1. The Lymphatic System & Lymphoid Tissue
Chapter 16

2. The Lymphatic System
A widespread system of tissues & vessels, scattered throughout the body
Services all regions of the body except:
Bone tissue
Cartilage
Epithelium
Central Nervous System

3. Functions Fluid Balance Protection from Infection
Clear fluid that circulates in the lymphatic system is called LYMPH (formed from blood plasma)
Excess fluid left in tissues is drained through LYMPHATIC VESSELS
Protection from Infection
Important component of the immune system
LYMPHOCYTES (a type of white blood cell) attack & destroy foreign organisms

4. Absorption of Fats
Digested fats that are too large to enter the blood capillaries are absorbed into the LYMPHATIC CAPILLARIES
Fats are then added to the blood when lymph joins the bloodstream

5. Lymphoid Tissue
Distributed throughout the body and makes up the specialized organs of the LYMPHATIC SYSTEM
LYMPH NODES
Designed to filter the lymph once it is drained from the tissue
Small, rounded masses varying from pinhead size to as long as one inch
Seldom isolated; they are massed together varying in number from 2 to 3 to well over one-hundred
Some are placed deeply, others superficially

6. Main Groups of Lymph Nodes
Cervical Nodes
Located in the neck
Both deep & superficial groups
Become enlarged during upper respiratory infections

7. Axillary Nodes Located in the armpits
May become enlarged after the infections of the upper extremities & breast
Breast cancer cells often metastasize to these nodes

8. TracheoBronchial Nodes
Located near the TRACHEA and around the large BRONCHIAL tubes
People living in highly polluted areas may have these nodes filled with carbon particles that actually resemble pieces of coal

9. Mesenteric Nodes Located near the lining of the stomach cavity
Approximately 100 to 150 of these nodes in this area of the body
Enlarged mesenteric lymph nodes indicated by the arrow

10. Inguinal Nodes Located in the groin region
May become enlarged after infections of the lower extremities

11. 2. The Spleen
An organ containing lymphoid tissue designed to filter the blood
Located in the upper left of the abdomen & is protected by the lower part of the rib cage
Soft, purplish & somewhat flattened
Contains phagocytes & lymphocytes
Cleanses blood of impurities
Destroys old, worn out red blood cells

12. 3. The Thymus
The thymus gland is a pink-grey organ that lies beneath the sternum
Key role in immune system development before birth & first few months of infancy
Most active during early life
After puberty, tissue shrinks in size & is replaced by connective tissue and fat

13. 4. The Tonsils
Masses of lymphoid tissue located in the vicinity of the pharynx (throat)
Remove contaminants from materials that are inhaled or swallowed
Located in three areas: palatine, pharyngeal & lingual

14. Palatine Tonsils
Located on each side of the soft palate

15. Pharyngeal Tonsils Commonly referred to as the ADENOIDS
Located behind the nose on the posterior wall of the upper pharynx

16. Lingual Tonsils
Small mounds of tissue located at the back of the tongue

17. Disorders of the Lymphatic System & Lymphoid Tissue
Lymphangitis – inflammation of the lymphatic vessels
May start in the region of an infected and/or neglected injury
Can be seen as red streaks, meaning bacteria has spread to the lymphatic system
If lymph nodes are NOT able to stop infection, pathogens enter the bloodstream & cause SEPTICEMIA (blood poisoning)

18. 2. Lymphedema Swelling due to obstruction of lymph flow
Causes include:
Infection of lymphatic vessels
Malignant growth blocking lymph flow
Loss of vessels & nodes as a result of injury or surgery

19. 3. Lymphadenopathy Disease of the lymph nodes
Sometimes common in a number of cancerous and infectious diseases:
HIV
Infectious Mononucleosis
Enlarged lymph nodes are commonly referred to as SWOLLEN GLANDS

20. 4. Splenomegaly An enlargement of the spleen
Accompanies certain acute infections:
Scarlet Fever (caused by a strep infection in the throat)
Typhus Fever (disease spread by lice or fleas)
Typhoid Fever (a bacterial infection - most commonly caused by Salmonella; spread by contaminated food or water. Following ingestion, the bacteria spread from the intestine via the bloodstream to the intestinal lymph nodes, liver, and spleen via the blood where they multiply.
Syphilis (bacterial STD)

21. 5. Lymphoma
Any tumor, benign or malignant, that occurs in lymphoid tissue
Malignant lymphoma includes:
Hodgkin’s Disease – a chronic, malignant disease of lymphoid tissue
Cause unknown, but thought to involve a viral infection
Rises in 2 age groups: early 20’s among men & women and again after age 50, primarily in men
Painless enlargement of lymph nodes in the neck, armpit, thorax or groin
May spread if not treated early
Symptoms include: weight loss, fever, night sweats, fatigue, anemia & decline of immune defenses

22. 2. Non-Hodgkin’s Lymphoma
More common than Hodgkin’s
Appears mostly in older adults and patient’s with immune deficiencies
Enlarged cervical nodes may be an early sign
More widespread through the lymphatic system than Hodgkin’s & spreads more readily to other tissues
May be related to a viral infection
Cure rate only 50% with chemotherapy & radiation