Mc Gavin 5th ed Ch4

Mechanisms of microbial infexctions

73 cards·by santhipriyadarsini

Study this deck

infectious organisms enter body through

ingestion, inhalation, or cutaneous penetration

infectious org interact with

mucosa or skin

if target organ isnt mucosa or skin they spread to

s/m or s/c LN (tonsils or PP)>> circulation>>prediilection site

protein expressed on surface of infectious org ligand that bind to

receptors on the membranes of host's target organs, mucus assoc w these cells, vascularized ECM beneath these cells, macriophages, lymphocyd

infection depends on creating---to establish, sustain, and spread the infection when orga first encounter the body

an initial beachhead

2 initial beach heads

1. mucosa of respir, aliment, lower urinary, repro, eye and ear 2. s/c tissues incl musc andendo cells of the skin.

org spread locally to

s/mucosa and s/cutis

org spread regionally to

org spread systemically to

organ systems

goblet cell secreated mucin contains

mucin glycoproteins

phagocytosis of infectious org trapped in the mucus id facilitated by

mucus assoc macrophages, mucosal dendritic cells and microfold (M) cells

mucin matrix has

bacteriocidal and static molecules

Bacteria target MALT via

mucosal macrophages, lymphocytes, dendritic cells, transcytosis or intercellular junctional spread, M cells

normal microflora observed in

outer luminal zone of mucus layer indicates that importance of mucus gel to prevent adherenceof bacteria to epithelial cells

effect of bioactive factors released from inf org or activation of immune cellsaffect goblet cells

function of goblet cells and change chemical composition of mucus

inf org+activation of immune cells+ stressors=making mucosa more susceptible to infection

stressors are dehydration, shipping, weather

3 mechanisms of bacteria to penetrate mucus layer

1. pentrating motlity 2. digestion and consumption as energy source 3.evasion of mucus layer in areas ard PP,Mcell and area devoid of mucus

pathogeneic advances provided by mucus to bacteria

1.nutrition 2. avoid expulsion 3. adhesion to molecules in mucin

microbial mucolysis degrade mucus and enables bacteria to

reach surface of epithelial cells

2 types of mucin

acidic and neutral

acidic type mucin divided into

sulfated (sulfomucins) and non sulfated (sialomucin)

biochemical differences in mucin signifies

segmental target cell specificity of inf org

route of ingestion

ingestion of inf fomites

mucus layer is a

physical and biological barrier against inf org

features of mucus layer signifies antiinfectious

thick, viscous, bind to bacterial adhesins,lysozyme n IgA reservoir, free radicalscavanger, enteric flora

more goblet cells among LI and SI

LI large intestine

more goblet cells among ileum, jejunum and duodenum

ileum

more goblet cells among crypts and villi

crypts

mucus inner layer and outer layer

inner gel layer and outer soluble layerr

mucus layer in colon

thickest 830um

mucus layer in jejunum

thinnest

more goblet cells among crypts and villi

crypts

more goblet cells among LI and SI

LI large intestine

moregoblet cells among jejunum, ileum and duodenum

ileum

mcus layer has inner and outer layers

inner gel layer and outer soluble layer

mucus layer in colon

thickest 830um

mucus layer in jejunum

thinnest 123um

why infectious org readfily interact with M cells

bcoz they aint covered by mucus layer

virulence determinates

bacterial proteins

IgA secreated by mature plasma cells within the lamina propria

passes thro mucosal epit cells into lumen - opsonizing defense mechanism

absence of mucus over

M cel and follicle assoc epith

M cells transfer antigens in the lumen of intestine acroos mucosa to

dendrtitic cellsand T lymphocytes within the nodule

PP have affernt lymphatics that drain

to regional LN

inhaled inf org deposited based on what properties?

size, shape, weight, and electrostatic charge

smallest inf org

virus

ize of virus range

5-300nm diameter

bacteria size

0.5 - 5 um

fungi size

5-60um

protozoa size

1-300um

larger inf fomites such as bac or fungi inhaled deposited mostly

nasal turbinates

smaller inf org can reach -- in resp system before trapped in mucosae

pharynx larynx trachea and bronchi

nasal turbinates trap particulate matter of 3-5um or greater at ?%

70-80%

nasal turbinates trap particulate matter of 2um or greater at ?%

60%

airways can branch -- times to enroute from trachea to alveoli

exchange prtn of respir sys

bronchioles, alveolar ducts, alveoli

exchange portion of resp sys lacks

cilia and protective mucus layer

important defensive mechanism of respir sys

mucociliary apparatus

mucociliary apparatus (MCA)

mucuc layer and cilialted mucosal epithelial cells

mucuc layer in MCA produced by

goblet cells and s/mucosal glands contains luminal viscoelastic gel layer to trap inf fomites

serous layer in MCA contains

cilia - tips of cilia enters the gel layer of mucus layer and the beat of cilia moves the gel and fomites

in nasal cavity and sinuses cilia move inf fomites

down ward towards pahrynx

in the conductive portion of resp sys cilia moves

inf fomites upwards toward pharynx

directioanlity of mucus flow in MCA is determined by

rhythmic unidirectional beating pattern of cilia

ant and ventral flow pattern of distribution of conductive system influenced by

gravity which helps deposition of inf fomites in case of failure of MCA

BALT has afferent lymphatic vessels that drain into

tracheobronchial LN

monocyte-macrophage system

network of phagocytic and immune cells that migrate thro'out the body in circulatory and lymphatic

monocyte-macrophage system

share antigens of new foreign matter or inf org with resident immune cells in local regional and sys LN

monocyte-macrophage system in liver and kidney

Kupfer cells and intraglomerular mesangial cells

monocyte-macrophage system in lungs, brain, spleen, LN

alveolar macrophages, microglia, sinus macrophages in spleen and LN

monocyte-macrophage system circulating blood and connective tissue

monocyte and CT histiocytes

surface of mucosal epithelial cell located abe the junctional complex and exposed to lumen is called

apical domain

surface of mucosal epithelial cell located below the junctional complex on the sides and base is called

basolateral domain

monocyte-macrophage system in skin

histiocytes, Langerhans' cells