Outline the functions and position of the structural components, i.e. vessels, tissues and organs involved in draining of lymph into the blood.
What was the year, place, discovering of these references?
**Functions and Position of Structural Components Involved in Lymph Drainage**
1. **Lymph Capillaries**:
- Found within most tissues.
- Functions: Absorb interstitial fluid that accumulates in tissues. Begin the return voyage of lymph to the bloodstream.
2. **Lymphatic Vessels**:
- Larger vessels that lymph capillaries drain into.
- Functions: Carry lymph fluid toward the larger lymphatic ducts. They have one-way valves to prevent backflow.
3. **Lymph Nodes**:
- Positioned along the lymphatic vessels.
- Functions: Act as filters for harmful substances. Contain immune cells that can attack and destroy pathogens carried in the lymph.
4. **Lymphatic Trunks**:
- Located near major blood vessels.
- Functions: Drain lymph from relatively large body regions.
5. **Lymphatic Ducts**:
- There are two major ducts: the thoracic duct and the right lymphatic duct.
- Functions: Drain lymph from the trunks into the bloodstream.
- Position: The thoracic duct begins near the lower spine and collects lymph from most of the body, emptying into the left subclavian vein. The right lymphatic duct drains the right upper part of the body, emptying into the right subclavian vein.
6. **Thymus**:
- Located in the chest, just above the heart.
- Functions: Development of a specialized type of immune cells known as T lymphocytes (T cells).
7. **Spleen**:
- Positioned on the left side of the abdominal cavity.
- Functions: Filters blood, removes old and damaged red blood cells, stores white blood cells and platelets, and fights certain kinds of bacteria.
8. **Tonsils**:
- Located at the pharynx (back of the throat).
- Functions: Trap and remove pathogens entering the throat.
9. **Peyer's Patches**:
- Found in the small intestine.
- Functions: Monitor intestinal bacteria populations and prevent the growth of pathogenic bacteria in the intestines.
**Discovery and Understanding of the Lymphatic System:**
The understanding of the lymphatic system has evolved over centuries and its components were discovered at different times by various researchers:
- The existence of lymphatic vessels was first described by the Italian physician Gaspare Aselli in 1622.
- The thoracic duct was discovered by the Danish anatomist Thomas Bartholin in 1652.
- The function of the lymph nodes and their role in immune defense were not fully understood until much later, with contributions from numerous scientists in the 17th and 18th centuries.
- The understanding of the lymphatic system as a distinct entity separate from the blood circulatory system was established through the work of Olaus Rudbeck and Thomas Bartholin around the mid-17th century.
It's crucial to remember that the timeline provided above is not exhaustive and that the discovery and understanding of the lymphatic system's components unfolded gradually, with contributions from many scientists across different times and locations, primarily in Europe where much of early anatomical study and documentation took place.