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Anatomy and Physiology - pure > Immune system > Flashcards

Immune system Flashcards

1
Q

What are non specific defence mechanisms?

A

Mechanisms that protect the body against a wide range of dangers
Usually present from birth
Sometimes termed innate

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2
Q

What are specific defence mechanisms?

A

Mechanisms directed against one specific invader
The body learns and remembers specific antigens building an immunological memory
Sometimes termed adaptive

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3
Q

What is an antigen?

A

Anything that stimulates an immune response

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4
Q

What are the 5 main non-specific defences?

A

Epithelial barriers
Phagocytosis
Natural antimicrobial substances
The inflammatory response
Immunological surveillance

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5
Q

What do epithelial barriers consist of?

A

Skin (barrier against pathogens) and mucous membranes

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6
Q

How do epithelial secretions protect the body against infection?

A

Anti-bacterial and often acidic containing antibodies and enzymes
Sebum and sweat contain antibacterial and anti fungal properties
One-way flow of urine minimises risk of infection ascending through the urethra

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7
Q

What does saliva do?

A

Washes away food debris to prevent bacterial growth, contains antibodies, lysozymes and buffers to neutralise bacterial acids that promote dental decay

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8
Q

What is a lysozyme?

A

An anti-bacterial enzyme present in tears

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9
Q

What are antibodies?

A

Protective proteins that inactivate bacteria and are found coating membranes exposed to th external environment

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10
Q

What are interferons?

A

Chemicals produced by T-lymphocytes, macrophages and body cells that have been infected by viruses, there activate immune cells, including killer T-cells, prevent viral replication within infected cells, and reduce the spread of viruses to healthy cells

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11
Q

What do phagocytes do?

A

Migrate to sites of inflammation and infection as they are attracted to chemicals that are released by invading microbes
They attack, digest and destroy foreign cells, damaged cells and debris
May also release a chemical which is toxic to the invading microbes into the interstitial fluid and alerts the immune system to the presence of a threat

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12
Q

What is the purpose of the inflammatory response?

A

To isolate, inactivate and remove both the causative agent and damaged tissue, so that healing can take place

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13
Q

What are the signs of inflammation?

A

Redness, heat, swelling, pain

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14
Q

What triggers and inflammatory response?

A

Extreme temperatures, pH, trauma, foreign bodies

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15
Q

What happens during the inflammatory response?

A

Increased blood flow, accumulation of tissue fluid, migration of leukocytes, increased core temperature, pain and suppuration (pus forming)

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16
Q

What substances are released during the inflammatory response?

A

Histamine, serotonin, prostaglandins, heparin, bradykinin

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17
Q

How and why is there an increased blood flow during the inflammatory response?

A

Arterioles dilate, capillaries expand
Provides more oxygen and nutrients to the area
Caused by local release of histamine and serotonin

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18
Q

What does increased blood flow in the inflammatory response cause?

A

Increased temperature, swelling and redness

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19
Q

What causes the accumulation of tissue fluid in the inflammatory response?

A

Fluid leaves blood vessels and moves into the interstitial space
Caused by increased blood flow and histamine, serotonin and prostaglandins making capillary walls more permeable

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20
Q

What causes the migration of leukocytes in the inflammatory response?

A

Loss of fluid from the blood thickens it, slowing flow and allowing the normally fast-flowing white blood cells to make contact with, and adhere to, the vessel wall
Neutrophils adhere to the blood vessel lining and enter the tissues for phagocytosis, macrophages begin phagocytosis after 24 hours

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21
Q

What does the increased core temperature do during the inflammatory response?

A

Inhibits the growth and division of microbes while promoting the activity of phagocytes

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22
Q

How and why does the inflammatory response cause pain?

A

Encourages protection
Local swelling compresses sensory nerve endings

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23
Q

What is suppuration?

A

Collection of material - dead phagocytes, dead cells, fibrin, inflammatory exudate and living and dead cells

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24
Q

What does immunological surveillance involve?

A

Natural Killer cells

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25
Q

What are natural killer cells?

A

A type of non-selective lymphocyte

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26
Q

What do natural killer cells do?

A

Patrol the body, searching for abnormal host cells and immediately kill them
Cells that have been infected with a virus or mutated cells that may become malignant frequently display unusual markers on their cell membranes which are recognised by NK cells

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27
Q

Why is specific immunity used?

A

If the non-specific defences are overwhelmed, the immune system is activated

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28
Q

What does specific immunity involve?

A

T lymphocytes and B lymphocytes

29
Q

How is specific immunity particularly useful?

A

It is targeted to one antigen (specificity)
A memory is created of each immuno-response so if encountered again, the response is faster and more powerful
Does not attack its own cells (tolerance)

30
Q

What do lymphocytes include?

A

NK cells, T cells and B cells

31
Q

Where are T cells and B cells produced?

A

Bone marrow and some lymphatic tissues

32
Q

How are T cells formed?

A

Immature T cells are produced in the bone marrow
They migrate to the thymus gland and mature under the influence of the hormone thymosim - becomes specialised
Becomes fully activated when it encounters infective connective tissues, especially in the lymph nodes

33
Q

What do T cells do once fully mature?

A

Continue circulating the bloodstream and lymphoid organs
Are programmed to recognise only one type of antigen and during its subsequent travels through the body will react to no other antigen

34
Q

How are B cells formed?

A

Immature B cells produced in the bone marrow
B cells are also matured in the bone marrow

35
Q

What do B cells do?

A

Produce antibodies (immunoglobulins) which are proteins that bind to and destroy antigens
Each B cell targets one specific antigen

36
Q

What are the 2 immune responses that are triggered by antigens?

A

Cell mediated (involves T cells)
Humoral/Antibody mediated (involves B cells)

37
Q

What are antigen-presenting cells and what is their importance?

A

T-cells cannot detect free antigens in body fluids, to recognise and be activated by antigens, the T-cell must be presented with it on the membrane of another cell - APCs
Many different cell types present antigens to T-cells so are important in activating the adaptive immune system

38
Q

What are the 4 types of T cells?

A

Cytotoxic (CD8)
Helper (CD4)
Regulatory
Memory

39
Q

What do cytotoxic T cells do?

A

Inactivate anything carrying antigens by releasing powerful toxins
Main function is to destroy abnormal body cells which are infected or cancerous

40
Q

What do helper T cells do?

A

Produce cytokines to support and promote cytotoxic T cells and macrophages
Stimulate B cells to produce antibodies
Essential for cell mediated and antibody mediated immunity

41
Q

What do regulatory T cells do?

A

Act as brakes, turning off activated T ands B cells
Limits the powerful and potentially damaging effects of the immune response.
Involved in immunological tolerance; help prevent the development of autoimmunity and protect the foetus in pregnancy

42
Q

What do memory T cells do?

A

Respond rapidly to subsequent encounters with the same antigen

43
Q

What is humoral immunity?

A

Antibodies that are made from B cells are released into the bloodstream for distribution around the body but each B cell also displays the antibody that it makes on its cell membrane
Helper T cells then enable the B cell to enlarge and proliferate (makes memory B cells and plasma cells)

44
Q

What do memory B cells do?

A

Provide long term immunity for that antigen

45
Q

What do plasma cells do?

A

Produce antibodies that bind to, and destroy the antigen

46
Q

What are antibodies and what do they do?

A

Antibodies belong to a group of glycoproteins - immunoglobulins
Bind to antigens, labelling them as targets for other defence cells such as cytotoxic T cells and macrophages
Bind to bacterial toxins, neutralising them

47
Q

What is the structure of an antibody?

A

2 heavy chains made of amino acids
2 light chains made of polypeptides
The chains are linked by disulphide bonds, making the antibodies a Y shape

48
Q

How are antibodies classified?

A

According to the structure and location of their heavy chains

49
Q

What are the 5 main types of antibody?

A

IgA
IgD
IgE
IgG
IgM

50
Q

What is the function of IgA?

A

Coats epithelial membranes and prevents antigens crossing them and invading deeper tissues
Found in breastmilk and saliva, effective against digestive tract pathogens

51
Q

What is the function of IgD?

A

Made by B-cells and displayed on their surfaces
Antigens bind here to activate B-cells

52
Q

What is the function of IgE?

A

Found on cell membranes
If it binds its antigen, it activates the inflammatory response
Often found in excess in allergy

53
Q

What is the function of IgG?

A

The largest and longest-lived and most common antibody type
Attacks many different pathogens and crosses the placenta to protect the foetus
Effective against viruses

54
Q

What is the function of IgM?

A

A sign of recent invasion as they are short lived and appear first
Effective against viruses
A potent activator of complement system

55
Q

What is the complement system?

A

A system of about 20 proteins found in the blood and tissues, activated by the presence of immune complexes (an antigen and antibody bound together) and by foreign sugars on bacterial walls

56
Q

What do the proteins in the complement system do?

A

Bind to and damage bacterial walls, destroying the microbe
Bind to bacterial cell walls, stimulating phagocytosis by neutrophils and macrophages
Attracts phagocytic cells into an area of infection, stimulates chemotaxis

57
Q

What is active immunity?

A

The individual has responded to an antigen and produced their own antibodies, lymphocytes are activated and the memory cells formed provide long-lasting resistance

58
Q

What is passive immunity?

A

The individual is given antibodies produced by someone else
The antibodies break down with time so passive immunity is relatively brief

59
Q

What is natural immunity?

A

The body may be stimulated to produce its own antibodies by either having the disease or having a subclinical infection (active). Acquired before birth by the passage of maternal antibodies across the placenta to the foetus, and to the baby in breast milk (passive)

60
Q

What is artificial immunity?

A

In response to the administration of dead or live artificially weakened pathogens (vaccines) or deactivated (toxoids) (active)
Ready-made antibodies, in human or animal serum, are injected into the recipient (passive)

61
Q

What does the lymphatic system do?

A

Maintains the fluid balance by returning tissue fluid into the venous blood stream

62
Q

What does the lymphatic system contain?

A

Lymphoid structures which contain lymphocytes
Tonsils, thymus, spleen, bone marrow

63
Q

How is lymphatic fluid filtered?

A

Through lymph nodes as it passes through them
May pass through several nodes before being filtered, cleared of foreign material and debris before being returned to the circulatory system

64
Q

Where are the tonsils located?

A

Located in a protective ring under the mucous membranes in the mouth and back of the throat

65
Q

What do tonsils do?

A

Help protect against bacteria that may invade tissues in the area around the openings between the nasal and oral cavities

66
Q

What odes the thymus do?

A

Immature lymphocytes are matured in the foetal thymus
The thymus begins secreting a group of hormones (thymosin) and other regulators that enable lymphocytes to develop into mature T cells

67
Q

What does the spleen do?

A

As blood passes through the vessels of the spleen, macrophages lining these venous spaces remove microorganisms from the blood and destroy them by phagocytosis
Contains T and B cells which are activated by the presence of antigens

68
Q

What is splenomegaly?

A

Abnormal spleen enlargement - observed in various disorders (scarlet fever, syphilis, typhoid fever)

Anatomy and Physiology - pure (11 decks)

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