Test 3 - Lymphatics

Question 1

What is the lymphatic system?

Answer 1

1. route for excess interstitial fluid to return to blood
2. allows for cells of immune system to travel, communicate, proliferate

Question 2

What are the lymphatic system components?

Answer 2

1. bone marrow
2. thymus
3. spleen
4. lymph nodes & lymphatic nodules
5. diffuse lymphatic tissue
6. lymph vessels

Question 3

Innate immunity

Answer 3

1. non-specific
2. pre-existing defense system that consists of chemical defense, physical barrier, phagocytic cells, and secretory substances that neutralize foreign cells

Question 4

Adaptive immunity

Answer 4

1. specific defense system
2. targets invaders that evaded innate (back-up)
3. two types: humoral & cellular immune

Question 5

Humoral response

Answer 5

antibody production

Question 6

Cellular immune response

Answer 6

targets “bad” cells for destruction by specific killer cells

Question 7

Which immunity goes with which progenitor line?

Answer 7

adaptive -> common lymphoid progenitor

innate -> common myeloid progenitor

Question 8

What are T-cells and where do they mature?

Answer 8

• responsible for cell-mediated immunity
• mature in thymus

Question 9

What are the 4 types of T-cells?

Answer 9

1. helper
2. cytotoxic
3. regulatory
4. gamma

Question 10

What are B-cells and where do they mature?

Answer 10

• reponsible for humoral response
• mature in bone marrow

Question 11

What are the 2 types of B cells?

Answer 11

1. plasma (make specific antibody)
2. memory (respond to next exposure)

Question 12

What is the function of a primary lymphoid organ?

Answer 12

where lymphocytes differentiate into immunocompetent cells

Question 13

Name primary lymphoid organs.

Answer 13

1. bone marrow (B)
2. thymus (T)

Question 14

What is thymic involution and why does it occur?

Answer 14

when the thymus starts to “deactivate” with age - around 20 the thymus becomes inactive, stops T-cell production and the organ turns into mainly adipose

Question 15

Histology of the thymus.

Answer 15

• CT capsule that extends from trabeculae
• Lymphoepithelial organ
• Lymphocytes & epithelioreticular cells
• Has cortex, medulla, Hassall’s corpuscle

Question 16

What are the secondary lymph tissues and organs and their functions? (2 fx)

Answer 16

1. sites of initial immune response
   - diffuse lymphatic tissue
   - lymphatic nodules
2. proliferation & differentiation
   - lymph node
   - spleen

(all are antigen-activated)

Question 17

Histology of the lymphatic nodule.

Answer 17

• doesn’t have a capsule
• discrete concentrations of lymphocytes in a reticular mesh framework
• active has a lighter germinal center (inactive dark throughout)

Question 18

What is the difference between the terms lymphatic nodule and lymph node?

Answer 18

nodule is patches of tissues that is not capsulated vs. nodes as “mini” organs that have a capsule and actually contain nodules

Question 19

What would you expect to see in a histology specimen of a lymph node?

Answer 19

• dense irregular CT capsule
• trabeculae extending into parenchyma
• reticular tissue

Question 20

What is the function of the spleen?

Answer 20

1. production of immunological response against bloodborne pathogens
2. removal of particulate matter & aged/defective blood cells from circulation

Question 21

Describe histology of the spleen.

Answer 21

• enclosed w/ capsule and has trabeculae
• 2 types of parenchyma (red pulp/white pulp)

Question 22

Differentiate between red and white pulp.

Answer 22

White pulp - dark because of lymphocyte nuclei - has nodules and immune functions
Red pulp - light reticular fibers and sinuses - filtration functions

Question 23

What is indicated by the presence of a secondary lymph nodule in the spleen?

Answer 23

that a pathogen has been detected since it is the first lymphatic organ to respond to a pathogen and also that the lymph nodule has been activated