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Microbiology Lecture 4 > Immunology > Flashcards

Immunology Flashcards

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1
Q

Immunology

A
  • the study of immunity
  • ability to ward of disease and protect against environmental factors
  • types
    • innate
    • adaptive
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2
Q

Innate immunity

A
  • present at birth
  • fast, general response
  • no memory response
  • includes:
    • first line of defense
    • second line of defense
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3
Q

Adaptive

A
  • slow, specific response
  • memory response
  • Includes:
    • third line of defense
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4
Q

First Line of defense

A
  1. skin
  2. mucous membranes
  3. body secretions
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5
Q

Skin

A
  1. physical barrier
    - several layers of tightly packed keratinized epithelial cells
  2. chemical barrier:
    - sebum (oily substance)
    - low pH 3-5
    - Lysozyme: enzyme that breaks down bacterial cell walls
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6
Q

Mucous Membranes

A

Physical barriers

  1. mucus lines open body cavities
  2. ciliary escalator: lining of trachea to propel microbes upward toward throat
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7
Q

Body Secretions

A
  1. Lysozymes:
    -found in tears, sweat, saliva, urine
  2. Perspiration:
    -flush microbes from surface
  3. saliva
    -flush microbes from teeth
  4. gastric juice
    -acidic pH 1-2
    5: urine
    -acidic pH 6
    -Uric acid and hippuric acid (inhibit microbes)
  5. Vaginal Secretions
    -acidic pH 3-5
    Cervical mucous (antimicrobial properties)
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8
Q

Second Line of Defense

A
  1. phagocytes
  2. inflammation
  3. fever
  4. antimicrobial substances
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9
Q

Phagocytes

A

cells that ingest other microorganisms and substances

  1. neutrophils (PMNs)
  2. Eosinophils
  3. monocytes
  4. dendritic cells
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10
Q

Neutrophils

A
  • polymorphonuclear leukocytes
  • highly phagocytic and motile
  • first to respond to an infection
  • can leave blood and go into infected tissue
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11
Q

Eosinophils

A
  • somewhat phagocytic

- Produce toxic proteins against parasites

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12
Q

Monocytes

A
  • not actively phagocytic in circulating blood
  • mature in tissues–> macrophages
    • macrophages
      1. Fixed (histiocytes): stay in certain tissues or organs’
      2. free (wondering): motile, roam tissues, gather at sites of infection
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13
Q

Dendritic cells

A
  • phagocytic

- initiate adaptive immunity (antigen presenting cell)

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14
Q

Mechanism of phagocytosis

A
  1. chemptaxis
  2. adherence
  3. ingestion
  4. digestion
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15
Q

chemotaxis

A

chemical attraction to microbes

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16
Q

adherence

A
  • contact between phagocyte and microbe
    • toll-like receptors (TLRs): protein receptors on phagocytes that attach to PAMPs on pathogens
    • PAMPs: pathogen associated molecular patterns
      - ex. LPS, flagellin, peptidoglycan
  • binding causes release of specific cytokines
    • cytokines recruit additional phagocytes
  • faciliated by opsonins
    • opsoninis: proteins that coat and promote attachment
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17
Q

Ingestion

A

pseudopods form and engulf microbe in a phagosome

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18
Q

Digestion

A

phagosome fuses with lysosome–> phagolysome

microbe is digested by hydrolytic enzymes

indigestible material (residual body) expelled

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19
Q

Inflammation

A
  • cardinal signs/symptoms
    1. redness
    2. heat
    3. swelling
    4. pain
  • caused by:
    1. tissue damage
    2. infection

function:
-destroys/slowdown pathogens

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20
Q

Inflammation steps

A
  1. chemicals released by damaged cells
    • vasodilation
    • increased permeability
      - chemotaxis (attracting phagocytes)
  2. phagocytic migration
    - margination (phagocytes stick to endothelium)
    - Diapedisis (phagocytes squeeze through endothelium)
  3. Phagocytosis
  4. Tissue repair
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21
Q

Fever

A

Abnormally elevated body temperature

Caused by:

  • Pyrogens:
    • Exogenus pyrogens: products of pathogens
    • Endogenous pyrogens: products of leukocytes (i.e. Interleukin 1)

Actions: adjusts hypothalamus (thermostat) to higher temperature

Results in:

  • constricting blood vessels to skin
  • increased rate of metabolism
  • shivering
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22
Q

Benefits of moderate fevers

A
  1. inhibits/ slows pathogen growth
  2. speeds up tissue repair
  3. intensifies actions of interferon
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23
Q

Complication of high fevers

A
  1. Tachycardia
  2. increased metabolic rate –> acidosis
  3. dehydration
  4. seizures
  5. neurological damage
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24
Q

Complement system

A
  • Group of over 30 proteins found circulating in blood serum
  • acts in cascade
  • Destroy microbes by:
    1. inflammation (3a)
    2. phagocytosis (opsonization) (C3b)
    3. cytolysis (C3b)
25
Q

Complement activation

A
  1. classical pathway
    activated by certain antigen-antibody complexes
  2. alternative pathway
    -activated by interaction between complement proteins and pathogens
26
Q

Interferon

A
  • Antiviral proteins
  • produced by:
    1. macrophages
    2. lymphocytes
    3. virus-infected-host cell
  • function: interfere with viral replication, signals to neighboring cells to produce anti-viral proteins
27
Q

Third line of defense

A

involves an immune response to specific antigens

28
Q

antigens

A

molecules that cause an immune response

-antigenic determinant (epitopes): area of an antigen that causes the response

29
Q

Antibodies

A
  • immunoglobins (Ig)
  • proteins produced in response to antigens
  • function: recognize and bind to antigens
  • structure:
    • 4 protein chains
      • 2 identical heavy chains
      • 2 identical light chains
    • chains joined by disulfide links
30
Q

Antibodies structure

A
  • Y shape
  • variable region: tips of Y arms, binds to epitopes
  • constant region: lower portion of arms and stem
  • Fc region: stem of Y, important for immunological reactions
31
Q

classes of antibodies

A

IgG, IgM, IgA, IgD, IgE

32
Q

IgG

A
  • monomer
  • Abundance: 80% of antibodies
  • enhances phagocytosis, neutralizes toxins and viruses
  • protects fetus and newborn (transplacental)
33
Q

IgM

A
  • pentamer
  • Abundance: 5-10% of antibodies
  • especially affective against microbes
  • First antibodies produced in response to initial infection
34
Q

IgA

A
  • dimer
  • abundance: 10-15% of antibodies
  • localized protection on mucosal surfaces
35
Q

IgD

A
  • monomer
  • abundance: 0.2% of antibodies
  • located on B cells
36
Q

IgE

A
  • monomer
  • abundance: .002% of antibodies
  • allergic reactions
37
Q

Types of antigen-antibody reactions

A

Agglutination: causes antigen to clump together

Neutralization: block virus, toxic, and bacteria binding sites

Complement fixation: binding activates complement cascade

Opsonization: coats antigen to enhance phagocytosis

38
Q

Lymphocytes

A

Cells that produce immune response, found in lymphoid tissue

  • Types:
    1. Natural Killer cells
    2. B cells
    3. T cells
39
Q

Natural Killer cells

A
  • part of innate immunity (non-specific)

- destroy target cell by cytolysis

40
Q

B cells

A
  • differentiate and mature in red bone marrow

- involved in humoral immunity (antibody) response

41
Q

T cells

A
  • differentiate and mature in thymus

- involved in cellular response

42
Q

Antigen presenting cells (APC)

A
  • present antigens to T cells
  • contain Major Histocompatibility Complex II (MHC II) on surface (identifies cell as “self”)
  • e.x. dendritic cells, activated macrophages, B cells
43
Q

B cell response Process

A
  1. each b cell has a specific b cell receptor for a specific antigen
  2. b cell is exposed to antigen
  3. englufs and presents antigen on MHC II to activated T-helper cell
  4. T-helper cell activates B cell via interleukin 2
  5. activated b cell divides:
    - plasma cells: produce antibodies
    - memory cells: remain in body, can later be stimulated if encounters same antigen
44
Q

Primary Reponse Process

A
  1. plasma cells produce antibodies that circulate in blood and lymph
  2. antibodies bind and neutralize antigen
45
Q

Secondary response process

A
  1. memory cell activated by the same antigen
  2. activated b cells divides–> plasma cells
  3. plasma cells produce antibodies that circulate in blood and lymph
  4. antibodies bind and neutralize antigen
46
Q

Secondary vs primary response

A
  1. faster
  2. more antibodies produced
  3. more sensitive
  4. last longer
47
Q

T cell response Process

A
  1. each t helper cell has a specific t cell receptor (TCR) for a specific antigen
  2. APC engulfs antigen and presents antigen on MHC II to t helper cell
  3. APC releases interleukin-1 to activate t helper cell
  4. activated t helper cell release IL-2 to activate other t cells
48
Q

T helper cells

A
  • commander of entire system
  • produce various cytokines
  • activate variety of t cell, b cells, macrophages, NK cells
49
Q

Cytotoxic t cells

A

when activated–> cytotoxic t lymphocyte (CTL)

CTL: destroys virus infected cells on contact

50
Q

T regulatory cells

A

turn off immune response (prevent autoimmune response)

51
Q

Memory t cells

A

recognize antigen in future infection for faster response

52
Q

Types of immunity

A

active vs passage

natural vs artificial

53
Q

Active vs passive

A
  1. active immunity
    - due to individuals own immune response
    - long lasting
  2. Passive immunity
    - due to another person’s immune response
    ex. obtaining others antibodies
    - short lasting
54
Q

Natural vs Artificial

A
  1. Natural immunity
    - due to natural exposure to antigens
  2. Artificial immunity
    - due to artificial exposure to antigen (vaccine)
55
Q

Vaccines

A
  • suspension of pathogens or antigens used to stimulate an immune response
  • Types:
    1. whole unit vaccines
    2. subunit vaccines
    3. toxoid vaccine
    4. conjugated vaccines
56
Q

Whole Unit Vaccines

A

Contain whole pathogens

  1. inactivated pathogens
    - killed bacteria or viruses
  2. live attenuated pathogens
    - weaken microorganisms
57
Q

Subunit vaccines

A

antigenic fragments of microbes

58
Q

toxoid vaccines

A

inactivated toxins

59
Q

Conjugated vaccines

A

Antigen combined with a protein to boost immune response

Microbiology Lecture 4 (4 decks)

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