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