphocyte production in fetus and infant, contracts during hemorrhage

afferent lymph vessels

lymph flows in through these in covex side. more numerous than efferent lymphatic vessels

thymus gland

lymphoid mass found low in throat overlying the heart. produces thymosin which programs lymphocytes. fully active only in youth

IgD antibody

monomer antibody believed to be cell surface receptor of immunocompetent B cell

IgE antibody

monomer antibody secreted by plasma cells in skin, mucosae of gastrointestinal and respiratory tracts and tonsils. binds to mast cells and basophils, triggering release of histamine and other chemicals that mediate inflammation and certain allergic reponses

IgG antibody

monomer antibody which is the most abundant antibody in plasma. primary defensive antibody, crosses placenta, fixes complement

plasma cells

most B cells formed via the primary humor response will become this. after initial lag period, producing huge numbers of antibodies for 4-5 days. antibody level in blood peak 10 days after response begins then declines

T cells

non-antibody-producing"in-transit" lymphocytes found in lymph node cortex which circulate coninuously between blood, lymph nodes, and lymphatic stream as watchdogs. constitute cell-mediated arm of adaptive defense system. become immunocompetent in thymus. activated to form clones by binding with recognized *presented* antigen

self-tolerance

not binding with self-antigens

anaphylactic shock

occurs when an allergen directly enters the blood and circulates rapidly through the body (eg bee sting, spider bite, injection). smooth muscles of lung passages and bronchioles contract, sudden vasodilation and fluid loss may cause circulatory collapse and death within minutes. like a local allergic reaction, except body-wide

neutralization

occurs when antibodies bind to specific sites on bacterial exotoxins (toxic chemicals secreted by bacteria) or on viruses that can cause cell injury, blocking those harmful effects

IgM antibody

pentameter antibody found attached to b cell or free in plasma. when bound to cell membrane serves as antigen receptor. potent agglutinating agent in plasma, also fixes complement (secreted by plasma cells).

natural killer (NK) cells

police the body in blood and lymph. a unique group of lymphocytes that can lyse and kill cancer cells and virus-infected body cells well before adaptive arm enlisted. non-specific to antigen, recognize sugars on intruder's surface and release perforins to disintegrate them

innate (non-specific) defense system

portion of immune system that responds immediately to protect the body from all foreign substances. consists of intact skin and mucous membranes and some lymphocytes

adaptive (specific) defense system

portion of immune system which mounts attack against particular foreign substances

self-antigens

protein molecules studding our own cells that recognized as self, do not trigger an immune response in us, but do in other people

four indicators of inflammation

redness, edema, heat, pain

variable (V) region

region at end of each of the four antibody chains which combines with others to form unique antigen-binding site

constant (C) region

region at inward end ("stem" of key) of each of the four antibody chains which is nearly the same between all antibodies

regulatory T cells

release chemicals that suppress activity of both T and B cells, vital for winding down and stopping immune response after antigen as been destroyed

interferon

released by virus-infected cells, bind to membrane receptors of nearby healthy cells and stimulate synthesis of protein that interfere with ability of viruses to multiply within them

Peyer's patches

resemble tonsils, found in wall of small intestine. contains macrophages which prevent bacteria from entering intestinal wall

passive immunity

results from serum of antibodies from a human or animal donor is injected or in a fetus when a mother's antibodies cross placenta. B cells are not challenged and memory does not occur; only temporary immunity granted (eg antivenom, antitoxin)

tonsils

small masses of lymphoid tissue that ring the pharynx, found in mucosa. Trap and remove any bacteria or other foreign pathogens entering the throat

hapten (incomplete antigen)

small particle that triggers an immune response only when combining with one of our own proteins

lymph capillaries

small very permeable vessels that absorb lymph via minivalves regulated by pressure differences

diapedesis

the process by which cells, such as neutrophils, squeeze through capillary walls, such as during inflammation

chemotaxis

the process by which phagocytes and WBCs are attracted to an area containing histamine and kinins by following a chemical gradient

opsonization

the process of making cell membranes of foreign cells sticky so they can be more easily phagocytized

xenografts

tissue grafts harvested from a different animal species

allografts

tissue grafts taken from a person other than an identical twin

autografts

tissue grafts transplanted from one site to another in the same person

isografts

tissues grafts donated by a genetically identical person

lymphoid organs

tonsils, thymus, spleen, peyer's patches

active immunity

when your B cells encounter antigens and produce antibodies against them. natural acquired during bacterial and viral infections and artificially acquired when we receive vaccines

complement fixation

wherein complement proteins bind to certain sugars or proteins on a foreign cell's surface