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Microbiology > Lesson 3.1 - Immune Defenses > Flashcards

Lesson 3.1 - Immune Defenses Flashcards

Immune Defenses

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Biology 101 flashcards
1
Q

Why is immunology important?

A
  • Health - Illness - Homeostasis
  • Immune system disorders
    • Opportunistic infections & cytokine storm
  • Understand vaccination & antibody therapy
  • Study bacteria and viruses
  • Educate patients and discredit pseudoscience
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2
Q

What is a cytokine storm?

A

Life-threatening systemic inflammatory syndrome caused by high cyotkine levels

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3
Q

Define antigens

A
  • Substances that bind to immunoglobulin receptors / T-cell receptor
  • Induce immune response
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4
Q

Define epitopes

A
  • Immunologically active regions of antigens
  • Part of antigen by which antibody attaches
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5
Q

Define Pathogen-associated molecular patterns (PAMPs)

A
  • Molecules unique to microorganisms (not human cells)
  • Recognized by innate immune cells & toll-like receptors (TLRs) on leukocytes
  • Have epitopes
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6
Q

Examples of PAMPs

A

Carbohydrates, lipoproteins, Lipid A-endotoxin, peptidoglycan, flagellar proteins, nucleic acids

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7
Q

Define cytokines

A
  • Low weight, soluble, chemical messengers
  • Regulate innate & adaptive immune systems
  • Stimulate hematopoiesis
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8
Q

*Cells that produce cytokines:

A

Macrophages, dendritic cells, T-lymphocytes, Natural killer cells, endothelial cells, & mucosal epithelial cells

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9
Q

Define chemokine

A

Cytokines produced during inflammation, that organize leukocytes

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10
Q

[3] Classifications of Cytokines

A
  • Pleiotropic
    • Cytokine acts on a # of different types of cells
  • Redundant
    • Different cytokines carry out same function
  • Multifunctional
    • Same cytokine regulates diff. functions
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11
Q

Variable region of antibody

A

Fab = fragment antigen binding; highly specific for epitope

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12
Q

Constant region of antibody

A

Fc = fragment crytallizable

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13
Q

[6] Parts of Antibody

A
  1. Fab region
  2. Fc region
  3. Heavy chain
    • w/ 1 variable, followed by 1 constant domain, 1 hinge, and 2 constant domains
  4. Light chain
    • w/ 1 variable & 1 constant domain
  5. Antigen binding site = paratope
  6. Hinge regions
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14
Q

[3] Lines of Defenses

A
  • 1st: External Barriers
  • 2nd: Innate - Non-specific
  • 3rd: Adaptive - Specific
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15
Q

External Barriers

A

1st line of defense

Skin, sebaceous gland, ear wax, cilia, nasal hair, mucous, saliva, tears (lysozome), stomach acid, urine flow, microflora in digestive/upper respiratory

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16
Q

Innate Defenses

A
  • Non-specific & lacks immunological memory
  • Acts immediately after foreign substance exposure
  • Contains cellular & non-cellular components
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17
Q

[2] Types of Innate Defenses

A
  • Cellular defenses
  • Non-cellular defenses
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18
Q

Cellular defenses

A
  • All cells originated from bone marrow stem cells
  • Several types involved in innate response
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19
Q

Non-cellular defenses

A
  • Heparin: anticoagulant
  • Histamines: inflammatory response
  • Lysozyme: hydrolyzes ß-1,4 peptidoglycan
  • Complement pathway: antimicrobial proteins
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20
Q

Examples of leukocytes (of innate immunity)

A

Basophils, neutrophils, eosinophils, monocyte (macrophages & dendritic cells), mast cells

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21
Q

Basophils

A

Inflammatory histamine & anti-coagulant heparin

22
Q

Mast cells

A

Histamines & heparin; confined to tissues

23
Q

Eosinophils

A

Phagocytic & secrete protein toxins (kills parasitic worms)

24
Q

Neutrophils

A
  • Phagocytic; release O2- and H2O2
  • Extracellular traps (NETs); DNA entangles cells
  • Perform diapedesis
25
Q

Diapedesis

A

Movement of leukocytes, through intact capillary walls, into surrounding body tissue

26
Q

Monocytes

A
  • Mature into macrophages & dendritic cells
    • Wandering macrophages
      • Move throughout body
      • ​Scavenge bacteria, fungi, spores, dust, and dead body cells
    • Fixed macrophages
      • ​Stay within defined area/organ
      • Alveolar (lung), microglia (CNS), Kupffer cells (liver)
27
Q

Dendritic Cells

A
  • Long, thin cytoplasmic extensions; phagocytic
  • Found under skin surface & mucous membranes
  • Migrate to lymph nodes
28
Q

Phagocytosis

A

phagosome + lysosome = phagolysosome

29
Q

Leukocyte chemotaxis

A
  • Movement of organism/cell along chemical concreation gradient either toward/away from chemical stimulus
    • Leukocytes attracted to injury because lots of attractants
30
Q

Complement Pathway - antimicrobial peptides (& Functions)

A
  • Can be brought in action by adaptive immune system
  • 20 antimicrobial proteins in C1 pathway
  • Functions:
    • Attach to bacteria via antibodies
    • Lyse bacterial cells
    • Signal phagocytes (chemotaxis)
    • Activate inflammation
    • Vasodilation
31
Q

___ binds to the Fc region of antibodies, a microbe or C-reactive protein

A

C1q

32
Q

_________ increases when there is a condition causing inflammation

A

C-reactive protein

33
Q

Activation of C1 during Classical Complement Pathway

A
  • Fab of 2 IgG molecules OR 1 IgM molecule bind to epitopes
  • C1 binds, becomes active enzyme
  • C1 cleaves C2 & C4
  • C2 & C4 combine, cleaves C3 = C3a + C3b
  • C3b joins C2, cleaves C5 = C5a + C5b
  • C3b & C4b = opsonins (facilitate binding)
  • C5b: used for membrane attack complex (MAC)
34
Q

3rd Line of Defense Overview

A
  • Antigen-specific
  • Immunological memory
35
Q

Define antigens

A
  • Pieces of foreign molecules
  • Adaptive immune system recognizes as part of microorganism
36
Q

Antigen-MHC complex

A

Macrophages & dendritic cells digest pathogens and present antigens

37
Q

Antigen Presenting Cells (APC)

A
  • Migrate to lymphatic system
    • Lymph nodes, spleen, & other lymphatic tissue
  • Release cytokines that attracted helper T cells (TH)
  • Interact with lymphocytes (B & T cells)
38
Q

Define Lymphocytes (and types)

A
  • Main cells of Adaptive Immune Sys.
  • Arise and mature in lymphatic system organs: bone marrow & thymus
  • Types:
    • B cells
    • T cells
      • Natural Killer cells
39
Q

B cells

A

Produce antibodies (Abs) that flag pathogens in blood, lymph, & tissue fluids

40
Q

T cells

A

Destroy virally infected & some neoplastic cells; regulate immune response

41
Q

Natural Killer cells

A

Secrete teoxins that kill virally infected cells & some neoplasms; don’t need to be activated

42
Q

Helper T cells (TH)

A
  • Have receptors that may bind to antigen by APC
    • Randomly generated during development
  • May have 100k identical receptors
  • Replicate furiously upon recognition
    • Some become effectors; others memory cells
    • Effector TH cells release cytokines to activate cytotoxic T cells (TC)
43
Q

Cytotoxic T cells (TC)

A
  • Kill infected cells; activated by interleukin-2 (IL-2)
  • Leave lymphatic system in search of infected host cells
  • Effector TC stimulates proliferation of TC cell
    • Bind and release perforin = infected cell dies
44
Q

Humoral immunity

A
  • Antibodies (Abs)
    • TH cells release IL-4 and IL-5 to activate B cells
    • B cells have antibodies on surface
45
Q

How are B cells activated?

A
  • Binds to both an antigen and is stimulated by a TH cell
    • Divides rapidly when activated (long-lived memory & short-lived plasma cells)
46
Q

Neutralization

A
  • Abs coat surface of viral particles preventing them from attaching to cell receptors
47
Q

Agglutination

A

Clumping of cells (i.e. bacteria, erythrocytes) in presence of antibody

48
Q

Define opsonins.

A

Any molecule that forms connections b/t phagocyte & antigen; increases efficiency (not required)

49
Q

What can affect the success of the adaptive response?

A
  • Number of pathogens
  • Virulence of pathogens
  • Status of host immune system
  • Immunocompromised
50
Q

Cellular vs Humoral Immunity

A

Microbiology (17 decks)

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