immune system Flashcards
(124 cards)
1
Q
what are neutrophils?
A
- most predominant type of granulocyte in blood
- phagocytic
2
Q
where are neutrophils found?
A
- sites of acute inflammation
3
Q
what is a granulocyte?
A
- immune cell
- has granules (small particles)
- has enzymes that are released during infections, allergic reactions, asthma
4
Q
what are eosinophils?
A
- ## granulocytes
5
Q
what are eosinophils important in?
A
- defence against parasitic infections (numbers increase)
6
Q
what are eosinophils involved in?
A
- atopic reactions eg. asthma
7
Q
what are basophils?
A
- granulocytes found in low numbers in blood
8
Q
what is function of basophils?
A
- similar and complimentary to eosinophils and mast cells
9
Q
what do granules contain?
A
- histamine
- leukotriene
- vasoactive mediators
- platelet activating factor
10
Q
what are macrophages?
A
- major phagocytic cells
11
Q
what do macrophages play a part in?
A
- innate immunity
12
Q
where are macrophages found?
A
- all body tissues
13
Q
what is a monocyte?
A
- circulating cell
- differentiates into macrophage upon migration into tissues
14
Q
what are the different forms of lymphocytes?
A
- B cells
- T cells
- natural killer (NK) cells
- mast cells
15
Q
what happens once B cells are activated?
A
- differentiate into antibody secreting plasma cells
- part of specific immune response
16
Q
what are T cells?
A
- thymus matured lymphocytes
17
Q
what are the two types of T cell?
A
- cytotoxic T lymphocyte (CTL)
- helper T lymphocyte
18
Q
what is the function of cytotoxic T lymphocyte?
A
- kills virus infected cells
19
Q
what is the function of helper T lymphocytes?
A
- activate other cells like B cells and macrophages
20
Q
what are natural killer cells?
A
- large, granular lymphocytes
- form part of innate immune response
21
Q
what do natural killer cells lack?
A
- antigen specific receptors
- but can still detect and attack some virus infected cells
22
Q
where are mast cells found?
A
- across many tissues, near small blood vessels
23
Q
what happens once mast cells are activated?
A
- release substances from granules that affect vascular permeability
24
Q
what do these granules contain?
A
- histamine
- heparin
25
what do mast cells have a role in?
- allergy
- protecting mucosal surfaces from pathogens
26
where are all immune cells created and matured?
- primary lymphoid tissues (thymus and bone marrow)
27
what are immune cells produced from?
- haematopoietic stem cells
28
what happens once the immune cells are matured?
- leave primary lymphoid tissue
- enter circulatory system
29
what can recirculate between non lymphoid tissue and secondary lymphoid tissue?
- lymphocytes
- mononuclear phagocytes
30
what are the benefits of recirculation?
- increases likelihood the lymphocytes will be exposed to pathogens picked up in tissues from all over body
31
where is primary lymphoid tissue found?
- thymus
- left and right subclavian vein
- heart
- bone marrow
32
where is secondary lymphoid tissue found?
- adenoid
- tonsil
- lymph node
- thoracic duct
- spleen
- Peyers patch (small intestine)
- appendix
33
what are primary lymphoid tissues?
- where lymphocytes develop and mature to stage where they can now recognise an antigen
34
what are primary lymphoid tissues also known as?
- central lymphoid organs
35
what do primary lymphoid tissues consist of?
- bone marrow
- thymus
36
what are all immune cells derived from?
- haematopoietic stem cells in bone marrow
37
what are the two types of marrow?
- red
- yellow
38
what is red marrow involved in?
- haematopoiesis (formation of blood cellular components)
39
what is yellow marrow made up of?
- adipocytes
40
where does haematopoiesis take place at birth?
- medullary cavities of bone
41
where does haematopoiesis occur in adulthood?
- axial skeleton
- medullary cavities are left with only adipocytes
42
what do lymphocytes descend from?
- common lymphoid progenitor
43
where do B cells mature?
- bone marrow
- enter blood but most die as fail to meet antigen
44
what happens to T cells?
- leave bone marrow as immature progenitors
- travel to thymus via blood
- complete maturation and undergo selection
45
where does the thymus sit?
- within thorax (superior and anterior mediastinum)
46
where is the thymus positioned?
- anterior/superficial to heart and pericardium
- posterior to sternum
47
where do T cells complete maturation?
- thymus
48
what happens to thymus during childhood?
- gradually enlarges when most active
49
what happens to thymus after puberty?
- beings to reduce in size and function
50
what occurs to developing T cells using maturation?
- die in thymus as fail to produce a T cell receptor useful immune system
51
where do pro T cells travel to?
- thymus and enter cortex
52
what happens with positive selection?
- selects for T cells capable of recognising self MHC molecules and peptides
53
what does MHC stand for?
- major histocompatibility complex
54
what do MHC molecules do?
- responsible for antigen presentation at cellular level
55
what are presented antigen examined by?
- cells of immune system (usually T cells)
56
what are the 2 MHC classes?
- MHC-1
- MHC-2
- different types of T cells are sensitive to each
57
what happens in thymus to cells able to detect MHC-1 and peptide?
- become cytotoxic T cells
58
what happens in thymus to cells able to detect MHC-2 plus peptide?
- become T helper cells
59
what do cortical epithelial cells do?
- present antigens to T cells on MHC-1 and MHC-2
60
what happens if T cell doesnt recognise the protein-MHC complex?
- T cell dies by apoptosis after 4 days
61
what percentage of al lT cells making it to thymus fall to this fate?
- 95%
62
what happens if T cell successfully recognises the MHC-protein complex?
- it receives 'survival signals' which prevent it entering apoptosis
63
where do surviving T cells advance to?
- medullary region
64
what happens once reach medullary region?
- negative selection eliminates T cells that would recognise self-peptide and be dangerous to body
65
what happens in the medulla?
- dendritic cells present self antigen to T cells on MHC-1 and MHC-2
66
what happens now to cells recognising and binding antigens?
- given death signal
- told to undergo apoptosis
67
what happens to the cells that don't bind after 4 days?
- deemed useful and leave thymus to enter bloodstream
68
where are secondary lymphoid tissues found?
- sites where mature lymphocytes are exposed to and stimulated by antigen
69
what are secondary lymphoid tissues also known as?
- peripheral lymphoid organs
70
what are examples of secondary lymphoid tissues?
- lymph vessels
- lymph nodes
- spleen
- mucosa associated lymphoid tissue (MALT)
71
is lymphoid migration to secondary lymphoid tissues random or specific?
- highly specific
72
what is the process of migration?
- enter high endothelial venules (HEVs)
- express specific adhesion molecules on endothelium so lymphocytes bind
73
what does this adhesion lead to?
- lymphocyte squeezing through endothelium into node
74
what do lymph vessels do?
- drain tissue fluid from connective tissue
75
where do lymph vessels empty via?
- thoracic duct to left venous angle between interior jugular vein and subclavian vein
76
what is the unidirectional flow ensured by?
- valves
- without anatomical pump
77
what happens to antigens and foreign materials?
- drained from site of infection (connective tissue)
- carried to lymph nodes
78
what are lymph nodes?
- highly organised
- bean shaped structures at unctions between lymph vessels
79
where are lymph nodes aggregated?
- neck
- groins
80
what is the function of lymph nodes?
- filter lymph from tissues
81
what happens to antigen in lymph node?
- is trapped
- taken up by antigen presenting cells
- presented to lymphocytes passing through node
82
where do afferent lympatics enter node?
- in cortex
- pass through paracortex
83
where do afferent lymphatics exit?
- via efferent lymphatic in medulla
84
where do high endothelial venules enter lymph node?
- paracortex
85
where are B cells located?
- in primary and secondary follicles in cortex
86
where are T cells located?
- paracortex region
87
what do lymphoid tissues contain?
- lymphoid follicles made up of lymphoid dendritic cells and B lymphocytes
88
what do primary follicles contain?
- resting B lymphocytes
89
what are primary follicles the site of?
- where germinal centres form when entered by activated B cells
- forms secondary follicles
90
where do antigens and cells from tissues enter lymph node?
- at afferent lymphatics
- through node
- exit via efferent lymphatics
91
where do lymphocytes an phagocytes enter HEVs?
- points where exposed to antigen
92
what happens if cell doesnt detect antigen?
- leaves via efferent lymph node
- later returns to blood via thoracic duct
93
what is the spleen?
- fist sized organ
- associated posteriorly with left ribs 9-11
94
where does the spleen rest?
- left colic flexure of large intestine
95
where does the tail of pancreas point?
- towards spleen
96
which side of the abdomen does it sit on?
- left side
- within hypochondrium region
97
what does the spleen do?
- collects antigen from the blood, presenting to lymphocytes
98
what is the purpose of the spleen?
- to filter blood, removes and disposes of ageing red blood cells and immune complexes
99
what are the two distinct compartments of the spleen?
- red pulp
- white pulp
100
what is the red pulp?
- well perfused tissue
- responsible for filtration role of spleen
- removes ageing and damaged rbc from circulation
101
what is the white pulp?
- many similarities to lymph node
- packed with T cells, B cells and dendritic cells
- sifts antigen from blood instead of lymph
102
where are T cells located?
- periarteriolar lymphoid sheath (PALS)
103
where are B cells located?
- beyond sheath in corona around a germinal centre
104
where are mucosa associated lymphoid tissues found (MALT)?
under epithelium of:
- respiratory tract
- gastrointestinal tract
- genitourinary tract
105
what dies the gut associated lymphoid tissues contain? (GALT)
- tonsils and adenoids
- peyers patches (small intestine)
- appendix
106
what do tonsils and adenoids have?
- small wrinkles called crypts
- subdivide further inside the tonsil
107
what are the different types of tonsil?
- palatine tonsils
- tubal tonsils
- lingual tonsils
108
what are palatine tonsils?
- located at back of oral cavity on each side
109
what are the tubal tonsils?
- located in nasopharynx
- near opening to inner ear internally
110
what are the lingual tonsils?
- sit at base of tongue
111
what do the 4 different tonsils create?
- ring around openings of nasal and oral cavities
111
what are the adenoids?
- type of tonsil (pharyngeal tonsil)
- located high in nasopharynx behind nasal cavity and soft palate
112
what does the ring provide?
- line of defence against pathogens which may enter into these openings
- known as waldeyers ring
113
what is the function of tonsils?
- present antibody to cells of immune system
- similar function to lymph nodes
114
what happens if you have infection?
- antigen from pathogen appears in lymphatics
115
what happens if antigen enters tonsils?
- presented to cels of immune system
- if recognised, begins to rapidly divide
116
what does the rapid division of cells cause?
- tonsils to swell
117
what are the symptoms of tonsillitis?
- sore throat
- pain or discomfort when swallowing
- fever
- swollen glands (lymph nodes) in neck
118
what is the treatment for tonsillitis?
- course of antibiotics
119
what is tonsillectomies?
- removal of tonsils
120
where are peyers patches located?
- mucosa throughout small intestine
- particularly in ileum
121
what are payers patches?
- specialised lymphoid tissue for collecting antigen present in GI tract
122
what do they comprise?
- primary and secondary follicles located immediately beneath specialist epithelium known as follicular associated epithelium
123
what is the appendix?
- part of large intestine
- associated with caecum and has role in immune system
- susceptible to infection
