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Intro Microbio > Host defences > Flashcards

Host defences Flashcards

1
Q

innate, first barriers

A 
non-specific
- complement
antimicrobial proteins
Phagocytes (neutrophils, macrophages)
inflamation
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2
Q

adaptive defensives

A

induced by infection and specific, based on antigen

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3
Q

normal microbiome on skin secrete ____

A

secretes bacteriocin

- has antimicrobial substances: FA, lysozyme, AMPs (antimicrobial peptides), antibodies (if the host I immune)

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4
Q

mucous membrane

A

traps bacteria

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5
Q

complement system

A

set of blood and tissue protein that creates the pores in the pathogen membrane and induces lysis
- known as complement bc they complement the action of antibodies

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6
Q

phagocytes

A

cells that take up and digest pathogens

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7
Q

second line innate defence includes

A

complment system
phagocytes
inflammation

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8
Q

explain the complement system activation

A

two activation systems

  • by antibodies
  • by microbial cell wall components ( polysaccharid)
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9
Q

activating the complement system results in the formation of ___

A

a membrane attack complex (MAC) that causes lysis of some gram negative NO EFFECT ON GRAM POSITIVE

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10
Q

the membrane attack complex has no effect on ?

A

gram positive ( properly too much peptidylglycan)

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11
Q

MAC formation

A

complex process that involveds lots of C# proteins and ends in the creation of a pore in membrane which leads to the lysis of cell

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12
Q

major cell types in human blood

A 
erythrocytes (RBC)
WBC: (3)
lymphocytes--> B cells, T cells ( helper and cytotoxic)
granulocytes--> neutrophil
monocytes-->dendrites and macrophages
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13
Q

three classes of WBC (leukocytes)

A

monocytes, granulocytes and lymphocytes

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14
Q

monocytes

A

turn to macrophages and dendritic cells

macrophages are phagocytic (along with neutrophil)

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15
Q

Granulocytes

A

cytoplasm contain granules (are lysosomes that contain hydrolytic enzymes)

  • mast cells, neutrophils and basophils
  • neutrophils are phagocytic and the main one
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16
Q

Lymphocytes

A

B cells: antibodies

T cells: T helper cells and cytotoxic T cells

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17
Q

Granules

A

(like endoscopes and lysomes) contain hydrolytic enzymes and these form phagolysosomes

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18
Q

oxidative burst

A

rapid uptake of O2–> production of reactive oxygen species

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19
Q

phagocytosis is carried out primarily by

A

neutrophils and macrophages

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20
Q

Vasodilation definition and what plays an important role in it?

A

increased permeability of capillaries
- caused by complementary proteins C3a—> releases histamine and this increased permeability of blood vessels
C5 attracts phagocytes to infected areas

21
Q

Diapedesis

A

passage of WBC through the intact wall of the capillaries

22
Q

Il-1

A

singling molecule (cytokine) produces by macrophages

  • acts on the thermoregulatory center in the brain which turns up the body temp
  • signal to the site of the wound
23
Q

what can sense the presence of endotoxins bc of specific receptors

A

macrophages, they then secrete Il-1

24
Q

pyrogen

A

fever producing molecule by macrophages

25
Q

when do adaptive defenses come into play? what do they rely on ?

A

if an infection is prolonged, rely on detection and response to foreign antigens

26
Q

immune cells (b cells and T cells) have surface receptors specific to ___

A

individual antigens

27
Q

once activated by the antigen they recognize, T cells and B cells…?

A

grow and produce copies of themselves. some differentiate into memory cells

28
Q

2 types of T cells

A

effective T helper cells–> activated by HMC II, release cytokines that activate B cells and macrophages
effective cytotoxic T cells–> activated by HMC 1, on any cell, release perforins and granzymes which kill host cells that display foreign antigen on their surfaces

29
Q

each T cell is specific for one

A

antigen

30
Q

APCs include?

A

macrophages and dendritic cells

31
Q

if the T cell is specific for the antigen being presented on the ABC, the T cell will become activated and produce ______

A

interleukin 2 (Il2)–> induces multiplication and differentiation into effector T cells and memory T cells

32
Q

the major histocompatibility complex (MHC) is an _____________

A

an antigen presenting molecular complex

33
Q

All cells have ___, only APC have ____

A

MHC I, MHC II

34
Q

APC’s have

A

MHC II, professional APC also have MHC I

35
Q

MHC I

A

expressed by all cells, present antigen that come from inside the cell (important during infection by viruses) Regonized by cytotoxic T cells–> release perforins and granzymes to kill the infected host cells

36
Q

MHC II

A

expressed by APC and B cells, presents antigen processed in the phagolysosomes ( form microorganisms that were phagocytksed ) recognized by T helper cells

37
Q

Cytotoxic T cells recognize what complex? and release what to kill cells?

A

cells that display foreign antigens on MHC 1 are killed by Cytotoxic T cells
- release perforins and granzymes that kill the cell

38
Q

Activation of macrophages by helper T cells turn into?

A
  • often called “angry Killer cells” because they have increased phagocytic activity and produce higher levels of hydrolytic enzymes
    once activated the helper T cells can activate marcrophages that are presenting antigens for which the T cells are specific
39
Q

what happens to B cells once activated? and how do they get activated?

A

once activated by helper T cells release cytokines, B cells multiply and differentiate into plasma cells and memory cells –> plasma cells release specific antibodies

40
Q

antibodies

A

group of related proteins- immunoglobulins
antigen binding sites (Fab)
-constant region is Fc which binds to the receptor on macrophages and activates complement

41
Q

IgG

A

major circulation antibody

42
Q

4 functions of antibodies

A

1) act as opsonins, which increase phagocytosis efficiency
2) bind to toxins, which prevent binding to host cells
3) bind to adhesions, which prevent adhesion to host cells
4) activation of complement

43
Q

primary response

A

IgM

44
Q

secondary response (another contact with he same antigen )

A

IgG

45
Q

Aquired active immunity

A

producing memory cells from the antigenic stimuli, can be natural - like an infection,
or artificial - vaccine

46
Q

aquired passive immunity

A

acquiring antiboties from a passive source. no direct expossure to the antigen, immunity achieved by injection
- natural - from birth
or artificial - serum from immune animal

47
Q

natural immunity

A

some animals can get it but humans or other species cant

48
Q

opsonins definition

A

usually an antigen that binds to the microorganism and increases phagocytic activity

Intro Microbio (18 decks)

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