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The Lymphatic The Lymphatic SystemSystem
and Lymphoid Tissueand Lymphoid Tissue
Anatomy & Physiology IIChapter 16
The Lymphatic SystemThe Lymphatic System
System of tissues and vessels
Scattered throughout the body
Services almost all regions
Functions of the Lymphatic Functions of the Lymphatic SystemSystem
Fluid balance
Lymph fluid
Protection from infection
Absorption of fats
Lymphatic vessels pick up fluid in the tissues and return it to the blood in vessels near the heart. Zooming In: What type of blood vessel receives lymph collected from the body?
lymphatic system in relation to the cardiovascular system
Lymphatic CirculationLymphatic Circulation
One-way system
Begins in tissues
Ends in bloodstream
Lymphatic CapillariesLymphatic Capillaries
Capillary walls (endothelium) are
flattened epithelial cells
More permeable than blood capillaries
Overlapping cells form one-way
valves
Arise blindly (closed at one end)
Lacteals absorb digested fats
Lymphatic VesselsLymphatic Vessels
Superficial sets
Deep sets
Nodes
Right lymphatic duct
Thoracic duct (left lymphatic duct)
◦Cisterna chyli
(A)Lymph nodes and vessels of the head.
(B)Drainage of right lymphatic duct and thoracic duct into subclavian veins.
Lymph Vessels and Lymph Lymph Vessels and Lymph NodesNodes
Movement of LymphMovement of Lymph
Segments of vessels located
between the valves contract
rhythmically
Skeletal muscles compress
vessels
Lymphoid TissueLymphoid Tissue
Distributed throughout the body
Makes up specialized organs of
lymphatic system
Lymph NodesLymph NodesStructure
◦ Fibrous connective tissue capsule◦ Afferent lymphatic vessel◦ Hilum◦ Sinuses◦ Cords◦ Nodules◦ Medulla◦ Efferent lymphatic vessel
Grouping◦ Cervical nodes◦ Axillary nodes◦ Mesenteric nodes◦ Inguinal nodes
(A)Arrows indicate the flow of lymph through the node.
(B) Section of a lymph node as seen under the microscope (low power).
Zooming In: What type of lymphatic vessel carries lymph into a node? What type of lymphatic vessel carries lymph out of a node?
Structure of a Structure of a lymph nodelymph node
The SpleenThe Spleen
Cleanses blood
◦Filtration
◦Phagocytosis
Destroys old red blood cells
Produces red blood cells before birth
Is reservoir for blood
The ThymusThe ThymusPlays key role in early immune
system development
Produces thymosin
◦Develops T lymphocyte cells
◦Promotes lymphocyte growth
◦Promotes lymphoid tissue activity
Shrinks after puberty
The TonsilsThe Tonsils
Remove contaminants and trap
pathogens
Palatine tonsils
Pharyngeal tonsil (adenoids)
Lingual tonsilsSurgery to treat if recurrent infection
or enlarged tonsils make swallowing/breathing difficult
Other Lymphoid TissueOther Lymphoid Tissue
Appendix
Mucosal-associated lymphoid tissue
(MALT)
◦Peyer patches
Gut-associated lymphoid tissue
(GALT)
The Reticuloendothelial The Reticuloendothelial SystemSystem
Cells responsible for destroying worn-out blood cells, bacteria, cancer cells and other harmful foreign substances
Monocytes
Macrophages
◦Kupffer cells
◦Dust cells
Disorders of the Lymphatic Disorders of the Lymphatic System and Lymphoid TissueSystem and Lymphoid Tissue
Lymphangitis
Septicemia
Lymphadenitis
◦Cervical
◦Chronic
LymphedemaLymphedemaTissue swelling due to obstruction
of lymph flow caused by
Infection of lymphatic vessels
Vessel blockage
◦Malignant growth
◦Parasites
Loss of lymphatic vessels from injury or surgery
LymphadenopathyLymphadenopathy
Enlarged lymph nodes accompany
certain diseases and infections
Acquired immunodeficiency
syndrome (AIDS)
Infectious mononucleosis
SplenomegalySplenomegalyEnlarged spleen accompanies certain diseases and infectionsScarlet feverTyphus feverTyphoid feverSyphilisTropical parasitic diseasesSplenic anemia
LymphomaLymphoma
Any tumor in lymphoid tissue
Malignant disease
◦Hodgkin disease
◦Non-Hodgkin lymphoma
End of PresentationEnd of Presentation