Unit 3 Lymphatics

Question 1

lymphatic functions

Answer 1

1. return interstitial fluid to the blood
2. filtration of lymph
3. filtration of blood
4. defense of body from invasion and damage by microorganisms and foreign substances

Question 2

lymphatic components

Answer 2

organs, tissue, nodes, vascular system

Question 3

primary lymph components

Answer 3

bone marrow (lymphocytes)
thymus (maturation of T lymphocytes)

Question 4

secondary lymph components

Answer 4

lymph nodes
spleen
tonsils

Question 5

lymph vascular system

Answer 5

capillaries (close ended)
vessels (interrupted by lymph nodes)
trunks (empty into subclavian veins)

Question 6

lymphoid tissue function

Answer 6

1. houses and provides proliferation sites for lymphocytes

2. offers surveillance vantage points for lymphocytes and macrophages as they filter through lymph

Question 7

lymphoid tissue components

Answer 7

reticular connective tissue

a. macrophages live on reticular fibers
b. spaces between fibers offer a place for lymphocytes to occupy when they return form patrolling the body

Question 8

reticular cells of thymus

Answer 8

1. derived from endoderm
2. called epithelial-reticular cells
3. do not produce reticular fibers
4. participate in maturation of T lymphocytes

Question 9

reticular cells of other lymphatic tissues

Answer 9

1. mesenchymal (mostly mesoderm)

2. produce reticular fibers (type III collagen)

Question 10

lymphocytes

Answer 10

cells involved in adaptive (specific) immunity

Question 11

B lymphocytes

Answer 11

responsible for humoral immunity, differentiate into plasma cells, form nodules

Question 12

T lymphocytes

Answer 12

responsible for cell mediated immunity
multiple classes:
helper, suppressor (regulatory), cytotoxic (cytolytic), memory T cells do not form nodules

Question 13

lymph nodules

Answer 13

cells responding to antigen, proliferating differentiating into plasma cells

Question 14

primary lymph nodules

Answer 14

uniformly densely stained, cells have not been exposed to antigen

Question 15

secondary lymph nodules

Answer 15

contain lightly stained central region (germinal center)

Question 16

unencapsulated (mucosa associated) lymphoid tissue (MALT)

Answer 16

1. lymphoid tissues in mucous membranes throughout body
2. protects from pathogens trying to enter body
3. largest collections of MALT is in tonsils, Peyer’s patches, appendix
4. also in mucosa of respiratory and genitourinary organs; rest of digestive tract

Question 17

tonsils

Answer 17

incompletely encapsulated in contact with epithelium

Question 18

palatine tonsils

Answer 18

a. paired
b. lateral wall of oral pharynx
c. epithelium is stratified squamous NK with crypts

Question 19

pharyngeal

Answer 19

a. single
b. superior-posterior portion of pharynx
c. epithelium is PCCE
d. hypertrophy produces adenoids

Question 20

lingual

Answer 20

a. numerous
b. base of Tonge
c. epithelium is stratified squamous NK

Question 21

lymph nodes

Answer 21

in line filters of lymph; has afferent and efferent lymphatics

Question 22

lymph node stroma

Answer 22

a. hilum (AN enter, VL exit)
b. capsule and trabecular of CT
c. sub capsular sinus and peritrabecular sinuses
d. reticular cells and fibers

Question 23

lymph node parenchyma

Answer 23

a. cortex (nodules of B cells)
b. paracortex (accumulations of T cells)
c. medulla: cords (mostly B cells, some plasma) and sinuses (partially lined with macrophages and reticular cells)

Question 24

lymph circulation

Answer 24

1. afferent lymphatics
2. subcapsular sinus
3. peritrabecular sinuses
4. medullary sinuses
5. efferent lymphatics

Question 25

blood circulation

Answer 25

1. arteries enter at hilum 2. branch into stroma 3. capillaries in cortex 4. postcapillary venules in paracortex – lymphocytes exit blood to 5. reside in node 6. veins exit at hilum

Question 26

thymus

Answer 26

1. lobulated; no nodules, no sinuses 2. size varies with age 3. capsule with trabeculae delineates lobules 4. each lobule has cortex and medulla

Question 27

thymus stroma

Answer 27

1. epithelial-reticular cells 2. no reticular fibers 3. cellular processes create framework supporting lymphocytes 4. secrete thymosin – necessary for differentiation of T cells

Question 28

thymus parenchyma cortex

Answer 28

1. thymocytes: immature T cells; not yet immunocompetent | 2. macrophages phagocytize many thymocytes

Question 29

thymus parenchym medulla

Answer 29

1. higher concentration of epithelial-reticular cells 2. larger lymphocytes 3. Hassall’s corpuscles – unique to thymus; function unknown

Question 30

thymus vascularization

Answer 30

capillaries in cortex surrounded by sheath of epithelial reticular cells; blood-thymus barrier

Question 31

spleen

Answer 31

1. largest lymphoid organ 2. filters blood 3. destroys old erythrocytes 4. produces activated lymphocytes in response to blood-borne antigens

Question 32

spleen stroma

Answer 32

1. capsule – dense connective tissue 2. trabeculae – carry nerves and arteries from hilum to splenic pulp; carries veins and efferent lymphatics from pulp to hilum 3. reticular connective tissue

Question 33

spleen parenchyma

Answer 33

aka splenic pulp a. white pulp – lymphoid tissue surrounding central arteries b. periarterial lymphatic sheath (PALS) composed of T cells c. splenic nodules – B cells

Question 34

red pulp

Answer 34

splenic cords | sinusoids

Question 35

splenic cords

Answer 35

aka cords of Billroth a. reticular cells and fibers b. macrophages, lymphocytes, blood cells

Question 36

splenic sinusoids

Answer 36

a. elongated endothelial cells b. transversely arranged reticular fibers c. macrophages between endothelial cells d. incomplete basal lamina

Question 37

marginal zone (spleen)

Answer 37

a. between red and white pulp b. lymphocytes – mostly B cells c. macrophages act as antigen presenting cells d. lymphocytes exit blood and enter white pulp

Question 38

splenic blood supply

Answer 38

a. trabecular arteries b. central arteries – surrounded by lymphocytes c. penicillar arteries (arterioles) d. arterial capillaries arterial capillaries

Question 39

splenic closed circulation

Answer 39

arterial capillaries empty directly into sinusoids of red pulp

Question 40

splenic open circulation

Answer 40

1. arterial capillaries end in splenic cords and blood must pass through wall of sinusoids to reenter circulation 2. old RBCs lose flexibility and cannot squeeze past 3. endothelial cells 4. sinusoids 5. red pulp veins 6. trabecular veins 7. splenic vein