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46 terms

Lymphatic system

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Lymphatic system consists of three parts.
1) A network of three parts
2) Lymph
3) Lymph nodes
Functions of the Lymphatic system.
Returns interstitial fluid and leaked plasma proteins back to the blood.
Together with lymphoid organs and tissues, provide the structural basis of the ______ _______.
immune system.
One way system,lymph flows toward the heart.
Lymphatic vessels.
what are the types of lymphatic vessels.
Lymphatic capillaries
Lymphatic collecting vessels
Lymphatic trunks and ducts.
Similar to blood capillaries, except
Very permeable
Endothelial cells overlap to form one-way minivalves.
Lymphatic capillaries.
Absent from bones, teeth bone marrow and the CNS
lymphatic capillaries
Specialized lymph capillaries present in intestinal mucosa.
Lacteals
Lymphatic collecting vessels
Similar to veins, except Have thinner walls, with more internal valves.
Lymphatic trunks
Formed by the union of the largest collection ducts.
Lymph
is delivered into one of two large ducts
Right Lymphatic duct
Drains the right upper arm and the right side of the head and thorax.
Thoracic duct
arises from the cisterna chyli and drains the rest of the body.
Right Lymphatic and Thoracic duct
each empties lymph into venous circulation at the junction of the internal jugular and subclavian veins on its own side of the body
What is lymph propelled by
Pulsations of nearby arteries and Contractions of smooth muscle in the walls of the lymphatics.
Lymphocytes
The main warriors of the immune system
Two main types of Lymphocytes
T Cells And B Cells
What protects against antigens?
T cells and b cells protect against antigens.
Macrophages
Phagocytize foreign substances and help activate T-cells
Dendritic cells
Cells that capture antigens and deliver them to lymph nodes.
Reticular cells
produce stroma that supports other cells in lymphoid organs.
Lymphoid tissue
Houses and provides a proliferation site for lymphocytes.
Two main types of Lymphatic tissue.
Diffuse Lymphatic tissue and Lymphatic follicles
Diffuse lymphatic tissue
comprises scattered reticular tissue.
Lymphatic follicles
nodules are solid, spherical bodies of tightly packed reticular elements and cells.
Germinal center
composed of dendritic and B cells
Lymph nodes
Principal lymphoid organs of the body
Functions of lymph nodes
Filter lymph and Immune system
Immune system
Lymphocytes are activated and mount an attack against antigens.
What are the two Histologically distinct regions
Cortex and medulla
Structure of a lymph node
Cortex contains follicles with germinal centers, heavy with dividing B cells
Deep cortex houses T cells in transit
T cells circulate continuously among the blood,lymph nodes, and lymphatic stream.
Spleen
Largest lymphoid organs
functions of the spleen
Site of lymphocyte proliferation and immune surveillance and response.
Cleanses the blood of aged cells and platelets and debris.
Structure of the spleen two distinct areas
white and red pulp
White pulp
around central arteries Mostly lymphocytes on reticular fibers and involved in immune functions
Red Pulp
in venous sinuses and splenic cords Rich in macrophages for disposal of worn-out RBCs and bloodborne pathogens
Thymus
Increases in size and is most active during childhood. Stops growing durning adolescence and then gradually atrophies.
Differs from other lymphoid organs in important ways.
Thymus
Functions of the Thymus
It functions strictly in T lymphocyte maturation.
It does not directly fight antigens.
Thymocytes
Provide the environment in which T lymphocytes become immunocompetent
Tonsils
Simplest lymphoid organs
Crypts trap and destroy bacteria and particulate matter
Tonsils
Aggregates of lymphoid follicles
Peyer's patches and Peyer's patches and the appendix
clusters of lymphoid follicles
In the wall of the distal portion of teh small intestine.
Clusters of lymphoid follicles
Peyers patches and the appendix
Destroys bacteria preventing them from breaching the intestinal wall
Generate "memory" lymphocytes
Except for the spleen and tonsils ____________ _________ are poorly developed at birth
Lymphoid organs