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