Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Histology > Lymphoid Organs > Flashcards

Lymphoid Organs Flashcards

(80 cards)

Start Studying
1
Q

What are primary lymphoid organs?

A

Bone marrow and thymus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are secondary lymphatic tissues?

A

Mucosa Associated Lymphatic Tissue (MALT)
1) Diffuse lymphatic tissue
2) Lymphatic nodules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Where is MALT found?

A

Respiratory, GI tract, Urogenital system, oral cavity
(i.e. tonsils - palatine, pharyngeal, lingual, tubal, appendix, Peyer’s patches)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are secondary lymphoid organs?

A

Lymph node - responds to lymph borne antigen
Spleen - responds to blood borne antigen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the function of primary lymphoid organs?

A

Site of lymphocyte formation and maturation; no immune reaction should occur

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the function of secondary lymphatic tissues?

A

Site of specific immune reaction due to local antigen exposure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the function of secondary lymphoid organs?

A

Site of specific immune reaction for systemic antigen exposure (humoral antibody mediated or cell mediated)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is one of the histological differences between MALT and secondary lymphatic organs?

A

MALT has epithelium covering LCT - no CT capsule. Secondary lymphatic organs have DICT capsule surrounding the organ.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is a specific immune reaction?

A

Involves activation of B cells and T cells through interactions with an antigen presenting cell (APC) and a specific antigen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What causes a humoral antibody mediated immune response?

A

Activated B cells -> plasma cells -> make antibodies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What causes a cell mediated immune response?

A

Activated T cytotoxic cells can kill directly infected cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

T or F: Both humoral (antibody mediated) and cell mediated immune response are innate immune responses.

A

False; both responses are adaptive immune responses.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is lymphocyte maturation?

A

involves lymphocytes learning to distinguish between self and non-self proteins/cells/tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the outcome of lymphocyte maturation?

A

Immunological tolerance and immunocompetence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is immunocompetence?

A

Ability to respond specifically to non-self antigens and mount a specific adaptive immune response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is immunological tolerance?

A

ability to recognize self-antigen but not react to self-antigen with immune response.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How is tolerance established?

A

By 2 processes:
1) Deletion of autoreactive during the maturation process and before release -> leads to central tolerance
2) Suppresion of autoreactive cells that escaped into the periphery -> leads to peripheral tolerance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is autoimmunity and what causes it?

A

Immune response against self proteins (self seen as foreign)
It’s caused by a failure to establish tolerance of B cells and T cells during maturation in bone marrow or thymus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the name of the cells responsible for educating T-cells? What is the best place to show an example of these cells?

A

Epithelial reticular cells facilitate T cell maturation. ERC act as APCs to present self-MHC and peptides to train T cells to learn to distinguish between self-antigen vs. foreign antigens (based on binding affinity to self-antigens presented in thymus)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the histology of bone marrow?

A

Red marrow in medullary cavity of bones
- Vascular sinusoids (discontinuous capillary) - allows RBCs and WBCs to enter peripheral blood
- Stroma - CT fibers and fixed cells produce growth factors which regulate hematopoietic cell maturation & may remove defective cells
- Developing hematopoietic cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the function of bone marrow?

A

Site of hematopoietic cell differentiation & maturation
- erythropoiesis (RBC development)
- granulopoiesis (neutrophil, eosinophil, basophil, monocyte, & mast cell development)
- lymphopoiesis (B cell, T cell, and natural killer cell development)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the route of lymphocytes from bone marrow?

A
  • granulocytes and new lymphocytes exit BM via blood vessels
  • new (naive) lymphocytes in BM enter blood as immunocompetent B cells and NK cells
  • immature T cells migrate from BM to thymus to mature then released into peripheral blood as immunocompetent T cells -> secondary lymphatic organs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the histology of the thymic cortex?

A

peripheral dark basophilic region - high # of immature T cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What cell types are present in the thymic cortex?

A
  • thymic cortical cells (immature thymocytes express TcR)
  • epithelial reticular cells (supportive cells that facilitate T cell maturation; produce hormones in T cell maturation and Thymic education; contributes to Blood Thymus Barrier)
  • thymic dendritic cell (act as APC to train T cells - part of thymic education)
  • macrophages (phagocytose self-reactive thymocytes)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What is the blood-thymus barrier?
selective barrier formed by ERC that protect immature T cells from blood-borne foreign antigens during T cell maturation
26
What layers comprise the blood-thymus barrier?
endothelial cells of continuous capillary, basement membrane, epithelial reticular cells
27
What must happen before cortical thymocytes can enter the medulla?
- T cell must have a functionally unique antigen receptor (TCR) on surface so T cell can bind antigen - T cell must be able to recognize self MHC I or MHC II
28
What happens if the T cell fails to mature and become immunocompetent?
leads to apoptosis and elimination of T cells (only 10% of T cells are positively selected to survive
29
What is the histological feature of the thymic medulla?
central region surrounded by cortex; lighter staining fewer cells and increased cell size
30
What cell types are present in the thymic medulla?
- Mature T cells (selective for either MHC I or MHC II complex & foreign Ag) - T helper cells (express CD4+ and TCR on surface -> specific for MHC II & Ag) (subtypes: Th1 - stimulate macrophages/T cytotoxic: inflammatory and Th2 - stimulate humoral B cell response: proliferative) - T cytotoxic cells (express CD8+ and TCR on surface -> specific for MHC I & Ag) (cell mediated immune response; require activation signal (cytokine) from Th1) - Epithelial reticular cells and dendritic cells - Macrophages (phagocytosis of self-reactive T cells)
31
What is the general function of T helper cells in the thymic medulla?
Facilitate cell-mediated and humoral IR
32
What is the function of epithelial reticular cells and dendritic cells in the thymic medulla?
In presenting Ag to developing T cells
33
What is recognized as Hassall's corpuscle?
senescent (old) epithelial reticular cells that form groups of worn-out cells (appear as flattened epithelial cells)
34
What is a key histological feature of the thymic medulla?
Hassall's corpuscle
35
What leads to a sustained chronic inflammatory response?
Autoreactive T cells (against self-antigens) are involved in the immunopathogenesis of many autoimmune diseases. In a reaction against self, it is usually impossible for immune effector mechanisms to eliminate the antigen completely.
36
What is the goal of maturing CD4+ and CD8+ T cells binding to self-proteins?
The affinity of binding determines cell survival and the goal is to recognize but don't react to self-proteins.
37
What must happen before the medullary thymocyte can exit the thymus into peripheral circulation?
- T cells are selective for MHC I or MHC II (based on CD surface protein on T cells) - T cells must recognize self-antigen & self MHC (immunological tolerance) - Mature T cells exit the thymus to enter circulation as immunocompetent and self-tolerant T cells -> migrate to secondary lymphoid organs and tissue
38
What is the outcome of T cells in the thymic cortex?
T cells first become immunocompetent by expressing TCR (Ag-R)
39
What is the outcome of T cells in the thymic medulla?
T cells become self-tolerant by learning to recognize self-proteins but not react
40
What is the histology of diffuse lymphatic tissue?
scattered T lymphocytes, APCs, plasma cells, granulocytes, mast cells scattered in lamina propria
41
What is the histology of lymphatic nodule/follicle?
groups of spherical aggregations of B lymphocytes; plasma cells; APC form nodules/follicle
42
What is the function of MALT?
- common site of antigen entry across epithelium - site of local antigen recognition by lymphocytes - site of local adaptive immune reaction (cell mediated or humoral antibody)
43
What are the key features of MALT?
- Lack CT capsule (epithelium covering) - immune cells distributed throughout - contains lymph capillaries & collecting lymphatic vessels -> drains to nodes - contains high endothelial venules (HEV)
44
What are lacteals?
small blinded-ended capillaries unique to the ileum CT drain into collecting/efferent lymphatic vessels that will transmit the collected lymph fluid to lymph nodes
45
What are high endothelial venules?
specialized post-capillary blood venules (contain cuboidal endothelial cells vs. simple squamous; serve as a site for naive immunocompetent lymphocytes to enter the CT from blood circulation)
46
What is the function of diffuse lymphoid tissue?
site of APC and antigen presentation to Th and T cell mediated response by T cytotoxic
47
What is the function of nodular lymphatic tissue?
site of B cell activation and plasma cell differentiation; humoral antibody mediated immune response via antibody production and secretion into blood
48
What are the two components of lymphatic nodule/follicle?
Mantle/corona - outer dark stained area of nodule Germinal centers - central light stained area of nodule
49
What's within the mantle/corona of a lymphatic nodule?
high number of tightly packed smaller inactive B cells
50
What's within a germinal center of a lymphatic nodule?
large pale stained cells that represent mature active B lymphocytes differentiating into plasma cells and memory B cells
51
What do plasma cells produce and secrete?
antibodies into blood and lymph nodes(IgM, IgE, IgA, IgG)
52
What are memory cells involved in?
second exposure to antigen. Secondary adaptive response is quicker and stronger.
53
What are examples of lymphatic nodules associated with MALT?
GALT (gut associated lymphatic tissue) - groups of follicles are called Peyer's Patches and are key features of the ileum and appendix BALT (bronchial associated lymphatic tissue) Tonsils (palatine, pharyngeal, lingual tonsils in oral cavity)
54
T or F: Lymphatic follicles are normally found in all secondary lymphatic tissue.
True; lymph nodes and spleen
55
What is a mechanism stimulating IR?
Antigen perforates epithelial lining or transported by epithelial cell and presence of Ag activates B and/or T cells
56
How is there a shift from a local to a systemic immune response?
Ag and APCs may drain to nearby lymph node via lymphatics to lymph node and stimulate an IR in lymph node.
57
What are key features of a lymph node?
Afferent lymph vessel, efferent lymph vessels, functional regions (outer cortex, paracortex, medulla)
58
What is the function of a lymph node?
- Filters lymph fluid (responds to lymph borne antigen) - Lymphatic nodules/follicles are isolated to cortex - Humoral antibody production (occurs in lymphatic follicles in cortex) - T cell mediated immune response/T cytotoxic (paracortex)
59
What occurs at the hilum of a lymph node?
Efferent lymphatic drain lymph fluid and blood vessels enter/exit
60
What is located along the convex border of a lymph node?
Multiple afferent lymphatic enters here and carries lymph for filtering
61
What is the function of the cortex of a lymph node?
Site of B cell activation and site of humoral immune response
62
What is the function of the paracortex of a lymph node?
Site of antigen presentation to T helper cell and T cytotoxic cells (site of cell mediated immune response)
63
What is the function of medullar cords in a lymph node?
Site of antibody release by plasma cells into blood and lymph nodes
64
What is the predominant cell type of medullary cords?
Antibody secreting plasma cells, memory B cells macrophages, activated T cells
65
What is the path of lymph drainage through a lymph node?
Afferent lymph vessels (along convex border; contains valves) -> subscapular (marginal) sinus (cell free zone appearing as space under CT) -> cortical (trabecular) sinus (lymphatic space between nodules) -> medullary sinus (surround cluster of medullary cells) -> efferent lymph vessels (located on hilum and receives drainage from all sinuses; similar to small vein valves)
66
Where are high endothelial venules located in a lymph node?
paracortex; site for naive and memory cell lymphocytes to enter node from blood vasculature
67
What are functional features of the spleen?
- site of hematopoiesis in early fetal development - storage of RBC and platelets - filters blood to remove cellular waste, debris, antigen, worn out RBC - lymphoid function (site of adaptive immune response to blood borne antigen)
68
What are features that are not found in the spleen that are found in lymph nodes?
No afferent lymph vessels (only efferent), no cortex or medulla
69
What are structural features of the spleen?
- Trabeculae (CT invaginating from capsule into organ; conveys blood vessels) - White pulp (region of lymph nodules randomly scattered that surround central artery) - Red pulp (region vascular sinuses and cords; comprises bulk of spleen and surrounds WP and marginal zone) - Marginal zone (boundary b/w white and red pulp; contains blood vessels/sinus and aggregation of lymphocytes, macrophages, and dendritic cells)
70
What cells are found within white pulp?
macrophages, T helper cells, B cells, plasma cells
71
What is the function of the lymphatic nodule in white pulp?
Site of humeral immune response; primary site of IgM production in body; B cells predominate here`
72
What is the function of the central artery in white pulp?
T helper cells predominate and region of CT with T cells is the periarteriole lymphatic sheath
73
What is the function of the marginal zone?
- Site of antigen presentation of T cell to B cell (B cell migrates to white pulp) - Site of cell mediated (T cytotoxic) repsonse - Site of naive and memory cell lymphocyte entry
74
T or F: HEVs are present in the spleen.
False; they are absent. Naive lymphocytes enter via the marginal sinus.
75
What do splenic (Billroth) cords consist of?
cells organized as clusters surrounded by vascular sinusoids (including macrophages, plasma cells, RBCs, and circulating lymphocytes)
76
What is the function of splenic cords?
Traps damaged erythrocytes and platelets that are then phagocytosed by macrophages if worn out
77
What lines sinusoids in the spleen?
Stave cells - specialized fenestrated endothelial cells and discontinuous BM
78
What is the function of splenic sinusoids?
Site of platelet and RBC breakdown by macrophage (HB broken down and recycled)
79
What happens when hemoglobin is broken down?
Iron is retrieved and stored as ferritin then transported to liver. Heme is broken down to bilirubin and transported to liver, conjugated, and excreted as bile
80

Histology (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions