lymphoid tissues

Question 1

primary lymphoid tissues

Answer 1

bone marrow and thymus
generation of mature but antigen-naive T and B cells
development of antigen-recognition

Question 2

secondary lymphoid tissues

Answer 2

spleen
lymph nodes
Peyer’s patches
tonsils
where naive lymphocytes wait to be activated
funnel antigen to antigen-specific B and T lymphocytes

Question 3

tertiary lymphoid tissues

Answer 3

skin, GI tract, lungs, vagina
where elimination of antigen occurs
battlefield where immune system defends tissues from microbes
typically have direct contact with external environment

Question 4

function of bone marrow and thymus

Answer 4

bone marrow: source of stem cells that can differentiate into all formed elements of peripheral blood
thymus: site of T lymphocyte maturation

Question 5

structure and function of lymph nodes

Answer 5

a

Question 6

structure and function of spleen

Answer 6

a

Question 7

role of Peyer’s patches in immune response

Answer 7

secondary lymphoid tissue in the GI tract (MALT)

expose immune system to antigens across the mucosal epithelium

Question 8

where are autoreactive T cells deleted

Answer 8

thymus

Question 9

at what stage are autoreactive B cells deleted

Answer 9

immature B cell stage (in bone marrow)

Question 10

which cells are known as thymic nurse cells

Answer 10

cortical epithelial cells

promote thymocyte differentiation by providing cell-to-cell contact, cytokines, and peptide hormones

Question 11

what happens to the thymus after puberty

Answer 11

atrophies and is replaced by adipose tissue

Question 12

how is T cell immunity maintained after atrophy of thymus

Answer 12

long-lived memory T cells and division of mature peripheral T cells

Question 13

what are Hassall’s corpuscles

Answer 13

thymocyte graveyards

only 5% of thymocytes mature and leave thymus

Question 14

when do thymocytes begin expressing TCR, CD3, CD4/8

Answer 14

after thymocytes migrate from the cortex to the medulla

become mature T lymphocytes when they reach the medulla

Question 15

when mature T cells leave the thymus, where do they go

Answer 15

secondary lymphoid tissues

Question 16

what are T cell precursors called when they leave the bone marrow and home to the thymus

Answer 16

prothymocytes

travel from bone marrow to thymus via peripheral blood

Question 17

purpose of lymphatic channels

Answer 17

to drain lymph (extracellular fluid) from tissues of the back and return it back to the bloodstream

Question 18

where are lymph nodes

Answer 18

interspersed along the course of lymphatic channels
serve to house immune system cells such as macrophages, B and T cells
prevalent in axillary, inguinal, and cervical regions

Question 19

where does the thoracic duct empty into

Answer 19

left subclavian vein

Question 20

within the thymus, thymocytes migrate from

Answer 20

cortex to medulla (toward center of thymus)

Question 21

what are found in germinal centers

Answer 21

proliferating B cells

Question 22

within the lymph node cortex, what are the three B cell rich areas

Answer 22

primary follicles = resting B cells
secondary follicles = antigen-activated B cells
germinal centers = proliferating B cells

Question 23

what is the paracortex

Answer 23

T cell rich area that houses T helper cells

Question 24

where are dendritic cells found in lymph nodes

Answer 24

throughout the T cell rich areas

Question 25

where are macrophages found in lymph nodes

Answer 25

in marginal sinus and medullary cords

Question 26

lymph empties from afferent lymphatic vessel into where in the lymph node

Answer 26

subcapsular sinus

Question 27

high endothelial venules

Answer 27

allow lymphocytes to enter lymph node from bloodstream

Question 28

what is the benefit of B cells percolating through T cell rich areas in the lymph nodes

Answer 28

enhances probability that antigen-specific B cell will interact with an antigen-specific T cell

Question 29

largest lymphoid tissue

Answer 29

spleen

Question 30

major functions of spleen

Answer 30

remove particulate matter and senescent RBCs from circulation
expose lymphocytes to antigens

Question 31

periarterial lymphatic sheaths (PALS)

Answer 31

cuffs of lymphocytes surrounding the central arteries and penicilliary arterioles in the spleen
constitute the T cell rich zones of the spleen
B cell rich follicles appear as extensions of the PALS at arterial branch points

Question 32

MALT

Answer 32

mucosa-associated lymphoid tissue
exposes immune system to antigens across mucosal epithelia
large surface area to protect
protects against pathogens in lungs, GI tract, GU tract

Question 33

how does antigen transport occur in MALT

Answer 33

antigen transport occurs across the mucosal epithelium, rather than afferent lymph

Question 34

Peyer’s patches

Answer 34

a type of MALT that is present in the lamina propria of the gut
localized in terminal ileum
HEVs transport lymphocytes to Peyer’s patches
B cell follicles are surrounded by a T cell rich zone
M cells transport proteins and microorganisms from GI lumen into lymphoid tissue

Question 35

how are T and B cells, macrophages, and DCs directed toward lymphoid organs

Answer 35

chemokines produced by stromal cells in lymphoid organs

Question 36

what types of cells are in tertiary lymphoid tissues

Answer 36

memory B and T cells

also macrophages

Question 37

Langerhans cells

Answer 37

immature dendritic cells present in epidermis
capture and transport antigen to nearest lymph node
act as APCs to activate T cells
large surface area, constantly sample environment