IL1: Histology Of Lymphatic Systems Flashcards
(95 cards)
1
Q
What is the flow of the lymphatic system?
A
lymphatic capillaries → collecting vessels → lymph nodes → lymph trunk → duct → vein
2
Q
What is one of the main functions of the lymphatic system?
A
Monitor body surfaces and recognize harmful antigens as ‘non-self’, autoimmune disease
3
Q
What are the components of the lymphatic system?
A
- cells
- lymphatic tissue (lymphocyte and antigen-presenting cells)
- lymphatic organs
- lymphatic vessels
4
Q
Where does lymph drainage occur for the right side of the body?
A
Right lymphatic duct to right subclavian vein
5
Q
What regions of the body does the right lymphatic duct drain?
A
- head
- Neck
- Arm
- Thorax
- right side
6
Q
Where does lymph drainage occur for the thorax?
A
Thoracic duct to right subclavian vein
7
Q
What are primary lymphoid organs?
A
- Bone marrow
- Thymus
8
Q
What is the role of primary lymphoid organs?
A
Sites where stem cells divide and become immunocompetent
9
Q
What are secondary lymphoid organs?
A
- Lymph nodes
- Spleen
- Thymus
- Other lymphoid tissues such as Mucosal Associated Lymphoid Tissue (MALTs)
10
Q
What occurs in secondary lymphoid organs?
A
Most immune responses
11
Q
What characterizes the innate immune response?
A
Rapid but nonspecific
12
Q
What characterizes the adaptive immune response?
A
Slower but specific
13
Q
What types of cells are involved in the immune response?
A
- Phagocytic cells
- Lymphocytes
- Cells containing cytoplasmic granules
14
Q
Where do B-cells develop and mature?
A
Bone marrow
15
Q
What do activated B-cells turn into?
A
Plasma cells for antibody production
16
Q
Where do T-cells develop and mature?
A
Develop in bone marrow and mature in thymus
17
Q
What do T-cells secrete?
A
Soluble factors that communicate with other adaptive immune cells or destroy infected cells
18
Q
Fill in the blank: The thymus is associated with _______.
A
[CD4 or CD8]
19
Q
What is the primary lymphoid organ responsible for lymphocyte differentiation?
A
Bone marrow and thymus serve as the initial education center for lymphocytes.
20
Q
What is the role of interleukin-7 in the bone marrow?
A
Interleukin-7 is crucial for the differentiation of lymphocytes into immunocompetent cells.
21
Q
What happens during the maturation of B cells?
A
Pro-B cells develop into pre-B cells, which begin synthesizing antibodies and develop into immature B cells.
22
Q
What occurs if a B cell strongly binds to a self-antigen?
A
Apoptosis occurs, leading to the elimination of the B cell from circulation.
23
Q
What is diapedesis?
A
Diapedesis is the process by which immune cells exit the bloodstream to enter inflammatory tissue.
24
Q
Where is the thymus located?
A
The thymus is located anterior to the great vessels in the anterior mediastinum.
25
What is the primary function of the thymus?
The thymus serves as the education center for T cells and can discriminate self from non-self.
26
What happens to the thymus during thymic involution?
The thymus shrinks as thymocytes leave to populate other lymphoid effector organs.
27
What are Hassall's corpuscles?
Hassall's corpuscles are concentrically arranged epithelial cells in the medulla of the thymus.
28
What cytokine do Hassall's corpuscles produce?
Hassall's corpuscles produce thymic stromal lymphopoietin, which stimulates the maturation of T cells.
29
In young thymus, there are lots of lymphocyte in cortex or medulla
cortex
30
31
What is the role of self-antigens in B cell apoptosis?
A self-antigen bound to the receptor complex causes apoptosis of a mature B cell.
32
What are the two main regions of the thymus?
Cortex and medulla.
33
What type of cells are Hassall's corpuscles composed of?
Concentrically arranged epithelial cells in the medulla.
34
What cytokine do Hassall's corpuscles produce?
Thymic stromal lymphopoietin.
35
What is the function of thymic stromal lymphopoietin?
Stimulates thymic dendritic cells to complete the maturation of single-positive cells.
36
What are epithelial reticular cells?
Specialized epithelial cells that form the support for thymocytes.
37
Where do precursor T cells enter the thymus from?
Bone marrow.
38
What is the characteristic of 'double-negative' T cells?
They lack surface molecules TCR, CD4, and CD8.
39
Where are 'double-positive' T cells located in the thymus?
Deeper in the cortex.
40
What happens to T cells that successfully bind to self-molecules?
They lose expression of either CD4 or CD8 and become mature 'single-positive' T cells.
41
Where do mature 'single-positive' T cells reside in the thymus?
In the medulla.
42
What is the blood-thymus barrier?
A barrier that prevents other cells or free antigens from entering the thymus.
43
Where is the blood-thymus barrier not present?
In the medulla.
44
How do T-cells enter the thymus?
Only via the bloodstream; no afferent lymph vessels.
45
What structures are involved in forming the blood-thymus barrier?
Thymic cortical epithelial cells, endothelial cells, and capillary endothelial cells linked by tight junctions.
46
What is the postcapillary venule's role in T cell maturation?
Functional T cells exit the thymus through the postcapillary venule at the corticomedullary junction.
47
What is the process by which mature T cells enter circulation?
Intravasion through post-venule endothelium.
48
Fill in the blank: Hassall's corpuscles are composed of _______.
closely packed whorls of epithelial cells.
49
True or False: T-cells can enter the thymus via afferent lymph vessels.
False.
50
What are the functions of lymph nodes?
1. Filter lymph, promoting lymphocyte contact with antigen.
2. Provide necessary microenvironment for antigen-dependent differentiation.
51
How does lymph flow through a lymph node?
Lymph enters through afferent lymphatic vessels, passes through the subcapsular sinus, trabecular sinuses, medullary sinuses, and exits via efferent lymphatic vessels.
52
What role do macrophages play in lymph nodes?
Macrophages in sinuses monitor fluids, phagocytose antigenic material, and present it to T- and B-cells.
53
What are the main zones of a lymph node?
Cortex, deep cortex (T-cell zone), and medulla.
54
What is the composition of the cortex in a lymph node?
The cortex contains lymphoid follicles, germinal centers, primary and secondary follicles, and is populated by B-cells.
55
What is found in the medulla of a lymph node?
The medulla contains medullary cords (B-cells, plasma cells, macrophages) and medullary sinuses lined by endothelial cells.
56
How do plasma cells function in lymph nodes?
Plasma cells can secrete immunoglobulins directly into the lumen of the medullary sinuses without leaving the lymph node.
57
What is the role of follicular dendritic cells (FDCs)?
FDCs are involved in the activation and proliferation of B-cells within the germinal center.
58
What happens to B-cells after activation?
Activated B-cells proliferate and differentiate into plasma cells and memory B-cells.
59
What is the significance of high endothelial venules (HEVs)?
HEVs facilitate the entry of lymphocytes into the lymph node from the bloodstream.
60
What do afferent lymphatic vessels do?
Afferent lymphatic vessels carry lymph from the surrounding tissues and neighboring lymph nodes into the elaborate network of lymphatic sinuses.
61
How do lymphocytes enter the lymph node?
Lymphocytes that migrate to the lymph node from the blood enter the deep cortex via high endothelial venules (HEVs) and also migrate to the superficial cortex.
62
What are the two main functions of the spleen?
1. Destroy old RBCs (red pulp)
2. Immune organ (white pulp)
63
What is the largest secondary lymphoid organ?
The spleen.
64
What are the components of white pulp in the spleen?
1. Central arteriole
2. Periarteriolar lymphoid sheath (PALS)
3. Corona formed by B cells and antigen-presenting cells
4. Germinal center
65
What are the immune functions of the spleen?
1. Monitoring antigens in blood
2. Proliferation of lymphocytes
3. Production of humoral antibodies
66
What are the hematopoietic functions of the spleen?
1. Formation of blood cells in fetal life
2. Removal and destruction of RBCs & platelets
3. Retrieval of iron from RBC hemoglobin
4. Storage of RBCs and platelets
67
What is the structure of the red pulp in the spleen?
The red pulp consists of a capsule and splenic sinusoids with splenic cords.
68
What is the significance of the corona in the spleen?
The corona consists of resting B cells.
69
What distinguishes the spleen from lymph nodes?
The spleen has no cortex or medulla, while lymph nodes contain a distinctive cortex.
70
What is the pathway of blood flow through the spleen?
Splenic a. → trabecular a. → central a. → penicillar a. → splenic sinusoid (closed) and open-ended vessel (open)
71
What type of tissue surrounds the central artery in the white pulp of the spleen?
Lymphatic tissue
72
What are the components of the white pulp in the spleen?
* Periarterial lymphatic sheath (PALS; T-cell)
* Lymph nodule (B-cell, monocyte, plasma cell)
* Marginal sinus (diffuse B-cell, macrophage)
73
What does the red pulp of the spleen consist of?
Splenic cord + splenic sinusoid
74
What types of cells are found in the red pulp of the spleen?
* Macrophage
* Plasma cells
* Granulocyte
* Erythrocyte
75
What occurs at the marginal zone of the white pulp?
Blood contacts the splenic parenchyma containing phagocytic macrophages and antigen-presenting cells
76
What is the role of macrophages in the white pulp?
Trap bacteria and present their antigens to lymphocytes
77
What is the structure of the splenic nodule in the white pulp?
* Corona region (Peripheral white pulp) containing B cells
* Germinal center containing proliferating B cells
* Periarterial lymphatic sheath (PALS) surrounding the central artery
78
What are the functions of activated B-cells in the spleen?
Set up proliferative germinal centers
79
What is located in the marginal zone between the white pulp and red pulp?
Macrophages that detect blood-borne antigens from the marginal sinus
80
What are the components of the splenic cord?
* RBCs
* Neutrophils
* Plasma cells
* Macrophages
* Blood platelets
81
What type of cell framework supports the splenic cord?
Reticular cell framework
82
What type of cells line the splenic sinusoids?
Elongated endothelial cells
83
Fill in the blank: The central arteriole in the spleen leads to _______.
Radial arterioles
84
True or False: The white pulp is primarily composed of red blood cells.
False
85
What are the main types of MALT?
Nasal-associated lymphoid tissue (NALT), Gut-associated lymphoid tissue (GALT), Bronchus-associated lymphoid tissue (BALT), lymphoid tissue associated with the genitourinary system
## Footnote
MALT is categorized based on its location in the body.
86
What basic compartments are found in all MALT?
Follicles, interfollicular regions, subepithelial dome regions, follicle-associated epithelium
## Footnote
These compartments are consistent across various sites of MALT.
87
What is the role of Peyer's patches?
Inductive site for immune responses in the gut
## Footnote
Peyer's patches are a type of GALT.
88
What is the structure of the appendix in relation to lymphoid tissue?
Large accumulation of lymphoid tissue in lamina propria and submucosa
## Footnote
The appendix is a small blind-ending diverticulum from the cecum.
89
What are the zones found within a Peyer's patch?
Dome epithelium, mixed cell zone, mantle zone, germinal centre, T-cell area
## Footnote
Each zone has specific types of immune cells.
90
What type of cells are found in the dome epithelium of Peyer's patches?
Intra-epithelial lymphocytes
## Footnote
These cells are crucial for immune surveillance.
91
What types of lymphocytes are present in the mixed cell zone of Peyer's patches?
T-lymphocytes, B-lymphocytes, macrophages
## Footnote
This zone is important for immune activation.
92
What types of cells are found in the mantle zone of Peyer's patches?
Small B-lymphocytes
## Footnote
This zone is involved in the maintenance of B-cell populations.
93
What types of cells are located in the germinal centre of Peyer's patches?
Centroblasts, centrocytes, follicular dendritic cells, macrophages
## Footnote
The germinal centre is critical for B-cell maturation.
94
What types of cells are found in the T-cell area of Peyer's patches?
T-lymphocytes, macrophages
## Footnote
This area is essential for T-cell responses.
95
True or False: MALT is present only in the gut.
False
## Footnote
MALT is found in various locations including nasal and bronchial tissues.
