ANATOMY - Histology Of Immune Sytsem Flashcards

1
Q

What are primary lymphoid organs ?

A

Organs in which immature lymphocytes acquire receptors to recognise antigens - they mature lymphocytes

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2
Q

What are the primary lymphoid organs? (2)

A

-thymus
-bone marrow

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3
Q

Where are T lymphocytes matured?

A

Thymus

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4
Q

Where are B lymphocytes matured?

A

Bone marrow

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5
Q

What are secondary lymphoid tissues ?

A

Tissues where lymphocytes are activated in response to an antigen.

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6
Q

Give 3 examples of secondary lymphoid tissues

A

-lymph nodes
-spleen
-MALT

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7
Q

Where is blood screened for pathogens?

A

Spleen

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8
Q

Where is lymph screened for pathogens?

A

Lymph nodes

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9
Q

Where are antigen activated lymphocytes found?

A

In blood, lymph and lymphoid organs - continuously circulating

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10
Q

What are 3 lymphoid cells?

A

-lymphocytes
-antigen presenting cells (APCs)
-reticular cells

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11
Q

What is a reticulocyte?

A

An immature red blood cell

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12
Q

What are 3 types of lymphocytes?

A
  • b lymphocytes
  • T lymphocytes
  • natural killer cells (NK)
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13
Q

What are the different types of T cells ?

A
  • helper T cells
  • Cytotoxic T cells
  • Suppressor T cells
  • Memory T cells
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14
Q

What is the function of antigen presenting cells?

A

-display antigens on MHC
- help to activate T cells

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15
Q

What are examples of APCs?

A
  • macrophages
  • dendritic cells
  • B lymphocytes
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16
Q

What do reticular cells do

A

Produce stroma which supports other cells in lymphoid organs

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17
Q

What is stroma?

A

Scaffolding

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18
Q

What are the 2 sections of the thymus?

A

Medulla and cortex

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19
Q

What is found in the medulla of the thymus ?

A

More mature T cells
Hassall’s corpuscles
Macrophages

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20
Q

What is found in the cortex of the thymus?

A

Less mature T cells

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21
Q

What kinds of cells are found in the thymus?

A
  • lymphocytes
  • macrophages
  • reticular cells
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22
Q

Where are macrophages found in the thymus

A

In the cortex and the medulla

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23
Q

What are reticular cells called in the thymus?

A

Epithelial cells

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24
Q

What do reticular cells do in the thymus ?

A

They form a cellular network

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25
Describe the scaffolding of the thymus
Epithelial cells form a cellular network - they line up together to form scaffolding
26
What is unusual about the scaffolding in the thymus?
Reticular fibres are not common in the thymus - instead linked cells form the scaffolding
27
What is a significant feature found in the medulla of the thymus?
Hassall’s / thymic corpuscles
28
What are Hassall’s / thymic corpuscles?
-keratinised epithelial cells - look like swirls - found in medulla of thymus
29
What cells are found in lymph nodes?
- B cells - T cells - APCs e.g macrophages - reticular cells
30
What do reticular cells do in lymph nodes?
They produce reticular fibres (collagen) which form a network
31
What is the function of the scaffolding in the lymph nodes?
Keeps the sinuses open
32
What is in the centre of follicles in lymphoid tissue?
Germinal centres - actively dividing B cells
33
What surrounds the centre of the follicle in lymphoid tissues?
resting B cells
34
What is the paracortex of the lymph nodes?
Deep cortex
35
What is contained in the paracortex of lymph nodes?
T cells
36
What type of lymphocyte is contained in the medulla of lymph nodes?
Plasma B cells
37
What is the largest lymphoid organ?
Spleen
38
What are the 2 blood cleansing functions of the spleen?
- removal or blood borne antigens - removal and destruction of old/defective RBCs
39
Where does haemopoeisis occur in an adult?
Bone marrow
40
Where does haemopoeisis occur in the foetus?
In the spleen
41
What are the 2 types of substance in the spleen?
-white pulp -red pulp
42
What is white pulp?
Thick sleeves of lymphoid tissue
43
What is red pulp composed of?
- venous sinuses - splenic cords
44
Where is red pulp found?
In the spleen, surrounding white pulp
45
What are the blood vessels which supply/ drain the spleen called?
Splenic artery & splenic vein
46
Does the spleen have trabeculae?
Yes
47
What is the composition of white pulp?
- lymphoid tissue - central arteries - sheathed capillaries surrounded my macrophages - T cells surround arteries - B cells form follicles
48
What is red pulp composed of ?
- splenic sinusoids - splenic cords (composed mainly of macrophages and reticular cells)
49
What are splenic cords?
Sheets of reticular CT Found in red pulp
50
What are PALS? In the spleen
PeriArterial Lymphoid Sheaths - white pulp surround central arteries in the spleen
51
How is blood passed from artery to vein in the spleen?
Splenic artery -> central arteries -> sheathed capillaries -> splenic cords of red pulp -> splenic sinusoids -> veins of red pulp -> splenic vein
52
Where are central arteries located?
White pulp
53
What surrounds sheathed capillaries?
Macrophages
54
What part of the red pulp do sheathed capillaries empty blood into?
Splenic cords
55
What kind of cells line the splenic sinusoids?
Endothelial cells
56
What surrounds the tonsils?
1/2 surrounded by stratified squamous epithelium 1/2 surrounded by Hemi-capsule
57
What are the invaginations found on the tonsils called?
Crypts
58
What happens to crypts during infection?
Pus collects in the crypts
59
Why is only half of the tonsil surrounded by a capsule?
So that antigens can come into contact with the tonsils on the part which doesn’t have hemi -capsule i.e epithelial cell covered part
60
Do tonsils have follicles?
Yes
61
Where are Peyer’s patches found?
Distal end of small intestine in the wall
62
Describe structure of a Peyer’s patch
Clusters of lymphoid follicles with germinal centres
63
What is immunity?
Resistance to disease
64
What are the two intrinsic systems of the immune system?
- innate immunity (non-specific) - adaptive immunity (specific)
65
What are the innate defences?
-surface Barriers -internal defences
66
What are the types of surface barrier that play a role in innate immunity ?
Skin Mucous membranes
67
What are the internal defences which play a role in innate immunity ? (5)
-phagocytes - natural killer cells - inflammation -antimicrobial proteins -fever
68
What are the 2 types of adaptive immmunity ?
- Humoral/antibody mediated immunity - cellular immunity
69
What cells are involved in humoral immunity ?
B cells
70
what kind of cells are active in cellular immunity ?
T cells
71
What are the 3 types of phagocytes involved in innate immunity?
Macrophages Neutrophils Eosinophils
72
What do natural killer (NK) cells do?
Cause apoptosis in cancer/virus infected cells
73
What happens to B lymphocytes during humoral immunity?
-they become plasma cells -they secrete antibodies
74
What do antibodies do?
Mark cells for destruction by macrophages
75
What are memory B cells?
Some B cells which are activated during humoral immunity do not become plasma cells. They are primes to respond to the same antigen upon second infection
76
What do cytotoxic T cells do?
- bind to antigen presenting cells -perforate the cell membrane - this signals the cell to undergo apoptosis
77
What do dendritic cells do?
Capture antigens and deliver them to lymph nodes
78
In lymph nodes, what are medulllary cords?
Found in the medulla between medullary sinuses. Filled with plasma cells & macrophages
79
What is the capsule of a lymph node composed of?
Connective tissue
80
What are trabeculae in the lymph nodes made of?
Connective tissue