Lymphoid Tissue Flashcards Preview

HDM Midterm > Lymphoid Tissue > Flashcards

Flashcards in Lymphoid Tissue Deck (27):
1

primary lymphoid organs

thymus and (red) bone marrow
produce lymphocytes

2

secondary lymphoid organs

tonsils, lymph nodes (cervical, axillary, inguinal) spleen, MALT in small intestine
diffuse, lymphocytes are activated in response to Ag

3

Diffuse non-encapsulated LT

Reticular CT houses lymphocytes deep to epithelium
GI tract, Genitourinary tract, respiratory passages

4

nodular non-encapuslated LT

primary nodule/follicle consists of only small
lymphocytes - inactive or naive, lack a germinal center

secondary nodule == activated version thats been presented - possesses germinal center - outer ring, mantle

5

germinal center

B cells localized to follicle, germinal center and mantle
T cells surround follicle

6

Tonsils: aggregate non-encapsulated LT

tonsils are large, irregular masses of LT - help protect against inhaled/ingested substances - can be partially encapsulated

7

palatine tonsil

stratified squamous epithelium
10-20 tonsillar crypts == deep invaginations
dense CT acts as partial capsule
contains germinal centers

8

pharyngeal tonsil

pseudostratified columnar ciliated
single structure at the posterior wall of nasopharynx
thin underlying capsule
shallow infoldings, no crypts

9

lingual tonsil

stratified squamous
base of tongue
germinal centers
lacks a capsule but has crypts

10

MALT: non-encapsulated aggregate nodular LT

single/clusters of nodules
found in GI tract (GALT), respiratory airways (BALT) and urinary tract
lumen open to external environment

11

GALT: aggregate nodular tissue

simple columnar with goblet cells
gut associated lymphoid tissue - prominent in small intestine (ileum**)
peyer patches
characterized by an abundance of villi
single or clusters of nodules

12

veriform appendix: aggregate nodule

simple columnar with goblet cells
short, small projection off cecum
filled with LT
crypts - no villi, no capsule

13

thymus

in mediastinum
lymphoblasts invade and proliferate here
lymphocytes mature into T cells
characterized by involution (decreased activity as its replaced with adipose tissue)
capsulated - lobulated by septa
contains T lymphocytes, macrophages, thymic epithelial cells

14

thymic epithelial cells

subcapsular (squamous) - form cortical compartment - some of these will form a sheet to separate cortex and medulla
cortical (stellate) - prdocue cytoreticulum of keratin and desmosomes - secrete cytokines for T cell development

15

blood-thymus barrier

in cortex - formed by TECs, basal lamina, endothelial cells
macrophages prevent circulating Ag from reacting with developing T cells

16

thymic medulla

houses mature T cells migrating from cortex
T cells enter postcapillary venules to exit thymus

17

Hassall's corpuscles

thymic - associated with medulla
closely packed whorls of TECs
secrete cytokines that aid in maturation of T cells

18

thymus compartments

cortex - contain T lymphocytes - subscapular TECs, cortical TECs, macrophages
at side proximal to postcapillary venule, single-positive T cells, followed by double positive and double-negative most distal
medulla - mature T cells - medullary TECs, hassall's corpuscles, DC, Mphage

19

spleen

initiates immune response to blood Ag
reservoir for platelets
hematopoiesis/RBC recycling center

20

spleen structure

surrounded by CT capsule - trebeculae incompletely separate
parenchyma with reticular fibers of white and red pulp
single splenic artery and vein

21

white pulp of spleen

T and B cells, macrophages
lymphoid nodules - central arteriole
PALS - periarteriolar lymphoid sheaths - T cells surrounding arteriole
MnA - corona/mantle - small lymphocytes surrounding GC
MgZ- marginal zone - blend of lymphocytes

22

red pulp of spleen

contains RBCs, platelets, macrophages, plasma cells
blood filtration/RBC turnover
splenic sinusoids and splenic cords

23

splenic cords

reticular tissue rich in macrophages and lymphocytes

24

stave cells

line sinusoids of red pulp
specialized endothelial cells that separate healthy and unhealthy RBCs

25

splenic blood flow

splenic artery -> trabecular arteries -> central arteriole/ PALS -> white pulp -> penicillar arteries -> splenic sinuses -> splenic cords

26

lymph

clear, yellow fluid comprised of interstitial fluid, solutes, foreign material

27

lymph nodes

encapsulated- positioned along lymphatic vessels
400-450
filter lymph - remove debris, facilitate Ab production, produce lymphocytes