1 Lymphatics System Выполнил: Ахмад Фавад Азиз Проверила: Группа: 030_2 Факультет: Общая Медицина

Lymphatics System

Lymphatic System  It is responsible for the removal of interstitial (extracellular) fluid from tissues.  protects body against foreign material  assists in circulation of body fluids between cells and bloodstream  transports dietary fats 3

Lymphatic System (cont.)  Consists of: - lymph - network of vessels - lymph nodes and nodules - tonsils - spleen - thymus gland - bone marrow 4

5 Lymphatic System  One way system: to the heart  Return of collected excess tissue fluid  Return of leaked protein  “Lymph” is this fluid  Edema results if system blocked or surgically removed

6  Lymph capillaries  Have one way minivalves allowing excess fluid to enter but not leave  Picks up bacteria and viruses as well as proteins, electrolytes and fluid (lymph nodes destroy most pathogens)

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8  Lymph capillaries  Absent from bone, bone marrow, teeth, CNS  Enter lymphatic collecting vessels  Lymphatic collecting vessels  Similar to blood vessels (3 layers), but thin & delicate  Superficial ones in skin travel with superficial veins  Deep ones of trunk and digestive viscera travel with deep arteries  Very low pressure  Distinctive appearance on lymphangiography  Drain into lymph nodes

9  Lymph nodes: bean shaped organs along lymphatic collecting vessels  Up to 1 inch in size  Clusters of both deep and superficial LNs

10 Superficial groups -Cervical -Axillary -Inguinal Deep groups -Tracheobronchial -Aortic -Iliac Drainage -Superior R 1/4 of body: R lymphatic duct (green) * -The rest: thoracic duct * Lymph Nodes * *

11  Fibrous capsule sends in dividing trabeculae  Afferent & efferent lymphatic vessels  Lymph percolates through lymph sinuses  Follicles: masses of lymphoid tissue divided into outer cortex & inner medulla (details in later slides)

12 Macrophages on reticular fibers consume pathogens and foreign particles Usually pathogen free lymph enters lymph trunks

13 Lymphatic Trunks (all are paired except the intestinal trunk)  Lumbar  Intestinal  Receives fatty lymph (chyle) absorbed through lacteals in fingerlike villi of intestines  Broncho- mediastinal  Subclavian  Jugular

14 Lymph ducts (variable)  Thoracic duct: everyone has  20% also have a right lymphatic duct * 20%

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Lymph Vessels  Lymphatic capillaries – diffuse, highly permeable due to presence of:  Minivalves loosely overlapping endothelial cells  Collagen fiber attachment to surrounding structures prevents collapse of capillary  Lymphatic collecting vessels like veins but thinner walled w/ more valves and anastomoses  Lymphatic trunks – lumbar, bronchomediastinal, subclavian, jugular and intestinal  Lymphatic ducts – Right Lymphatic Duct & Thoracic Duct 16

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Lymphatic Capillaries  During inflammation, lymph capillaries can absorb:  Cell debris  Pathogens  Cancer cells  Cells in the lymph nodes cleanse and “examine” this debris  Lacteals – specialized lymph capillaries present in intestinal mucosa  Absorb digested fat and deliver chyle to the blood 18

Lymphatic Collecting Vessels  Have the same three tunics as veins  Have thinner walls, with more internal valves  Anastomose more frequently  Collecting vessels in the skin travel with superficial veins  Deep vessels travel with arteries  Nutrients are supplied from branching vasa vasorum 19

Lymph Transport  The lymphatic system lacks a pumping organ  Vessels are low-pressure conduits  Uses the same methods as veins to propel lymph:  Pulsations of nearby arteries  Contractions of smooth muscle in the walls of the lymphatics 20

Lymphoid Tissue  Diffuse lymphatic tissue – scattered reticular tissue elements in every body organ  Larger collections appear in the lamina propria of mucous membranes and lymphoid organs  Lymphatic follicles (nodules) – solid, spherical bodies consisting of tightly packed reticular elements and cells  Germinal center composed of dendritic and B cells  Found in isolation and as part of larger lymphoid organs 21

Spleen  largest lymphatic organ  located in upper left abdominal quadrant  between fundus of stomach and diaphragm  5-6 inches long, 2-3 inches wide  resembles a large lymph node  filters blood 22

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Structure of Spleen  capsule - covering of dense connective tissue  hilum - depression on medial surface - nerves and arteries enter spleen, veins and lymphatic vessel exit 24

Thymus Gland  two-lobed organ  located in upper part of chest along trachea  inferior to thyroid gland, posterior to sternum  largest and most active during prenatal period and infancy  after puberty it decreases in size 25

Thymus  Prominent in newborns, almost disappears by old age  Function: T lymphocyte maturation (immunocompetence)  Has no follicles because no B cells 26

Tonsils  Simplest lymphoid tissue: swellings of mucosa, form a circle 27 Palatine (usual tonsillitis) Lingual (tongue) Pharyngeal (“adenoids”) Tubal