BIOL 435 Ch. 2 Part Two (Cells and Organs of the Immune System)

Question 1

during embryogenesis and the fetal period

Answer 1

• blood cell formation shifts from site to site

- bone marrow hasn’t arisen yet

Question 2

steps in ‘blood cell’ formation

Answer 2

• hematopoiesis begins the yolk sac
• fetal HSCs arise near the kidney
• mature HSCs capable of populating the hematopoietic system can be isolated from yolk sac, placenta, and fetal liver
• HSCs seed the bone marrow late in fetal development
• HSCs ultimately populate the bone marrow postnatally

Question 3

by 18years of age (bone marrow sites)

Answer 3

• vertebrae
• ribs
• sternum
• skull
• pelvis
• humerus
• femur

Question 4

primary lymphoid organs

Answer 4

1. Bone marrow
2. Thymus
   * where immune cells develop

Question 5

bone marrow has

Answer 5

• B-cells
• monocytes
• dendriteic cells
• granulocytes

Question 6

HSCs reside (bone marrow)

Answer 6

• in the perivascular niche

- develop in contact with the stromal cells of the bone marrow

Question 7

perivascular niche

Answer 7

• directs the development of blood cells
• HSCs
• marcrophages
• blood vessel
• cytokines and GFs
• sympathetic neuron

Question 8

endosteal niche

Answer 8

-osteoblasts
>generate bone
>regulate differentiation of lymphoid cells

Question 9

stromal cells facilitate

Answer 9

• HSC proliferation
• direct migration
• stimulate differentiation

Question 10

stromal cells include

Answer 10

• endothelail cells: lining blood vessels
• sympathetic nerves
• macrophages
• osteoblasts

Question 11

T and B cell maturity

Answer 11

• T-cells leave bone marrow immature and mature in thymus

- B-cells mature more in bone marrow but still not fully

Question 12

stepwise changes in thymocytes (T-cells)

Answer 12

• due to microenvironment of the thymic cortex and medulla
  1. Immature T-cells enter at CMJ
  2. DN
  3. DP
  4. SP

Question 13

CMJ

Answer 13

• cortico-medullary junction

- where immature T-cells enter

Question 14

DN

Answer 14

• double negative T-cell
• no CD4 or CD8
• TCR expressed

Question 15

DP

Answer 15

• double positive T-cell

- CD4 and CD8

Question 16

thyme epithelial cells (TEC)

Answer 16

-coritcal and medulluary
-95% of T-cells ‘die’ (don’t recognize MHC)
-other 5% undergo postive and negative selection
>need to recognize MHC, just the right amount

Question 17

positive and negative selection

Answer 17

-driven by TCR affinity of binding with MHC-peptides

Question 18

secondary lymphoid organs

Answer 18

-areas where lymphocytes:
>encounter antigens
>become activated
>undergo clonal expression
>differentiate into effector cells

Question 19

secondary lymphoid organ areas include

Answer 19

• lymph nodes
• spleen: blood
• mucosa-associated lymphoid tissue (MALT)
• other diffuse and loosely organized areas
• connected to each other via blood and lymphatic circulatory systems

Question 20

lymph nodes and spleen

Answer 20

-most highly organized secondary lymphoid organs

Question 21

in lymph node

Answer 21

-lymphocyte activity is seperated into distinct microenvironments
>cortex (B-cells)
>paracortex (T-cells)

Question 22

innermost lymph node medulla

Answer 22

• macrophages and dendritic cells

- also get B-cells that become plasma cells

Question 23

antigens enter via

Answer 23

-afferent vessel

Question 24

exit via effernt vessel

Answer 24

-lymphocytes

Question 25

naive lymphocytes enter by

Answer 25

-high endothelial venule (HEV)

Question 26

3 roughly concentric regions of lymph nodes

Answer 26

1. Cortex
2. Paracortex
3. Medulla

Question 27

cortex (lymph nodes)

Answer 27

• lymphocytes
• macrophages
• follicular dendritic cells arranged in follicles

Question 28

paracortex (lymph nodes)

Answer 28

• T-cells

- migrating dendritic cells

Question 29

medulla

Answer 29

• site of lymphocyte egress

- plasma cells secreting Ab

Question 30

follicle (B-cell zone)

Answer 30

-when activated move to cortex and can activate T-cells

>both cells work together

Question 31

germinal centre

Answer 31

-explosion of B-cell differentiation

>why lymph nodes swell

Question 32

lymphoid cells actively migrate

Answer 32

-toward each other during activation events for their required interactions

Question 33

lymphoid FRCC

Answer 33

• lymphoid fibroblastic reticular cell conduit

- guides T-cells and APCs toward activation interactions

Question 34

differentiation into effector cells

Answer 34

-takes place in follicles of secondary lymphoid organs

>both B and T-lymphocytes will develop into long-lived memory cells

Question 35

CD4+ T-cells differentiate

Answer 35

-into helper T-cells that assist in B-cell differentiation

Question 36

CD8+ T-cells differentiation

Answer 36

-into killer (or cytotoxic) T-cells that destory virally infected cells

Question 37

spleen is the first line of defense

Answer 37

• against bloodborne pathogens

- Ag+lymphoctyes in through splenic artery and out throug splenic vein

Question 38

spleen divided into lobes

Answer 38

-each contain red pulp, white pulp seperated by a marginal zone
>RBCs: red pulp
>WBCs: white pulp
>marginal zone

Question 39

marginal zone

Answer 39

• a specialized region of macrophages and B-cells

- borders the white pulp

Question 40

MALT

Answer 40

• loosely associated
• mucoas-associated lymphoid tissue
• important layer of defense against infection at mucosal and epitheial layers
• organizes responses to antigens taht enter mucosal tissues
  ex. GALT, SALT, BALT

Question 41

GALT

Answer 41

• gut-associated lymphoid tissues

- includes a network of follicles and lymphoid microenvironments assocaited with the intestines

Question 42

M-cells

Answer 42

-responsbile for transcytosis