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consists of a network of vessels that penetrates nearly every tissue of the body, and a collection of tissues and organs that produce immune cells

lymphatic system functions

fluid recovery, immunity, lipid absorption

fluid recovey

reaxcess fluid absorbs and returns it to the blood. inteference can lead to adema


pick upsthe foreign cells with lymph nodes, where immune cells stand guard gainst foreign matter. then activate immune response if they encounter any foreigners

lipid absorption

lacteals( lymphatic vessels) absorbs dietary lipid which are not absorb by the blood capillaries

lymphatic system components

lymphatic vessels, lymphatic tissue( Lymphocytes and macrophages), lymphatic organs


clear, colerless fluid, similar to blood plasma. low in protein

in the lymphatic system

lymph leaving the lymph nodes contains a large number of lymphocytes. it is the main supply of lymphocytes in blood stream (lymph nodes).

lymphatic vessels

where lymph flows. penerate every tissue but are absent in nervous tissue, cartilage, cornea, bone, and bone marrow.

unlike the cells of blood capillaries

lymphatic endothelial cells are not joined by tight junctions and do not have a continuous basal lamina.

when pressure is higher in the lymphatic capillarie than in the tissue fluid

the flaps are pressed outward ( they are closed)

when tissue fluid is high in lympatic capillaries

the flaps are pushed inward ( the open)

route from tissue fluid back to the blood stream:

lymphatic capillaries- collecting vessels- six lymphatic trunks- two collecting ducts-subclavian veins.

lymphatic capillaries

converge to form collecting vessels.

lymph nodes

converge to form lymphatic trunks

lymphatic trunks

grains to major portion the body. their names indicate where the deposit to.

lymphatic trunks

converge to form 2 collecting ducts: lymphatic duct and thoracid duct.

cisterna chyli

section in thoracic duct. where the 2 lumbar meets. have a large amount of chyle(fatty interstial lymph) which it collects after a meal.

lymph flow

have a lower pressure and speed than venous flow. can be produced by skeletal muscles squezzzing lymph nodes

primary mechanism of lymph flow

rhythmic contractions of the lymphatic vessels themselves

Lymphatic cells

Natural killer cells(NK), T Lymphocytes (T cells), B Lymphocytes (B cells), Macrdophages, Dentric cells and Reticular cells.

natural killer cells

large lymphocytes that attack and destroy bacteriatransplanted tissues and host cells that have either become infected with viruses or turned cancerous

T lymphocytes

lymphocys that matures in the thymus and later depend on thymic hormones; T stands for thymus- dependent.

B lymphocytes

lyphocytes that differentiates into plasma cells. they mature in the bone marrow

plasma cells

connective tissue cells that secrete antibodies


very large. they develop from monocytes that have migrated from the blood stream. they phagocytize tissue debris, dead neutrophils and other foreign matter. process foreign matter and display antigenic fragments of it to specific Tcells. This alerts the immune system of the presence of an enemy

dendritic cells

branched, mobile APCs, locaded in the epidermis, mucous menbrane, and lymphatic organs. called langerhans cells in skin.the engulf matter by by receptor meiated phagocytosis. migrate to nearby lymph node after initializing an antigen and activates immune reactions.

reticular cells

braned. statiaonary APC that contributes to the connective tissue framework of lymphatic organs

lymphatic tissues

are aggregations of the lymphocytes in the connective tissues of mucous menbrane and various organs.

diffuse lymphatic tissue

type of lymphatic tissue in which lymphocytes are scatered rather than densely clustered

mucosa-associated lymphatic tissue

types of lymphatic tissue where there is mucous menbrane. EX respiratory, digestive, urinary, and reproductive track

lymphatic nodules

lymphocytes and macrophages. they come and go as pathogens invaded the tissues and the immune system answers the challenge.

lymphatic organs

limphoids. red marrow, thymus, lymph nodes, tonsils and spleen.

primary lymphatic organs

red bone marrow and thymus. the cite of the B an T lymphocytes.

B and T Lymphocytes

will become immunocompetent and are able to recognize and respond to antigens

secondary lymphatic organs

lymph nodes, tonsils, and spleen immunocompent lymphocytes will migrate to these organs after they mature in the primary organs

bone marrow

2 types red and yellow. yellow is fat. red bone marro where hemopoiesis and immunity occurs.


menber of endocrne, lymphatic and immune systems . secrete homones. it's lobules has a central medulla housed by T cells and the cortex is housed by reticular epithelial cells

reticular cells

form blood-thymus barrier, produces signaling molecules that promote the development and action of T cells, including thymosins, thymopoetin, thymulin, interleukins, and interferon.

lymph nodes

serve 2 funtions: cleanse the lymph and act as a site of T and B cell activation. common site of metastatic cancer

germinal centers

acquired when lymph node is fighting pathogen. and the cite where B cells mmultiply and differentiate in to plasma cells.


body's largest lymphatic organ

red pulp in spleen

consist of sinus gorged with erythrocytes

white pulp spleen

have lymphocytes and macrophages


viruses, bacteria, fungi and other microbes tha can cause diseases

number of body line defenses


first line of defense

exterbal barriers: skin and mucous menbrane

second line of defense

leukocytes and macrophages antibacterial proteins, immune surveillance, anflammation and fever. against pathogen that cross first line of dense

third line of defense

immune sytem which defeats pathogens and leaves a memory

acid mantle in sweat

thin film of lactic acid that inhibits bacterial growth


a sweat antibacterial protein

defensins and cathelicidins

peptides produced by keratinocytes, neutriphils, and macrophages that destroy bacteria virus and fungi. enhance by vitamin D


enzyme that destroy bacteria by destroying their celll walls

the five types of leukocytes

neutrophils, Eosinophils basophils, lymphocytes and Monocytes


wanders in connective tissues to kill bacteria.kill by sime phagocytosis and digestion. has a respiratory burst that forms two defenses: hydrogen peroxide and hypochlorite; these chemicals form a killing zone arround the neutrophil. can damage host connective tissue and sometimes contributes to rheutmatoid arthritis


found in the mucous menbrane. standing against parasites, allergens and other foes. secrete enzymes that degrade and limit the action of histamine inflammatory chemicals that can cause damage.


secrete chemicals that aid the motility of other leukocytes

mast cells

types of connective tissue cell similar to basophils


NK cell, T-cell, B-cells


leukocytes that emigrate from blood into connective tissues and transforms into macrophages

macrophage system

all of the body's phagocytotic cells except leukocytes


proteins from an infected cell that alert other cells and protect non infected cells from becoming infected. also activates NK cells and macrophages to desroy infected cells to they don't replicate viruses and cancer cells.

complement system

a goupr of 30 or more globulins that make powerful contribution to both nonspecific resistance and specific immunity. complete actions of antibody. produced by the liver

activated complement contributes to pathogens destructions by four methods:

inflammation, immune clearance, phagocytosis, and cytolysis

pathways of activation to complement system:

classical , alternative , lectin

classical pathway

require antibody- antigens complexes form on pathogen suface;then it set off reaction cascade( complement fixation)

alternatve pathway

requires no antivbody.belong to nonspecific defenses. C3 dissociates into fragments C3a and C3b then C3b binds to pathogen surface. Next, reaction cascade and autocatalytic effect.

Lectin Pathway

antibody independent. belong to nonspecific defenses. binds to carbohydrates on pathogen surface and causes reaction cascade

inflammation method

C3a stimulates mast cells and basophils to secrete histamine and other inflammatory chemicals. also activates neutrophils and macrophages

clearance method

C3b binds Ag---Ab complexes to RBCs. as the RBCs circulate through the liver and pleen, the macrophages of these organs destroys the Ag---Ab complexes. principal means of clearing foreign antigens from the blood stream

phagocytosis method

cell eating. pathogens are digested by neutrophils and macrophages.

Cytolysis method

cell drinking.all the Cs are bind up to 17 molecules to form a menbrane attack complex. then complex forms a hole in target cell. water and electrolytes leaks out and cell ruptures

immune suveillance

phenomenom in which NK cells continually patrols the body for pathogens and disease host cells.


NK's group of protein-degrading enzymes


Nk's kiss of death. that make a hole in target cell wich allows a rapid inflow of water and salts




antipyreptic medicine

advantages of a fever

promotes inteferon activiies, elevate metabolic rate, accelerates tissue repair and inhibits reproduction of bacteria

exogens pyrogens

fever- producing agents. like the surfaces glycolipids of bacteria and viruses.

endogenous pyrogens

produced by neutrophils and macrophages to attack fever producing agents


small proteins that serves as a chemical communication network among immune cells


increalood increasing blood flow beyond normal


cell-adhesion molecules


stimulates pain receptors.


dead cells other tissues debris that form a pool of yellowish fluid.

monocytes and tissue repair relation

monocytes are major agents of tissue clean up and repair


cavity where pus is acumulates

2 types of immunity non specific resistance:

Specifity and Memory


immunity is directed against a particular pathogen


when reexposed to same pathogen, the body reaccts so quickly that there is no noticeable illness.

types of cell immunity

cellular(cell-mediated) immunity, humoral (antibody-mediated) immunity: Natural active immunity, artificial active immunity, natural passive immunity, artificial passive immunity.

Natural active immunity

production of host antibodies or T cells as a result of natural exposure to antigen

artificial active immunity

production of host antibodies or T cells as a result of vaccination

natural passive immunity

temporary immunity that results from acquiring antibodies produced by another person. EX: mother to fetus

artificial passive immunity

a temporary immunity that results from injection of an immune serum obtained another person or animal


amy molecule that triggers an immune response.


antigenic determinants. that stimulate immune responses


stimulate immune response by binding to a host macromolecule and the body recognizes as foreigners.

negative selection

a process where T-cell eliminated

forms of negative selections

clonal deletions and anergy

clonal deletion

self reactive T-cells die and macrophages eat them


T-cell remain alive but unresponsive

positive selection

T-cells move onto the medulla of thymus and multiply and form clones of identical T cell programmed to respong to a particular antigen

MHC proteins

proteins on the APC surface

cellular immunity 4 classes

cytotoxic T-cells(Tc), Helper T cells, regulatory T-cells, or T-reds, Memory T cells

Cytotoxic T cells

are effectors of cellular immunity that carry out the attack on foreign cells

Helper T cells

helps with the action of Tc cells

Regulatory T Cells

limit the immune system response by inhibiting multiplication and cytokine secretion by other T cells. pevent auto immune disease

Memory T cells

descended from Tc cells and are responsiblee for memory in cellular immunity

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