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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

Study These Flashcards
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
Complement activation
1. classical pathway activated by certain antigen-antibody complexes 2. alternative pathway -activated by interaction between complement proteins and pathogens
26
Interferon
- 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
Third line of defense
involves an immune response to specific antigens
28
antigens
molecules that cause an immune response | -antigenic determinant (epitopes): area of an antigen that causes the response
29
Antibodies
- 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
Antibodies structure
- 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
classes of antibodies
IgG, IgM, IgA, IgD, IgE
32
IgG
- monomer - Abundance: 80% of antibodies - enhances phagocytosis, neutralizes toxins and viruses - protects fetus and newborn (transplacental)
33
IgM
- pentamer - Abundance: 5-10% of antibodies - especially affective against microbes - First antibodies produced in response to initial infection
34
IgA
- dimer - abundance: 10-15% of antibodies - localized protection on mucosal surfaces
35
IgD
- monomer - abundance: 0.2% of antibodies - located on B cells
36
IgE
- monomer - abundance: .002% of antibodies - allergic reactions
37
Types of antigen-antibody reactions
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
Lymphocytes
Cells that produce immune response, found in lymphoid tissue - Types: 1. Natural Killer cells 2. B cells 3. T cells
39
Natural Killer cells
- part of innate immunity (non-specific) | - destroy target cell by cytolysis
40
B cells
- differentiate and mature in red bone marrow | - involved in humoral immunity (antibody) response
41
T cells
- differentiate and mature in thymus | - involved in cellular response
42
Antigen presenting cells (APC)
- 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
B cell response Process
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
Primary Reponse Process
1. plasma cells produce antibodies that circulate in blood and lymph 2. antibodies bind and neutralize antigen
45
Secondary response process
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
Secondary vs primary response
1. faster 2. more antibodies produced 3. more sensitive 4. last longer
47
T cell response Process
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
T helper cells
- commander of entire system - produce various cytokines - activate variety of t cell, b cells, macrophages, NK cells
49
Cytotoxic t cells
when activated--> cytotoxic t lymphocyte (CTL) | CTL: destroys virus infected cells on contact
50
T regulatory cells
turn off immune response (prevent autoimmune response)
51
Memory t cells
recognize antigen in future infection for faster response
52
Types of immunity
active vs passage natural vs artificial
53
Active vs passive
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
Natural vs Artificial
1. Natural immunity - due to natural exposure to antigens 2. Artificial immunity - due to artificial exposure to antigen (vaccine)
55
Vaccines
- 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
Whole Unit Vaccines
Contain whole pathogens 1. inactivated pathogens - killed bacteria or viruses 2. live attenuated pathogens - weaken microorganisms
57
Subunit vaccines
antigenic fragments of microbes
58
toxoid vaccines
inactivated toxins
59
Conjugated vaccines
Antigen combined with a protein to boost immune response

Microbiology Lecture 4 (4 decks)

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