Lymphatic System

1) A network of three parts 2) Lymph 3) Lymph nodes

Returns interstitial fluid and leaked plasma proteins back to the blood.

immune system.

Lymphatic vessels.

Lymphatic capillaries Lymphatic collecting vessels Lymphatic trunks and ducts.

Lymphatic capillaries.

lymphatic capillaries

Lacteals

Similar to veins, except Have thinner walls, with more internal valves.

Formed by the union of the largest collection ducts.

is delivered into one of two large ducts

Drains the right upper arm and the right side of the head and thorax.

arises from the cisterna chyli and drains the rest of the body.

each empties lymph into venous circulation at the junction of the internal jugular and subclavian veins on its own side of the body

Pulsations of nearby arteries and Contractions of smooth muscle in the walls of the lymphatics.

The main warriors of the immune system

T Cells And B Cells

T cells and b cells protect against antigens.

Phagocytize foreign substances and help activate T-cells

Cells that capture antigens and deliver them to lymph nodes.

produce stroma that supports other cells in lymphoid organs.

Houses and provides a proliferation site for lymphocytes.

Diffuse Lymphatic tissue and Lymphatic follicles

comprises scattered reticular tissue.

nodules are solid, spherical bodies of tightly packed reticular elements and cells.

composed of dendritic and B cells

Principal lymphoid organs of the body

Filter lymph and Immune system

Lymphocytes are activated and mount an attack against antigens.

Cortex and medulla

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.

Largest lymphoid organs

Site of lymphocyte proliferation and immune surveillance and response. Cleanses the blood of aged cells and platelets and debris.

white and red pulp

around central arteries Mostly lymphocytes on reticular fibers and involved in immune functions

in venous sinuses and splenic cords Rich in macrophages for disposal of worn-out RBCs and bloodborne pathogens

Increases in size and is most active during childhood. Stops growing durning adolescence and then gradually atrophies.

Thymus

It functions strictly in T lymphocyte maturation. It does not directly fight antigens.

Provide the environment in which T lymphocytes become immunocompetent

Simplest lymphoid organs

Tonsils

Peyer's patches and Peyer's patches and the appendix

Clusters of lymphoid follicles

Destroys bacteria preventing them from breaching the intestinal wall Generate "memory" lymphocytes

Lymphoid organs