Organs and Tissues of the Immune System

Question 1

What are the primary lymphoid organs of the B and T cells?

Answer 1

B cells mature in bone marrow

T cells mature in thymus (precursor cells migrate from bone marrow)

Question 2

Once in the thymus, T cells begin expressing surface ____ molecules

Answer 2

TCR

Question 3

These are the organs where lymphocytes respond to antigens by undergoing clonal selection and proliferation

Answer 3

secondary lymphoid organs

Question 4

The most important secondary lymphoid organs are?

Answer 4

spleen, lymph nodes, MALT

Question 5

What is the major site of hematopoiesis in adults?

Answer 5

bone marrow - especially sternum, vertebrae, iliac bones, and ribs

Question 6

Hematopoietic stem cells express what two markers?

Answer 6

CD34 and Stem cell antigen-1

Question 7

Stem cell differentiation is stimulated by cytokines secreted by bone marrow ___ cells

Answer 7

stromal

Question 8

Give the stages of B cell maturation in the bone marrow

Answer 8

Stem cell - pro B cell - pre B cell - Immature B cell - Mature B cell - memory or plasma cell

Question 9

The thymus is an encapsulated organ that develops from the epithelium of the ___ pharyngeal pouch. It is a bilobed structure that reaches its maximum size at ____ and then atrophies at age

Answer 9

third; puberty

Question 10

Persons with a chromosome __ deletion are born with little or no thymus and suffer from ____ syndrome. These patients are highly susceptible to viral infections and cancer because they have few or no functional T cells

Answer 10

22; DiGeorge

Question 11

The subscapular region of the thymus contains what?

Answer 11

double-negative thymocytes that expresses neither CD4 or CD8 and no TCR

Question 12

At some point in the subscapular region, double-negative cells being partial expression of the TCR. At this point, they are called what?

Answer 12

pre T cells

Question 13

The cortex region of the thymus contains what?

Answer 13

immature thymocytes and double-positive T cell precursors

Question 14

The medulla of the thymus contains what?

Answer 14

mature single-positive T cells

note: medulla also contains Hassal’s corpuscles which may play a role in DC or T reg cell differentiation

Question 15

Lymph nodes respond primarily to what?

Answer 15

antigens entering the body through the skin and subcutaneous tissues

Question 16

What are the 3 functions of lymph nodes?

Answer 16

survey of the lymph by macrophages, storage and activation of B and T cells, antibody production

Question 17

The lymph system’s primary function is what?

Answer 17

isolate infectious agents and cellular debris from the rest of the body

Question 18

Lymph filters through ___ where sentry ___ lie waiting to engulf and destroy any foreign particles in the fluid

Answer 18

nodes; macrophages

Question 19

Antigens processed by the macrophages in lymph nodes are presented to ___ cells, which secrete cytokines in response

Answer 19

T helper

note: activate B cells to make antibodies and Tc cells to kill infected host cells

Question 20

Efferent lymphatics from most of the body eventually converge in the ___ duct, which empties into the left subclavian vein and then into the superior vena cava

Answer 20

thoracic

note: in this way, lymphocytes re-enter the circulation

Question 21

Re-ciruclation of the lymphocytes increases the likelihood of what?

Answer 21

that a given lymphocyte will make contact with the pathogen for which it is specific

Question 22

The Cortex (B cell area) of the lymph node has primary and secondary follicles. What do each contain?

Answer 22

primary follicle: naive B cells that have never contacted antigen
secondary follicle: germinal centers composed of B cells undergoing mitosis in response to antigen stimulation

Question 23

The paracortex (T cell area) of the lymph node contains what?

Answer 23

T cells

Question 24

Lymphocytes in the blood enter the paracortex region of the lymph node through specialized post-capillary venues called ___ ____ ___

Answer 24

high endothelial venules (HEVs)

Question 25

HEVs contain specialized cuboidal cells that express ____ molecules in high density

Answer 25

adhesion

Question 26

The paracortex becomes greatly enlarged during extreme cellular responses. This area is poorly developed in ____ syndrome

Answer 26

DiGeorge

Question 27

The medulla of the lymph node contains cords and sinuses. What do they contain?

Answer 27

medulllary cords contain closely packed lymphocytes and plasma cells
medullary sinuses contain macrophages

Question 28

Medullary sinuses communicate with ____ lymphatics

Answer 28

efferent

Question 29

The spleen responds primarily to ___-___ antigens

Answer 29

blood-borne

Question 30

The spleen is the major organ where ____ are synthesized and released into circulation

Answer 30

antibodies

Question 31

Asplenic persons are highly susceptible to infection by ____ ____

Answer 31

encapsulated bacteria (strep, h flu, neisseria, salmonella)

note: this is because antibodies are needed as opsonins to neutralize the anti-phagocytic property of bacterial capsules

Question 32

The spleen is located in the what quadrant of the abdomen

Answer 32

upper left

Question 33

The white pulp of the spleen comprises what region of the spleen? What does it contain?

Answer 33

lymphocyte-rich region; contains T cells arranged in PALS around central arteriole and B cell rich follicles occupying the space between the PALS and marginal sinus

Question 34

The red pulp of the spleen contains what?

Answer 34

plasma cells, resident macrophages, erythrocytes, platelets, granulocytes, and lymphocytes

Question 35

What is the main function of red pulp in the spleen?

Answer 35

hemocatheresis, the destruction of aged platelets and erythrocytes. Recycled iron is also stored here

Question 36

Mucosa-associated lymphoid tissue (MALT) responds primarily to antigens that enter the body through ___ surfaces

Answer 36

mucosal

Question 37

B lymphocytes in the MALT produce what?

Answer 37

secretory IgA

Question 38

MALT accounts for > ___% of the body’s lymphoid tissue

Answer 38

50

Question 39

Bronchus-associated lymphoid tissue (BALT) lines what?

Answer 39

respiratory tract

Question 40

Peter’s patches are loose clusters of lymphoid tissue where?

Answer 40

small intestine

Question 41

These are epithelial cells overlying Peyer’s patches specialized for transcytosis o antigens from the lumen to sub epithelial T cells

Answer 41

M cells