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HUBS191 > immune system > Flashcards

immune system Flashcards

1
Q

what is the immune system?

A

an organised system of organs, cells, and molecules that work together to defend the body against any potential disease causing invaders

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2
Q

what is the function of the primary lymphoid organs?

A

are where white blood cells are produced

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3
Q

what is the function of the secondary lymphoid organs?

A

are where the immune response is initiated

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4
Q

what are the lymphoid organs in the body? (5)

A
  • tonsils
  • thymus
  • spleen
  • bone marrow
  • lymph nodes
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5
Q

what are the primary lymphoid organs?

A
  • thymus

- bone marrow

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6
Q

what are the secondary lymphoid organs?

A
  • tonsils
  • spleen
  • lymph nodes
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7
Q

what are lymphocytes?

A

white blood cells

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8
Q

what is the function of the thymus?

A

teaches T-cells to recognise foreign material and not recognise own body cells

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9
Q

how many T-cells make it through the thymus to actually function in the body?

A

10%

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10
Q

where are T-cells developed?

A

in the thymus

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11
Q

what is the function of the bone marrow?

A

is a rich source of stem cells

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12
Q

what is the function of the stem cells?

A

can develop into cells of either the innate, or adaptive, immune system

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13
Q

what is the feature of stem cells that allows them to develop into different types of cells?

A

they are pluripotent

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14
Q

where do B-cells develop?

A

the bone marrow

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15
Q

what is the function of the spleen?

A
  • filters blood which is important because dont want infections in blood
  • is the site of initiation for immune responses against blood-borne pathogens
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16
Q

what are lymph nodes? structure

A

small, white, round aggregates of cells within a capsule

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17
Q

where are lymph nodes found? what is the function of the lymphatic system?

A
  • found along lymphatic vessels
  • it goes throughout the body; drains fluids, molecules, and cells from tissues and blood, and brings them up to lymph nodes through lymphatic vessels
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18
Q

how are lymph nodes involved in the immune response?

A

molecules from an infection travel to the local lymph node, causing an immune response to start at that lymph node

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19
Q

how many layers of defence are in the body? what are they?

A

3 layers of defence:

  • physical and chemical barriers
  • innate immune system
  • adaptive immune system
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20
Q

what is the function of the physical and chemical barriers of the immune system?

A

to stop organisms from getting into our body

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21
Q

what are the differences between the innate and adaptive immune system? (dynamic, speed, specificity, memory)

A 
innate:
- fixed, cells already in place
- rapid response (hours)
- limited specificity
- no memory
adaptive:
- improves during the response, variable cells (B-cells)
- slow response (days-weeks)
- highly specific
- has memory
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22
Q

what are the cells of the innate immune system? (3)

A
  • phagocytes
  • natural killer cells
  • complements
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23
Q

what are the cells of the adaptive immune system?

A

B-cells and T-cells

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24
Q

describe the specificity of the innate immune system?

A

can recognise pathogens but tend to be molecules on pathogens that are common to many pathogens
e.g- double stranded RNA only in viral infection so can recognise double stranded RNA but cant tell different viruses apart

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25
Q

both phagocytes and natural killer cells destroy cells, but what makes them different?

A

phagocytes engulf and destroy microbes whereas natural killer cells destroy infected cells

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26
Q

how does the adaptive immune system improve during the response?

A

antibodies produced by B-cells get more specific

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27
Q

what makes the adaptive immune system highly specific?

A

B-cells can distinguish between different viruses

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28
Q

what is the structure of the skin?

A

-consists of 2 layers:

epidermis and dermis

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29
Q

what is the composition of the epidermis?

A
  • composed of dead cells

- keratin and dendritic cells underneath layer of dead skin

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30
Q

what is the composition of the dermis?

A
  • thick layer of connective tissues, collagen, and blood vessels
  • has lots of dermal dendritic cells
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31
Q

what is the purpose of the dermal dendritic cells being in the dermis (and epidermis)?

A

are there to alert the rest of the immune cells to any invading microbes

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32
Q

what makes the skin a good physical barrier?

A

because it consists of tightly woven cells

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33
Q

what composes the chemical defences of the skin? (4)

A
  • antimicrobial peptides
  • lysozyme
  • sebum
  • salt
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34
Q

what are antimicrobial peptides? what do they work against? how in bacteria?

A
  • are small protein, peptide antibiotics
  • work against bacteria, fungi, and viruses
  • often work by forming pores in bacterial membranes, causing the leaching of nutrients and essential ions -> death
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35
Q

what is a lysozyme? where are they found?

A
  • an enzyme that attacks microbial invaders by breaking down their cell walls -> lead to death
  • found in sweat, tears, saliva, mucous, and urine
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36
Q

what is an advantage of having many sweat glands with respect to lysozyme?

A

we have lots of sweat glands which are constantly producing sweat so the surfaces of our bodies are constantly bathed in sweat which allows the production of the enzyme to breakdown cell walls

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37
Q

what is sebum? where is it produced?

A

is a fatty and oily secretion produced in sebaceous glands

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38
Q

how does sebum act as a chemical defence?

A

it has a low pH which prevents microbial growth on our skin making it prohibitive to microbial colonisation

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39
Q

how does salt act as a chemical defence? why does this not happen to our skin?

A

salt draws water out, which dehydrates pathogens leading to their death

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40
Q

what is the function of mucous membranes?

A

produce mucus to protect the opening of our body because they are good places for microbes to enter and be potentially harmful

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41
Q

structure of mucous membrane? (layers and name of one in body)

A
  • can be made up of one or two layers: epithelial layer

- maybe a connective tissue layer beneath (layer in gut called lamina propria)

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42
Q

what is the structure of the epithelial layer of the mucous membrane? (cells)

A
  • formed of tightly packed cells that are constantly removed (renewed by stem cells) and so are alive
  • contain mucus producing goblet cells
43
Q

where are the mucous membranes located?

A
  • lines any part of the body that leads to the outside and is exposed to air
  • e.g- eyes, respiratory tract, gastrointestinal tract, urogenital tract, oral
44
Q

why is the mucous membrane not as good of a physical barrier as skin?

A

because its outer layer consists of live cells and there are not as many layers

45
Q

what is the structure in the lungs that draws out inhaled particles and pathogens?

A
  • mucociliary escalator
46
Q

describe the basis of how the mucociliary escalator works?

A
  • lower respiratory tract has columnar cells which have cilia on top of them
  • cilia continually beat in tandem to move a layer of mucus with trapped inhaled particles up the respiratory tract
  • mucus layer with inhaled particles can then be coughed or sneezed out of the body
47
Q

why are people who smoke more prone to developing respiratory infections?

A

because smoking causes the paralysis of cilia so they no longer beat and inhaled particles arent moved up and out of the respiratory tract

48
Q

how can the stomach prevent microbial growth?

A
  • it has a low pH in which bacteria cannot survive

- has digestive enzymes that can breakdown enzymes

49
Q

how does the gall bladder prevent microbial growth?

A
  • produces bile which breaks down lipids and some bacterial cell walls
50
Q

how do the intestines prevent microbial growth?

A
  • small intestine produces digestive enzymes that can breakdown microbes
  • able to produce mucus inside which can prevent and get rid of microbial growth
51
Q

how are the eyes protected from microbial infection?

A
  • flushing action: constantly producing tears and bathing eye, is then drained and swallowed
  • tears contain lysozyme which can break down bacterial cell walls
52
Q

what is the process of tear movement in the eye? (production, drainage)

A
  • tears are produced in the lacrimal gland
  • tears bathe eye
  • drained into lacrimal canal
  • tears are swallowed
53
Q

what defences does the urogenital tract have that prevents microbial growth?

A
  • the flow of urine flushes microbes out of the body
  • lysozyme produced
  • low pH prevents microbial growth
  • high osmolarity
54
Q

what are antimicrobial peptides? what kinds of microbes can they target?

A
  • small molecular weight proteins

- have broad spectrum activity against microbes

55
Q

what happens when there is an infection with a pathogen in the body?

A
  • antimicrobial proteins are produced
  • interferons produced (type of cytokine)
  • activation of complement system
56
Q

where are antimicrobial peptides produced?

A
  • by epithelial cells lining mucosal surfaces

- by keratinocytes in the skin

57
Q

how do antimicrobial peptides attack microbes?

A
  • by interfering with their growth and reproduction

- often work by forming pores in cell walls resulting in leaching of nutrients and essential ions

58
Q

what is another function other than attacking microbes that antimicrobial peptides have?

A

they can act as chemoattractants to inflammatory cells and draw them in to a site of inflammation

59
Q

what are 2 types of antimicrobial proteins that are produced? what makes them different?

A

defensins
- mostly work by producing pores in cell walls
cathelicidins
- can directly attack microbes but also work as chemoattractant

60
Q

what are interferons?

A

they are a type of cytokine which are produced to combat viral infections

61
Q

how are interferons produced? an example?

A

they are produced by many different cell types
- interferons produced by virus-infected cells can prevent infection of neighbouring cells in a way that lasts 3-4 days = can prevent infection from taking over

62
Q

what is the function of interferons? an example?

A
  • combat viral infections
    interferons produced by virus-infected cells prevent infection of neighbouring cells for 3-4 days = prevents infection from taking over
63
Q

how to interferons work? (brief)

A
  • cells detect that they are infected with a virus and produce interferons
  • interferons bind to interferon receptors on neighbouring cells
  • depending on the state and type of cells (unaffected neighbouring, affected neighbouring, or immune) the interferon produces a different response
64
Q

what action does the binding of an interferon cause in an unaffected neighbouring cell during a viral infection? why is this action taken in this type of cell?

A
  • the unaffected cell is told to destroy its protein synthesis pathway so it gets rid of RNA and destroys enzymes that are involved in protein synthesis
  • this is the action taken because a virus can only survive by taking over a cell’s protein synthesis pathway in order to reproduce, but this way the cell is prevented from developing a productive infection
65
Q

what occurs in neighbouring affected cells after the binding of an interferon during a viral infection? why?

A
  • signals them to undergo apoptosis: programmed cell death

- because the virus needs the cell in order to multiply but it cannot do so in a dead cell, thus infection is limited

66
Q

what action occurs in immune cells after the binding of an interferon during a viral infection? why?

A
  • the immune cell is activated

- this enhances their microbial function, making them more effective at clearing infection

67
Q

what are erythrocytes?

A

red blood cells

68
Q

how many leukocytes are there in blood?

A

5000-9000 per mL of blood

69
Q

what is the source of blood cells in the body?

A

the stem cells of the bone marrow found in long bones

70
Q

what is the process by which blood cells and platelets are produced from the bone marrow called?

A

hematopoiesis

71
Q

what are the three blood cell lineages called? what cells do they produce?

A
  • erythroid -> reb blood cells (erythrocytes)
  • myeloid -> innate immune cells (granulocytes, monocytes, dendritic cells, platelets)
  • lymphoid -> adaptive immune cells (B and T lymphocytes)
72
Q

what are the cells of the innate immune system? (3)

A
  • granulocytes
  • monocytes
  • dendritic cells
73
Q

what are the types of granulocytes? (4)

A
  • neutrophils
  • eosinophils
  • basophils
  • mast cells
74
Q

how many granulocytes are there in the body?

A

they account for 3/4 of all leukocytes

75
Q

what are granulocytes? (structure) what is their function?

A

they are granular cells: they have large granules that store pre-formed chemical that are able to exact immune responses

76
Q

what are the features of neutrophils? (phagocytosis? number? 2 more)

A
  • they are highly phagocytic
  • most abundant granulocyte: 40-75% of leukocytes
  • have a short half-life (1-2 days) and thus a high turnover
  • they dont tend to recirculate: major component of pus is dead neutrophils
77
Q

what are the features of eosinophils? (number? phagocytosis? role (2)?)

A
  • low numbers: 1-6% of leukocytes
  • some phagocytosis
  • main role to release toxic granules which breakdown and kill microbes and parasites (particularly worms)
  • mediate allergic reaction
78
Q

what are the features of basophils? (numbers? phagocytosis? roles (2)?)

A
  • very low numbers
  • no phagocytosis
  • have pre-formed granules that mediate allergic reactions or fight worm infectons
  • contains chemicals to draw in other cells to a site of infection
79
Q

what is the one way that basophils can draw in other cells to a site of infection?

A
  • by inducing vasodilation in blood vessels which increases the number of cells that can be drawn into an area
80
Q

what are features of mast cells? (location? role?)

A
  • are found lining mucosal surfaces rather than in the blood
  • release granules with pre-formed chemicals that attract other leukocytes to areas of tissue damage
  • similar to basophils
81
Q

where are monocytes found? what are they? (2) phagocytosis?

A
  • they are present in the blood
  • have no granules
  • are broad-acting immune cells that circulate in the blood
  • have low phagocytosis
82
Q

what happens to monocytes when they leave the blood and enter tissue?

A
  • they develop into macrophages in tissue
83
Q

what are the two kinds of macrophage?

A
  • sessile macrophage
    they are resident to the tissue they are in ie-stay in the tissue
  • migratory macrophage
    can move through and between tissues
84
Q

what are the functions of macrophages?

A
  • phagocytosis
  • release of chemical messengers (cytokines)
  • are an important link between the innate and adaptive immune system
85
Q

how do macrophages act as an important link between the innate and adaptive immune system?

A

they alert adaptive immune cells (T-cells) that there is an infection by showing them information about pathogenic microbes

86
Q

dendritic cells: numbers? location? phagocytosis? role in adaptive immune system?

A
  • found in low numbers in blood and in all tissues in contact with the environment
  • phagocytic
  • most important cell to trigger adaptive immune responses
87
Q

what are the 2 ways that cells in the immune system move around the body?

A

cells are carried in the blood and in the lymph

88
Q

how are cells in the blood move around the body?

A
  • beating of the heart moves blood around the body

- cells can leave blood to enter tissue by a process called diapedesis

89
Q

how are cells in the lymph moved through the body?

A
  • lymphatic fluid has no pump action so is moved through body via body’s movement: contraction of muscle move lymph round
  • lymph in tissues collects into lymphatic vessels and drains into lymph nodes
90
Q

what are the 5 cardinal signs of inflammation?

A
  • heat
  • redness
  • swelling
  • pain
  • loss of function
91
Q

what occurs during inflammation?

A
  • there is infected or injured tissue
  • release of chemical messengers -> allows vasodilation
  • cells can get through blood vessels and into the blood because vasodilation makes blood vessels more permeable and leaky
92
Q

why does swelling, heat, redness, and pain occur during inflammation?

A
  • swelling occurs due to an increase in the number of cells and fluid in the site of infection
  • pain occurs due to the deformation of the tissue due to swelling
  • redness occurs due to the dilation of the blood vessels at the site of infection
  • heat occurs due to the increased blood flow at the site
93
Q

damage to mast cells cause them to release their pre-formed granules; what is found in them and what is the function of each?

A 
- histamine
causes vasodilation
- prostaglandins
increase vascular permeability
- leukotrienes
increase vascular permeability
94
Q

what is the overall effect of activating mast cells?

A

causes vasodilation and makes blood vessels more leaky to allow cells to get out of blood and into the tissues more easily

95
Q

what occurs during the process of diapedesis?

A

cells and fluid leave dilated blood vessel

e. g- involving a neutrophil
- neutrophil is initially round but flattens against vessel wall and sticks to it (margination)
- neutrophil is able to squeeze through vessel walls which are now more permeable
- neutrophil follows chemical gradient towards the cell producing it
- then enters the site of infection

96
Q

what cell produces the chemical gradient that cells entering the tissue follow and how?

A

mast cells produce the chemical gradient by releasing their granules which are filled with pre-formed chemicals

97
Q

summarise the main components of the inflammation response (5)

A
  • increased blood flow to site of inflammation
  • increased vascular permeability
  • migration of inflammatory cells from blood into inflamed tissue
  • removal of invader microbes and debris
  • promote repair of tissue and regeneration of new cells
98
Q

what is fever? why does it occur?

A
  • fever is when the core body temperature increases above what is normal (>37 degrees C)
  • occurs due to a resetting of the internal thermostat (hypothalamus)
99
Q

how is the hypothalamus reset? example?

A

-driven by pyrogens
one of the pyrogens is interleukin-1 (IL-1)
- trigger fevers by inducing prostaglandin production which resets the thermostat in the hypothalamus

100
Q

how is the effect of IL-1 on the thermostat in the hypothalamus regulated?

A
  • is produced by phagocytes after ingesting bacteria
  • when phagocytosis stops (bc all bacteria are gone), production of IL-1 decreases, resulting in temeperature coming down to normal
101
Q

what are the chemicals released from mast cells that affect blood vessels?

A

histamine
prostaglandin
leukotrienes

102
Q

what is another word for fever?

A

pyrexia

103
Q

what effect does fever have on the body?

A
  • some leukocytes are more active at 38-40 degrees Celsius

- growth rate of some microbes is slowed down

HUBS191 (3 decks)

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