Lymphatic Tissues and Organs- Sum 6

Question 1

lymphatic system

Answer 1

consists of: cells + tissues + organs

collectively form part of the immune/defense system to monitor and protect body from harm (microorganisms, foreign substances, tumor cells, transplanted cells, virus)

Question 2

lymphatic tissue

Answer 2

very cellular with large numbers of lymphocytes

either primary or secondary

Question 3

primary lymphatic tissues

Answer 3

donors to secondary

site of development and maturation

bone marrow
thymus

Question 4

secondary lymphatic tissues

Answer 4

recipients from primary

site of immunological surveillance and formation of defense vs antigens/pathogens CONFRONTATION

Question 5

MALT

Answer 5

mucosa-associated lymphatic tissue

1. GALT (gut associated lymphatic tissues, in mucosa of GI tract)
2. BALT (bronchus associated lymphatic tissue. in mucosa of respir tract)
3. GU tract (mucosa tract)
4. tonsils

secondary

Question 6

examples of secondary

Answer 6

diffuse lymphatic tissue (MALT)
lymphatic nodules (MALT)
tonsils
lymph nodes (filter lymph)
spleen (filters blood)

Question 7

diffuse lymphatic tissue

infiltrate

Answer 7

infiltrate lamina propria of
1. GI tract as GALT
2. respiratory tract as BALT
3. GU tract

Question 8

diffuse lymphatics function

Answer 8

waiting to confront antigens or pathogens passing thru epithelium

is location of initial immune response

Question 9

diffuse lymphatics structure

Answer 9

simplest, loose

reticular fibers

cells: B and T lymphocytes, monocytes, macrophages, plasma cells

Question 10

primary lymphatic nodules

Answer 10

homogenous appearance

small lymphocytes

Question 11

secondary lymphatic nodules

structure

Answer 11

mantle zone (MZ)= dark, small mature lymphocytes

germinal center = inner lighter zone, larger immature lymphocytes
-will swell and stimulate lymphocyte proliferatoin + plasma cell differentiate + antibody secretion

Question 12

solitary lymphatic nodules

Answer 12

temporary

Question 13

aggregates of lymphatic nodules

Answer 13

permanent

@ tonsils, lymph nodes, spleen, BALT, appendix, ileum

Question 14

tonsils

Answer 14

aggregates of lymphatic nodules w/ B and T lymphocytes

@nasopharynx = pharyngeal tonsil/adenoid
@fauces = palatine
@dorsal surface of poster 1/3 tongue = lingual

Question 15

pharyngeal tonsil

appearance

Answer 15

pseudostratified columnar with cilia

pleats, NO crypts

Question 16

palatine tonsil

appearance

Answer 16

stratified squamous nonkeritanized

have crypts

Question 17

lingual tonsils

Answer 17

stratified squamous nonkeritanized

have crypts

Question 18

lymph nodes function

Answer 18

filter lymph before it passes into blood vascular system

Question 19

lymph node structure

Answer 19

1. capsule- dense irregular collagenous CT, trabeculae carry blood vessels and nerves into lymph nodes
2. hilum- concave, where blood vessels and efferent lymphatic vessels leave node
3. sinuses- lined by simple squamous endothelial-like cells to permit exit/entrance of sinus

Question 20

parts of a sinus

lymph node

Answer 20

subcapular- deep to CT capsule
paratrabecular- surround trabeculae
medullary- wide and tortuous

Question 21

lymph node framework

Answer 21

reticular tissue w/

1. stellate reticular cells: like fibroblasts so syn/secrete coll III, processes wrap around bundles of reticular fibers to seal/isolate them from tissue parenchyma
2. dendritic cells- antigen presenting cells monitor foreign substances
3. macrophages- phagocytic, antigen presenting
4. follicular dendritic cells- bind ag-ab complexes for long periods of time

Question 22

lymph node parenchyma

Answer 22

cortex + paracortex + medulla

Question 23

cortex contents

lymph nodes

Answer 23

B lymphocytes
dendritic cells
follicular dendritic cells
macrophage
plasma cells

Question 24

paracortex contents

lymph node

Answer 24

T lymphocytes
postcapillary venules aka high endothelial venules (HEV)

B and T exit bloodstream via HEVs to para
B migrates to cortex

Question 25

medulla contents | lymph node

Answer 25

-stellate reticular cells -reticular fibers -B lymphocytes (leave cortex > migrate to medullary sinuses > exit via efferent vessels) -plasma cells -dendritic cells -macrophages

Question 26

medullary sinuses contents | lymph node

Answer 26

1. reticular fibers made by and covered by stellate reticular cell processes 2. macrophages- piggy back stellate cells to phagocytose particulate matter 3. lymphocytes 4. plasma cells 5. dendritic cells

Question 27

thymus

Answer 27

where T lymphocytes mature originate in bone marrow as immature > migrate to thymus to become immunocompetent in thymic cortex > migrate to thymic medulla > leave

Question 28

thymus structure

Answer 28

2 lobes 1. capsule - dense irregular CT 2. trabeculae- partition thymus to form lobules 3. lobules- has cortex and medulla (continuous w/ lobules of surrounding lobules)

Question 29

thymus- has/has nots

Answer 29

1. no afferent lymphatic vessles aka does not filter lymph 2. no stellate reticular cells- has epithelial reticular cells 3. no 3D reticular fiber framework- has epithelial reticular cell framework 4. no lymphatic nodules- has cortex and medulla 5. no B lymphs- has T lymphs 6. no sinuses or sinusoids

Question 30

type I epithelial reticular cells | thymus

Answer 30

form seal via occluden junctions around cortex form sleeve around tunica adventitia of vessels create antigen proof compartment for T lymphs in cortex

Question 31

blood thymus barrier

Answer 31

cortical capillary endothelium + basal lamina + macrophages + type I epithelial reticular cells to isolate developing T lymphs from macromolecules in blood

Question 32

type II epithelial reticular cells

Answer 32

@mid cortex branching, stellate shaped cells form meshwork/cytoreticulum

Question 33

type III epithelial reticular cells

Answer 33

form seal b/t cortex and medulla

Question 34

type IV epithelial reticular cells

Answer 34

establish barrier @ corticomedullary junction

Question 35

type V epithelial reticular cell

Answer 35

form meshwork/cytoreticulum aka framework of medulla

Question 36

type IV epithelial reticuluar cells

Answer 36

form thymic corpuscles (Hassall) concentric, eosinophilic whorls @medulla exhibit keratinization

Question 37

reticular cells of thymus cortex | function

Answer 37

protect/guard create an antigen free environment for maturing lymphocytes in the cortex

Question 38

immuno-competent T Lymph | pathway

Answer 38

medulla thymus residence in: 1. deep cortex (paracortex) of nodes 2. PALS of spleen 3. GALT (Peyer's patches) but mostly B 4. BALT mostly B some T

Question 39

DiGeorge's Syndrome

Answer 39

developmental disorder (thymic hypoplasia or aplasia) so can't produce T lymphocytes = death from infection

Question 40

spleen | function

Answer 40

filters blood site of B and T proliferation site of blood cell elimination

Question 41

spleen structure

Answer 41

1. capsule 2. trabeculae 3. hilum 4. CT Stroma 5. parenchyma (white and red pulp)

Question 42

white pulp

Answer 42

has PALS (T lymphs) + splenic nodules (B lymphs)

Question 43

red pulp

Answer 43

splenic cords (of Billroth) -stellate reticular cells, platelets, RBCs, WBCs, macrophages, plasma cells, dendritic + splenic sinuses/sinusoids -blood cells

Question 44

vascular supply to spleen

Answer 44

1. trabecular arteries 2. central artery w/ PALS 3. splenic nodule 4. penicillar arteriole 5. pulp arteriole 6. sheathed arterioles 7. splenic sinuses

Question 45

splenic circulation

Answer 45

blood filtered in splenic cords old blood cells and particulates phagocytosed by macrophages in cords