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

lymph

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

bones
Teeth
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

arteries

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
Mucus

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

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

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

redness
heat
Swelling
Pain
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

lymphocytes

Which body cells produce the alpha (x) interferon

the WBC's

Which body cels produce the beta(B) interferon

fibroblasts

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

Hapten

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