chapter 20 lymphatic system
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describe the two systems of the LS
lymphatic system- a network of lymph vessels containing lymph and lymph nodes and its job is to maintain fluid balance.
lymphoid organs and tissues- are the structural basis of our immune system.
about how much is returned VIA lymphatic vessels.
capillary beds do not reclaim some of their lost fluids.
what is lymph
a clear watery fluid found in the the lymphatic vessels.
** has a much lower percentage of proteins than blood.
**only flows to the heart and does not clot.
what does the lymphatic system transport.
tissue fluids, fats and proteins. to the general circulation.
** they begin blindly in intercellular spaces of soft tissues and do not form a closed circut.
describe the lymphatic capillaries?
blind ended vessels found in capillary bed and is made of simple squamous epithelium. the cells overlap each other and are anchored down by collagen fibers.
- **not found in bones teeth and cartilage cornea bone marrow and the central nervous system.
- **flaps open when interstitual pressure is high
describe the lymph flow
- lymphatic capillaries
- -larger lymphatic vessels
- -main lymphatic trunks
- -right lymphatic duct and thoracic
- -juction between internal jugular and subclavian vein.
Lymph from the upper right quadrant empties into _________ duct and the rest of the body goes into the ___________duct
- **throacic duct originates as the cisterna chyli
- under the lumbar reigon of abdominal cav
what is lymphangits
caused by proliferation of WBC in response to an underlying infection virus and all.
when the lymph vessels become inflammed and their vaso vasorum becomes congested with blood.
**seen thru skin and tender to touch
describe the structure of lymph vessels
- almost like veins but...
- thinner walls and more valves and contain lymph nodes
as the capillaries increase in size the walls become thicker and have 3 layers.
**one way valves are seen sometimes in larger and often in the smaller.
describe the fuction of lymphatic vessels
proteins that accumilate in tissue spaces can only be returned to blood by lymphatics.
maintains osmotic pressure in the blood
- lacteals absorb fats and neutrients
- chyle milky fluid found in lacteals 1-2%
describe the lymphatic pump
lymph moves through the system by the larger number of valves.
Breathing movements and skeletal muscle contractions establish a fluid pressure gradient.
what are some other factors that move lymph
- interstiual fluid pressure
- pulsations of near by arteries & rhythmic smooth muscles contractions in lymph vessel walls.
**lymph pours into central veins at peak of inspiration.
caused by common flies and mosquitos which inject parasitic worms into host cells.
it casues severe inflammation and pain and the skin develops ulcer like growths can cause fevers pain and chills.
**mostly effects legs and torso.
what does the t cells do?
what does B cells do?
manage immune response & directly attack infected cells.
-produce plama cells that secrete antibodies and marks antigens for destruction by phagocytes.
what are macrophages and reticular cells and dendric cells
macrophages phagocytize and help activate T cells.
reticular cells make reticular fibers.
dendric cells capture antigens and carry them to lymph nodes.
describe lymphoid tissue
home for lymphocytes and and main spot for lymphocytes and macrophages also made or reticular CT
what is diffuse lymphoid tissue
loosly arranged cells and reticular fibers and found in most organs
what are lymphoid nodules.
solid body of tightly packed cells and reticular fibers germinal centers where b cells prolifertate.
what are lymph NODES
a cluster along thy lymph vessels. they filter and activate during immune attacks
macrophages remove micro organisims.
what is the structure of a lymph node
bean shaped and is a dense fiberous capsule.
the trabeculae divides nodes into compartments and have framework of reticular fibers.
the cortex is densley packed follicles and centers for B and T cells to divide.
- meduallary cords are inward extentions of cortex.
- lymph sinuses- lymph flows through the sinus and encounters macrophages.
decribe the circulation in the lymph nodes?
it enters thru afferent vessels and travels thru from cortex to medulla and exits thru the efferent vessels at the hilum.
** there are less efferent vessels so that the lymphocytes and macro phages can do their work.
what can swollen lymph nodes be a sign of?? and what is a bubonic plague.
can be a sign of cancer, blocked lymph drainage, or other health conditions.
bubonic plague is bacterial infected lymph nodes and gangre.
all lymph nodes are...
composed of reticular tissue except the thymus and they all help protect the body.
**only lymph nodes filter lymph
describe the spleen and its location in the body.
the left hypochondrium directly below diaphragm on the left side of the stomach. its surrounded by inward extensions that divide the organ into compartments.
its a blood cleanser- it extracts old and defective blood cells and platelets from the blood.
what are the functions of the spleen?
Macrophages remove micro organisims from blood and phagocytose.
Mono and lymphocytes complete their development in the spleen.
takes iron and goblin from old RBC's and reuses
The pulp of spleen and sinus store blood.
B4 birth rbcs are made in the spleen after that it only makes RBC's in extreme hemolytic anemia.
in terms of histology what is the white pulp and what is the red pulp?
W.Pulp- dense masses of developing lymphocytes and macrophages.
Red pulp- near outer region made up of fine reticular fibers submerged in blood site of blood cell and pathogen destruction.
describe a splenectomy
removal of ruptured spleen. direct blow or injury causes it.
bone marrow and liver takes over in its absence but will have high risk of infections. IT REPAIRS ITSELF.
describe the Thymus role in lymphatic system
its the primary central organ of the lymphatic system.
highly active in first year and then it begins to atrophy.
what does the thymus do in the lymphatic system to the cells. and describe the structure
- where t cells become imunocompetent(able to fight)
- has a cortex and medulla
cortex- rapidly dividing t cells and few macrophages.
medulla-less t cells and thymic corpusules.
what is the function of the thymus
no reticular fibers and no reticular fibers
secretes thymosin, enables lymphocytes to transform into tcells
lymphoid cells test the 5% of the tcells that mature each day and to be relesed into the bloodstream.
MALT( mucous associated lymphoid tissue) what is it and what does it do.
lymphoid tissues located in the mucous membrane, protects us from germs that want to get in. and they
tonsils, peyers patches appendix and areas found in the respiratory and genitourinary organs.
what are the different tonsils and their responsibilities.
form a entrance around the throat.
2 palatine make up the right and left side, they are the largest and most commonly infected.
pharyngeal tonsil- top of the mouth and called adenoids when its infected.
- lingual tonsil- base of tongue
- tubal tonsils- near openings of the Eustachian tubes.
what do the tonsils do?
protect against bacteria between nasal and oral cavities.
when bacteria is caught they are put into tonsillar crypts and thrown to the immune system to destroy them.
the immune cells also creates memories of these pathogens.
what are peyers patches?
large clusters of lymphoid follicles almost like tonsils.
located in the distal wall of the small intestine.
what is the appendix
little piece off of the cecum and contains high volumes of lymphoid follicles.
destroys bacteria before the get into the wall
the immune cells develop memory so you can get long term immunity.
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