Lymphatic System

Question 1

Primary lymphoid organs

Answer 1

Production and maturation

1. Bone marrow- B cells
2. Thymus- T cells, involuted now
3. Fetal liver

Question 2

Secondary lymphoid organs

Answer 2

Lymphocyte activation

1. Lymph nodes
2. Spleen
3. Mucosal-associated lymph tissue (MALT)

Question 3

Lymphatic vessels

Answer 3

Transports lymph and leukocytes
Not found where stimulation causes damage
*cartilage, CNS, cornea, epidermis
Muscle contractions and one-way valves
Lymphatic and circulatory connected- thoracic duct and cisterna chylie

Question 4

Thymus

Answer 4

Bilobed
1. Outer cortex- darker staining, more T cells
2. Inner medulla- lighter staining, less T cells, dendritic cells, epithelial cells, macrophages, Hassall’s Corpuscles
*above heart
Stromal cells- helps prevent autoimmunity

Question 5

Hassall’s Corpuscles

Answer 5

In inner medulla of thymus

Don’t really know what function is

• might have autoimmune function
• not found in all mammals

Question 6

Lymph nodes (secondary lymphoid organ)

Answer 6

Numerous
Grand central station of immune response
Antigens and dendritic cells enter afferent vessels (exit=efferent)
*follow chemokine signals
Swelling

Question 7

Spleen (secondary lymphoid organ)

Answer 7

Like giant lymph node
Stops infection from spreading- filters blood
*Red pulp- phagocytosis of old/damaged RBCs and antigens/microbes from blood
*While pulp- area of lymphocytes around arteriolese

Question 8

Asplenia

Answer 8

Life-long risk of infection
*encapsulated bacteria can’t be phagocytized
Vaccinate
Prophylactic antibiotics

Question 9

Mucosal Immune system (secondary lymphoid organ)

Answer 9

Encounter antigens in greater number and frequency

1. GI
2. Respiratory
3. Urogenital
4. Salivary and lacrimal glands

Question 10

Peyer’s Patches (secondary lymphoid organ)

Answer 10

Like lymph nodes w/o encapsulation

*in epithelial lining of gut

Question 11

Extravasation

Answer 11

Blood cells thru unruptured vessel wall into tissue
CAMs
1. Selectins
2. Integrins

Question 12

Chemotaxis

Answer 12

Receptor-mediated movement thru tissue

Chemokines > neutrophils to area > T/B cells to secondary tissue

Question 13

Lymphocyte recirculation

Answer 13

Naive cells recirculate between blood and lymph until antigen encounter or death

• Enter lymph nodes via endothelial venules, re-enter blood thru lymphatic and thoracic duct
• Enter/exit spleen thru blood vessels