Lymphatic SystemLymphatic System

FunctionsFunctions

►Picks up excess fluids (lymphatic Picks up excess fluids (lymphatic fluid/lymph) from tissues and filters out fluid/lymph) from tissues and filters out pathogenspathogens

►Returns cleansed fluid back to blood Returns cleansed fluid back to blood streamstream

►Able to pick up larger molecules that may Able to pick up larger molecules that may not fit into cardiovascular vesselsnot fit into cardiovascular vessels

ArrangementArrangement

►Lymphatic vessels run throughout the Lymphatic vessels run throughout the entire bodyentire body

►They are blind ended vessels that They are blind ended vessels that carry fluid only one waycarry fluid only one way

►Lymphatic vessels end at lymphatic Lymphatic vessels end at lymphatic capillaries that are deeply embedded capillaries that are deeply embedded in body tissuesin body tissues

Lymphatic CapillariesLymphatic Capillaries

►MicroscopicMicroscopic

►Very porous (more than cardiovascular Very porous (more than cardiovascular capillaries) one layer of simple capillaries) one layer of simple squamous epithelium squamous epithelium

►This arrangement allows for larger This arrangement allows for larger molecules to be absorbedmolecules to be absorbed

Holding ChambersHolding Chambers

►Two major areasTwo major areas

RIGHT LYMPHATIC DUCTRIGHT LYMPHATIC DUCT

THORACIC DUCTTHORACIC DUCT

Right Lymphatic DuctRight Lymphatic Duct

►Drains lymph from the right upper Drains lymph from the right upper extremity and right side of head, neck extremity and right side of head, neck and upper torsoand upper torso

Thoracic DuctThoracic Duct

►Largest lymphatic vesselLargest lymphatic vessel

►Drains lymph from remaining three Drains lymph from remaining three fourts of the bodyfourts of the body

►Large pouch: cisterna chyliLarge pouch: cisterna chyli

LactealsLacteals

►Specialized larger lymphatic capillaries Specialized larger lymphatic capillaries that are found in the intestinal wallthat are found in the intestinal wall

►Able to pick up fat molecules (extra Able to pick up fat molecules (extra large molecules)large molecules)

Other parts of lymphatic Other parts of lymphatic systemsystem

►Lymph nodesLymph nodes►Thymus glandThymus gland►TonsilsTonsils►SpleenSpleen

Lymph nodesLymph nodes

►Actual filtering stationsActual filtering stations►Lymph passest through and nodes trap Lymph passest through and nodes trap

pathogenspathogens►Nodes may become enlarged when Nodes may become enlarged when

overwhelmed with number of pathogens overwhelmed with number of pathogens and white blood cells killing themand white blood cells killing them

►Excess fluid develops; pusExcess fluid develops; pus►Also store immature B-cellsAlso store immature B-cells

Structure of a lymph nodeStructure of a lymph node

►Afferent vessels pick up excess fluid Afferent vessels pick up excess fluid (several)(several)

►Efferent vessel drains lymph node Efferent vessel drains lymph node (only one)(only one)

Location of lymph nodesLocation of lymph nodes

►Back of throatBack of throat►NeckNeck►ArmpitArmpit►GroinGroin►Behind kneeBehind knee►Abdominal wallAbdominal wall

TonsilsTonsils

►Lymph nodes at back of throatLymph nodes at back of throat►3 parts3 parts►Palatine (tonsilsPalatine (tonsils►Pharyngeal (adenoids)Pharyngeal (adenoids)►LingualLingual

►See page 341See page 341

Thymus GlandThymus Gland

►Located in mediastinumLocated in mediastinum►Produces T-cells at an early ageProduces T-cells at an early age►Makes hormonesMakes hormones►Gets smaller after adolescenceGets smaller after adolescence►Replaced by fatReplaced by fat►Process of involution; turns in on itselfProcess of involution; turns in on itself

SpleenSpleen

►Largest lymphatic organLargest lymphatic organ►Located in LUQLocated in LUQ►Fi;ltration of bacteriaFi;ltration of bacteria►Phagocytes present (large quantities)Phagocytes present (large quantities)►Large rervoir of old RBC’sLarge rervoir of old RBC’s►Very rich blood supplyVery rich blood supply►Removed: splenectomyRemoved: splenectomy