Lymphatic System Notes
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The lymphatic system functions to: 1) Transport clean fluids back to the blood from tissues; 2) Drain excess fluids from tissues; and 3) Remove debris from cells of the body. Lymph is transported through lymphatic vessels in a passive, one-way system toward the heart, where it is returned to circulation. Along the way, lymph passes through lymph nodes which filter the lymph and provide an immune response. Other lymphoid organs like the spleen, thymus, tonsils, and Peyer's patches also contribute to lymphatic function and immune defense.
Lymphatic System Notes
- 1. Essentials of Human Anatomy & Physiology Anatomy & Physiology II The Lymphatic System Mr. Hildebrandt
- 2. The Lymphatic System • Lymphatic system functions: • Transport clean fluids back to the blood • Drains excess fluids from tissues • Removes “debris” from cells of body • Transports fats from digestive system Slide 12.1
- 3. When things go wrong…..
- 4. Lymphatic Characteristics • Lymph – excess tissue fluid carried by lymphatic vessels • It’s a passive system: • One way system toward the heart • No pump • Lymph moves toward the heart • Milking action of skeletal muscle • Rhythmic contraction of smooth muscle in vessel walls • Gravity effects movement
- 5. Lymphatic Capillaries • Fluid leaks through mini-valves into lymph capillaries • Higher pressure on the inside closes mini-valves
- 6. Lymphatic Vessels • Collects lymph from lymph capillaries • Delivers lymph to lymph nodes • Returns fluid to circulatory veins near the heart • Right lymphatic duct • Thoracic duct
- 8. Lymph Nodes • Filter lymph before it is returned to the blood • Defense cells in nodes: • Medulla houses macrophages which engulf and destroy foreign substances • Cortex nurtures lymphocytes which provide immune response to antigens (cortex)
- 9. Flow of Lymph Through Nodes • Lymph enters the convex side through afferent lymphatic vessels • Lymph flows through a number of sinuses inside the node • Lymph exits through efferent lymphatic vessels • Fewer efferent than afferent vessels causes flow to be slowed
- 10. Lymphoid Organs • Several other organs contribute to lymphatic function • Spleen • Thymus • Tonsils • Peyer’s patches Figure 12.5
- 11. The Spleen • Filters blood • Destroys worn out blood cells • Forms blood cells in the fetus • Acts as a blood reservoir
- 12. The Thymus • Functions at peak levels only during childhood • Produces hormones (like thymosin) to program lymphocytes
- 13. Tonsils • Small masses of lymphoid tissue around the pharynx • Trap and remove bacteria and other foreign materials • Tonsillitis is caused by congestion with bacteria
- 14. Peyer’s Patches “Tonsils of the intestine” • Found in the wall of the small intestine • Capture and destroy bacteria in the intestine
- 15. Mucosa-Associated Lymphatic Tissue (MALT) • Includes: • Peyer’s patches • Tonsils • Other small accumulations of lymphoid tissue • Acts as a sentinal to protect respiratory and digestive tracts