Transcript The Lymphatic System

The Lymphatic System
The Lymphatic System
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Series of vessel/ducts
– Carry excess tissue fluid to blood vessel
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Structures
– Lymph nodes
– Spleen
– Thymus
– Tonsils
– Gut-associated lymph tissue (GALT)
The Lymphatic System
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Lymph= the fluid carried in the vessels
– Cellular componentlymphocytes
Lymph Formation
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Excess Tissue Fluid=more fluid leaves
blood capillaries, than is coming back
Arterial end of capillary-plasma leaves
the capillaries due to pressure
– Plasma delivers nutrients, oxygen,
hormones to bathe cells
– Fluid now in Interstitial space
Lymph formation
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Venous end of the capillaries
– Blood pressure drops, so not pushing plasma out
of capillary
– Proteins still within capillaries-Increases oncotic
pressure pulls fluid back into the capillary (this
force is not as strong normally as BP  lymph is
formed)
– Lymphatics collect excessive fluid
– (Also can collect tumor cells, BT, proteins )
Lymph formation-gone
wrong!
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What happens with low protein levels?
What happens with high venous
pressure??
Lymphedema
Lymph Capillaries
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Lymph capillaries start as blind ended
structures.
Smaller lymph vessels come together
to form larger vessels
Lymphatic
Circulation
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Vessels contain one way valvesprevent backward flow
Vessels ultimately return to the
circulation via Thoracic ducts
Lymphatics are not located in CNS and
avascular structures such as cartilage,
bone and teeth
Thoracic Duct
Lymphatic Circulation
Lymphatic Circulation
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Lymphatic vessels from
the hindend drain into
Cisterna chyli in cranial
abdomen. Then joins the
Thoracic Duct.
Where does the Thoracic
duct join the circulation?
All lymphatic vessel travel
through at least one
lymph node
Lymph Composition
– More water, sugar, electrolytes than plasma
– Less of the large proteins (albumin, globulin
and fibrinogen) than plasma
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Chyle = lymph from the digestive
system
– After meals-contains fat (chylomicrons)
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Increased fat in the plasma after meal =
Lipemia
Lipemia
Function of the Lymphatic
System
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Removal of excess tissue fluid
Waste material transport-cellular waste
Filtration of lymph-microorganisms, cell
debris, foreign material>before it enters the
bloodstream
Protein Transport-large proteins in
interstitium can’t reabsorb into blood
capillaries
Lymph Nodes
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Drain specific areas of the body
Structure
– CT capsule
– Afferent vessels-enter
– Efferent vessels-exit
– Cortex and medulla
Cortex-location of lymphocytes clustered in
Lymph nodules
 Medulla-macrophage located (filter)
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Lymph Node Anatomy
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Lymph node palpation
Popliteal ln.
Mandibular ln.
Fine Needle Aspiration
Inguinal ln.
Prescapular ln.
Axillary ln.
Lymphoma
Lymphosarcoma
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Tumor of the lymph node system
Spleen
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Lymphatic and Hematological function
****Left side of the abdomen****
Connective tissue capsule surrounded
by smooth muscle
Trabeculae (branches of the capsule)
sent into tissue of the spleen
– Contains blood vessels, nerves, smooth
muscle and lymph vessel
Spleen
Spleen
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Splenic contraction-contraction of the
smooth muscle
(carnivores>ruminants)
Squeezes blood into circulation!!!
– HBC!
Spleen
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Interior of spleen
– Red pulp-blood vessels and macrophages
– White pulp-area of lymphoid tissue
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Lymphocytes –clonal division when needed
Function of the Spleen
Blood storage in red pulp
 Removal of foreign material-by
macrophages in red pulp
 Removal of dead, dying and abnormal
RBC’s-macrophages in red pulp
 Lymphocyte cloning-in white pulp
***Not essential for life***
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Good thing it is not
essential!!
Splenic mass-hemangioma vs.
Hemangiosarcoma
Splenectomy to remove mass
Thymus
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Found in Cranial Thoracic region
– Found on either side of the trachea
– Found in young animals then shrinks
– Processes T lymphocytes to “kick start”
developing immune system
Thymus
Tonsils
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Tonsils - This lymphoid tissue encircles the
pharynx and screens pathogens entering in
air or food.
– Palatine - Palate
– Pharyngeal - Nasopharynx
– Lingual - Base of tongue
Gut-Associated Lymph
Tissue
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Lymphatic tissue found in the lining of the
GI tract
-largest lymphoid organ – if all put together!
– Similar to Bursa of Fabricius in bird intestines
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Process B lymphocytes
Peyers patches - aggregates of lymphoid
follicles Ileum of the intestines
Clinical
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Why remove a lymph node near a cancer site?
– That is where cancerous cells/antigens will be
brought if the tumor is metastasizing.
Removal of a lymph node causes localized edema.
Why?
– There is decreased removal of interstitial fluid
until the vessels from a nearby lymph node grow
into the area.
Why do spleens rupture so easily?
– Their capsules are very thin.
Immune System Function
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Protect the animal from anything that
could cause disease or damage!
Must recognize “self” vs. “foreign
invader”
– Detects surface proteins Antigen
Mechanisms to destroy
foreign matter
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Phagocytosis and destruction of
foreign cells
Lysis of foreign cell membranes
Inactivation of organism or chemical
substances
Clumping (agglutination) of cells
Excessive Immune
Response
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Immune mediated disease
Anaphylaxis (excessive allergic
reaction)
Introduction to WBCs
Neutrophilsphagocytosis
EosinophilsAllergic reaction
Basophils-initiates
Immune and allergic
reactions
Introduction to WBCs
Lymphocytes
B
T
NK
MonocytePhagocytosis
Nonspecific ImmunityRapid response
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Barrier tissues-???
Inflammation
Phagocytosis
Natural killer (NK) cells-type of lymphocyte
that kills cancer cells and viruses
Interferon-protein produced by cell infected
by virus, trying to prevent spread
Complement-enzymes in plasma that can
cause rupture of cell membrane of foreign
cell
Specific Immunity
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Specific reactions to destroy specific
antigens
– Different viruses/but have different
antigens
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Two types
– Humoral immunity
– Cell Mediated immunity
Cell Mediated Immunity
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T lymphocytes attach to antigens on
surface of the foreign cell
Usually viruses, fungi, cancerous cells
Process responsible for rejection of
transplant tissue
Humoral Immunity
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Function of the B lymphocyte
B lymphocyte (plasma cell) produces
antibodies (immunoglobulin)
Activated B lymphocytes clonal
division
Become plasma cells produce only
one type of Antibody for life
IgG, IgA, IgE, IgM
Just a little something to
memorize!!!
Memory Cells
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B or T lymphocytes that remember the
foreign invader
Next exposure greater response, faster!!
Active immunity-Exposure to the antigen
– Infection or Vaccination
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Passive immunity-Ab received from mothers
milk
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