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Lymphatic system immune system and respiratory system
updated 10 years ago by ines
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Lymphatic system conists of 3 parts what are they

lymphatic vessels, lymph, & lymph nodes


What is the function of the lymphatic system

returns interstitial fluid and leaked plasma proteins back to the blood - together with the lymphoid organs and tissues provides the structural basis of the immune sytem


what is interstitial fluid called once it enters the the lymphatics



describe lymphatic vessels

a one way system lymph flows towards the heart


Lymph vessels - lymphatics include what

lmphatic capillaries
Lymphatic colecting vessels
Lymphatic trunks and ducts


lymphatic capillaries are similar to blood capillaries except for what

they are very permiable
Ehdothelials overlap to form one way mini valves and are anchored by collagen filaments preventing the colapse of the capillaries


where are lymphatic capillaries NOT found

Bone marrow
And the central nervous system


What are lacteals

specialized lymph capilaries present in intestinal mucosa they absorb digested fat and deliver fatty lymph (chyle) to the blood


Collecting vessels are similar to veins except for what

they have thinner walls with more internal valves and they anastomose more frequently


Collecting vessels in the skin travel with what

superficial veins


Deep vessels travel with what



How are collecting trunks formed

by the union of the largest collecting vessels


What are the two large ducts that lymph is delivered to

the right lymphatatic duct and the thoracic duct


The right lymphatic duct drains what part of the body

right upper arm
Right side of the head
And the throrax


the thoracic duct drains what part of the body

the remainder of the body -- anything the right lymphatic duct doesnt drain


Which duct arises from the cisterna chyli

the thoracic duct


Where do the lymphatic duct and the thoracic duct empty the lymph

each empties into venous circulaton at the junction of the intenal jugular vein and the subclavian vein on its own side of the body


How is lymph propelled

Pulsations of nearby arteries
Contractions of smooth muscle in the walls of the lymphatics
Milking action of the skeletal muscles
Pressure changes in the thorax
Presence of one way valves


what are lymphocytes considered

the main warriors in the immune system


What are the two main varieties of lymphoid cells

t cells and b cells


What is the main function of t cells and b cells

to protect against antigens


What are antigens

Anything the body percieves as forgein
Such as bacteria and their toxins, viruses
Mismatched red bllod cells or cancer cells


what is the function of tcells

to manage the immune system
Attack and destroy forgein cells


What is the function of b cells

produce plasma cells which secrete antibodies


What is the function of macrophages

to phagocytize forgein substances and help activate t cells


What is the function of dendritic cells

to capture antigens and deliver them to the lymph nodes


WWhat is the function of reticular cells

to produce stoma (that supports other cells in lymphoid organs)


What are the two funtions of lymphoid tissue

houses and provides a proliferation site for lymphoctyes
Furnishes a surveillance vantage point


What are the main types of lymphatic tissue

diffuse lymphatic tissue and lymphatic follicles


Where is the diffuse lymphatic tissue found

comprises scattered recitular tissue elements in every body organ but larger collections are also found in the lamina propria of mucus membranes and lymphoid organs


Describe lymphatic follicles

nodules they are solid spherical bodies of tightly packed reticular elements and cells the germinal center is composed of dendritic and b cells and they may form part of a larger organ


What are lymph nodes and where are they located

they are the principle lymphoid organs of the bodyand are located embedded in connective tissue in clusters along lymphatic vessels, near the body surface in inguinal, axillary and cervical regions of the body


What is the function of the lymph nodes

to filter lymph (macrophages destroymicroorganisms and debris) and in the immune system lymphocytes are activated and mount an attack against antigens


Describe the structure of a lymph node

bean shaped external fibrous capsule
Trabeculae extend inward and divide the node into ckmpartments
Two histologicaly distinct regions the cortex and the medulla


Describe the cortex

Contains follicles with germinal centers hea y with dividing B cells, dendritic cells nearly encapsulate the follicles,the deep cortex houses tcells in transit, tcells circukate continouosly among the blood, lymph nodes, and lymphatic stream


Describe the medulla

medullary cords extend knward from the ortex and contain Bcells Tcells and plasma cells and the lymph sinusesc ontain macrophages


desribe the process of circulation in the lymph nodes

Lymph enters via te afferent lymphatic vessels, travels through large subcapsular sinus and smaller sinuses then exits at the hillus via efferent vessels


Why are there fewer efferent vessels than afferant vessels

this cause the lymph to stagnate allowing lymphocytes and macrophages to carry out their functions


describe the spleen

largest of the lymphoid organs, served by the splenic artery and the vein which enter and exit at the hilus


what is the primary function of the spleen

it cleanses the blood of aged cells and platelets and debris
Has a fibrous capsule and trabeculae
Contains lymphocytes, macrophages, and huge numbers of erythrocytes


What are other functions of the spleen

site of lymphocyte proliferationand immune surveillanceand response
Storesbreakdown products of red blood cells (iron) for later use
Stores blood platelets
Site of fetal erythrocyte production (normally ceases after birth)


what are the two distinct regions of the spleen and describe each

white pulp - arou d the central arteries contains mostly lymphocytes on reticular fibers and involved in immune functions
Red pulp found in ghe venous sinuses and splenic cord ch in macrophages for disposal of worn out red blood cellsand bloodborne pathogens


describe the thymus

found in the inferior neck of infants it increases in size and is most active during childhood it stops growing during adolesenceand then gradually atrophies


How does the thymus difer from other lymphoid organs

It functions strictly in T lymphocyte maturation
It does not directly fight antigens


what do thymocytes provide

n atmosphere in which T lymphocytes become immunocompetent


What is the simplest lymphoid organ

the tonsils


Describe the tonsils

they form a ring of lymphatic tissue around the pharynx
Contain follicles with germinal centers
Are not fully encapsullated
Epithelial tissue overlying thetonsil masses invaginates forming tonsular crypts


What is the purpose of the tonsular crypts

to trap and destroy bacteria and particulate matte


Palatine tonsilsare located where

posreiorend of the oral cavity


Lingual tonsils are located where

grouped at the base of the tongue


Pharyngeal tonsils are located where

in the posterior wall of the nasopharynx


tubal tonsils are located where

surrounding the openings of the auditory tubes into the pharynx


what are peyers patches

clusters of lymphoid follicles


Where are peyers patches located

in the wall of the distal portion of the small intestine (ileum) and the appendix


What is the function of peyers patches

appendix - destroy bacteria preventing it from breaching the intestinal wall
To generate "memory lymphocytes"


What is MALT

mucosa associated lymphatic tissue such as peyers patches and the appendix (digestive tract)
Lymphoidnodules in the walls of the bronchi (respiratory tract)


What is the job of MALT

protects the digestive and respiratory systems from forgein matter


what is immunity

Resistance to disease


What are the two intrinsic systems of the immune system

Innate (nonspecific ) defence systemand the addaptive (specific )defense system


Describe the innate defense system

Consists of two lines of defense
The first is the skin and mucosae which keep antigens out by forming a barrier
The second line of defense is antimicrobial proteins phagocytes and other cells which inhibit the spread of invadors - inflamation is its most important mechanism


Describe the adaptive (specific) defense system

the third line of defense attacks particular forgein substances
it takes longer to react than the innate system


what are examples of surface barriers and what kind of barriers do they provide

They provide a physical barrier to most microorganisms
Skin mucous membranes and their secretions


what kind of protection does keratin provide

resistance to weak acids and bases, bacterial enzymes and toxins


what type of protection does mucosae provide

a mechanical barrier


What are the protective chemicals which inhibit or destroy microorgamisms (surface barriers)

skin acidity
Lipids in sebum and dermicidin in sweat
HCl and protein digesting enzymes of stomach mucosae
lysozyme of saliva and lacrimal fluid


What are some respiratory system modifications that counteract potential invaders

mucus coated hairs in the nose
The cilia of the respiratory tract which sweep dust and bacteria laden mucus from lower respiratory passages


What is necessary if microorganisms invade deeper tissues

Natural killer cells NKC
Inflamitory response (macrophages mast cells WBC's and inflammatory chemicals)
Antimicrobial proteins (Interferons and complement proteins)


what are the two phagocytic cells in the immune system

macrophages and neutrophils


what is the role of macrophages

they develop from monocytes to become the chief phagocytic cells


what is the role of neutrophils

they become phagocytc on encountering infectious material in tissues


Describe opsonization and during what stage of phagocytosis does it occur

coating of pathogen by compliment proteins and antibodies
During the first stage when the phagocyte adheres to pathogens or debris


Describe the events of phagocytosis

1. Phagocyte adheres to pathogens or debris
2. Phagocyte forms pseudopods that eventually engulf the particles forming a phagosome
3. Lysosome fuses with the phagocytic vesicle, forming a phagolysosome(which contains acid hydrolase enzymes)
4. Lysosomal enzymes digest the particles leaving a residual body
5. Exocytosis of the vesicle removes indigestible and residual material


What is a respiratory burst

when a bacteria is too large to ingest the helper T cells are activated and produce free radicals that have potent killing abilities such as nitric oxide and superoxide and another substance which is identical to household bleach


How are defensins produced

Nuetrophils produce antimicrobial chemicals called defensins that pierce the pathogens membrane


What do phagocytes do when they are unable to ingest their targets (because of size) and which phagocytes are more likely to survive and why

they release their toxic chemicals into the extracellular fluid
Monocytes are more likely to survive, neutrophils destroy themselves in the process
the monocytes are more robust


what are natural killer cells NK cells

they are large granular lymphocytes
They lack self cell surface receptors
They induce apoptosis in cancer cells and virus infected cells
They secrete chemicals that enhance the inflammatory response
They are not phagocytitic


When is the inflammatory response triggered

whenever body tissues are injured or infected


What is the purpose of inflammation

to prevent the spread of damaging agents
To dispose of cell debris and pathogens
To set the stage for repair


what are the cardinal signs of acute inflammation

And somtimes impairment of function


What occurs in response to inflammation

macrophages and epithelial cells of boundary tissues bear toll like receptors which recognize specific classes of infecting microbes


What do activated toll like receptors do

they trigger the release of cytokines that promote inflammation


Histamine, (from mast cells ) blood proteins, kinins, prostaglandins(PG ) leukotrienes and complement are all what type of chemical

inflammatory mediators which are released by injured tissues, phagocytes, lymphocytes, basophils and mast cells


What reaction do inflammatory chemicals cause what

dialation of the arterioles resulting in hyperemia (an excess of blood in part of the body) increased permeability of local capilaries and edema ( leakage of exudate - infalmmatory response)


What does exudate contain and what does it do

Proteins clotting factors and antibodies
Moves forgein material into lymphatic vessels
And delivers clotting proteins to form a scaffold for repair and to isolate the area


What gets to the inflamed area first neutrophils or phagocytes

neutrophils lead followed by phagocytes


What are the steps for phagocyte mobilization

1. Leukocytosis - release of neutrophils from bone marrow in response to leukocytosis inducing factors from injured cell
2. Margination neutrophils cling to the walls of capillaries in the inflaMmd area
3. Diapedesis of neutrophils - neutrophils flattten out and squeeze out of capillaries
4. Chemotaxis inflammatory chemicals (chemotactic agent) promote positive chemotaxis of neutrophils- neutrophils follow the chemical trail


What are antimicrobial proteins and what do they do

interferons and complement proteins
They attack microorganisms directly and hinder microorganisms ability to reproduce


Describe the interferon mechanism against viruses

Host cell 1 infected by virus, makes interferon, is killed by virus
Host cell 2 binds interferon from cell 1 interferon induces synthesis of protective proteins


Which body cells produce the interferon gamma(y) or immune interferon



Which body cells produce the alpha (x) interferon

the WBC's


Which body cels produce the beta(B) interferon



What is another purpose of interferons besides destroying viruses

to activate macrophages and mobilize NK cells


How many complement proteins are there

20 blood proteins that circulate in an inactive form they include C1- C9 factors B,D,and P and regulatory proteins


what are complement proteins

major mechanism for destroying forgein substances, they amplify all aspects of the inflammatory response, they kil bacteria and certain other celltyppes by cell lysis and they enhance both specific and non specific defenses


Complement can be activated by two pathways what are they

classical pathway and alternative pathway


Activated compements do what

enhance inflammation
promote phagocytosis via opsonization and cause cell lysis


What is MAC

when cel lysis initiates fromation of a membrane attack complex (MAC) by inducing a massive influx of water


What is a fever

a systemic respone to invading microrganisms the leukocytes and macrophages exposed to forgein substances secrete pyrogens which reset the bodies thermostat upward


What are high fevers dangerous

Because they denature enzymes


What are the benefits of a moderate fever

causes the liver and spleen to sequester iron and zinc (needed by microorganisms) and increases the metabolic rate which in turn speeds up repair


What is the adaptive defense system

Is specific, protects against infectious agents and abnormal body cells, it amplfies the inflammatory response activates complement


wHat is the adaptive immune response

specific - recognises and is directed against particular pathogens or forgein substances that initiate the immune response
Systemic- immunity is not restricted to the initial infection site
Has memory - remembers and mounts even stronger attacks on previously encountedered pathogens


There are two overlapping arms of the adaptive immune system - what are they

The humoral - antibody mediated immunity
The cellular - cell mediated immunity


what are antigens

substances that can mobilize the adaptive defenses and provoke an immune response - most are large, complex molecules not normally found in the body (nonself)


What are important functional properties of complete antigens

immunogenicity - the ability to react with products of activated lymphocytes and antibodies and reactivity - the ability to react with products of activated lymphocytes and antibodies released examles are forgein proteinn, polysaccharides, lipids and nucleic acids



an incomplete antigen a small molecule which may link to a protein then be seen by the body as an invador and the body then mounts an attack (hypersensitivities) examples - poison ivy animal dander detergents anddcosmetics


What are antigenic determinants

certain parts of an entire antigen that are immunogenic, antibodies and lymphocyte receptors bind to them


most naturally occuring antigens have numeros antigenic determinants that

mobilize several differnet lymphocyte populations and form different kinds of antibodies against it