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Microbiology FINAL > Host defenses > Flashcards

Host defenses Flashcards

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1
Q

What are innate defences?

A

properties of normal host, NON-SPECIFIC defences

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2
Q

What are adaptive defences?

A

induced by the infection, SPECIF to the pathogen (based on antigens)

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3
Q

what are some examples of first barriers (innate defences)?

A 
skin
stomach acidity
normal microbiota
flushing of urinary tract epithelial cells
rapid pH change
mucus
cilia lining trachea
lysozyme in secretions
nose hairs
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4
Q

What does the normal microbiome do?

A

it competes for attachment sites and nutrients, secretes BACTERIOCIN

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5
Q

what are some antimicrobial substances? (4)

A
  • fatty acids
  • lysozymes!!!!
  • antimicrobial peptides (AMPs)!!!!
  • antibodies (if the host is immune)
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6
Q

Whats a mucous membrane?

A

mucus

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7
Q

skin is a thick layer of ______.

A

dead cells

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8
Q

How does the innate defense of the airways work?

A

mucous membrane; mucus traps bacteria; ciliated cells remove mucus and trapped bacteria

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9
Q

What are the three second line of defences if a pathogen manages to overcome the first line of defense (skin, mucosa)? explain each

A
  • complement system: set of proteins that creates pores in the pathogen membrane and induces lysis
  • Phagocytes: cells that take up and digest pathogens
  • inflammation: general nonspecific response of the innate system to toxins, pathogens and tissue damage
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10
Q

What is the complement system?

A

set of blood proteins - also present in tissues - known as complement because they complement the action of antibodies. proteins: C1-9.

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11
Q

What are the two action pathways of the complement system?

A
  • activation by classical pathway: antibodies

- activation by alternative pathway: microbial cell wall components (polysaccharides, liposaccharides)

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12
Q

What does the activation of the complement system result in? and what does it cause?

A

it results in the formation of a membrane attack complex (MAC, made of proteins C5b6789) that causes lysis of SOME gram negatives, NO EFFECT on gram positives.

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13
Q

how do you test pathogen sensitivity to complement system?

A

by exposing pathogens to serum (blood without red blood cells)

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14
Q

What are the cells of the innate immune system? (5) and their function

A
  • dendritic cell + macrophage: antigen presentation
  • neutrophil + dendritic cell + macrophage: phagocytosis
  • mast cell: inflammatory response
  • > all from myeloid precursor
  • natural killer cell: cell-mediated immunity
  • > from typhoid precursor
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15
Q

What are the cells of the adaptive immunity? (2)

A
  • T cell: cell mediated immunity
  • > from lymphoid precursor
  • Plasma cell: antibody-mediated immunity
  • > from B cell -> from lymphoid precursor
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16
Q

What are the major cell types found in normal human blood? (4)

A
  • red blood cells (erythrocytes)
  • lymphocytes
  • neutrophil
  • monocyte
17
Q

What are the three types of white blood cells (leukocytes)?

A
  • monocytes
  • granulocytes: their cytoplasm contains granules
  • lymphocytes
18
Q

What are the 2 sub-categories of lymphocytes?

A
  • B cells: antibodies

- T cells: T helper cells, cytotoxic T cells

19
Q

What are monocytes?

A

white blood cells that circulate in blood stream, differentiate into macrophages (and dendritic cells) in tissues, attracted to inflamed tissues, PHAGOCYTIC. Macrophages are present in all tissues and take on different forms in different tissues

20
Q

What are eosinophils, basophils, neutrophils, mast cells? what’s the particularity of neutrophils?

A

they are granulocytes (white blood cells/ leukocytes).

neutrophils are the most abundant, PHAGOCYTIC, often called polymorphonuclear leucocytes

21
Q

What are the 4 steps of phagocytosis? carried out primarily by macrophages and neutrophils

A
  • attachment of the organism to the membrane of the phagocyte
  • ingestion: the organism become enclosed in a phagosome
  • A. granules (endoscopes, lysosomes) containing hydrolytic enzymes fuse with the phagosome, formation of the phagolysosomes. B. oxidative burst: production of reactive oxygen species
  • killing and digestion of the microorganism
22
Q

What is oxidative burst?

A

rapid increase in uptake in O2 -> produces reactive oxygen species (O2-; H2O2; OH. ; OCl-)

23
Q

What are the 3 important enzymes in the generation of toxic reactive oxygen species?

A
  • myeloperoxidase
  • NADPH oxidase
  • V-type ATPases (pumps H+ in)
24
Q

What are the primary antibodies produced during the primary response?

A
  • Immunoglobin M (IgM)
25
Q

What happens during the primary response?

A
  • Initial antigen contact at day 0 initiates a primary immune response
  • after several days, IgM antibody is produced at detectable bu low tier (concentration)
  • in the absence of antigen, the tiger decreases with time
26
Q

What is the primary antibody present during the secondary response?

A
  • Immunoglobin G (IgG)
27
Q

What happens during the secondary response?

A
  • another contact with the same antigen (as the primary response) at day 100 initiates the secondary response
  • antibody class switches rapidly to IgG, now produced in high tiers (concentration)
  • in the absence of antigen, the tiger again decreases with time
28
Q

What are the two types of acquired immunity? What do they involve?

A
  • active immunity: involves the production of memory cells in response to antigenic stimulus
  • passive immunity: involves the acquisition of performed antibodies
29
Q

What are the two subcategories of active immunity? explain

A
  • natural: following infection

- artificial: vaccination (live, attenuated, dead agents or subunit: adhesins, capsular polysaccharide, toxoids)

30
Q

What are the two subcategories of passive immunity? explain

A
  • natural: placental transfer or COLOSTRUM (first form of milk)
  • artificial: serum from an immune animal
31
Q

What is natural immunity (species resistant)?

A

humans are naturally resistant to many infectious diseases of lower animals and vice versa.

32
Q

Does Actinobacillus pleuropneumonia cause a disease in humans?

A

No, it causes pleuropneumonia in pigs

33
Q

Salmonella typhi causes typhoid only in _____.

A

humans

34
Q

How can natural immunity be explained?

A

it can be explained in part by the absence or presence of the appropriate respecters in the animal for the adhesins expressed by the pathogen (same rationale for toxins and other virulence factors)

Microbiology FINAL (4 decks)

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