The Lymphatic System
Consists of two parts
Lymphoid tissues and organs
Lymphatic system functions
Transports escaped fluid back to the blood
Plays essential roles in body defense and resistance to disease
Also has a role in digestion
DevelopmentalAspects of the lymphatic system and the Body Defenses
Except for the thymus and spleen, the lymphoid organs are poorly developed before birth.
Anewborn has no functioning lymphocytes at birth, only passive immunity from the mother
If lymphatics are removed or lost, severe edema results, but the vessels may grow back in time.
Central Lymphoid tissue
Hematopoietic stem cells: precursor for all blood cells
Leukocytes except T lymphocytes fully develop here.
T lymphocytes migrate from bone marrow to thymus
Develop maturity in thymus.
Thymus turns to fat as we get older because most diseases are seen when we are younger.
Vaccines is modern technology to reveal us to diseases so we know how to fight them.
Peripheral Lymphoid tissue
Spleen. lymph nodes, tonsils, adenoid, appendix, Peyer’s patches
Collection of B cells, T cells, and macrophages.
Functions to trap microorganisms and foreign particles Work to expose them to leukocytes in high concentrations
Spleen and Lymph nodes filter blood and lymph.
Lymphoid Organs that contribute to Lymphatic Function
Located on the left side of the abdomen
Filters blood and destroys worn out blood cells
Forms blood cells in the fetus
Acts as a blood reservoir
located low in the throat, overlying the heart
Functions at peak levels only during childhood
Produces hormones (like thymosin) to program lymphocytes
Masses of lymphoid tissue around the pharynx
Trap and remove bacteria and other foreign material
Tonsillitis is caused by congestion with bacteria
Found in the wall of the small intestine and