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biology 3/4 > chapter five: responding to antigens acquiring immunity > Flashcards

chapter five: responding to antigens acquiring immunity Flashcards

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1
Q

explain what an antigen is

A

antigens are substances that causes/stimulates/trippers an immune response

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2
Q

describe the difference between self and non-self antigens

A

self antigens

  • some causes an immune system response (autoimmune)
  • a self marker (MHC) labels the body’s cells as a ‘friend’ and are tolerated by the immune system

non-self

  • all causes an immune system response
  • an antigen is a molecule that the immune system recognises as foreign (non-self) and treats as a ‘foe’
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3
Q

describe the difference between MHC-I and MHC-II self markers

A

major histocompatibility complex (MHC)

MHC-I

  • is present on all uncleared cells of the body

MHC-II

  • is present on specific immune cells
  • these proteins present fragments from the foreign antigens that have been exported from within the cell, on the cells surface
  • if immune system cells recognise them as non-self it triggers the adaptive immune response
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4
Q

explain what a pathogen is

A

pathogens are microbes that causes infectious disease

  • they can be cellular or non-cellular
  • most pathogens are species-specific and tissue-specific
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5
Q

explain the differences between pathogens and antigens

A

all pathogens acts as antigens however not all antigens are pathogens

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6
Q

list the 6 main types of pathogens

A
  • bacteria
  • worms (parasites)
  • fungi
  • protist
  • virus
  • prions
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7
Q

compare infection and disease

A

disease

  • a disease is a condition that interferes with the normal functioning of an organism; usually with specific symptoms

infection

  • when a pathogen is in your internal environment (bloodstream - where its supposed to be sterile) in which causes specific symptoms
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8
Q

describe the difference between cellular and non-cellular pathogens

A

cellular

  • living organisms
  • able to reproduce independently

non-cellular

  • non-living
  • can only reproduce with host cell present
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9
Q

state which pathogens are cellular and which are non-cellular

A

cellular

  • bacteria
  • protist
  • fungi
  • worms

non-cellular

  • prion
  • virus
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10
Q

state which pathogens are extracellular and which are intracellular when they infect the body

A
  • extracellular pathogens are pathogens that live on the body (cells), so they are in the spaces between the organism’s cells. eg. worms
  • intracellular pathogens are pathogens that live in the body (cells), so they live and produce in host cells. eg. bacteria
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11
Q

explain how viruses damage cells

A

viruses cause disease by killing body cells

  • to make more viruses, a virus takes over a host cell and uses it as a ‘factory’
  • release by cell lysis
  • infected host cell ‘explodes’ as its plasma membrane disintegrated and viral particles are released into the extra cellular fluid to then infect other cells
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12
Q

explain how bacteria cause disease

A

bacteria live in and on you

  • if bacteria multiply in areas they are not normally found they can cause disease
  • symptoms of bacterial infection are often caused by the toxins the bacterium produces
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13
Q

compare allergens and antigens

A

antigens are substances that causes an immune response

  • allergies are caused by an immune system response to antigen (allergen)
  • all non-self antigens cause an immune system response
  • some self antigens cause an immune system response
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14
Q

outline what an allergic response is

  • the general process of response
A

before you develop an allergy, mast cell need to be primed

sensitisation: initial exposure to allergen

  • allergen (e.g. pollen grain) enters into the bloodstream
  • B cells differentiate into plasma cells and make antibodies
  • antibodies attach to mast cells

allergic reaction: secondary exposure to same allergen

primed mast cells release histamine when they encounter the allergen

  • allergen bind to antibodies on mast cell (cross links form which activates more than one antibody)
  • histamine is released from the mast cell (cytokines are released to attract more immune cells)
  • an allergic reaction ensues (increased blood blow, increased permeability of blood vessels)
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15
Q

describe the role of mast cells in

  • with clear references to allergic response
A

mast cells and antibodies drive allergic responses

  • mast cells are granulocytes located wherever there is likely to be interaction with the outside world - skin, digestive tract
  • activated mast cells release histamine which promotes allergic responses
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16
Q

describe 3 difference physical barriers in:

  • animals
  • plants
A

animals

  • mucus
  • earwax
  • intact skin

plants

  • waxy covering
  • formation of galls
  • thorns and spikes
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17
Q

describe 3 difference chemical barriers in:

  • animals
  • plants
A

animals

  • sweat
  • stomach acid
  • saliva

plants

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18
Q

explain how microbiological barriers in animals can prevent infection

A

presence of normal flora

  • non-pathogenic bacteria in regions of the body
  • inhibits the growth of pathogenic microbes
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19
Q

describe the process of phagocytosis

A
  • the phagocyte recognised the microbe via a receptor
  • the phagocyte engulfs the microbe via endocytosis
  • the vesicles containing the microbe fuses with a lysosome
  • the lysosome empties its digestive enzyme into a vesicle
  • the enzyme digest the microbe
  • the particles are released from the phagocyte via exocytosis
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20
Q

list the main phagocytes in the immune response

A
  • macrophages
  • dendritic cells
  • neutrophils
  • eosinophils
  • monocytes
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21
Q

compare the role of:

  • macrophages
  • neutrophils
  • dendritic cells
A

macrophages:

  • works as innate cells through phagocytosis
  • identify and eliminate pathogens
  • considered an antigen presenting cell that can activate the adaptive immune response

neutrophils:

  • one of the first cells to respond
  • engulfs and destroys pathogens by phagocytosis
  • travels to the infection site and kills pathogens by ingesting them and releasing cytokines that kills

dendritic cells:

  • APC’s that fight against invasive pathogens
  • help present antigens to the lymphocytes and initiate the adaptative immune respone
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22
Q

describe the role of eosinophils and how they perform this role

A

are white blood cells that destroy large internal pathogens –> e.g. worms using enzymes contained within their vesicles

  • kill large pathogens
  • they contain toxic chemicals, enzymes and ribonuclease (RNases)
  • granules with toxic chemicals and histamine that are released playing a role in allergic reactions
23
Q

describe the role of natural killer cells and references how they they destroy virally-infected cells

A

they are referred to as NK cells

  • they destroy infected and diseased body cells
  • when NK cell recognises an abnormal cell it releases proteases and perforin
  • perforin punches holes in the cell membrane, allowing the proteases to enter
  • these trigger apoptosis (cell death)
24
Q

state where mast cells are located and what they contain

A

mast cells are usually located throughout the body in loose connective tissue

  • they contain histamine that chemically attract immune cells and releases signals to trigger an immune response in a certain area (inflammation is caused)
25
Q

state what complements proteins are

A

inactive enzymes in blood that complements the function of immune cells

  • activated when they make direct contact with molecules on the surface of a pathogen
  • complement proteins activate other complement proteins to form a cascade
26
Q

describe the three ways complement proteins can help to remove pathogens

A

opsination

  • complement proteins stick on the outside surface of pathogens, making it easier for immune cells such as phagoctypes to recognise them as foreign

chemotaxis

  • complement proteins gather around a pathogen and attract phagocytes to it, making it more likely to be destroyed

lysis

  • complement proteins form a membrane attack complex (MAC) on the surfcae of pathogens, creating pores in their membrane.
  • this causes lysis and destroys the pathogen by making it burst
27
Q

state where interferons are made

A

virally infected cells

  • interferons released to prepare neighbouring cells for a possible ‘attack’
28
Q

state three effects that interferons can have on neighbouring cells

A
  • signal change in plasma membrane making entry of the virus more difficult
  • activates immune cells such as NK cell
  • signals neighbouring cells to undergo apoptosis
29
Q

explain how interferons can prevent the spread of viruses

A

interferons can prevent the spread of viruses through activating immune cells, signals neighbouring infected cells to undergo apoptosis, signals neighbouring uninfected calls to reduce protein synthesis and destroy RNA, and signals cells to change plasma membran to make entry of viruses more difficult.

30
Q

describe the three stages of inflammation, including the role of various cells and protein

A
  1. initiation and vasodilation
  • damaged mast cells release histamines causing capillaries to become permeable (leaky) and wider (vasodilation)
  1. migration of phagocyte
  • phagocytes are attracted to the site by cytokines —> they phagocytose antigens and release more cytokines and histamines
  • phagocytes attack the antigens by engulfing them by phagocytosis
  • platelets travel to the site to block the open wound
  1. resolution of inflammation
  • once the antigen is removed, resolution occurs
  • it occurs when tissue is returned to normal state —> infection is under control and new tissue/cells to replace dead damaged ones
  • the release of cytokines stops and anti-inflammatory cytokines are released
31
Q

state how APCs present antigens and which cells are presented to

A

once a pathogen has entered the body and is recognised, an antigen presenting cell such as macrophages or dendritic cells will come and engulfs the pathogen.

  • it will then break down the pathogen and display its antigen on the MHC-II receptors
  • it will be present to a Helper T cells that has the right receptor to then begin the adaptive immune system
32
Q

explain the initial response from helper T cells when they are presented with an antigen specific to their receptors on an MCH-II marker

A

helper T cells are activated when presented with an antigen on an APC that is complementary to its receptor on a MCH-II marker

  • activated helper T cells clone themselves
  • helper T cells release cytokines to activate other immune responses
33
Q

explain the initial response from cytotoxic T cells when they are presented with an antigen specific to their receptors on an MCH-II marker and cytokines from helper T cells

A

cytotoxic T cells will bind to a complementary antigen on the MHC-II of an APC

  • if further stimulated by cytokines from helper T cells, they will undergo clonal expansion (clone themselves)
  • activated cytotoxic cells will sample MHC-I on all body cells
  • when it finds cells with the complementary antigen it will secrete a chemical induces apoptosis
34
Q

state where antigen presentation occurs

A

lymphoid tissues

35
Q

why is it important for there to be a site for antigen presentation

A

So the APC can quickly find a cells with the right receptor so it can bind and educate the other cells of which cells are infected with the pathogen

36
Q

outline the function of lymphatic system

A

it acts as a transport network and consists of lymph, lymph vessels and lymph organs

  • is a series of blind-ending vessels that contain lymph fluids and lymphocytes and has lymph nodes
  • production and maturation of immune cells
  • the removal of excess fluids from the body tissues
  • absorption and transportation of fatty acids to the digestive system
  • allowing for the process of antigen recognition by T and B lymphocytes
37
Q

list the main features in the lymphatic system

A
  • lymph
  • lymphatic vessels
  • primary lymphoid organs
  • secondary lymphoid organs
38
Q

list the primary and secondary lymphoid organs

A

primary

  • bone marrow
  • thymus

secondary

  • lymph nodes
  • spleen
  • tonsils
39
Q

describe both the structure and function of lymph nodes

A

structure:

  • are small bean-shaped structures located along blood vessels and lymphatic vessels, which enable B cells and T cells to enter and exit the lymph nodes

function:

  • where antigen presentation occurs + T and B lymphoctyoes mature at the primary lymph nodes
  • lymph nodes are where B and T cells are activated
  • lymph nodes are the site of antigen recognition, in which T and B lymphocytes come into contact with their specific antigens –> resulting in local selection and expansion
40
Q

describe how the lymphatic system acts as a transport network for immune cells

A

the lymphatic system acts as a transport network and works very closely with the circulatory system, carefully monitoring the body for signs of infection

  • the lymphatic system produces lymphocytes and transport them to the lymph nodes to elicit the immune response
41
Q

describe the key features of the adaptive immune response

A

adaptive immunity (the third line)

  • dendritic cells and macrophages can activate specific defences by presenting antigens on MHC-II markers
  • they travel to the lymph nodes and present antigens to helper T cells and cytotoxic T cells until they find a matching receptor
  • once a match is found (coned selection) the helper T cell will make more copies of itself (cloned expansion)
  • the helper T cells will then activate the cytotoxic T cells (that also have been activated by APCs) and B cells
  • the cytotoxic T cells will search for body cells presenting the specific antigen on MHC-I and trigger apoptosis
42
Q

outline how the humoral and cell-mediated parts of the adaptive immune response

A

cell mediated:

  • antigen presenting cells bind to specific help t cells, activating the cell, releasing cytokines.
  • then the specific cytotoxic t cell binds to the antigen presenting cell and gets activated by the cytokines released by the helper t cell.
  • after the t cells are activated, they will undergo clonal expansion (into more cytotoxic t cells and memory t cells).
  • the cytotoxic t cells will go on to target infected cells that are infected with the specific pathogen.

humoral:

  • antigen presenting cell binds to specific b cell and gets activated by helper t cells.
  • activated b cell will mature into plasma cells.
  • plasma cells will undergo clonal expansion (into more plasma cells and memory b cells) and then create antibodies for the specific antigen.
43
Q

describe the key components and function of the humoral adaptive response

A

humoral immunity is when the response occurs in body fluids

  • B cells activated by binding to free-pathogen and cytokines from TH
44
Q

outline how the cell-mediated immune response removes body cells infected by viruses (or cancerous)

A

once a T helper cell has been presented with the receptor of the pathogen, it matures and releases histamines that activate the cytotoxic T cells, which punches holes into the virally infected cell, releasing perforin and triggers apoptosis

45
Q

features of antibodies

A
  • a Y-shaped structure/molecule which consists of 4 chains (2 heavy ones and 2 light ones)
  • each antibody has a different amino acid sequence at the tips (antigen-binding sites) of the ‘Y’, where the antibody binds to specific antigens, hence why antibodies all have different shapes
46
Q

describe three ways the antibodies can neutralise pathogens

A
  • tagging a pathogen for phagocytosis
  • preventing the antigen from binding to its target
  • activating the complement cascade
    (a series of reactions that occurs on the surface of pathogens and generates active components with various effector functions)
47
Q

describe the difference between natural and artificial immunity

A

natural:

  • acquired from exposure to the disease through an infection from the actual disease

artificial:

  • antibodies produce as a response to controlled exposure to a disease
48
Q

describe the difference between active and passive immunity

A

active (natural):

  • our own immune system is responsible for protecting us from a (long term —> memory cells are made however you can get infected again)

passive (artificial):

  • occurs when we are protected from a pathogen by immunity gained from someone else (give = no immune response; you can no get infected again)
49
Q

state the 2 ways (each) in which natural and artificial immunity can develop

A

natural (unintentional —> make it):

  • infection
  • mother to child

artificial:

  • vaccine
  • injection (antibodies)
50
Q

state the 2 ways (each) in which passive and active immunity can develop

A

active:

  • vaccine
  • infected

passive:

  • mother to child
  • injected
51
Q

Describe, from the point at which the bacteria entered the body, the steps that a person’s immune system was taking in response to the bacteria.

A
  • phagocytes will engulf the pathogen
  • phagocytes will move to the lymph nodes and present the antigen to T cells on a MHC-II marker
  • when a TH cell with matching receptor is found it will be activated and clone itself
  • activated TH will activate specific B cells
  • activated B cells will clone themselves to become plasma cells and memory B cells
  • plasma cells will produce antibodies
52
Q

what are the 2 types of immunity

A

innate/non-specific immunity:

  • a response that is general to any pathogen
  • what we are born with

adaptive/specific immunity:

  • it is built and developed through infections and vaccinations
  • could have been exposed to a specific type of pathogen and developed an immunity against it
  • specific as it initiates a response to a specific pathogen
53
Q

classes of antibodies

A

IgE —> stimulates the release of histamine and other chemicals that causes allergies

  • a persons mast cells have been primed in which IgE antibodies have previously attached to them
  • when the antigen attaches to the IgE on mast cells, the mast cells releases histamines causing the symptoms

biology 3/4 (12 decks)

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