• formed by the continual seepage of fluid from blood across capillary walls into the surrounding CT
• primarily water plus small plasma proteins, nutrients, wasts, gases, electrolytes, enzymes, & hormones
• returns plasma proteins back to the blood stream, transports antigens to lymph nodes, & transports lipids & lipid-soluble vit absorbed in the GI tract to blood stream - also the means for lymphocytes to circulate
• lymphocytes found in lymph

• diffuse lymphatic tissue
• lymphatic nodules
  • tonsils
  • Peyer's patches
  • Appendix
• lymphatic organs
  • primary organs - bone marrow, thymus
  • secondary organs - lymph node, slpeen

• accumulation of immune cells
• usually found in CT underneath an epithelium sheet in GI tract, respiratory tract, & genitourinary tract
• GALT: gut-associated lymphatic tissue
• MALT: mucosa-associated lymphatic tissue
• BALT: Bronchial-associated lymphatic tissue
• these cells recognize foreign antigens that have broken through epithelial barriers

• groups of B-lymphocytes in CT
• group of lymphatic nodules found in tonsils, tongue, lymph nodes, slpeen, sm intestine Peyer's patches, & apendix
• contain immune cells that will react to foreign molecules & start to destroy them

Bone Marrow

• called a primary lymhatic organ because it's the location for B cell or B lymphocyte maturation
• if B cells do not mature properly in the marrow there will not be B cells in any other lyphatic tissue in the body

• called primary lymphatic organ because it's major function is the maturation & differentiation of T cells or T lymphocytes
• if it's missing or non-functional, there will not be any T cells in lymphatic organs throughout body

• cortex: periphery of thymus
  • immature T cells that cannot function in immune reactions
• medulla: central protion of thymus
  • T cells that can leave the thymus & function in the body to combat antigens & infections

• secondary lymphatic organ
• connected to lymphatic vessels which permit the lymph flow through the lymph nodes
• functions:
  • filter lymph
  • remove dead bacteria & other particulate matter from lymph
  • produce lymphocytes & antibodies
  • store lymphocytes

• cortex: contains lymphatic nodules w/lots of B cells
• deep cortex: contains lots of T cells
• medulla: contains lots of plasma cells

• lymph enters lymph node & flows through tissue
• lymph slowed down & particulate matter & degenerating cells are removed
• andibodies & T & B lymphocytes are added to lymph as it passes through lymph node

• secondary lymphatic organ
• largest lymphatic organ

• hemopoiesis during fetal developement & compensatory hemopoiesis in adult life
• destruction of aged & abnormal RBC
• filtration of blood: removal of antigenic material & cellular debris from body by macrophages & dendritic cells
• activation of T & B cells & production of antibodies
• acts as a reservoir for erythrocytes & platelets

• in fresh spleen it appears as round pale white areas
• blood vessel called a central artery
• lymphatic nodules w/B cells
• periarterial lymphatic sheath (PALS) w/T cells

• in fresh state, it is red because of all the blood
• material surrounding white pulp
• all positive types of blood & immune cells
• capillary called splenic sinusoid

• antigens enter spleen from blood
• antigens reach central artery in white pulp
• antigen presenting cells, T cells in PALS, & B cells in lymphatic nodules interact w/antigens & each other
• B cells are introduced to proliferate into plasma cells
• plasma cells release antibodies into circulation