Ch 20 & 21 Lymphatic System and Immunity

Ch 20 & 21 Lymphatic System and Immunity - Ch 20...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Ch. 20: The Lymphatic System Overview Anatomical organization: 3 components o Lymphatic vessels originate in periphery, drain into veins o Lymph fluid w/in lymphatic vessels; similar to plasma but lower [protein] o Lymphoid organs & tissues contain lymphocytes connected to lymphatic vessls Functions: 3 primary tasks o Production and distribution of lymphocytes o Return of fluids and solutes from peripheral tissues to blood Aids in maintenance of blood volume and blood pressure Stabilizes composition of interstitial fluid o Absorption of digested fat from the gut Lymphatic vessels Lymphatic capillaries Smallest lymphatic vessels Originate as blind-ended pockets in peripheral tissue Differ structurally from cardiovascular capillaries in the following ways: Lger diameter Thinner walls =>leaky = less selectively permeable lge proteins, viruses, bacteria excluded from blood can enter lymph due to endothelium but basement membrane incomplete endothelial cells not held together, just overlapped =>overlap creates one-way door, prevents outflow Smaller lymphatic vessels Resemble small and medium veins Collect lymph from lymphatic capillaries Have internal valves, like veins, to prevent backflow Major lymph-collecting vessels 2 sets: Superficial lymphatics drain the skin and mmbs of body cavities Deep lymphatics drain organs =>larger than superficial lymphatics Both sets converge to form the largest lymphatic vessels: Thoracic duct =>collects from ¾ body: all lower, upper left quadrant =>begins at cisterna chyli =>drains into left subclavian vein, near left internal jugular Right lymphatic duct =>collects from upper right quadrant =>drains into right subclavian vein Blockage of lymphatic vessels prevents collection of excess extravasated fluid and results in the accumulation of fluid in interstitial spaces around organs and tissues = EDEMA
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Types of Lymphocytes Lymphocytes are agranular leukocytes (white blood cells, or WBCs) Circulating lymphocytes make up ~30% of total circulating WBCs =>most lymphocytes are not in circulation, they in lymphoid organs 3 classes of lymphocytes: T-cells B-cells NK (natural killer) cells All lymphocytes are formed in bone marrow. T-cells (80% circulating lymphocytes) During maturation of the immune system, some lymphocytes migrate out of bone marrow to the thymus (a lymphoid organ), come under the influence of thymic hormones and become T-cells. The “T” stands for thymus-dependent . Subtypes of T-cells : Cytotoxic T-cells (T c ) Responsible for cell-mediated(cellular) immunity Attack foreign or infected cells directly and kill them Helper T-cells (T H ) Coordinate activation of both cytotoxic T-cells and B cells = Regulatory T-cells Suppressor T-cells (T s ) Coordinate inhibition of both cytotoxic T-cells and B cells = Regulatory T-cells B-cells (10-15% circulating lymphocytes) During maturation of the immune system, B cells remain in bone marrow and are influenced by
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 07/23/2009 for the course BIOL 1141 taught by Professor Loripaul during the Summer '09 term at UMSL.

Page1 / 12

Ch 20 & 21 Lymphatic System and Immunity - Ch 20...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online