The Lymphatic The Lymphatic SystemSystem

The Lymphatic SystemThe Lymphatic System

Series of vessel/ducts Series of vessel/ducts – Carry excess tissue fluid to blood Carry excess tissue fluid to blood

vesselvessel StructuresStructures

– Lymph nodesLymph nodes– SpleenSpleen– ThymusThymus– TonsilsTonsils– Gut-associated lymph tissue (GALT)Gut-associated lymph tissue (GALT)

The Lymphatic SystemThe Lymphatic System

Lymph= the fluid carried in the Lymph= the fluid carried in the vesselsvessels– Cellular componentCellular componentlymphocyteslymphocytes

Lymph FormationLymph Formation

Excess Tissue Fluid=more fluid Excess Tissue Fluid=more fluid leaves blood capillaries, than is leaves blood capillaries, than is coming backcoming back

Arterial end of capillary-plasma Arterial end of capillary-plasma leaves the capillaries due to leaves the capillaries due to pressure pressure – Plasma delivers nutrients, oxygen, Plasma delivers nutrients, oxygen,

hormones to bathe cellshormones to bathe cells– Fluid now in Interstitial spaceFluid now in Interstitial space

Lymph formationLymph formation

Venous end of the capillariesVenous end of the capillaries– Blood pressure drops, so not pushing Blood pressure drops, so not pushing

plasma out of capillaryplasma out of capillary– Proteins still within capillaries-Increases Proteins still within capillaries-Increases

oncotic pressureoncotic pressure pulls fluid back into the pulls fluid back into the capillary (this force is not as strong capillary (this force is not as strong normally as BP normally as BP lymph is formed) lymph is formed)

– Lymphatics collect excessive fluidLymphatics collect excessive fluid– (Also can collect tumor cells, BT, proteins )(Also can collect tumor cells, BT, proteins )

Lymph formation-gone Lymph formation-gone wrong!wrong! What happens with low protein What happens with low protein

levels?levels? What happens with high venous What happens with high venous

pressure??pressure??

Lymphedema

Lymph CapillariesLymph Capillaries

Lymph capillaries start as blind Lymph capillaries start as blind ended structures. ended structures.

Smaller lymph vessels come Smaller lymph vessels come together to form larger vessels together to form larger vessels

Lymphatic Lymphatic CirculationCirculation Vessels contain one way valves-Vessels contain one way valves-

prevent backward flowprevent backward flow Vessels ultimately return to the Vessels ultimately return to the

circulation via circulation via Thoracic ductsThoracic ducts Lymphatics are not located in Lymphatics are not located in

CNS and avascular structures CNS and avascular structures such as cartilage, bone and teethsuch as cartilage, bone and teeth

Thoracic DuctThoracic Duct

Lymphatic CirculationLymphatic Circulation

Lymphatic CirculationLymphatic Circulation

Lymphatic vessels from Lymphatic vessels from the hindend drain into the hindend drain into Cisterna chyli in cranial Cisterna chyli in cranial abdomen. Then joins abdomen. Then joins the Thoracic Duct.the Thoracic Duct.

Where does the Where does the Thoracic duct join the Thoracic duct join the circulation? circulation?

All lymphatic vessel All lymphatic vessel travel through at least travel through at least one lymph nodeone lymph node

Lymph CompositionLymph Composition

– More water, sugar, electrolytes than More water, sugar, electrolytes than plasmaplasma

– Less of the large proteins (albumin, Less of the large proteins (albumin, globulin and fibrinogen) than plasmaglobulin and fibrinogen) than plasma

Chyle = lymph from the digestive Chyle = lymph from the digestive systemsystem– After meals-contains fat (chylomicrons)After meals-contains fat (chylomicrons)

Increased fat in the plasma after meal = Increased fat in the plasma after meal = LipemiaLipemia

LipemiaLipemia

Function of the Function of the Lymphatic SystemLymphatic System Removal of excess tissue fluidRemoval of excess tissue fluid Waste material transport-cellular Waste material transport-cellular

wastewaste Filtration of lymph-microorganisms, Filtration of lymph-microorganisms,

cell debris, foreign material>before it cell debris, foreign material>before it enters the bloodstreamenters the bloodstream

Protein Transport-large proteins in Protein Transport-large proteins in interstitium can’t reabsorb into blood interstitium can’t reabsorb into blood capillariescapillaries

Lymph NodesLymph Nodes

Drain specific areas of the bodyDrain specific areas of the body StructureStructure

– CT capsuleCT capsule– Afferent vessels-enterAfferent vessels-enter– Efferent vessels-exitEfferent vessels-exit– Cortex and medullaCortex and medulla

Cortex-location of lymphocytes Cortex-location of lymphocytes clustered in Lymph nodulesclustered in Lymph nodules

Medulla-macrophage located (filter)Medulla-macrophage located (filter)

Lymph Node AnatomyLymph Node Anatomy

Lymph node palpationLymph node palpation

Prescapular ln.

Mandibular ln.

Axillary ln.

Inguinal ln.

Popliteal ln.

Fine Needle Aspiration

LymphomaLymphomaLymphosarcomaLymphosarcoma Tumor of the lymph node systemTumor of the lymph node system

SpleenSpleen

Lymphatic and Hematological Lymphatic and Hematological functionfunction

****Left side of the abdomen********Left side of the abdomen**** Connective tissue capsule Connective tissue capsule

surrounded by smooth musclesurrounded by smooth muscle Trabeculae (branches of the capsule) Trabeculae (branches of the capsule)

sent into tissue of the spleensent into tissue of the spleen– Contains blood vessels, nerves, smooth Contains blood vessels, nerves, smooth

muscle and lymph vesselmuscle and lymph vessel

Sple

en

SpleenSpleen

Splenic contraction-contraction of Splenic contraction-contraction of the smooth muscle the smooth muscle (carnivores>ruminants)(carnivores>ruminants)

Squeezes blood into circulation!!!Squeezes blood into circulation!!!– HBC!HBC!

SpleenSpleen

Interior of spleenInterior of spleen– Red pulp-blood vessels and Red pulp-blood vessels and

macrophagesmacrophages– White pulp-area of lymphoid tissueWhite pulp-area of lymphoid tissue

Lymphocytes –clonal division when Lymphocytes –clonal division when neededneeded

Function of the SpleenFunction of the Spleen

Blood storage in red pulpBlood storage in red pulp Removal of foreign material-by Removal of foreign material-by

macrophages in red pulpmacrophages in red pulp Removal of dead, dying and Removal of dead, dying and

abnormal RBC’s-macrophages in abnormal RBC’s-macrophages in red pulpred pulp

Lymphocyte cloning-in white pulpLymphocyte cloning-in white pulp

***Not essential for life******Not essential for life***

Good thing it is not Good thing it is not essential!!essential!!

Splenic mass-hemangioma vs. HemangiosarcomaSplenectomy to remove mass

ThymusThymus

Found in Cranial Thoracic regionFound in Cranial Thoracic region– Found on either side of the tracheaFound on either side of the trachea– Found in young animals then shrinksFound in young animals then shrinks– Processes T lymphocytes to “kick Processes T lymphocytes to “kick

start” developing immune systemstart” developing immune system

ThymusThymus

TonsilsTonsils

Tonsils - This lymphoid tissue encircles Tonsils - This lymphoid tissue encircles the pharynx and screens pathogens the pharynx and screens pathogens entering in air or food.entering in air or food.– Palatine - PalatePalatine - Palate– Pharyngeal - NasopharynxPharyngeal - Nasopharynx– Lingual - Base of tongueLingual - Base of tongue

Gut-Associated Lymph Gut-Associated Lymph TissueTissue Lymphatic tissue found in the lining of Lymphatic tissue found in the lining of

the GI tractthe GI tract-largest lymphoid organ – if all put together!-largest lymphoid organ – if all put together!– Similar to Bursa of Fabricius in bird Similar to Bursa of Fabricius in bird

intestinesintestines Process B lymphocytesProcess B lymphocytes

Peyers patches - aggregates of Peyers patches - aggregates of lymphoid follicles Ileum of the lymphoid follicles Ileum of the intestinesintestines

ClinicalClinical

Why remove a lymph node near a cancer site?Why remove a lymph node near a cancer site?– That is where cancerous cells/antigens will That is where cancerous cells/antigens will

be brought if the tumor is metastasizing.be brought if the tumor is metastasizing. Removal of a lymph node causes localized Removal of a lymph node causes localized

edema. Why?edema. Why?– There is decreased removal of interstitial There is decreased removal of interstitial

fluid until the vessels from a nearby lymph fluid until the vessels from a nearby lymph node grow into the area.node grow into the area.

Why do spleens rupture so easily?Why do spleens rupture so easily?– Their capsules are very thin.Their capsules are very thin.

Immune System Immune System FunctionFunction Protect the animal from anything Protect the animal from anything

that could cause disease or that could cause disease or damage!damage!

Must recognize “self” vs. “foreign Must recognize “self” vs. “foreign invader”invader”– Detects surface proteinsDetects surface proteins AntigenAntigen

Mechanisms to destroy Mechanisms to destroy foreign matterforeign matter Phagocytosis and destruction of Phagocytosis and destruction of

foreign cellsforeign cells Lysis of foreign cell membranesLysis of foreign cell membranes Inactivation of organism or Inactivation of organism or

chemical substanceschemical substances Clumping (agglutination) of cellsClumping (agglutination) of cells

Excessive Immune Excessive Immune ResponseResponse Immune mediated diseaseImmune mediated disease Anaphylaxis (excessive allergic Anaphylaxis (excessive allergic

reaction)reaction)

Introduction to WBCsIntroduction to WBCs

Neutrophils-phagocytosis

Eosinophils-Allergic reaction

Basophils-initiatesImmune and allergicreactions

Introduction to WBCsIntroduction to WBCs

LymphocytesBT NK

Monocyte-Phagocytosis

Nonspecific Immunity-Nonspecific Immunity-Rapid responseRapid response

Barrier tissues-???Barrier tissues-??? InflammationInflammation Phagocytosis Phagocytosis Natural killer (NK) cells-type of Natural killer (NK) cells-type of

lymphocyte that kills cancer cells and lymphocyte that kills cancer cells and virusesviruses

Interferon-protein produced by cell Interferon-protein produced by cell infected by virus, trying to prevent infected by virus, trying to prevent spreadspread

Complement-enzymes in plasma that can Complement-enzymes in plasma that can cause rupture of cell membrane of cause rupture of cell membrane of foreign cellforeign cell

Specific ImmunitySpecific Immunity

Specific reactions to destroy Specific reactions to destroy specific antigensspecific antigens– Different viruses/but have different Different viruses/but have different

antigensantigens Two typesTwo types

– Humoral immunityHumoral immunity– Cell Mediated immunityCell Mediated immunity

Cell Mediated Cell Mediated ImmunityImmunity T lymphocytes attach to antigens T lymphocytes attach to antigens

on surface of the foreign cellon surface of the foreign cell Usually viruses, fungi, cancerous Usually viruses, fungi, cancerous

cellscells Process responsible for rejection Process responsible for rejection

of transplant tissueof transplant tissue

Humoral ImmunityHumoral Immunity

Function of the B lymphocyteFunction of the B lymphocyte B lymphocyte (plasma cell) produces B lymphocyte (plasma cell) produces

antibodies (immunoglobulin)antibodies (immunoglobulin) Activated B lymphocytesActivated B lymphocytes clonal clonal

divisiondivision Become plasma cellsBecome plasma cells produce only produce only

one type of Antibody for lifeone type of Antibody for life IgG, IgA, IgE, IgMIgG, IgA, IgE, IgM

Just a little something Just a little something to memorize!!!to memorize!!!

Memory CellsMemory Cells

B or T lymphocytes that remember the B or T lymphocytes that remember the foreign invaderforeign invader

Next exposureNext exposure greater response, greater response, faster!!faster!!

Active immunity-Exposure to the Active immunity-Exposure to the antigenantigen– Infection or VaccinationInfection or Vaccination

Passive immunity-Ab received from Passive immunity-Ab received from mothers milkmothers milk

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