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The Lymphatic System

The Lymphatic System . 3/5/14. What is it?. Lymphatic System = A vast collection of cells and biochemicals that travel in lymphatic vessels, and the organs and glands that produce them. Pathogens = disease-causing agents. Lymphatic Pathways.

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The Lymphatic System

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  1. The Lymphatic System 3/5/14

  2. What is it? • Lymphatic System = A vast collection of cells and biochemicals that travel in lymphatic vessels, and the organs and glands that produce them. • Pathogens = disease-causing agents.

  3. Lymphatic Pathways • Begin as lymphatic capillaries that merge to form larger lymphatic vessels. • Lymphatic vessels then lead to larger vessels that unite with the veins in the thorax. • Lymphatic capillaries – microscopic, closed-ended tubes that extend from interstitial (“between tissues”) spaces forming complex networks. • They resemble the blood vessels, except they don’t carry blood.

  4. Lymphatic Vessels • Lymph – fluid inside a lymphatic capillary. • Lymphatic vessels – tube-like tunnels that resemble blood vessels except with thinner walls. • Three layers • Endothelial layer(inner lining) • Smooth muscle (middle layer) • Connective tissue (outer layer)

  5. Lymph Nodes • Lymph node = specialized organs that lymph vessels lead to. • After leaving the lymph nodes, vessels merge into lymph trunks. • Lymph trunks: • Drain lymph from the lymphatic vessels • Named for the regions they serve • Example: intestinal trunk drains lymph from the abdominal area.

  6. Ducts • Lymphatic trunks then join 1 of 2 collecting ducts: • Thoracic duct • Right lymphatic duct **see figure 16.4 on pg. 619

  7. Thoracic Duct • = the larger and longer of the 2 collecting ducts • Originates in the abdomen • Drains lymph from intestinal, lumbar, and intercostal (rib area) trunks.

  8. Right Lymphatic Duct • Originates in the right thorax • Lymph from the right side of the head and neck, the right upper limb, and the right thorax enters this duct.

  9. Structure of a Lymph Node • Lymph nodes vary in size and shape, but are usually less than 2.5 cm (1 inch) long and are somewhat bean-shaped. • Hilum – indented region of the node. • Lymph nodules – masses of lymphocytes and macrophages in the cortex that are the functional units of the lymph nodes.

  10. Locations of Lymph Nodes • Cervical Region • Axillary Region • Supratrochlear Region • Inguinal Region • Pelvic Cavity • Abdominal Cavity • Thoracic Cavity

  11. Functions of Lymph Nodes 2 Primary Functions • Filtering potentially harmful particles from lymph before returning it to the bloodstream • Monitoring body fluids provided by lymphocytes and macrophages. **Lymphocytes attack viruses, bacteria, and other parasitic cells within the lymph nodes.

  12. Thymus • Thymus – soft, bilobed (2 lobes) structure enclosed in a connective tissue capsule. • Located anterior to the aortic arch, posterior to the superior part of the body of the sternum. • It varies in size, and is proportionally larger during infancy and early childhood.

  13. Spleen Spleen – largest lymphatic organ and is located in the upper left portion of the abdominal cavity, inferior to the diaphragm, posterior and lateral to the stomach. • Spaces in the in the chambers of the spleen are filled with blood.

  14. Unit Assignment • Do pg. 648, “Chapter Assessment”: 3-5, 7, 9-10, 12-14,18,28,31,39,47, and critical thinking #4. Due Friday, March 21st by midnight.

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