1. Chapter 20: Lymphatic System

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Lymph
Lymph: clear fluid that resembles plasma and is formed from plasma during capillary exchange
Composition of lymph: water, electrolytes (Na+ and Cl-), waste from metabolizing cells, and some Albumin (protein) that leaks out of the capillaries of the systemic circulation
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Lymph (cont’d.)
Formation: water and dissolved solute filters out of capillaries and into tissues  tissue fluid drains into lymphatic vessels  drains into larger ducts and then into blood
20 L/24 hours is formed
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Lymphatic Vessels
Lymph capillaries and blood capillaries.
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5. Lymphatic Vesselks (cont’d.)
Lymphatic vessels: includes lymphatic capillaries and several larger lymphatic vessels; “run with” the veins
Veins similar to blood vessels, including valves
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6. Lymphatic Vessels (cont’d.)
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7. Lymphatic Vessels (cont’d.)
Drainage of lymph:
Most lymph drains into the thoracic duct
Lymph from the right arm, right side of
head, and thorax drain into right lymphatic
duct
Both ducts empty into the subclavian veins
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8. Lymphatic Vessels (cont’d.)
Forces that move lymph:
Not pumped like blood
Moves in response to:
skeletal muscle contraction
chest movement
contraction of smooth muscle in the
lymphatic vessels
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9. Lymphatic Vessels (cont’d.)
Elephantiasis
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10. Lymphatic Vessels (cont’d.)
lymphedema
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Lymphoid Organs
Organs:
Lymph nodes
Tonsils
Thymus gland
Spleen
Functions:
Filter particles from lymph, tissue fluid, and blood
Support immune activities of lymphocytes
Protect body against infection
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12. Lymphoid Organs (cont’d.)
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13. Lymphoid Organs (cont’d.)
Lymph nodes: small pea-shaped patches of lymphatic tissue that filter lymph as it flows through the lymphatic system
Cervical lymph nodes drain and cleanse lymph from head and neck areas
Axillary lymph nodes drain and cleanse lymph from upper extremities, shoulders, and breast area
Inguinal lymph nodes drain and cleanse lymph from lower extremities and external genitalia
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14. Lymphoid Organs (cont’d.)
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15. Lymphoid Organs (cont’d.)
Lymphoma
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16. Lymphoid Organs (cont’d.)
Tonsils: partially encapsulated lymph nodes in the throat area
Locations:
Palatine tonsils: opening of oral cavity into pharynx
Pharyngeal tonsils: opening of nasal cavity in upper pharynx (also called “adenoids”)
Lingual tonsils: back of the tongue
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17. Lymphoid Organs (cont’d.)
Tonsils
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18. Lymphoid Organs (cont’d.)
Tonsillitis
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19. Lymphoid Organs (cont’d.)
Tonsillectomy
Postoperative bleeding is a concern
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20. Lymphoid Organs (cont’d.)
Thymus gland: produces and helps differentiate the lymphocytes (T cells), located in the upper mediastinum thoracic cavity, shrivels up after puberty
Plays an important role in the immune response
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21. Lymphoid Organs (cont’d.)
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22. Lymphoid Organs (cont’d.)
Spleen: largest lymphoid organ in the body; located in the upper left quadrant of the abdominal cavity just beneath the diaphragm
Very vascular
Considered a large
lymph node
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23. Lymphoid Organs (cont’d.)
Functions of the spleen:
Filters blood
Stores blood
Has resident WBCs that phagocytose microorganisms
Removes worn-out red blood cells and platelets
Produces RBCs before birth
When injured, presents a major bleeding problem  spleenectomy may be needed
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