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Human Bio 122 > The immune system > Flashcards

The immune system Flashcards

1
Q

The first line of defence of the immune system consists of skin and mucous membranes. What does the second line of defence of the immune system consist of?

A
  • Antimicrobial substances
  • Natural killer cells
  • Phagocytes
  • Inflammation
  • Fever
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2
Q

The 1st line of immune defence has a rapid onset and involves what…?

Also known as?

A

The skin and mucous membranes (their physical barrier and secretions)

Innate immunity

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3
Q

The 2nd line of immune defence allows the body to defend against specific invading pathogens and involves white blood cells such as…?

A

Phagocytes and natural killer cells.

(also involved antimicrobial substances, inflammation and fever)

(non-specific immunity)

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4
Q

The 3rd line of defence evokes antibody- and cell-mediated defences. The particular foreign molecules which evoke this immune response are called what?

A second encounter with the same antigen prompts a rapid and stronger defence response due to the presence of WHAT cells from previous encounters?

A

Antigens

Memory cells

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5
Q

What is the third line of defence also called?

A

Adaptive or specific immunity

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6
Q

What are phagocytes and what are the two major types?

A

Specialised white blood cells that undergo phagocytosis.

Neutrophils and macrophages (which develop from monocytes) are the two major types of phagocytes.

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7
Q

Identify the 5 major phases of phagocytosis

A
  1. Chemotaxis
  2. Adherence
  3. Ingestion
  4. Digestion
  5. Killing
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8
Q

What are the 3 major stages of inflammation?

A
  1. Vasodilation and increased vascular permeability
  2. Phagocyte emigration
  3. tissue repair
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9
Q

What are the two types of lymphocytes that adaptive immunity involves?

A
  1. T cells (mature in the thymus)
  2. B cells (mature in the red bone marrow)
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10
Q

There are two major types of T cells that exit the thymus. What are they?

A

T helper cells (CD4 T cells)

T cytotoxic cells (CD8 T cells)

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11
Q

Where are T and B cells activated?

A

Secondary lymphatic organs and tissues (e.g. lymph nodes, spleen and nodules)

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12
Q

B cells are involved in anti-body mediated immunity. What does this mean?

A

Directed against extracellular pathogens

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13
Q

T cells are involved in cell-mediated immunity. What does this mean?

A

Directed against intracellular pathogens (also some cancer cells and tissue transplants)

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14
Q

Cells that directly kill target cells by releasing granules of perforin are called…

A

Natural killer cells

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15
Q

T helper cells, due to a protein on their plasma membrane, are also known as…?

A

CD4 T cells

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16
Q

Cytotoxic T cells, due to a protein on their plasma membrane, are also known as…?

A

CD8 T cells

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17
Q

Vasodilation and increased permeability of blood vessels is due to the release of…?

A

Histamine

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18
Q

Is inflammation a 1st or 2nd line of defence?

A

2nd

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19
Q

Is perspiration a 1st or 2nd line of defence?

A

1st

20
Q

Virus-infected cells release a cytokine to aid neighbouring uninfected cells to produce antiviral proteins called…?

A

Interferons

21
Q

The growth of bacteria may be inhibited by which substance?

A

Iron-binding proteins

22
Q

A population of identical cells is known as a…?

A

Clone

23
Q

What is an antigen?

A

Something produced by a pathogen (such as bacteria or virus) that triggers an immune response

They have reactivity (ability to react to the cells or antibodies they provoke)

(it means antibody generator)

24
Q

Antigens that get past the non-specific immune defences are directed to which type of tissue?

A

Lymphatic

25
Q

Antigens tend to be large, complex molecules (usually proteins). There is a small part of an antigen called an epitope - what is this?

A

The antigen determinant, i.e. the feature that lets the immune system recognise the substance as an antigen and distinguished one antigen from another.

26
Q

Where are antigen receptors located?

A

Lymphocytes

27
Q

What are MHC antigens (or major histocompatibility complex antigens)?

A

‘Self’ antigens that help T cells recognise that an antigen is foreign not ‘self’

28
Q

There are two types of MHC antigens. What are they and what is their broad job?

A

MHC class I antigens > used to recognise antigens inside calls

MHC class II antigens > used to recognise antigens outside cells

29
Q

The immune system has different ways of processing antigens depending on whether they’re outside the cells (exogenous) or inside (endogenous).

What are the six steps in exogenous antigens and which MHC molecule are they associated with?

A

Associated with MHC II molecules (outside cell)

  1. Phagocytosis or endocytosis of antigen
  2. Digestion of antigen into peptide fragment
  3. Synthesis and packaging of MHC II molecules into a vesicle
  4. Vesicle-containing antigen peptide fragments and MCH II molecules fuse
  5. Antigen peptide fragments bind to MCH II molecules
  6. Vesicle undergoes exocytosis and antigen-MHC II complexes are inserted into the plasma membrane
30
Q

The immune system has different ways of processing antigens depending on whether they’re outside the cells (exogenous) or inside (endogenous).

What are the six steps in endogenous antigens and which MHC molecule are they associated with?

A

Associated with MHC I molecules (inside the cell)

  1. Digestion of antigen into peptide fragments
  2. Synthesis of MHC I molecule
  3. Antigen peptide fragments bind to MHC I molecules
  4. Packaging of antigen-MHC I molecules into a vesicle
  5. Vesicle undergoes exocytosis and antigen-MHC I complexes are inserted into the plasma membrane

(same as exogenous but no phagocytosis)

31
Q

What are cytokines?

A

Small protein hormones that stimulate or inhibit normal cell function, such as cell growth or differentiation.

32
Q

What are the two types of T cells?

A

Helper T cells
Cytotoxic T cells

33
Q

Each type of T cell needs to receive two signals to activate. What are these?

A

First signal - antigen recognition by a T cell receptor

Second signal - co-stimulation by co-stimulator or plasma membrane molecules

34
Q

Activated Helper T cells undergo clonal selection to form Active Helper T Cells or Memory Helper T cells. What do these helper T cells do?

A

Active helper T Cells - secrete cytokines

Memory helper T Cells - available for a swift response if second exposure should occur

35
Q

Activated Cytoxic T Cells undergo clonal selection to produce either active or memory clones. What do these cells do?

A

Active Cytotoxic T Cells - attack other body cells that an antigen has infected

Memory Cytotoxic T Cells - available for a swift response if a second exposure should occur

36
Q

What are the steps that cytotoxic T cells can undergo to kill a cell?

A
  1. Release granzymes (protein-digesting enzymes that trigger apoptosis)
  2. Release proteins from their granules (perforin and granulysin)
  3. Secrete lymphotoxin that activates enzymes in the target cells causing its DNA to fragment
  4. Secrete gamma-interferon to activate phagocytic cells
37
Q

Immunological surveillance is when the immune system finds, recognises and destroys cells with tumour antigens. What cells carry out this process?

A

Cytotoxic T cells, macrophages and natural killer cells

38
Q

Antigens trigger antibody production, and the antibodies then attack foreign cells.

Antibodies belong to a group of glycoproteins called globulin. It is, for this reason, antibodies are also called what…?

A

Immunoglobulins

39
Q

Antibodies can combine specifically with the antigenic determinant (epitope) on the antigen that triggered its production. There are 5 principal classes of immunoglobulins - what are they?

(GAMED)

A

IgG - most abundant; blood, lymph, intestines; crosses placenta

IgA - sweat, tears, saliva, mucous, breast milk, gastrointestinal secretions; levels decrease during stress

IgM - blood and lymph

IgE - mast cells and basophils; involved in allergic reactions; protect against worms

IgD - surface of B cells

40
Q

What is antibody-mediated immunity?

A

Destruction of antigens by antibodies in extracellular fluid

41
Q

What are the 3 major steps in the antibody-mediated immune response?

A
  1. activation of B cells
  2. clonal selection and antibody secretion
  3. antigen-antibody complex formation
42
Q

What are the 4 steps of B cell activation?

A
  1. stimulation
  2. antigen binding
  3. antigen processing
  4. co-stimulation
43
Q

Once activated, clones of B cells are produced, and rapid cell division and differentiation occur to form what?

A
  • long-lived memory B cells
  • plasma cells (produce and secrete antibodies)
44
Q

The Complement System is a defensive system made up of over 30 inactive proteins (produced by the liver) and found circulating in blood plasma and within tissues. Together they are involved in what functions?

A
  • phagocytosis
  • inflammation
  • cell lysis
45
Q

Immunological memory is achieved due to…?

A
  • long-lasting antibodies
  • long-lived lymphocytes that arise during clonal selection of antigen-stimulated B and T cells
46
Q

What is an autoimmune disease?

A

When there is no self-tolerance, i.e. they react to own proteins

Human Bio 122 (13 decks)

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