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Immune System Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what forms the immune system?

A

white blood cells

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2
Q

What pathogens can the immune system fight?

A

Viruses

  • Bacteria
  • Fungi
  • Worms
  • Protozoans
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3
Q

Role of the immune system

A

Detect non-self (pathogens) + respond by removing non-self invaders

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4
Q

A pathogen?

A

Agent that causes disease, can be cellular or non-cellular

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5
Q

What can white blood cells have?

A
  • non-specific generalized response

- specific targeted response

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6
Q

What does the lymphatic system contain?

A

Spleen

  • Thymus
  • Lymph nodes
  • Bone marrow
  • An open network of lymphatic vessels
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7
Q

what happens when it is a open Lymphatic System?

A

the vessels have an open ending and can collect excess fluid including pathogens

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8
Q

what happens when it is a closed Lymphatic System?

A

such as in the circulatory system it means arteries, capillaries and veins all join, and blood flows continuously through them in the circuit.

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9
Q

what is Lymph?

A

Tissue fluid and white blood cells (leukocytes)

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10
Q

Role of the lymphatic system?

A
  1. Return excess tissue fluid back to the circulatory system

2. Transport antigen presenting cells (type of WBC) to lymph nodes where specific immune response is triggered

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11
Q

What are lymph nodes?

A

Part of the lymphatic system where specific immune response takes place

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12
Q

Role of Lymph nodes?

A
  1. Contain lymphocytes (T+B Cells)
  2. Filter and trap pathogens and cancer cells
  3. A specific immune response can be triggered here
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13
Q

Which WBC have a non-specific immune response?

A

Natural Killer Cells

Basophils

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14
Q

Natural Killer Cells?

A
  • Kills virus infected and tumour cells
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15
Q

Basophil (inflammation)

A

secretes histamines

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16
Q

Which WBC are phagocytes?

A

Neutrophil

Macrophage

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17
Q

Neutrophil?

A
  • Engulfs foreign particles and microorganisms
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18
Q

Macrophage?

A
  • Engulfs foreign particles and microorganisms and secretes component proteins
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19
Q

Which WBC are Involved in specific immune responses?

A 
Eosinophils
B cell
T helper Cells
Cytotoxic T cell
Platelets (blood clotting)
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20
Q

Eosinophils

A
  • Secretes enzymes that break down cell walls in pathogens
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21
Q

B cell

A
  • Activated plasma cells produce antibodies

- Memory B cells provide immunity

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22
Q

T Helper Cells

A
  • Secretes interleukin to stimulate
    o B and T cells, to divide
    o Action of macrophages and neutrophils
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23
Q

Cytotoxic T cell

A
  • Produce chemical that cause death in foreign, infected and altered cells
  • Memory TC cells provide immunity
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24
Q

Platelets

A
  • Cellular fragments without a nucleus they assist blood clotting and wound repair to prevent entry of pathogen
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25
Q

why is essential to distinguish self from non self?

A

is vital for specific and non-specific immune responses in order to detect and respond to foreign material

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26
Q

What do foreign material have that recognize foreign immune cekks

A

their own self markers (antigens)

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27
Q

Does the response alter in 1st and second?

A

does not alter, even if the same pathogen is encountered ( no memory of previous pathogens)

28
Q

4 ways of preventing entry of foreign material in first line defence

A
  • Intact skin
    o A physical barrier
  • Mucus and cilia
    o Trap pathogen and also acts as a protective barrier
  • Natural secretions
    o Contain bactericidal agents such as enzymes (in tears, saliva) or stomach acid
  • Commensal Organism
    o Inhibits growth of pathogenic bacteria as they take up space and nutrients inhibiting the growth of potential pathogens
29
Q

Why are open wounds dangerous?

A

provide entry for pathogen, there fore important to have blood clotting

30
Q

blood clot structure?

A

Wound  arteries constrict  platelets clump  fibrinogen  fibrin factor 8  (forms) blood clot!

31
Q

How does the second line of defense occur?

A

initiated after the foreign material has entered

32
Q
  1. Inflammation
A

Non-specific, same level of response, even if pathogen encountered

33
Q
  1. Phagocytosis
A

= recognise, engulf and destroy microorganisms and debris, using digestive enzymes

34
Q

What phagocytes can be used in phogocytosis?

A
  • Neutrophils and monocytes
    o In blood
  • Macrophages and dendritic cells
    o In tissues
35
Q
  1. Complement
A
  • The biochemical cascade of more than 20 blood proteins
    Complement is activated by presence of antigen/antibody complexes formed as a result of the specific immune response and by the pathogen it self
36
Q

Functions of complement

A
  1. Cell membrane is ruptured (not cell walls)
  2. Attract phagocytes (chemotaxis)
    The phagocytes help to remove ab/ag complexes
  3. Coat bacteria (= opsonisation) which enhances phagocytosis (to engulf the bacteria)
37
Q
  1. Cytokines
A

Signalling molecules (messengers) of the immune system

  • Their effect is dependent on cells having appropriate receptors for the cytokines
  • They’re released by cells (often th, any wbc) after tissue injury or infection
38
Q

What do cytokines trigger?

A
  • non-specific immune responses such as activation of macrophages, inflammation and blood clotting
  • Specific immune responses such as increasing the antibody response
39
Q

How are cytokines similar to hormones?

A

as they are found circulating in blood must bind to specific receptor to cause a cellular response

40
Q

How are cytokines different to hormones?

A
  • Many different cells can produce cytokines and can act on wide variety
  • Less cytokines than hormones
41
Q
  1. Interferon
A

Particular type of cytokine produced by wbc and by virally infected cells
- Makes cells more resistant to infection by stimulating the production of antiviral proteins
o Activates NK cells and macrophages to help remove the viral infection

42
Q
  1. Natural Killer cells
A

Major role in the rejection of tumours and cells infected by virus

  • Can be activated by cytokines
  • They kill by expressing a death signal or releasing chemicals such as perforin, triggering apoptosis of the infected cell so the virus cannot be spread
43
Q
  1. Fever
A

Develops in response to
- Cytokines from macrophages
- Pyrogens (toxins released) from bacteria
High temps can inhibit bacterial growth but increase human enzyme activity and production of immune cells.

44
Q

Third line of defence is…

A
  • Slower than non-specific
  • Provides long lasting immunity due to memory cells
  • On repeat infection by same organism, response is greater and quicker
45
Q

Antigen

A
  • Part of the foreign material that is recognised as foreign and initiates an immune response
46
Q

Antibody

A

Protein produced by specific plasma cells, their purpose is to bind antigens and inactivate them, are part of humeral immunity

47
Q

Are antibodies specific?

A
  • Specific and made in response to antigens. ( Epitopes must fit the antigen bonding site of the antibody)
48
Q

Where are antibodies found and what are they involved in?>

A
  • Involved in humoral immunity

- Found free within blood and surface of B lymphocytes

49
Q

What are antigen presenting cells?

A
  • Include macrophages, dendritic cells and B cells
  • Macrophages and dendritic cells engulf (via phagocytosis), and display the fragments of the foreign material on their MHC Class II markers
  • Binding antigens makes them activated and they migrate to local lymph nodes to activate T cells, therefore stimulating cell immunity
50
Q

What cells are involved in Cell Mediated Specific Immune Response?

A
  • T cells involved
    o Produced in bone marrow, mature in thymus
    o They migrate to the lymph nodes
  • Two main types
    o T helper
    o T cytotoxic
  • Most effective in removing virus infected cells
    o Also participate in defending against fungi, protozoans, cancers and intracellular bacteria.
    o Major role in transport rejection
51
Q

What are T helper lymphocytes

A
  • Require the antigen to be presented to them on a Antigen presenting cell = macrophage or dendritic cell
  • T cells have T cell receptors on their surface that recognise foreign antigen on the APC
  • When specific T cell is stimulated, clonal expansion follows so there are many T helper cells specific for that antigen,
    Memory T cells are also produced
52
Q

what happens when T helper cells are activated?

A

they release cytokines that
o Allow B cells to differentiate into antibody producing plasma cells and memory cells (part of the specific immune response)
 Can activate Tc
 Increase NK cell activity and phagocytosis (parts of the non-specific immune responses)

53
Q

What are t cytotoxic cells used for?

A

killing any host cells that have been infected by viruses
o Display fragments of the antigen on their surface which can be recognised by the T cytotoxic cells as foreign
o Can kill cells often before the virus can release a fresh crop of viruses
- Useful in fighting cancerous cells, which have new and foreign antigens on their surface
- Involved in transplant rejection if the donated tissue is not well matched for the MHC markers, so the donated tissue is recognised as foreign and destroyed by the patient

54
Q

What are T cytotoxic cells stimulated by?

A

APC or by Th cells or by recognition of foreign fragments of the antigen on the surface of any infected cells

55
Q

What is the humoral response?

A
  • Refers to the immune response mediated by antibodies (released from plasma cells). T helper cells essential to complete the response
  • Specific antibodies bind to the antigens (of bacteria), antigen/antibody complex and they cross link. This is called Aggulination
56
Q

what is agglutination?

A

– activates complement and phagocytosis

57
Q

B cells?

A

o Produced in the bone marrow, migrate to the lymph noes
o Have antibodies on their cell membrane and these act as the receptors for the antigens
o B cells are specific (like T cells), can only bind with one type of antigen
o Only a few B cells are made with any one surface

58
Q

Memory cells?

A

o After an infection has been removed, most pf the memory cells are no longer required and they are killed by apoptosis (organised cell death, where organelles can be recycled)
o SAVES SPACE WOOHOO

59
Q

What is the clonal selection theory?

A

During Embryonic development millions or randomly generated B cells are formed
These are able to recognize many different antigens including those that have never ever been encountered
The variety of B cells is possible to the structure of antibodies

60
Q

Advantage of active immunity?

A
  • Long term immunity due to the production of memory cells
    On a second injection  get a quicker, larger and longer lasting secondary response
  • Due to pre-existing memory cells specific to the pathogen
61
Q

Herd Immunity

A
  • Where the majority of the population is immune to a particular disease, usually by vaccination. This prevents the spread of diseases to more vulnerable of the community.
62
Q

Advantage and Disadvantage of herd immunity?

A

ad - Does provide short term immunity to pathogens by the Ab’s binding to the foreign antigens + agglutinate them
dis- - Only short term immunity and does not produce memory cells for long term immunity

63
Q

Where do Antibodies from passive immunity come from?

A
  1. Specific antibodies can come from horses or rabbits that have not been exposed to the antigen
    o Initially the does of toxin is very small, to not kill the animal but enough to stimulate antibody production and memory cells
  2. B cells can be cultured in a laboratory and the antibodies is collected
  3. Fusing mouse B cells with tumour cells.
    o Each hybrid cell produces clones of itself and each clone produces the same antibody = monoclonal antibodies
64
Q
  1. Hypersensitivity
A

Sometimes the immune system reacts to antigen that cause no real threat to body, but the subsequent immune response can cause moderate to serious tissue damage and even death

65
Q

1a. Allergies

A

A rapid and vigorous overreaction of our immune system to a previously encountered antigen – which is called an allergen as it produces an allergic reaction

66
Q

Treatment of allergic reactions

A
  • To administer anti-histamine to suppress some allergic reactions
     Cortisone can be used as it reduces the immune system in general
  • To desensitise people by the repeated administration of tiny amount of allergen extracts under the skin. Specific IgA antibodies are made against the allergen.

Biology (21 decks)

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