(Unit IX) Lymphatic System .pptx........

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1. Lymphatic System A&P-I Unit- IX

2. Objectives At the end of this lecture the students will be able to: Define lymph & lymphatic system Identify the organs and tissues of lymphatic system Describe the general functions of the lymphatic system Describe how lymph is formed Describe the lymph vessels & how lymph is returned to the blood vessels Describe the structure and functions of the lymph nodes, nodules, spleen and the thymus glands.

3. Lymphatic System An organ system consisting of lymphatic vessels, lymph nodes, tonsils, spleen, thymus and functions that include the recovery of tissue fluid and immunity.

4. Terms Definitions Lymph The fluid in lymphatic vessels and lymph nodes produced by the absorption of tissue fluid. Lymph Node A small structure found along the course of a lymphatic vessel that filters the lymph and contains lymphocytes and macrophages which respond to antigens in lymph.

5. Lymphatic System Lymphatic system consists of: fluid called lymph Lymphatic vessels Structures—lymphatic organs and tissues Lymph (=clear) is actually interstitial fluid but called lymph when passed into lymphatic vessels. And interstitial fluid is plasma but with less minor plasma proteins.

6. Lymph Flow Lymphatic capillaries  Lymph collecting vessels  Lymph nodes (sit along collecting vessels)-clean lymph of pathogens, they are NOT glands)  Lymphatic trunks (larger collecting vessels )  Lymphatic ducts (the largest collecting vessels that finally empty into veins of neck)

7. Forces to make lymph flow Lymph flow through vessels is facilitated by: Pulsation of nearby arteries Contraction of surrounding skeletal muscle Regular movement of body Inhalation process Lymph flows at lower speed than venous blood. Like veins the lymph vessels have valves to prevent back flow of lymph.

8. Lymphatic System Functions: to collect excess tissue fluid and return it back into bloodstream. To carry out immune response. To transport dietary lipid and lipid soluble vitamins.

9. Lymphatic Capillaries Lymphatic capillaries are blind vessels and slightly larger in diameter than blood capillaries. Lacteals (milky) In mucosa of small intestine, the lymph vessels receive digested fat. Due to milky appearance they are called lacteals. Fatty lymph becomes milky called Chyle . Chyle goes to bloodstream.

10. Lymph Trunks and Ducts Lymph passes from lymphatic capillaries into lymphatic vessels. Lymphatic vessels unite to form lymph trunks. The trunks are: Lumbar, intestinal, bronchomediastinal, subclavian, and jugular trunks.

11. Lymph Trunks and Ducts cont …. Lumber Trunks ( Rt and Lt)—drain lymph from lower limbs, pelvis, kidneys, adrenal gland and abdominal wall. Intestinal Trunk —drains lymph from the stomach, intestines , pancreas, spleen, and liver. Bronchomediastinal Trunks —drain lymph from the thoracic wall, lungs, and heart. Subclavian Trunks —drain the upper limbs. Jugular Trunks —drain the head and neck. These trunks open into larger vessels called lymph ducts.

12. Lymph Ducts The two ducts are the left and right lymphatic duct. Left L ymphatic Duct or Thoracic Duct : 15—18 inch in length. Begins as a dilation at the level 2 nd lumber vertebra anteriorly called cisterna (cavity/reservoir) chyli . The main duct for lymph return. Cystena chyli receives lymph from Rt and Lt lumber trunks and intestinal trunk. In the chest, the thoracic duct receives lymph from left bronchomediastinal trunk .

13. Thoracic Ducts cont … In the neck, the thoracic duct receives lymph from left jugular, and left subclavian trunk. The thoracic duct receives lymph from the left side of head, neck, chest, upper limb, and the entire body inferior to the ribs. The thoracic duct in turn drains lymph into venous blood at the junction of the left internal jugular and left subclavian vein.

14. Lymph Ducts cont …. Right Lymphatic Duct: 0.5 inch long It receives lymph from the right jugular, right subclavian, and right bronchomediastinal trunk. Thus, the right lymphatic duct receives lymph from the upper right side of the body. It finally drains its lymph into the venous blood at the junction of the right internal jugular and right subclavian vein.

15. Right and Left Lymphatic Drain

16. Lymphatic Organs and Tissues Primary Lymphatic Organs –the sites where B and T lymphocytes are produced and trained. They are Bone marrow and Thymus gland. Secondary Lymphatic Organs and tissues —the sites where immune responses are carried out. Secondary organs are lymph nodes and spleen. T he aggregations of lymph nodules are called tonsils.

17. Lacteals

18. Function of Lymphatic System  To collect and return interstitial fluid (approximately 3 liters daily), including plasma protein to the blood and thus help maintain fluid balance. To defend the body against disease by producing lymphocytes . To absorb lipids from the intestine (in the villi of the small intestine) and transport them to the blood via the lacteals and lymph vessels.