Introduction to Immune System Flashcards

1
Q

What are examples of barrier against foreign pathogens?

A
  • Physical
    • Mucosal membranes
    • Mucociliary escalator
    • Skin
  • Chemical
    • Acidic pH of stomach
    • Rapid pH change in duodenum and alkaline pH in jejunum and ileum
    • Skin sebum to lower pH
    • Lyzozymes (anti-bacterial enzyme) in tears, saliva and sweat
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2
Q

Describe the anatomy of the immune system?

A

Formed from

  • Lymphoid organs
    • Bone marrow
    • Spleen
  • Lymph nodes
  • Mucosal membranes
    • Mucosa-associated lymphoid tissue (LALT)
    • Bronchus-associated lymphoid tissue (BALT)
    • Gut-associated lymphoid tissue (GALT), including Peyer’s patches
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3
Q

What are the lymphoid organs?

A
  • Bone marrow
  • Spleen
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4
Q

What mucosal membranes contribute to the immune system?

A
  • Mucosa-associated lymphoid tissue (LALT)
  • Bronchus-associated lymphoid tissue (BALT)
  • Gut-associated lymphoid tissue (GALT), including Peyer’s patches
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5
Q

What are the cells of the immune system derived from?

A

Formed in bone marrow from multipotential haematopoietic stem cell (haemocytoblast)

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6
Q

What cells form the immune system?

A
  • Megakaryocyte
    • Location – bone marrow
    • Structure – lobulated nucleus
    • Function – production of platelets
    • Life span – 7 to 10 days
  • Platelets
    • Location – bone marrow and circulation
    • Structure – small anucleate disc shaped cell fragments with granules
    • Function – blood clotting
    • Life span – 7 to 10 days
  • Erythrocyte
    • Location – bone marrow and circulation
    • Structure – biconcave and anucleate
    • Function – transport oxygen, damaged RBC removed via reticuloendothelial system
  • Mast cell
    • Location – connective tissues and mucous membranes
    • Structure – large granulocyte, granules contain histamine
    • Function – important role in allergy, main cell targets are parasites, activated by cross linking of IgE antibodies bound to their FC receptors, activation resulting in degranulation
    • Life span – few weeks to months
  • Basophil
    • Location – bone marrow and circulation
    • Structure – granulocyte, granules contain histamine
    • Function – main target parasites, activated by cross-linking of IgE antibodies that they have bound to their FC receptors, activation results in degranulation, also capable of phagocytosis
    • Life span – hours to days
  • Neutrophil
    • Location – bone marrow and circulation
    • Structure – granulocyte, granules contain substances to kill and digest pathogens such as peroxidase
    • Function – first cells to migrate to site of infection, target is extracellular pathogens like bacteria and fungi, perform phagocytosis or degranulation
    • Life span – few days
  • Eosinophil
    • Location – bone marrow and circulation, tissues such as lungs and oesophagu
    • Structure – granulocyte, granules contain substances to digest and kill pathogens such as peroxidase
    • Function – targets multicellular parasites too big for phagocytosis, important role in allergy
    • Life span – 8 to 12 days
  • Monocyte
    • Location – bone marrow and circulation
    • Structure – kidney shaped nucleus
    • Function – migrates to tissue where they become macrophages and dendritic cells in response to inflammation, capable of phagocytosis, large quantities of hydrolytic enzymes
    • Life span – 24 hours
  • Macrophage
    • Location – bone marrow and are tissue-based progeny of monocytes, name changes depending on what tissue in
    • Function – phagocytosis, antigen presenting cell to CD4+ Th cells, cytokine release (TNF-alpha, IL-2, IL-6)
    • Life span – months to years
  • Dendritic cell
    • Location – tissues exposed to external environment
    • Structure – long narrow processes which resemble neuronal dendrites
    • Function – antigen presenting cell to CD4+ T cells via MHC II, phagocytosis, cytokine secretion (TNF-alpha, IL-12, IL-23)
    • Life span – days to weeks
  • Natural killer cell
    • Location – bone marrow, circulation and spleen
    • Structure – large granular lymphocyte, granules contain special proteins such as perforin and proteases
    • Function – activated by IFN and macrophage derived cytokines, or activated by abnormal MHC I signals (cancerous cells or virally infection cells) to cause apoptosis of cell
  • T-lymphocyte
    • Location – completes maturation in thymus, mature T cells reside in bone marrow, circulation and places such as lymph nodes
    • Structure – all T cells express T cell receptors on their cell surface, there are 3 types: Helper T cells (CD4+), Cytotoxic T cells (CD8+) and Regulatory T cells (CD4+, CD25+)
    • Function – involved in cell mediated adaptive immune response
  • B-lymphocyte
    • Location – completes maturation within lymph nodes and spleen, mature B cells reside in bone marrow, circulation and lymph nodes
    • Structure – all B cells express B cell receptors on surface, 2 kinds: plasma B cells and memory B cells
    • Function – involved in humoral mediated adaptive immune response by producing specific antibodies against certain antigens
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7
Q

For megakaryocyte:

  • location
  • structure
  • function
  • life span
A
  • Megakaryocyte
    • Location – bone marrow
    • Structure – lobulated nucleus
    • Function – production of platelets
    • Life span – 7 to 10 days
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8
Q

For platelets:

  • location
  • structure
  • function
  • life span
A
  • Location – bone marrow and circulation
  • Structure – small anucleate disc shaped cell fragments with granules
  • Function – blood clotting
  • Life span – 7 to 10 days
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9
Q

For erythrocyte:

  • location
  • structure
  • function
A
  • Location – bone marrow and circulation
  • Structure – biconcave and anucleate
  • Function – transport oxygen, damaged RBC removed via reticuloendothelial system
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10
Q

For mast cell:

  • location
  • structure
  • function
  • life span
A
  • Mast cell
    • Location – connective tissues and mucous membranes
    • Structure – large granulocyte, granules contain histamine
    • Function – important role in allergy, main cell targets are parasites, activated by cross linking of IgE antibodies bound to their FC receptors, activation resulting in degranulation
    • Life span – few weeks to months
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11
Q

For basophil:

  • location
  • structure
  • function
  • life span
A
  • Basophil
    • Location – bone marrow and circulation
    • Structure – granulocyte, granules contain histamine
    • Function – main target parasites, activated by cross-linking of IgE antibodies that they have bound to their FC receptors, activation results in degranulation, also capable of phagocytosis
    • Life span – hours to days
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12
Q

For neutrophil:

  • location
  • structure
  • function
  • lifespan
A
  • Neutrophil
    • Location – bone marrow and circulation
    • Structure – granulocyte, granules contain substances to kill and digest pathogens such as peroxidase
    • Function – first cells to migrate to site of infection, target is extracellular pathogens like bacteria and fungi, perform phagocytosis or degranulation
    • Life span – few days
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13
Q

For eosinophil:

  • location
  • structure
  • function
  • life span
A
  • Eosinophil
    • Location – bone marrow and circulation, tissues such as lungs and oesophagu
    • Structure – granulocyte, granules contain substances to digest and kill pathogens such as peroxidase
    • Function – targets multicellular parasites too big for phagocytosis, important role in allergy
    • Life span – 8 to 12 days
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14
Q

For monocyte:

  • location
  • structure
  • function
  • life span
A
  • Location – bone marrow and circulation
  • Structure – kidney shaped nucleus
  • Function – migrates to tissue where they become macrophages and dendritic cells in response to inflammation, capable of phagocytosis, large quantities of hydrolytic enzymes
  • Life span – 24 hours
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15
Q
A
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16
Q

For macrophage:

  • location
  • function
  • life span
A
  • Location – bone marrow and are tissue-based progeny of monocytes, name changes depending on what tissue in
  • Function – phagocytosis, antigen presenting cell to CD4+ Th cells, cytokine release (TNF-alpha, IL-2, IL-6)
  • Life span – months to years
17
Q

What cytokines do macrophages release?

A

(TNF-alpha, IL-2, IL-6)

18
Q

For dendritic cell:

  • location
  • structure
  • function
  • lifespan
A
  • Dendritic cell
    • Location – tissues exposed to external environment
    • Structure – long narrow processes which resemble neuronal dendrites
    • Function – antigen presenting cell to CD4+ T cells via MHC II, phagocytosis, cytokine secretion (TNF-alpha, IL-12, IL-23)
    • Life span – days to weeks
19
Q

What cytokines do dendritic cells release?

A

(TNF-alpha, IL-12, IL-23)

20
Q

For NK cell:

  • location
  • structure
  • function
A
21
Q

For T cell:

  • location
  • structure
  • function
A
22
Q

For B cell:

  • location
  • structure
  • function
A
  • Location – completes maturation within lymph nodes and spleen, mature B cells reside in bone marrow, circulation and lymph nodes
  • Structure – all B cells express B cell receptors on surface, 2 kinds: plasma B cells and memory B cells
  • Function – involved in humoral mediated adaptive immune response by producing specific antibodies against certain antigens
23
Q

What are the 2 divisions of the immune system?

A
  • Innate immunity
  • Adaptive immunity
    • Cell mediated – T cell
    • Humoral mediated – B cell
24
Q

What do the innate and adaptive immune system differ in?

A

They differ from each other in speed of response time, cellular components and functions:

  • Innate is fast to response but not specific, adaptive is slower to respond but is specific to pathogen and creates immunological memory, allowing for faster response next time same pathogen
25
Q

What does MHC stand for?

A

Major histocompatibility complex

26
Q

What are the 2 types of MHC?

A
  • Class 1
    • Found on cell surface of all nucleated cells in body
    • Display self-markers but also responsible for presenting intracellular forign antigens to immune system
  • Class 2
    • Found only on professional antigen presenting cells, such as dendritic cells, macrophages and B lymphocytes
    • Responsible for presenting extracellular antigens from pathogens
    • Brings antigen to attention of T cells
27
Q

What is MHC also referred to as?

A
  • Also referred to as human leukocyte antigen (HLA)
28
Q

What does HLA stand for?

A

Human leukocyte antigen

29
Q

What cells do MHC I and MHC II molecules present antigens to?

A

MHC I receptor presents antigens to CD8+ cytotoxic T cells, which destroy them

MHC II receptor on antigen presenting cells presents their antigen to CD4+ helper T cells, causing it to release cytokines that activates B cells, which release specific antibodies against the pathogen to improve macrophage phagocytosis and recruit primed CD8+ cells to target pathogen

Sometimes immune cells can attack our own cells that are displaying self-antigens, this is autoimmunity

30
Q

What is immune tolerance?

A

This is when our immune cells do not attack our own cells, achieved through:

  • Central tolerance
  • Peripheral tolerance
31
Q

What are the 2 forms of immune tolerance?

A
  • Central tolerance
  • Peripheral tolerance
32
Q

Where does central tolerance occur?

A
  • T cells in thymus
  • B cells in bone marrow
33
Q

What happens in central tolerance?

A
  • Any cell showing inappropriate response to self-antigens are either edited, transformed or destroyed
34
Q

Where does periphral tolerance occur?

A
  • Occurs in secondary lymphoid organs
    • Contains mature cells already released into circulation
35
Q

What happens in peripheral tolerance?

A
  • If any cell inappropriately recognises and reacts to self-antigens they are made useless, destroyed or suppressed by regulatory T cells
36
Q

What can immune tolerance be exploited by?

A

Immune tolerance can be exploited by intracellular pathogens or malignant cells to evade host immune responses