Med Micro 3 - 1st Line (mucous etc)

Question 1

Mucous membranes

Answer 1

Line all body cavities open to the outside. 2 layers: epithelium and connective layer (deeper). Goblet cells secrete mucous.

Question 2

Lacteal and function

Answer 2

A capillary of the lymph system. During an infection, blood vessels get leaky and empty into lacteals. Leads to lymph node unidirectionally

Question 3

Lymph node

Answer 3

Lacteals empty in there. Important in adaptive immunity.

Question 4

Epithelium of mucous membrane

Answer 4

Thin outer layer covering mucous membrane. Living cells. Packed tightly (no crossing for pathogens). Constant shedding and movement (peristalsis). Secrete defensins

Question 5

Defensins - what are they? Where are they found?

Answer 5

Anti-microbial peptides. Found on skin (in sweat), in mucous and neutrophils. Amphipathic.

Question 6

How are defensins triggered? What is their function?

Answer 6

Punch holes in bacterial membrane and cause leakiness; enter cell and disrupt pathways; or promote chemotaxis. Triggered by sugar and PAMPs

Question 7

Compare skin and mucous membranes

Answer 7

Chart

Question 8

Lacrimal apparatus

Answer 8

Makes and drains tears (into nasal cavity, then throat). Contain lysozyme, lactoferrin (binds free iron) and salt.

Question 9

PAMPs and examples

Answer 9

pathogen-associated molecular patterns. ex. LPS and peptidoglycan, lipoteichoic acid, nucleic acids. We have receptors for them on our phagocytes

Question 10

Interest in defensins

Answer 10

Could be used as an antibiotic, and they enhance killing by antibiotics (more can access the cell)

Question 11

What kind of structure may protect a pathogen against defensins?

Answer 11

Capsules, S-layers outside cell, proteases

Question 12

How do you activate a phagocyte?

Answer 12

Cytokines from keratinocytes, PAMPs

Question 13

Pattern recognition receptors

Answer 13

in innate immune cells, identify PAMPs, Some external and some internal ex. TLR and NOD

Question 14

Toll-like receptors (TLRs)

Answer 14

At least 13 types which recognize specific molecules (PAMPs). Identify live and dead bacteria or metabolites. Critical in innate immunity.

Question 15

What types of cells are most likely going to express TLRs?

Answer 15

Dendritic cells, phagocytes

Question 16

Action of TLRs

Answer 16

Binding can result in cytokine production, defensin secretion, phagocytosis and antigen presentation, interferon production, apoptosis

Question 17

Based on some of the virulence factors we’ve discussed so far, what types may help a pathogen avoid TLRs?

Answer 17

Signals for internalization of internal pathogens, clotting (cloaking), etc

Question 18

Nucleotide Oligomerization Domain (NOD) Proteins

Answer 18

Intracellular receptors for PAMPs. In adaptive immune response (MHC II presentation). Mediate inflammation (chemokine production), apoptosis, and possibly defensins

Question 19

Mutation in NOD

Answer 19

Mutation in NOD2 can cause Crohn’s disease (auto-immune disease).

Question 20

Chemokines

Answer 20

Involved in chemotaxis. Released by cell to recruit help (important in momement).

Question 21

MHCI and II

Answer 21

MHCI are antigen presenting cells resulting from viral infections. MHCII present epitopes after phgocytosis.

Question 22

Epitope

Answer 22

A small part of the antigen

Question 23

Antigen types

Answer 23

Exogenous, endogenous, auto-antigens. NOT always something foreign.

Question 24

How does microbial antagonism regulate the growth of other bacteria?

Answer 24

Based on normal microflora. Finite nutrients (like Fe), defensins (microbes make them too), reduce binding sites, help activate innate immune response, create unfavourable environment (pH)

Question 25

Some of our body’s defenses are used (subverted) by pathogens to provide an avenue for entry. Give examples.

Answer 25

Infect phagocytes which signal chemokines to helper T cells and infects them (HIV); get through lacrimal apparatus to get into the throat (cold); use phagocytosis to get in then escape phagosome.