Lab 2: Lymph Nodes and Organs Flashcards
1
Q
Name the two general features of lymphoid tissue?
A
- Aggregates of predominately lymphocytes
- A supporting skeleton usually composed of reticular fibres
2
Q
Describe the structure of lymphocytes
A
- Small round cells of size similar to an erythrocyte
- Approx. 7 μm in diameter
3
Q
Describe the histology of a lymphocyte
A
They are mostly filled by a dark (heterochromatic) nucleus, indented on one side, with a minimal amount of basophilic cytoplasm.
4
Q
A Basophil granulocyte stains which colour and by which type of staining?
A
It was stain dark purple upon H&E (Haemotoxylin and Eosin) stain
5
Q
T and B lymphocytes are identical morphologically thus name the technique required to distinguish T and B lymphocytes
A
Special immunological staining techniques (immunocytochemistry) is required to distinguish them.
6
Q
Describe reticular fibres
A
They are fine bundles of collagen fibres
7
Q
Describe the histological features of reticular fibres
A
Reticular fibres stain black with a silver-based stain.
8
Q
List the primary lymphoid organs
A
Bone marrow
Thymus
9
Q
What is the difference between primary and secondary lymphoid organs
A
In the primary organs, the lymphocytes are formed and mature.
In secondary, is the place where the lymphocytes will be activated by encountering foreign antigens producing an immune response.
10
Q
Name the secondary lymphoid organs?
A
Lymph nodes
Tonsils
Spleen
Mucosa-associated lymphoid tissue (MALT)
11
Q
List the lymphoid organs
A
Bone marrow
Thymus
Tonsils
Lymph nodes
Spleen
Mucosa-associated lymphoid tissue
12
Q
Where are mucosa-associated lymphoid tissue located?
A
Digestive tract
Respiratory tract
Bone
Peyer patches (small masses of lymphatic tissue found throughout the ileum region of the small intestine)
13
Q
The early cohorts of T-lymphocytes originate from the ____ and travel to the _____ where they are programmed i.e. become immunocompetent.
A
The early cohorts of T-lymphocytes originate from the bone marrow and travel to the thymus where they are programmed i.e. become immunocompetent
14
Q
Early cohorts of T-lymphocytes originate from where?
A
The bone marrow
15
Q
Early cohorts of T-lymphocytes are programmed i.e. acquire immunocompetence, where?
A
In the thymus
Remember: T cell = Thymus
16
Q
Why is the thymus a unique lymphoid organ?
A
It does not, itself, take part in immune responses, but the other lymphoid organs – lymph nodes, spleen, tonsil, mucosa-associated lymphoid tissue – are all dependent on it for their T-cell populations and function.
17
Q
Early cohorts of B-lymphocytes originate from where?
A
Bone marrow
B cells for Bone marrow
18
Q
Early cohorts of B-lymphocytes are programmed i.e. acquire immunocompetence, where?
A
Bone marrow
B cells for Bone marrow
19
Q
T cells arise from lymphocytes that were carried to and matured where?
A
In the thymus gland
20
Q
What stimulates B cells to differentiate into plasma cells and to secrete antibodies?
A
Cytokines
21
Q
B cells remain and mature where?
A
In bone marrow
22
Q
How does B cells recognise antigens?
A
Recognise antigens as a result of antigen receptors on cell membranes and become activated.
Response is more intense when antigen-presenting CD4 T cells present antigens to B cells
23
Q
CD4+ vs CD8+ T cells
A
CD4+ refers to helper T cells
CD8+ refers to cytotoxic T cells
24
Q
Which of the lymphoid organ does not fit the definition of a lymphoid organ?
A
The bone marrow
25
Why does the bone marrow not fit the definition of a lymphoid organ?
As the lymphocytes are not predominant cell type within the bone marrow.
The lymphocytes are rather masked by all the other blood cell precursors: all the progenitor stages of the erythrocytes, and of the neutrophils, the eosinophils and basophils as well as the megakaryocytes that produce the platelets.
26
This is a section through which structure?
Lymphoid tissue
Can see the bundle of reticular fibres and aggregates of predominantly lymphocytes
27
What is more outer in lymph nodes:
Medulla or Cortex?
Cortex
Cortex surrounds the inner medulla
28
Which structures are located in the medulla of a lymph node?
Medullary cord
Medullary sinus
29
Name these parts of the lymph node
30
Name these parts of the lymph node
31
What is the function of lymph nodes?
They serve as filters of the lymph (excess fluid from intestitial tissue) and drains into the subclavian vein, via the thoracic duct- returning it to the bloodstream
32
Lymph enters the bloodstream by which vein?
Subclavian vein
33
The node artery and vein enter and leave the lymph node at which part?
At its hilum
34
Name these parts of this histological section of the medulla of a lymph node
35
What is the structure the arrow is pointing at that is located in the medullary sinus in the lymph node
This is debris that is being broken down in the cytoplasm of stellate macrophages
36
The lymph is drained into the lymph node via what?
The afferent lymphatic vessel
Generally several incoming vessels that have drained lymph from the surrounding regions
_NOTE_: **A** for **A**rrival
37
The lymph is drained from the lymph node by which vessel?
The efferent lymphatic vessel
Generally a single outcoming vessel.
_NOTE_: **E** for **E**xit
38
The parenchyma of a lymph node is supported by a delicate framework composed of?
Reticular fibres
39
Describe the location of the subcapsular sinus?
Lies between the capsule and the cortex
40
Describe the medullary cords?
Lymphocytes are arranged in irregular cords of lymphocytes.
Contain macrophages, plasma cells and lymphocytes
41
Describe the flow of the lymph through the lymph node?
The lymph enter into the lymph node via **afferent** **lymphatic** **vessels** (MANY) into the **subcapsular** **sinus**.
The lymph passes into the medulla either by passing into the **medulla round the edges of the cortex** of by the **cortical** **sinuses**.
In the medulla, the lymph travels in **medullary** **sinuses** and eventually exits via an **efferent** **lymphatic** **vessel** (ONE)
42
The flow of lymph through the lymph nodes is very slow. What causes this to occur and why is it significant?
The afferent lymphatics are very narrow while the sinuses of the lymph node (subcapsular, cortical and medullary) are very wide. Each sinus is wider than the next
As a result, the flow is very slow.
Significant as it allows the debris material in the lymph to settles out and land on the cells of the lymph node i.e. allows the lymph to be cleaned
43
Lymph is rich in:
a) carbohydrates
b) protein
c) fat
b) protein
44
Put the following in order for the flow of lymph through the lymph node:
## Footnote
1. Cortical sinus
2. Afferent lymphatic vessels
3. Efferent lymphatic vessel
4. Medullary sinus
5. Subcapsular sinus
2. Afferent lymphatic vessels
5. Subcapsular sinus
1. Cortical sinus
4. Medullary sinus
3. Efferent lymphatic vessel
45
The edges of the sinuses of the lymph node is lined by ____ cells except for ____ sinus, which is lined by ____ type cells.
The edges of the sinuses of the lymph node is lined by **littoral** cells except for **subcapsular** sinus, which is lined by **endothelial** type cells.
46
What is the function of the stellate macrophages in the lymph node?
They travel in a loose latticework (so loose it does not impede lymph flow)
Role is to phagocytose the debris of the lymph as it lands on them
47
There are two types of filtration in the lymph node that is termed mechnical and biological.
Briefly outline them
Mechnical filtration is the settling out of the debris of the lymph through the flowing of the flow.
Biological filtration occurs after mechanical and refers to the degradation that occurs by the fixed macrophages
48
Which of the following organ(s) of the immune system involute(s) in adults?
## Footnote
a) Spleen
b) Thymus gland
c) Lymph node
d) Spleen + Lymph node
e) Thymus gland + Lymph node
b) Thymus gland
The thymus is essential in newborn and young individuals to establish immunity in the organism, after which it involutes and becomes fatty
49
T lymphocytes cells arise from the:
## Footnote
a) thymus gland and matures in the bone marrow
b) Bone marrow and develop in the lymph nodes
c) Lymph nodes and mature in the thymus gland
d) Thymus gland and mature in the thymus gland
e) Bone marrow and mature in the thymus gland
e) Bone marrow and mature in the thymus gland
T lymphocytes cells arise in the bone marrow and mature in the thymus gland. From bone marrow, the T lymphocytes are carried to the thymus gland where they are mature and become immunocompetent
50
Which cells release immune chemicals called cytokines (interleukins)
## Footnote
a) Plasma cells
b) All lymphocytes
c) CD8+ T lymphocytes
d) CD4+ T lymphocytes
e) All T lymphocytes
d) CD4+ T lymphocytes
CD4+ T lymphocyte cells release cytokines, which stimulate B cells to transform into plasma cells and activate macrophage phagocytic activities
51
Maturation and activation of B lymphocytes cells takes place in the:
## Footnote
a) Connective tissue and lymph nodules
b) Lymph nodes
c) Bone marrow
d) Thymus
e) Spleen
c) Bone marrow
After maturation in the bone marrow, B lymphocytes are distributed to thymic lymphoid tissues or organs
52
B lymphocytes' response to particular antigens is more intense when:
## Footnote
a) More plasma cells are present
b) More antibodies are present
c) More lymphocytes are formed in lymphoid organs
d) The lymphocytes are immature
e) Antigen-presenting cells present antigens to B lymphocytes
e) Antigen-presenting cells present antigens to B lymphocytes
53
Which cells secrete antibodies to fight against foreign organisms?
## Footnote
a) B lymphocytes
b) CD4+ T lymphocytes
c) Natural killer cells
d) Plasma cells
e) CD8+ T lymphocytes
d) Plasma cells
When stimulated by antigens, B lymphocytes differentiate into plasma cells that then secrete antibodies
54
The thymus gland exhibits high activity during which time period?
## Footnote
a) Before birth
b) Middle age
c) Old age
d) Early childhood
e) Throughout life
d) Early childhood
During early childhood, the lymphocytes mature immunocompetent T-cell variety
55
Which cells of the immune system attach to virally infected cells and cancer cells?
## Footnote
a) CD4+ T lymphocytes
b) B lymphocytes
c) Plasma cells
d) Natural killer cells
e) Tissue macrophages
d) Natural killer cells
Natural killer cells recognise altered cells and destroy them
56
Describe the littoral cells
These are cells that line the inner surface of the subcapsular sinus and all round the medullary sinuses
They have pores between them
Their function is not fully understood but they are thought to have a role in lymphocyte traffic to or from the sinuses and perhaps in antigen recognition and presentation
57
The inner surface of the subcapsular sinus is lined by which cell type?
Littoral cells
58
The lymph node cortex is separated from the connective tissue capsule by what structure?
The subcapsular sinus
59
What is the other name of the cortical sinuses?
Trabecular sinuses because they sperate the lymphatic nodules in the cortex of the lymph node
60
Which part of the lymph node is stained darker?
a) Cortex
b) Medulla
a) Cortex
The outer dark-staining cortex and the inner light-staining medulla
61
The outer cortex has lymphatic nodules that mostly contain which cell type
B lymphocytes
62
Describe how lymphocytes enter the lymph nodes
Most of the lymphocytes enter the lymph nodes via blood vessels, and about 10% enter through the lymph.
63
Describe the pathway in which lymphocytes enter the lymph nodes via blood vessels
Lymphocytes recognise and adhere to high endothelial venules, post-capillary venule located in the deep cortex.
Lymphocytes squeeze through them into the deep cortical regions of the lymph nodes.
64
Reticular fibers are composed primarily of which type of collagen
Type III collagen
65
A cell- mediated response is characterised by division and enlargement of discrete lymphocytes in which region of the cortex?
The deep cortex
66
A humoral response is characterised by the development of lymphoid nodules/follicles in which region of the cortex?
Outer cortex
67
What changes occur in the lymph node during a humoral response
There is development of lymphoid nodules/follicles in the outer cortex and enlargement of the medullary cords which become populated by plasma cells
68
What changes occur in the lymph node during a cell-mediated immune response
Division and enlargement of discrete lymphocytes in the thymus-dependent region, the deep cortex
69
Which area of the lymph node becomes populated by plasma cells during a humoral immune response
The medullary cords
70
Which part of the lymph node is thought to be the site of the production of memory B-lymphocytes
Lymphoid nodules
71
The lymphoid nodules are ovoid clusters of activated and dividing lymphocytes and are always composed of which type of lymphocyte?
B-lymphocytes.
72
Which lymphocyte does not form nodules?
T-lymphocytes
73
Which lymphocyte does form nodules:
a) T-lymphocytes
b) B-lymphocytes
b) B-lymphocytes
74
The presence of lymphoid nodules in lymphoid tissue is a sign of?
A humoral immune response
The lymphoid nodules only develop during humoral immune response. We know they are important for the humoral response as they are predominately composed of B-lymphocytes, which are a major player in the humoral response.
75
Which region of the cortex is thymus-dependent?
The deep cortex
76
Which region of the lymph node is thought to be the B-lymphocyte region
The outer cortex and medullary cord
77
The germinal centre is located in which region of the cortex
a) outer cortex
b) deep cortex
a) outer cortex
78
Plasma cells in the medullary cord are differentiated (comes from) which B-lymphocyte population
This is not fully understood yet
It is thought the B-lymphocytes of the outer cortex and of the medullary cords are carrying out related but separate functions and that the plasma cells of the cords arise in situ. Recent work, however, suggests that this is a controversy
79
How does lymphoid nodule form
They form by clonal proliferation of activated B lymphocytes
The activated daughter cells enlarge to medium-sized and large lymphocytes and immunoblasts/lymphoblasts, the largest lymphocyte form.
80
What is the largest lymphocyte form?
Immunoblast/lymphoblasts
Some 25 – 30 μm in diameter.
81
Describe the histological features of the immunoblasts/lymphoblasts
They have a large pale (euchromatic) nucleus, a prominent nucleolus and foamy cytoplasm, all signs of high activity.
82
What happens to the other cells in the lymphoid nodules as the activated B-lymphocyte undergoes clonal proliferation
Other cells occur among the dividing lymphocytes, particularly dendritic cells and macrophages whose cytoplasm contains many lymphocyte nuclei undergoing degradation.
83
What immune cell degrades the other cells in the lymphoid nodule during humoral immune response
The tingible body macrophages
84
Describe a tingible body macrophage
A type of macrophage predominantly found in germinal centers, containing many phagocytized, apoptotic cells in various states of degradation
85
Why does lymphoid nodules appears paler in histology sections than the surrounding outer cortex
Because of the more abundant cytoplasm of the activated lymphocytes
86
As the lymphoid nodule enlarges it start to subdivision into two sections.
What is the name of these two sections
The germinal centre and its overlying cap/corona of small lymphocytes
87
The cap of small lymphocyte in the lymphoid nodule faces towards which part?
a) medulla
b) subcapsular sinus
A cap/corona of small lymphocytes forms facing towards the source of the antigen, the subcapsular sinus.
88
The pale oval profile of dividing cells within the lymphoid nodule is known as
The germinal centre
89
In large lymphoid nodules, the germinal centres can be divided into two regions. These regions are?
Light and dark poles
90
The light pole lies at the side of the lymphoid nodule towards \_\_\_\_\_
The light pole lies at the side of the nodule towards **the cap and source of antigen**
91
The dark pole lies at the side of the lymphoid nodule towards \_\_\_\_\_
The dark pole lies at the side of the lymphoid nodule towards **the deep cortex**
92
What causes the polarity in large lymphoid nodules i.e. the differentiation between dark and light pole
The polarity is caused by a greater content of macrophages in the light pole and is due to their abundant pale cytoplasm.
93
Which pole in the lymphoid nodule has a greater content of macrophages?
a) Dark pole
b) Light pole
b) Light pole
94
What is been understood as the site of memory B-lymphocyte production in lymph nodes?
The lymphoid nodule
95
The cell-mediate immune response involves which part of the cortex
a) deep cortex
b) outer cortex
a) deep cortex
96
How does lymphocytes leave the lymph node and why is this important they do this?
Lymphocytes from the lymph node leave the node in the efferent lymph and probably also enter local blood capillaries.
Lymphocytes responding to a particular antigenic stimulus can thus be disseminated to other parts of the body, ready to mount immune responses should the antigen be encountered at other sites
97
Which part of the lymph node contains high endothelial venules
## Footnote
a) Medullary cord
b) Cortical sinus
c) Subcapsular sinus
d) Deep cortex
e) Outer cortex
d) Deep cortex
98
What is the significance of high endothelial venules
They allow circulating lymphocytes to enter the deep cortex. The lymphocytes squeezing between the rounded endothelial cells, allowing them enter rather than leaving the node.
99
Lymphocytes squeeze between high endothelial venules in the deep cortex, moving from [*inside/outside*] to [*inside/outside]* of the lymph node.
Why lymphocytes is it mainly?
Lymphocytes squeeze between high endothelial venules in the deep cortex, moving from **outside** to **inside** of the lymph node
Mainly T lymphocytes but there is evidence to suggest B-lymphocytes also
100
