Lymphoid Tissue Flashcards
(146 cards)
1
Q
Which part of the lymph node has many more cells?
A
follicles
2
Q
What does MALT produce?
A
secretory IgA
3
Q
Where do B- and T-cells enter the lymph node after exiting the blood stream via diapedesis?
A
parenchyma
4
Q
Where would you find diffuse lymphoid tissue?
A
throughout the body associated with mucous membranes (MALT)
5
Q
What are stromal cells?
A
fibroblasts and reticular cells (cells with phagocytic capabilities)
6
Q
What type of lymphoid tissue has B and T cells that acquire surface receptors?
A
primary lymphoid tissue (bone marrow and thymus)
7
Q
The sinus under the capsule in a lymph node is the ____; the sinus within the cortex is the ___.
A
subcapsular sinus; cortical sinus
8
Q
What cells in the thymus cortex and medulla represent degenerate reticular and epithelial nurse cells?
A
Hassal’s corpuscles
9
Q
What are some hormones that the thymus secretes?
A
thymotaxin, thymosin, thymopoietin
10
Q
Do B-cells undergo systemic clonal expansion?
A
NO - but T-cells do
11
Q
What do the various hormones of the thymus do?
A
attract, regulate, and promote T-cell proliferation and differentiation into Tc, Ts, and Th cells (and eventual destruction)
12
Q
What type of organ is the appendix in humans?
A
vestigial (more active in young children and atrophied in adults)
13
Q
What does the outer cortex of a lymph node contain?
A
B-cells, T-cells and plasma cells
14
Q
Do Peyer’s patches produce IgA?
A
NO - not significant quantities
15
Q
What divides the thymus into lobules?
A
interlobular septa (trabeculae)
16
Q
Secondary follicles contain high numbers of what immune cells?
A
lymphoblasts, macrophages, immature B- and T-cells
17
Q
Both the palatine tonsils and lingual tonsils contain characteristic luminal ___ tissue.
A
stratified squamous nonkeratinized epithelial
18
Q
What are the largest lymph nodes with fairly certain positions?
A
submandibular cervical axillary femoral popliteal hilar
19
Q
____ are the sites of B-cell proliferation (secondary hemopoiesis).
A
secondary follicles
20
Q
What is the benefit of a discontinuous endothelium in a lymph node?
A
allows the fluid to percolate and collect in the node
21
Q
Which large lymphatic ducts eventually drain lymph back into the bloodstream?
A
thoracic duct or right lymphatic duct
22
Q
Are lymph and antigen brought to the thymus like lymph nodes?
A
NO - T-cells are immature
23
Q
What do mature T-cells express?
A
(team jerseys)
- antigen specific T-cell receptors
- cluster of differentiation surface markers
- Class I and Class II HLA surface markers
24
Q
What do the medullary sinuses contain?
A
lymphocytes, plasma cells, macrophages
25
MALT contains mostly __-cells.
B
26
Because the thymus has absent secondary follicles, it is limited ___.
local clonal expansion of T-cells
27
How do lymphoid cells enter the node?
through the bloodstream
28
Which type of lymphoid tissue has a hemicapsule and epithelium with crypts and lacks a cortex and medulla?
palatine tonsils
29
What are lymphoid cells?
lymphocytes of all types
30
Can you distinguish B-cells from T-cells under the microscope?
NO - not without a special stain
31
Where do blood vessels enter and leave the lymph nodes?
hilus
32
____ are immune accessory cells (macrophages) at the periphery of germinal centers that present antigens.
Follicular dendritic cells
33
MALT operates analogous to ____, in that it ____.
lymph nodes; samples antigenic material, produces lymphoblasts, and secretes antibodies
34
What is MALT?
diffuse, unencapsulated lymphoid aggregates located in lamina propria
35
Where and how are lymph nodes arranged?
in chains or clusters along vessels of lymphatic origin
36
What is the blood-thymus barrier?
thymic blood vessels are surrounded by this extra layer of connective tissue to form antigenic barrier to isolate thymus
37
Does the palatine tonsil have a distinct cortex and medulla?
NO
38
What tonsils are associated with the Eustachian tubes?
pharyngeal tonsils
39
Which two zones do splenic white pulp follicular areas have?
mantle zone AND marginal zone
40
___ have a cortex and a less cellular medulla.
Lymph nodes
41
What does the spleen lack that other lymphoid organs have?
cortex and medulla
42
What is the bulk of the spleen made up of?
spongy matrix of red pulp
43
How do lymphocytes respond to an antigen?
by increasing antibody production via clonal expansion
44
___ are paired structures located at the junction of the oral and pharyngeal cavities between tonsillar pillars (palatoglossal and palatopharyngeal arches) in the tonsillar crypts.
Palatine tonsils
45
What can large aggregates of B-cells form?
germinal centers similar to lymph nodes
46
If it has a germinal center in it, it must be a ___ focus.
B-cell
47
Blood eventually drains out of the spleen via the ___.
trabecular veins (and then into splenic vein)
48
What are the immune accessory cells?
antigen-presenting cells (macrophages, B-cells and T-cells)
49
Which type of lymphoid tissue has a robust capsule and trabeculae with no cortex or medulla, but has red and white pulp?
spleen
50
Lymphoid tissue contains large numbers of ____.
lymphocytes (T and B cells)
51
What type of cells does the appendix contain primarily?
B-cells
52
Where do the medullary sinuses converge?
at the hilus
53
The cortex in the thymus is mostly __ cells, whereas the medulla is mainly __ cells.
T; B
54
Why does the spleen have a fibroelastic outer layer?
it is important in splenic contraction for some species where the spleen acts as a reservoir for red blood cells
55
Most lymphoid organ cortexes contain many __-cells; the thymus's cortex contains many more __-cells.
B; T
56
Which lymph vessel drains lymph out of the node?
efferent
57
The ___ has lymphoid follicles (some with germinal centers) that are spread evenly throughout the parenchyma.
palatine tonsil
58
Are afferent or efferent lymphatic vessels present in the thymus?
only efferent for lymph drainage
59
What are the functions of the spleen?
- B- and T-cell replication
- manufacture of antibodies and antigen removal
- removes aged or defective particulate matter from circulation
- recycles Fe from hemoglobin
- hemopoiesis in fetuses
60
If the spleen is removed, what is the function taken over by?
liver and bone marrow
61
Which type of lymphoid tissue has a cortex with primary and secondary follicles and a medulla with medullary cords and sinusoids?
lymph nodes
62
How many afferent and efferent lymphatic vessels are located on each node?
afferent - many
| efferent - 1
63
What acts as the filtering mechanism in splenic circulation?
blind ending capillaries with surrounding macrophages
64
MALT in the gut contains specialized ____ in microfolds that sample antigens and transfer them from gut lumen into lymphoid follicles.
M-cells (squamoid enterocytes)
65
The ___ of a lymph node has densely packed, highly cellular lymphoid follicles (lymphatic nodules or 1' follicles).
cortex
66
____ are immune accessory cells (macrophages) that possess numerous phagocytic vesicles.
Tingible body cells
67
Why does the thymus have a continuous epithelium on inner surface of capsule?
to isolate it from the rest of the immune system
68
What are located within the spongy matrix of the spleen?
pulp cords and sinusoids
69
When do the germinal centers of MALT form?
after they're exposed to afterbirth - so about 6 months until they are fully active
70
Will you see the same types of cells in lymph follicles and sinuses?
YES
71
What lymphoid organ has characteristic large, thick bands of dense connective tissue trabeculae that extend into body?
spleen
72
Which part of the lymph node has much more lymph?
sinuses
73
What makes post-capillary venules unique and allow for diapedesis with reduced fluid loss?
thicker lining of cuboidal to columnar endothelium (vs. flatter cells in other vessels)
74
Can you see MALT with the naked eye?
NO - but you can see Peyer's patches
75
___ are encapsulated aggregates of lymphocytes and lymphoid tissue distributed throughout the body.
Lymph nodes
76
Central artery of the white pulp branch into penicillar arteries and then into arterioles, to terminate into ___.
sheathed capillaries
77
Where does blood enter the lymph node?
at and through the hilum
78
Immature ___ migrate from the bone marrow to the thymus to mature.
T-cells
79
If a follicle has a germinal center, it is a ____.
secondary follicle
80
Do lymph nodes possess an outer, fibrous capsule of dense irregular connective tissue?
YES
81
When is MALT formed?
in fetal development
82
What structure would be 100% indicative of thymus tissue?
Hassal's corpuscles
83
What are the two kinds of structures of lymphoid tissue?
dense and diffuse tissue
84
What are interspersed throughout the lymph node cortex and medulla for structural support?
very thin, collagenous, trabeculae
85
Malignant tumors of the immune system are referred to as ___ when solid organs are involved and ___ when blood it involved.
lymphomas; leukemias
86
What are the epithelial cells within the thymus that provide nurse function and structural support?
Nurse cells
87
The ___ is hemicapsulated, supported by a cup-shaped collagenous hemicapsule.
palatine tonsil
88
What does the thymus lack that lymph nodes possess?
lacks lymphoid follicles, medullary cords, and medullary sinuses
89
Germinal centers of the splenic white pulp contain ___.
B-cells with a central artery
90
___ of Peyer's patches are frequent and associated with foci of B-cells.
Germinal centers
91
What makes up the bulk of the lymphatic medulla?
interconnecting lymphatic sinuses
92
What forms a "ring" of immunological protection of the palatal, lingual, and pharyngeal tonsils?
Waldenyer's ring
93
____ are a network of blind-ended vessels in connective tissue.
Lymphatic vessels
94
The lymph drains through the sinuses into the outer cortex. What are these sinuses called?
cortical sinuses, trabecular sinuses, or peritrabecular sinuses
95
What is the purpose of clonal deletion by the thymus?
- development of immunological self-tolerance
| - failure to clonal delete may cause autoimmune disease
96
What are the 4 functions of lymph nodes?
- non-specific filtering of particulate matter and microorganisms from lymph
- interaction of circulating lymphocytes with antigen
- aggregation, activation, and proliferation of B-cells with subsequent antibody production
- aggregation of proliferation of T-cells and induction of cytotoxic immunity
97
What is the thymus embryologically derived from?
epithelial outgrowths of the 3rd pharyngeal pouch (hemopoietic organ during fetal development)
98
What forms the connective tissue skeleton of lymphoid tissue?
stromal cells and extracellular products (and some epithelial tissue)
99
What indicates that a node is responding to an antigen?
the presence of a paler and less dense germinal center in a secondary follicle
100
____ are a specialized type of MALT scattered throughout the ileum (small intestine).
Peyer's patches
101
Are lymphatic sinuses open spaces?
NO - they are filled with reticular fibers and macrophage processes
102
What are the 3 types of lymph cells we see?
lymphoid cells
immune accessory cells
stromal cells
103
Where are lymphoid and immune accessory cells derived?
bone marrow
104
The subcapsular sinus is the space where numerous ___ lymph vessels drain into it.
afferent
105
What do these PALS foci lacks?
germinal centers due to minimal T-cell proliferation
106
What does the blood-thymus barrier consist of?
epithelioreticular cells, reticular fibers, fibroblasts, macrophages, plasma cells around the basement membrane
107
Is MALT dome?
NO
108
What lymphoid organ is the largest in the body?
spleen
109
What is the job of the thymus?
- production of mature and immunocompetent T-helper and T-cytotoxic cells
- clonal proliferation of Tc cells
- clonal deletion of self-antibodies
- secretion of hormones regulating T-cell development and maturation
110
Which type of lymphoid tissue is composed of mostly T-cells, contains Hassal's corpuscles, and has both a medulla and cortex present?
thymus
111
What are the white pulp areas considered?
follicular areas with germinal centers
112
The ___ has a fibroelastic outer capsule that contains smooth muscle cells.
spleen
113
__ of the spleen contain mostly blood, whereas the pulp cords contain ___.
Sinusoids; macrophages and lymphocytes
114
Where would you find dense lymphoid tissue?
lymph nodes, spleen, thymus, tonsil
115
What prevents lymph from leaking out of the lymph node?
the endothelium on the side where lymph is entering is continuous to prevent leakage
116
What is the pathway of lymphocytes through the lymph node?
afferent lymphatic >> subcapsular sinus >> cortex >> cortical sinus >> medulla >> medullary sinus >> efferent lymphatic
117
What results in lymph node enlargement?
proliferation of lymphocytes (antigenic stimulation)
118
What are the extensions of cortical tissue into the lymph node medulla called?
medullary cords
119
In what vessel to T- and B-cells primarily exit at? Where are they located?
post-capillary venules; paracortical zone of corticomedullary junction
120
Do Peyer's patches contain M-cells?
YES
121
Sinusoids are surrounded by an unusual type of endothelial cell called ___.
Stave cells
122
Normally, the white pulp is primarily B-cells. However, there are areas of high T-cells. What is formed when a central artery is surrounded by T-cells?
periarteriolar lymphatic sheaths (PALS)
123
In this class, we are using the ____ model of the spleen.
open circulation
124
The discreet nodules of white pulp within the red pulp of the spleen contain large numbers of ___.
white blood cells
125
What system of the body concentrates antibodies for elimination within lymph nodes?
lymphatic system
126
What types of cells are in high numbers in the splenic white pulp mantle and marginal zones?
macrophages, plasma cells, helper T-cells
127
What are medullary cords separated by?
broad medullary sinuses
128
Do Peyer's patches contain both B- and T-cells?
YES - large numbers of both
129
What do splenic germinal centers possess that lymph node germinal centers do not?
a central artery
130
White pulp can be mis-categorized as ___.
PALS
131
Branches of the ___ enter the white pulp within trabeculae via trabecular artery, then branch and form central artery to white pulp.
splenic artery
132
Where would you find diffuse lymphoid tissue?
appendix and lymphoid-associated tissues (MALT: GALT, BALT, NALT)
133
Where is the region of antigen presentation in the lymph node follicle?
mantle zone surrounding the germinal center
134
___ lack endothelial lining and are surrounded by macrophage "cuff" in splenic circulation.
Blind ending capillaries
135
Where are Peyer's patches most common? Least common?
ileum; duodenum
136
___ are enlarged germinal centers visible to the naked eye/
Splenic nodules
137
What facilitates the diapedesis of white blood cells out of the bloodstream?
complementary adhesion molecules (present on both endothelial cells and lymphocytes)
138
What happens to the thymus at puberty?
undergoes thymic involution (fatty infiltration and lymphatic depletion)
139
Blind-ended tonsillar crypts are located on the surfaces of ___.
tonsils
140
What are the pulp cords of the spleen supported by?
connective tissue skeleton of reticular cells and reticular fibers
141
What type of lymphoid tissue has mature B and T cells that migrated there?
secondary lymphoid tissue (lymph nodes, spleen tonsils, etc.)
142
If a paler, less dense germinal center is present in the follicle of a lymph node, it is referred to as a ____.
secondary follicle
143
Peyer's patches project into the lumen of the gut in ____.
dome areas
144
___ tonsils are present at the base of the tongue; ___ tonsils are in the nasopharynx.
Lingual; pharyngeal/adenoid
145
On which side of the capsule of the lymph node is the endothelium discontinuous?
the side next to the parenchyma (facing the lymph node)
146
Which system allows cells and large molecules in extracellular matrix to reenter the bloodstream?
lymphatic vessels
