Lymphatic System

Question 1

primary action of lymphatic system

Answer 1

• production and distribution of lymphocytes

- return of lost tissue fluid (lymph) to bloodstream

Question 2

components

Answer 2

1. lymph:
   - reabsorbed tissue fluid
   - similar to plasma with less protein
   - may contain lymphocytes, platelets, and fat globules
2. lymph capillaries:
   - dead-ended, simple endothelial tubes
   - uneven distribution (none in CNS, epidermis, or cartilage)
   - “lacteals”: special lymph capillaries throughout small intestine; absorb dietary fat (chyle)
3. lymph vessels:
   - very thin, contain many valves
   - travel between connective tissue and skeletal muscles
4. lymph nodes:
   - small (< 1in) lymphoid organs along lymphatic pathway
   - abundant in cervical, axillary, and inguinal regions
   - contain macrophages to filter bacteria, foreign debris, and cell fragments
   - produces lymphocytes that add antibodies to lymph

Question 3

lymph vessel destination

Answer 3

1. thoracic duct:
   - enters bloodstream at junction of the left subclavian/jugular vein.
   - drains entire left and lower right side of the body
2. right lymphatic duct:
   - enters bloodstream at the junction of the right subclavian/jugular vein
   - drains upper right side only

Question 4

major lymphatic organs and tissues

Answer 4

-not directly in lymph flow; possess only efferent lymph vessels

1. Spleen:
   - ovoid; in upper left quadrant
   - contractile; smooth muscle covering
   - white pulp= source of lymphocytes that manufacture and release antibodies
   - red pulp= stored or developing erythrocytes
2. Tonsils (palatine, pharyngeal, lingual) :
   - lymphoid nodules (connective tissue + lymphocytes)
   - guard oral and nasal entrances
3. Thymus:
   - two lobes; in mediastinum
   - retrograde development
   - manufacturers/distributes “active” T lymphocytes
   - hormonal secretion of thymosin, which promotes immune functions

Question 5

Summary of lymphatic functions

Answer 5

1. produces lymphocytes (agranular wbc)
2. filters lymph; removes foreign material
3. receives fatty food products from small intestine
4. returns lost tissue fluid and plasma proteins to circulation
5. responsible for immunity via antibody production