Lymphatic System (chapter 18)

Lymphatic System -blood pressure pushes ______ from the blood into the _______ spaces around the ____ =>called _______ fluid -most of the fluid is ________ at the _____ end, but about _ liters a day is not -The Lymphatic system functions to ____ this _____ to the _____ stream =>called _____

Functions -Returns leaked ______ to the __________ -lymphatic ______ transport dietary _____ -lymphatic ______ house _________ Generates an ______ ______ and _______ the _________ population

Lymph and Lymph Vessels -lymph _______ return ______ to the venosus bloodstream (by ______ and ________) -lymphatic _______=>pick up _______ fluid (leaked ______) =>fluid is called ______ when it enters the _________ -Lymphatic ______ -Lymphatic ____ -Lymphatic ____ =>empty _____ back into _____ ciurculation

Lymph Capillaries -____ -______ tubes -overdosed ________ cells form ___-way flaps -occur everywhere blood ________ -Lacteals (special types of _______ _______) =>pick up ________ fluid, dietary _____, and _____-soluble _______ =>__lymph is called _____ -Absent from ___ _____ marrow, _ _ _, and _______ tissues

Lymphatic Vessels -Receive the _____ from the _______ -resemble small _____, have _ tunics and _____ -valves prevent _______ in the ___ pressure system

Lymphatic Trunks -drain _____ from the _____ _____ regions =>_______ , __________, ________________, ________, ________

Lymphatic Ducts -Thoracic duckt =>drains ______ left quadrant and _____ lower body -Righth lymphatic duct =>drains upper _____ quadrant

Lymphedema -accumulation of interstitial fluid usually caused by obstruction =>surgical removal of nodes =>malignant tumors of nodes =>radiation causing scar tissue =>trauma of infection of lymph vessels -lymphatic filariasis: type of edema where worms lodge in the lymphatic system -extreme cases is called elephantiasis -common in southeast Asia and Africa -No cure, but can be controlled

Lymphatic Cells -Macrophages =>monocytes tat have migrated from bloodstream =>phagocytes -Nurse Cells =>special epithelial cells that secrete thymic hormones -Dendritic Cells =>internalize antigens and present them to other lymphatic cells -Lymphocytes =>most abundant cell type =>B-lymphocyte, T-lymphocytes, and NK cells =>all three types migrate through the lymphatic system and search for antigens

Lymphopoieses RED BONE MARROW Hemopietic stem cell (all cells) Lymphoid stem cell NK cells B-lymphocytes

Lymphopoieses RED BONE MARROW Hemopietic stem cell (all cells) Lymphoid stem cell Thymic hormones help differentiate T-lymphocytes

T lymphocytes TWO MAIN TYPES 1. Helper -initiate and oversee immune response -present antigens to other cells -secrete cytokines =>chemical signals that bind to and activate other cells -targeted by AIDS 2. Cytotoxic (more direct) -kill by either secreting substances that break down the invading cell membrane or by triggering cell death TWO SUBSETS 1. Memory: patrol body after attack 2. Suppressor: turn off immune response

B Lymphocytes -respond to one particular antigen and produce immunoglobulins (antibodies) -cannot be activated until a helper T-lymphocytes present it with an antigen -Once activated creates plasma cells and memory B-lymphocytes =>plasma cells create antibodies =>antibodies bind to antigens. They immobilize, neutralize, and “tag” their targets for destruction by T-cells =>WBC

NK (Natural Killer) cells -NK cells can respond to multiple antigens =>each B and T cell can only respond to a single antigen =NK calls can kill a wide variety of infected cells and some cancerous cells

T-Lymphocyte Helper T-lymphocytes=initiates and oversees the immune response Cytotoxic T-lymphocytes=directly kills foreign cells, must be activated by a helper T-lymphocyte first Memory T-lymphocyte=a type of cytoctoxic T-lymphocyte that has already killed: patrols the body looking for the same antigen again Suppressor T-lymphocyte=helps “turn off” the immune response once it has been activated