A P2 Wk7 Class Slides Lymphatics

8/8/2019 A P2 Wk7 Class Slides Lymphatics

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A&P2 wk7 LymphaticsA&P2 wk7 Lymphatics 1 1

Anatomy & Physiology 2Anatomy & Physiology 2

Cardiovascular System VII:Cardiovascular System VII:

Lymphatic SystemLymphatic System

Special CirculationsSpecial Circulations


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Lymphatic SystemLymphatic System

second circulatory systemsecond circulatory system

transporting fluid called lymph throughouttransporting fluid called lymph throughout

bodybody Lymph is transported through vesselsLymph is transported through vessels

called lymphatic vesselscalled lymphatic vessels

LymphLymph

interstitial fluid that has entered the lymphaticinterstitial fluid that has entered the lymphaticvesselsvessels

clear, paleclear, pale--yellow fluidyellow fluid



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Lymphatic SystemLymphatic System -- continuedcontinued

Includes number of organs and tissuesIncludes number of organs and tissues lymphatic vessels, lymph, lymph nodes,lymphatic vessels, lymph, lymph nodes,

thymus, spleen, GALT & MALT, red bonethymus, spleen, GALT & MALT, red bonemarrowmarrow

Lymphatic tissueLymphatic tissue specialized form of reticular connective tissuespecialized form of reticular connective tissue

contains large numbers of lymphocytescontains large numbers of lymphocytes



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Functions of Lymphatic SystemFunctions of Lymphatic System

1. Drains excess interstitial fluid1. Drains excess interstitial fluid

2. Transports dietary lipids2. Transports dietary lipids 3. Carries out immune responses3. Carries out immune responses



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55A&P2 wk7 LymphaticsA&P2 wk7 Lymphatics


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ComponentsComponentsLymphaticLymphatic

SystemSystem



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Lymphatic Vessels & LymphLymphatic Vessels & Lymph

CirculationCirculation Begins as lymphatic capillariesBegins as lymphatic capillaries

tiny and closed at one endtiny and closed at one end

located in spaces between cellslocated in spaces between cells

Lymphatic capillaries unite to formLymphatic capillaries unite to formlarger lymphatic vesselslarger lymphatic vessels

resemble veins but have thinner walls andresemble veins but have thinner walls andmore valvesmore valves

Lymph flows through lymph nodesLymph flows through lymph nodes



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CirculationCirculation -- continuedcontinued

In skin:In skin:

Lymphatic vessels located in subcutaneousLymphatic vessels located in subcutaneoustissuetissue

follow same route as veinsfollow same route as veins

In viscera:In viscera:

Lymphatic vessels follow same route asLymphatic vessels follow same route asarteriesarteries

form plexuses (networks) around visceraform plexuses (networks) around viscera



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CirculationCirculation -- continuedcontinued

Tissues that lack lymphatic vessels:Tissues that lack lymphatic vessels:

Avascular tissuesAvascular tissues cornea, lens, cartilage, CNScornea, lens, cartilage, CNS -- brainbrainand spinal cordand spinal cord

Some portions of the spleen and RBMSome portions of the spleen and RBM



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Lymphatic CapillariesLymphatic Capillaries

Larger in diameter than blood vesselsLarger in diameter than blood vessels

Have a one way structureHave a one way structure -- only permits inonly permits inflow of interstitial fluidflow of interstitial fluid

Overlapping endothelial cells creating aOverlapping endothelial cells creating a one way swinging door one way swinging door

high interstitial pressurehigh interstitial pressure pushes interstitial cellspushes interstitial cellsapartapart interstitial fluid flows ininterstitial fluid flows in

high lymphatic pressurehigh lymphatic pressure cells adhere morecells adhere morecloselyclosely prevent outflowprevent outflow

A&P2 wk7 LymphaticsA&P2 wk7 Lymphatics 1010


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LactealsLacteals

Specialised lymphatic capillaries in smallSpecialised lymphatic capillaries in smallintestineintestine

Carry dietary lipids into lymph (andCarry dietary lipids into lymph (andultimately blood)ultimately blood)

Lipids cause lymph to appear creamy whiteLipids cause lymph to appear creamy white

(chyle)(chyle)



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Lymphatic TrunksLymphatic Trunks

As lymphatic vessels merge, they unit toAs lymphatic vessels merge, they unit toform lymph trunksform lymph trunks

Principle trunks include:Principle trunks include: L & R Lumbar trunksL & R Lumbar trunks

Intestinal trunkIntestinal trunk

L & R Bronchomediastinal trunkL & R Bronchomediastinal trunk L & R Subclavian trunkL & R Subclavian trunk

L & R jugular trunkL & R jugular trunk



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Lymphatic TrunksLymphatic Trunks -- continuedcontinued

Lumbar trunksLumbar trunks -- drains lymph fromdrains lymph from Lower limbs, Wall and viscera of the pelvis,Lower limbs, Wall and viscera of the pelvis,

Kidneys, Adrenal glands, Abdominal wallKidneys, Adrenal glands, Abdominal wall

Intestinal trunkIntestinal trunk -- drains lymph fromdrains lymph from Stomach, Intestines, Pancreas, Spleen & PartStomach, Intestines, Pancreas, Spleen & Part

of the liverof the liver

Bronchomediastinal trunksBronchomediastinal trunks -- drain lymphdrain lymphfromfrom

Thoracic wall, Lung, HeartThoracic wall, Lung, Heart



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Lymphatic TrunksLymphatic Trunks -- continuedcontinued

Subclavian trunksSubclavian trunks -- drains lymph fromdrains lymph from

Upper limbsUpper limbs

Jugular trunksJugular trunks -- drains lymph fromdrains lymph from

Head, neckHead, neck



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Lymphatic DuctsLymphatic Ducts

Lymph passes from trunks into two mainLymph passes from trunks into two mainchannelschannels

1. Thoracic duct (aka left lymphatic duct)1. Thoracic duct (aka left lymphatic duct)

2. Right lymphatic duct2. Right lymphatic duct



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1. Thoracic Duct1. Thoracic Duct(left lymphatic duct)(left lymphatic duct) 3838--45cm long45cm long

Begins as dilation called cisterna chyliBegins as dilation called cisterna chylianterior to L2anterior to L2

Main duct for the return of lymph to bloodMain duct for the return of lymph to blood

Drains lymph from following trunksDrains lymph from following trunks

L & R Lumbar, Intestinal, L Jugular, L Subclavian,L & R Lumbar, Intestinal, L Jugular, L Subclavian,

L BronchomediastinalL Bronchomediastinal

Then drains lymph into venous bloodThen drains lymph into venous bloodstream at junction of L internal jugular & Lstream at junction of L internal jugular & L

subclavian veinsubclavian vein A&P2 wk7 LymphaticsA&P2 wk7 Lymphatics 2020


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2. Right Lymphatic Duct2. Right Lymphatic Duct

1.2 cm long1.2 cm long

Drains lymph from following trunksDrains lymph from following trunks

R Jugular, R Subclavian, R BroncomediastinalR Jugular, R Subclavian, R Broncomediastinal

Then drains lymph into venous blood atThen drains lymph into venous blood atjunction of R internal jugular and Rjunction of R internal jugular and R

subclavian veinsubclavian vein



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Flow of LymphFlow of Lymph

Excess filtered fluid from blood capillariesExcess filtered fluid from blood capillariesdrains into lymphatic vessels and becomesdrains into lymphatic vessels and becomes

lymphlymph

Lymphatic vessels contain valves (likeLymphatic vessels contain valves (likeveins) which ensure one way movementveins) which ensure one way movement

of lymphof lymph Lymph flows through lymph nodes locatedLymph flows through lymph nodes located

at intervals along lymphatic vesselsat intervals along lymphatic vessels



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Flow of LymphFlow of Lymph

Blood capillaries (blood)Blood capillaries (blood)

Interstitial spaces (interstitial fluid)Interstitial spaces (interstitial fluid)

Lymphatic capillaries (lymph)Lymphatic capillaries (lymph)

Lymphatic vessels (lymph)Lymphatic vessels (lymph)

Lymphatic ducts (lymph)Lymphatic ducts (lymph)

Junction of the internal jugular andJunction of the internal jugular andsubclavian veins (blood)subclavian veins (blood)



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Moving LymphMoving Lymph

Same two pumps involved in venous returnSame two pumps involved in venous returnof blood to heart maintain flow of lymphof blood to heart maintain flow of lymph

1. Skeletal muscle pump1. Skeletal muscle pump milking actionmilking action

of skeletal muscles compresses lymphaticof skeletal muscles compresses lymphaticvesselsvessels

2. Respiratory pump2. Respiratory pump Pressure changesPressure changesoccuring during inhalation and exhalationoccuring during inhalation and exhalation Inhalation: volume of lungs increases, pressureInhalation: volume of lungs increases, pressure

decreasesdecreases lymph flow up towards heartlymph flow up towards heart

Exhalation: valves prevent backflowExhalation: valves prevent backflow



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Lymphatic Organs & TissuesLymphatic Organs & Tissues

Widely distributed throughout bodyWidely distributed throughout body

Classified into two groups according toClassified into two groups according totheir functionstheir functions

Primary Lymphatic OrgansPrimary Lymphatic Organs

Secondary Lymphatic OrgansSecondary Lymphatic Organs



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Primary Lymphatic OrgansPrimary Lymphatic Organs

Sites where stem cells divide and becomeSites where stem cells divide and becomeimmunocompetentimmunocompetent Red Bone MarrowRed Bone Marrow pluripotent stem cellspluripotent stem cells

give rise togive rise to

Immunocompetant B cellsImmunocompetant B cells

PrePre--T cellsT cells

ThymusThymus

PrePre--T cells migrate to thymus to finish theirT cells migrate to thymus to finish theirmaturationmaturation immunocompetent T cellsimmunocompetent T cells



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Secondary Lymphatic OrgansSecondary Lymphatic Organs

Sites where most immune responsesSites where most immune responsesoccuroccur

Lymph nodesLymph nodes organ (surrounded byorgan (surrounded bya capsule)a capsule)

SpleenSpleen -- organorgan

Lymphatic nodules (follicles)Lymphatic nodules (follicles) nonnonorgan (lacks a capsule)organ (lacks a capsule)



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ThymusThymus



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ThymusThymus

BilobedBilobed Located in mediastinumLocated in mediastinum

Between sternum and aortaBetween sternum and aorta

Individual lobes surrounded byIndividual lobes surrounded byconnective tissue capsuleconnective tissue capsule

Enveloping layer of connective tissueEnveloping layer of connective tissuesurrounds both lobessurrounds both lobes -- keeping themkeeping them

togethertogether TrabeculaeTrabeculae

Extensions of capsule that penetrate inward andExtensions of capsule that penetrate inward anddivide lobes into lobulesdivide lobes into lobules



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ThymusThymus -- continuedcontinued



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CortexCortex

Composed of large numbers of T cells,Composed of large numbers of T cells,dendritic cells, epithelial cells anddendritic cells, epithelial cells andmacrophagesmacrophages

Dendritic cells (dendr = tree)Dendritic cells (dendr = tree) assist maturation of preassist maturation of pre--T cellsT cells

Epithelial cellsEpithelial cells

serve as framework for up to 50 T cellsserve as framework for up to 50 T cells Produce thymic hormonesProduce thymic hormones

Involved in T cell positive selectionInvolved in T cell positive selectionprocessprocess



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MedullaMedulla

Consists of widely scattered, more matureConsists of widely scattered, more matureT cells, epithelial cells, dendritic cells &T cells, epithelial cells, dendritic cells &macrophagesmacrophages

Displays concentric arranged layers ofDisplays concentric arranged layers ofdegenerating epithelial cellsdegenerating epithelial cells

called thymic (Hassalls)corpusclescalled thymic (Hassalls)corpuscles

T cells leave thymus via blood & migrateT cells leave thymus via blood & migrateto lymph nodes, spleen & other lymphaticto lymph nodes, spleen & other lymphatictissuestissues



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Thymus sizeThymus size

Thymus atrophies (shrinks) as we ageThymus atrophies (shrinks) as we age Foetus: Mass about 70gFoetus: Mass about 70g

After puberty: Thymic tissue begins to beAfter puberty: Thymic tissue begins to be

replaced with adipose and areolarreplaced with adipose and areolarconnective tissueconnective tissue

Maturity: Atrophied significantlyMaturity: Atrophied significantly

Old Age: Mass about 3gOld Age: Mass about 3g

Before it atrophies, it populatesBefore it atrophies, it populatessecondary lymphatic organs and tissuessecondary lymphatic organs and tissueswith T cellswith T cells



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Lymph nodesLymph nodes

BeanBean--shaped organsshaped organs

11--25 mm long & encapsulated25 mm long & encapsulated

Extensions calledExtensions called trabeculaetrabeculae extend intoextend intonodenode

Contain masses of B cells and T cellsContain masses of B cells and T cells

Located along lymphatic vesselsLocated along lymphatic vesselsApprox. 600 lymph nodesApprox. 600 lymph nodes

Occur in groupsOccur in groups



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Lymph nodesLymph nodes --continuedcontinued

Supporting NetworkSupporting Network

Stroma:Stroma: supporting CT of lymph nodesupporting CT of lymph node

IncludesIncludes -- Capsule, Trabeculae, Reticular fibers,Capsule, Trabeculae, Reticular fibers,

FibroblastsFibroblasts ParenchymaParenchyma

Functioning part of a lymph nodeFunctioning part of a lymph node

Divided into:Divided into: CortexCortex

Outer & InnerOuter & Inner

MedullaMedulla



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Outer CortexOuter Cortex

Consist of lymphatic nodulesConsist of lymphatic nodules(follicles)(follicles)

eggegg--shaped aggregates of B cellsshaped aggregates of B cells

may bemay be

Primary nodulesPrimary nodules

Secondary nodulesSecondary nodules

contain a germinal centrecontain a germinal centre



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Outer CortexOuter Cortex --continuedcontinued

Primary & Secondary NodulesPrimary & Secondary Nodules Primary nodulesPrimary nodules

Consist chiefly of B cellsConsist chiefly of B cells

Secondary nodulesSecondary nodules Form in response to antigenic challengeForm in response to antigenic challenge

Sites of plasma cell & memory B cell formationSites of plasma cell & memory B cell formation

Develop fromDevelop from primary lymphatic nodulesprimary lymphatic nodules when Bwhen Bcells recognize an antigencells recognize an antigen

centre contains acentre contains a germinal centregerminal centre

contains B cells, follicular dendritic cells & macrophagescontains B cells, follicular dendritic cells & macrophages



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Outer CortexOuter Cortex -- GerminalGerminal CenterCenter

Follicular dentritic cells present an antigenFollicular dentritic cells present an antigen B cells develop & proliferate intoB cells develop & proliferate into

plasma cellsplasma cells (produce antibodies) or(produce antibodies) or

memory B cellsmemory B cells..

Note: B cells that do not develop properlyNote: B cells that do not develop properly

undergo apoptosisundergo apoptosis cleared by macrophagescleared by macrophages



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Inner CortexInner Cortex

Does not contain lymphatic nodulesDoes not contain lymphatic nodules

Consists mainly of T cells andConsists mainly of T cells anddendritic cellsdendritic cells

Dendritic cells (APCs)Dendritic cells (APCs)

present antigens to T cells causing theirpresent antigens to T cells causing theirproliferationproliferation T cells migrate away fromT cells migrate away fromlymph node to infected body tissueslymph node to infected body tissues



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MedullaMedulla Contains plasma B cells that haveContains plasma B cells that have

migrated from the cortex, andmigrated from the cortex, andmacrophagesmacrophages

cells are imbedded in a network ofcells are imbedded in a network ofreticular fibres and reticular cellsreticular fibres and reticular cells



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Lymph Flow through a NodeLymph Flow through a Node

Afferent Lymphatic vesselsAfferent Lymphatic vessels

Penetrate convex surface of nodePenetrate convex surface of node

Contain valves encouraging inflowContain valves encouraging inflow

SinusesSinuses Lymph flows through these leaky capillariesLymph flows through these leaky capillaries

Subcapsular sinuses, trabecular sinuses , MedullarySubcapsular sinuses, trabecular sinuses , Medullarysinusessinuses

Efferent Lymphatic vesselsEfferent Lymphatic vessels

Sinuses drain into efferent vesselsSinuses drain into efferent vessels

Contain valves encouraging flow away from nodeContain valves encouraging flow away from nodeA&P2 wk7 LymphaticsA&P2 wk7 Lymphatics 4747


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Lymph Node as a FilterLymph Node as a Filter

Lymph enters one endLymph enters one end foreign substances are trapped by reticularforeign substances are trapped by reticular

fibres within sinusesfibres within sinuses

Macrophages destroy these foreignMacrophages destroy these foreignsubstances by phagocytosissubstances by phagocytosis

B cells or T cells may become activatedB cells or T cells may become activated

against and mount immune responseagainst and mount immune response

Filtered lymph leaves the other end ofFiltered lymph leaves the other end ofthe lymph nodethe lymph node



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SpleenSpleen



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SpleenSpleen

Oval shapedOval shaped

12 cm long12 cm long

Largest single mass of lymphatic tissueLargest single mass of lymphatic tissue

Located in LHR between stomach andLocated in LHR between stomach anddiaphragmdiaphragm

Superior surface is convexSuperior surface is convex -- conforms toconforms toconcave shape of diaphragm above itconcave shape of diaphragm above it



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SpleenSpleen Visceral surfaceVisceral surface



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SpleenSpleen --continuedcontinued

Visceral surface is indented from variousVisceral surface is indented from variousorgansorgans

Gastric impressionGastric impression -- stomachstomach Renal impressionRenal impression -- L kidneyL kidney

Colic impressionColic impression -- L colic flexure of Lge intestineL colic flexure of Lge intestine

Has aHas a hilumhilum through which passes the splenicthrough which passes the splenicartery, splenic vein, and efferent lymphaticartery, splenic vein, and efferent lymphaticvessels.vessels.



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SpleenSpleen -- continuedcontinued

Surrounded by protective capsuleSurrounded by protective capsule Dense connective tissueDense connective tissue

Trabeculae extend inward from theTrabeculae extend inward from thecapsulecapsule

Stroma consists of theStroma consists of the

CapsuleCapsule TrabeculaeTrabeculae

Reticular fibresReticular fibres

FibroblastsFibroblasts



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Parenchyma of SpleenParenchyma of Spleen

Functional part of spleenFunctional part of spleen

Consists of two kinds of tissueConsists of two kinds of tissue White PulpWhite Pulp

Red PulpRed Pulp



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White Pulp of SpleenWhite Pulp of Spleen

Lymphatic tissue consisting mostly ofLymphatic tissue consisting mostly of

lymphocytes and macrophageslymphocytes and macrophages mostly surrounds central arteriesmostly surrounds central arteries

Blood Flows through central arteriesBlood Flows through central arteries

of white pulpof white pulp



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Red Pulp of SpleenRed Pulp of Spleen

Consists of bloodConsists of blood--filled venous sinusesfilled venous sinuses

Consists of Cords of splenic tissueConsists of Cords of splenic tissue called Splenic (Billroths) cordscalled Splenic (Billroths) cords

consists of RBCs, macrophages, lymphocytes,consists of RBCs, macrophages, lymphocytes,plasma cells & granulocytesplasma cells & granulocytes

Red pulp mostly surrounds veinsRed pulp mostly surrounds veins



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Blood Flow through SpleenBlood Flow through Spleen

Splenic arteries enter the spleenSplenic arteries enter the spleen

branch off into central arteriesbranch off into central arteries

Blood leaves throughBlood leaves through

Splenic veins which merge from venousSplenic veins which merge from venoussinusessinuses



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Functions of the White PulpFunctions of the White Pulp

Blood Flows through central arteries ofBlood Flows through central arteries ofwhite pulpwhite pulp

B cells and T cells in white pulp carry outB cells and T cells in white pulp carry outimmune functionsimmune functions

Macrophages destroy bloodMacrophages destroy blood--borne pathogensborne pathogensby phagocytosisby phagocytosis



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Functions of the Red PulpFunctions of the Red Pulp

Macrophages remove ruptured, worn out,Macrophages remove ruptured, worn out,or defective blood cells or plateletsor defective blood cells or platelets

Stores platelets (1/3 of bodys supply)Stores platelets (1/3 of bodys supply)

Produces blood cells (hemopoiesis) duringProduces blood cells (hemopoiesis) duringfetal lifefetal life



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Lymphatic NodulesLymphatic Nodules

EggEgg--shaped masses of lymphatic tissueshaped masses of lymphatic tissue

Not surrounded by a capsuleNot surrounded by a capsule

Scattered throughout the laminaScattered throughout the lamina propriapropria ofofmucous membranes lining themucous membranes lining the GITGIT

Urinary TractUrinary Tract

Reproductive TractReproductive Tract

Respiratory AirwaysRespiratory Airways

Called MALT in these areasCalled MALT in these areas



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Special CirculationSpecial Circulation

Hepatic Portal CirculationHepatic Portal Circulation

Pulmonary circulationPulmonary circulation FetalFetal circulationcirculation



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Hepatic Portal CirculationHepatic Portal Circulation

Carries venous blood from GIT organs andCarries venous blood from GIT organs andspleen to the liverspleen to the liver

Hepatic portal veinHepatic portal vein Receives blood from the capillaries of GITReceives blood from the capillaries of GIT

organs and spleenorgans and spleen

Delivers blood to the sinusoids of the liverDelivers blood to the sinusoids of the liver



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Hepatic Portal CirculationHepatic Portal Circulation -- continuedcontinued

Liver stores some nutrientsLiver stores some nutrients

E.g. glucoseE.g. glucose glycogenglycogen

Liver destroys bacteria ingested from foodLiver destroys bacteria ingested from food

Phagocytes line sinusoidsPhagocytes line sinusoids

Liver modifies some nutrients before theyLiver modifies some nutrients before they

pass into general circulationpass into general circulation E.g. Detoxifies alcoholE.g. Detoxifies alcohol



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Hepatic Portal CirculationHepatic Portal Circulation -- continuedcontinued

LiverLiver receives:receives:

NutrientNutrient--rich but deoxygenated blood via therich but deoxygenated blood via the

hepatic portal veinhepatic portal vein Oxygenated blood from theOxygenated blood from the hepatic arteryhepatic artery

Deoxygenated and oxygenated bloodDeoxygenated and oxygenated blood

mixes in liver sinusoidsmixes in liver sinusoids Blood leaves liver viaBlood leaves liver via hepatic veinshepatic veins

which drain into the inferior vena cavawhich drain into the inferior vena cava


P l i l tiP l i l ti


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Pulmonary circulationPulmonary circulation



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Pulmonary circulationPulmonary circulation

Pulmonary TrunkPulmonary Trunk

Left and Right Pulmonary ArteriesLeft and Right Pulmonary ArteriesCarry deoxygenated bloodCarry deoxygenated blood

Left and Right Pulmonary VeinsLeft and Right Pulmonary Veins

Carry oxygenated bloodCarry oxygenated blood



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Pulmonary CirculationPulmonary Circulation -- continuedcontinued

Carries deoxygenated bloodCarries deoxygenated blood

From right ventricle to left atriumFrom right ventricle to left atriumVia air sacs in the lungsVia air sacs in the lungs



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FetalFetal CirculationCirculation

Exists only inExists only in fetusfetus

Involves exchange of materials betweenInvolves exchange of materials between fetusfetus

and mother via placentaand mother via placenta FetusFetus derives O2 and nutrients from andderives O2 and nutrients from and

eliminates CO2 into maternal bloodeliminates CO2 into maternal blood

At birthAt birth

lungs, digestive & liver functions begin >lungs, digestive & liver functions begin >special structures ofspecial structures of fetalfetal circulation are nocirculation are nolonger neededlonger needed



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A P2 Wk7 Class Slides Lymphatics