immune system Flashcards
(103 cards)
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
2
Q
what is the function of the primary lymphoid organs?
A
are where white blood cells are produced
3
Q
what is the function of the secondary lymphoid organs?
A
are where the immune response is initiated
4
Q
what are the lymphoid organs in the body? (5)
A
- tonsils
- thymus
- spleen
- bone marrow
- lymph nodes
5
Q
what are the primary lymphoid organs?
A
- thymus
- bone marrow
6
Q
what are the secondary lymphoid organs?
A
- tonsils
- spleen
- lymph nodes
7
Q
what are lymphocytes?
A
white blood cells
8
Q
what is the function of the thymus?
A
teaches T-cells to recognise foreign material and not recognise own body cells
9
Q
how many T-cells make it through the thymus to actually function in the body?
A
10%
10
Q
where are T-cells developed?
A
in the thymus
11
Q
what is the function of the bone marrow?
A
is a rich source of stem cells
12
Q
what is the function of the stem cells?
A
can develop into cells of either the innate, or adaptive, immune system
13
Q
what is the feature of stem cells that allows them to develop into different types of cells?
A
they are pluripotent
14
Q
where do B-cells develop?
A
the bone marrow
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
16
Q
what are lymph nodes? structure
A
small, white, round aggregates of cells within a capsule
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
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
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
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
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
22
Q
what are the cells of the innate immune system? (3)
A
- phagocytes
- natural killer cells
- complements
23
Q
what are the cells of the adaptive immune system?
A
B-cells and T-cells
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
25
both phagocytes and natural killer cells destroy cells, but what makes them different?
phagocytes engulf and destroy microbes whereas natural killer cells destroy infected cells
26
how does the adaptive immune system improve during the response?
antibodies produced by B-cells get more specific
27
what makes the adaptive immune system highly specific?
B-cells can distinguish between different viruses
28
what is the structure of the skin?
-consists of 2 layers:
| epidermis and dermis
29
what is the composition of the epidermis?
- composed of dead cells
| - keratin and dendritic cells underneath layer of dead skin
30
what is the composition of the dermis?
- thick layer of connective tissues, collagen, and blood vessels
- has lots of dermal dendritic cells
31
what is the purpose of the dermal dendritic cells being in the dermis (and epidermis)?
are there to alert the rest of the immune cells to any invading microbes
32
what makes the skin a good physical barrier?
because it consists of tightly woven cells
33
what composes the chemical defences of the skin? (4)
- antimicrobial peptides
- lysozyme
- sebum
- salt
34
what are antimicrobial peptides? what do they work against? how in bacteria?
- 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
35
what is a lysozyme? where are they found?
- an enzyme that attacks microbial invaders by breaking down their cell walls -> lead to death
- found in sweat, tears, saliva, mucous, and urine
36
what is an advantage of having many sweat glands with respect to lysozyme?
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
37
what is sebum? where is it produced?
is a fatty and oily secretion produced in sebaceous glands
38
how does sebum act as a chemical defence?
it has a low pH which prevents microbial growth on our skin making it prohibitive to microbial colonisation
39
how does salt act as a chemical defence? why does this not happen to our skin?
salt draws water out, which dehydrates pathogens leading to their death
40
what is the function of mucous membranes?
produce mucus to protect the opening of our body because they are good places for microbes to enter and be potentially harmful
41
structure of mucous membrane? (layers and name of one in body)
- can be made up of one or two layers: epithelial layer
| - maybe a connective tissue layer beneath (layer in gut called lamina propria)
42
what is the structure of the epithelial layer of the mucous membrane? (cells)
- formed of tightly packed cells that are constantly removed (renewed by stem cells) and so are alive
- contain mucus producing goblet cells
43
where are the mucous membranes located?
- 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
why is the mucous membrane not as good of a physical barrier as skin?
because its outer layer consists of live cells and there are not as many layers
45
what is the structure in the lungs that draws out inhaled particles and pathogens?
- mucociliary escalator
46
describe the basis of how the mucociliary escalator works?
- 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
why are people who smoke more prone to developing respiratory infections?
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
how can the stomach prevent microbial growth?
- it has a low pH in which bacteria cannot survive
| - has digestive enzymes that can breakdown enzymes
49
how does the gall bladder prevent microbial growth?
- produces bile which breaks down lipids and some bacterial cell walls
50
how do the intestines prevent microbial growth?
- small intestine produces digestive enzymes that can breakdown microbes
- able to produce mucus inside which can prevent and get rid of microbial growth
51
how are the eyes protected from microbial infection?
- flushing action: constantly producing tears and bathing eye, is then drained and swallowed
- tears contain lysozyme which can break down bacterial cell walls
52
what is the process of tear movement in the eye? (production, drainage)
- tears are produced in the lacrimal gland
- tears bathe eye
- drained into lacrimal canal
- tears are swallowed
53
what defences does the urogenital tract have that prevents microbial growth?
- the flow of urine flushes microbes out of the body
- lysozyme produced
- low pH prevents microbial growth
- high osmolarity
54
what are antimicrobial peptides? what kinds of microbes can they target?
- small molecular weight proteins
| - have broad spectrum activity against microbes
55
what happens when there is an infection with a pathogen in the body?
- antimicrobial proteins are produced
- interferons produced (type of cytokine)
- activation of complement system
56
where are antimicrobial peptides produced?
- by epithelial cells lining mucosal surfaces
| - by keratinocytes in the skin
57
how do antimicrobial peptides attack microbes?
- by interfering with their growth and reproduction
| - often work by forming pores in cell walls resulting in leaching of nutrients and essential ions
58
what is another function other than attacking microbes that antimicrobial peptides have?
they can act as chemoattractants to inflammatory cells and draw them in to a site of inflammation
59
what are 2 types of antimicrobial proteins that are produced? what makes them different?
defensins
- mostly work by producing pores in cell walls
cathelicidins
- can directly attack microbes but also work as chemoattractant
60
what are interferons?
they are a type of cytokine which are produced to combat viral infections
61
how are interferons produced? an example?
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
what is the function of interferons? an example?
- combat viral infections
interferons produced by virus-infected cells prevent infection of neighbouring cells for 3-4 days = prevents infection from taking over
63
how to interferons work? (brief)
- 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
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?
- 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
what occurs in neighbouring affected cells after the binding of an interferon during a viral infection? why?
- 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
what action occurs in immune cells after the binding of an interferon during a viral infection? why?
- the immune cell is activated
| - this enhances their microbial function, making them more effective at clearing infection
67
what are erythrocytes?
red blood cells
68
how many leukocytes are there in blood?
5000-9000 per mL of blood
69
what is the source of blood cells in the body?
the stem cells of the bone marrow found in long bones
70
what is the process by which blood cells and platelets are produced from the bone marrow called?
hematopoiesis
71
what are the three blood cell lineages called? what cells do they produce?
- erythroid -> reb blood cells (erythrocytes)
- myeloid -> innate immune cells (granulocytes, monocytes, dendritic cells, platelets)
- lymphoid -> adaptive immune cells (B and T lymphocytes)
72
what are the cells of the innate immune system? (3)
- granulocytes
- monocytes
- dendritic cells
73
what are the types of granulocytes? (4)
- neutrophils
- eosinophils
- basophils
- mast cells
74
how many granulocytes are there in the body?
they account for 3/4 of all leukocytes
75
what are granulocytes? (structure) what is their function?
they are granular cells: they have large granules that store pre-formed chemical that are able to exact immune responses
76
what are the features of neutrophils? (phagocytosis? number? 2 more)
- 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
what are the features of eosinophils? (number? phagocytosis? role (2)?)
- 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
what are the features of basophils? (numbers? phagocytosis? roles (2)?)
- 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
what is the one way that basophils can draw in other cells to a site of infection?
- by inducing vasodilation in blood vessels which increases the number of cells that can be drawn into an area
80
what are features of mast cells? (location? role?)
- 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
where are monocytes found? what are they? (2) phagocytosis?
- they are present in the blood
- have no granules
- are broad-acting immune cells that circulate in the blood
- have low phagocytosis
82
what happens to monocytes when they leave the blood and enter tissue?
- they develop into macrophages in tissue
83
what are the two kinds of macrophage?
- 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
what are the functions of macrophages?
- phagocytosis
- release of chemical messengers (cytokines)
- are an important link between the innate and adaptive immune system
85
how do macrophages act as an important link between the innate and adaptive immune system?
they alert adaptive immune cells (T-cells) that there is an infection by showing them information about pathogenic microbes
86
dendritic cells: numbers? location? phagocytosis? role in adaptive immune system?
- 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
what are the 2 ways that cells in the immune system move around the body?
cells are carried in the blood and in the lymph
88
how are cells in the blood move around the body?
- beating of the heart moves blood around the body
| - cells can leave blood to enter tissue by a process called diapedesis
89
how are cells in the lymph moved through the body?
- 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
what are the 5 cardinal signs of inflammation?
- heat
- redness
- swelling
- pain
- loss of function
91
what occurs during inflammation?
- 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
why does swelling, heat, redness, and pain occur during inflammation?
- 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
damage to mast cells cause them to release their pre-formed granules; what is found in them and what is the function of each?
```
- histamine
causes vasodilation
- prostaglandins
increase vascular permeability
- leukotrienes
increase vascular permeability
```
94
what is the overall effect of activating mast cells?
causes vasodilation and makes blood vessels more leaky to allow cells to get out of blood and into the tissues more easily
95
what occurs during the process of diapedesis?
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
what cell produces the chemical gradient that cells entering the tissue follow and how?
mast cells produce the chemical gradient by releasing their granules which are filled with pre-formed chemicals
97
summarise the main components of the inflammation response (5)
- 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
what is fever? why does it occur?
- 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
how is the hypothalamus reset? example?
-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
how is the effect of IL-1 on the thermostat in the hypothalamus regulated?
- 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
what are the chemicals released from mast cells that affect blood vessels?
histamine
prostaglandin
leukotrienes
102
what is another word for fever?
pyrexia
103
what effect does fever have on the body?
- some leukocytes are more active at 38-40 degrees Celsius
| - growth rate of some microbes is slowed down
