Host Barriers Flashcards
skin
- physical/mechanical barrier
- chemical agents
- normal flora
physical/mechanical barrier
- closely connected cells called keratinocytes with cross-linked keratin
- high turn over rate
- prevents evaporation
antimicrobial agents of the skin
- cathelicidins
- defenses
- dermicidin
- propionic acid
pH of the skin
- acidic pH
- create an environment where bad bacteria don’t want to live
normal flora
- commensals
- bacteria in the epidermis that do no harm
- and in some cases possibly benefit
Langerhans cells location
- dendritic cells located among keratinocytes
Langerhans cells origin
- derived from the bone marrow
Langerhans cells function
- function as antigen presenting cells in immune responses to contact antigens (like skin allergies) and some skin grafts
what do Langerhans cells contain?
- contain birbeck granules
organization of mucous membranes
- mucosa
- submucosa
- muscular externa
- external layer
mucosa composed of
- epithelium
- lamina propria
- muscularis mucosae
lamina propria
- loose connective tissue with glands
muscularis mucosae
- smooth muscle
submucosa
- dense irregular connective tissue
muscularis externa
- inner smooth muscle
- outer smooth muscle
external layer
- adventitia
- serosa
adventitia
- loose connective tissue
serosa
- loose connective tissue
- mesothelial lining from peritoneum
intercellular junctions
- tight junction
- zonula adherens
- desmosome
- gap junction
desmosome composed of
- desmoplakins
- plakoglobins
tight junction type of junction
- an occludens junction
tight junction composed of
- Claudins
- occludins (protein)
- Claude sounds like the name of someone who is uptight
tight junction function
- prevents leaking between cells
- prevents movement of membrane proteins
zonula adherens type of junction
- adherens junction
zonula adherens composed of
- cadherins
zonula adherens function
- binds to actin of the terminal web (cytoskeleton)
desmosome type of junction
- adherens junction
- macula adherens or spot desmosome
desmosome composed of
- desmoplakins and plakoglobins
desmosome function
- join keratinocytes at cell-cell junctions
- join side to side or up to down
gap junction type of junction
- communicating junction
gap junction composed of
- connexins
hemidesmosome type of junction
- adherens junction
- NOT AN INTRACELLULAR JUNCTION
hemidesmosome function
- join cells in basal layer to basement membrane
mucosal immunity in intestine
- epithelial products
- antimicrobial factors
- normal flora
- lymphoid tissue
- ## peristalsis
epithelial products in intestine
- acidic pH in stomach
- pancreatic enzymes
- bile
- intestinal secretions
- mucus
antimicrobial factors in intestine
- lysozyme
what makes lysozyme in the intestine
- Paneth cells
- full of secretory vesicles
goblet cell
- secretes mucus precursors to surface of intestine
mucosal immunity in intestine
- antigens in gut bound by M cells and undergo transcytosis into their intraepithelial pockets
- dendritic cells take up antigen, process it, and present to helper T lymphocytes
- B lymphocytes stimulated to differentiate into plasma cells which secrete igA antibodies
- IgA transported to gut lumen where it binds its antigen on the surface of microorganisms, neutralizing potentially harmful invaders before they penetrate the mucosa.
antigens in gut - mucosal immunity
- bound by M cells
- undergo transcytosis into their intraeplial pockets
dendritic cells - mucosal immunity
- take up antigen
- process it
- present to helper T lymphocytes
B lymphocytes - mucosal immunity
- stimulated to differentiate into plasma cells
plasma cells - mucosal immunity
- secrete IgA antibodies
IgA - mucosal immunity
- transported to gut lumen
- binds antigen on surface of microorganism
- neutralizes potentially harmful invaders before they penetrate the mucosa.
why can IgA coexist with proteases in the gut lumen
- it is resistant to proteolytic enzymes
how many bacterial species in oral cavity
- 400
mucosal immunity in oral cavity
- epithelium
- lamina propria
- saliva
epithelium - mucosal immunity in oral cavity
- physical barrier as in skin
- cells slough off and prevent biofilm formation
epithelium contains - mucosal immunity in oral cavity
- contains Langerhans cells and intraepithelial lymphocytes
lamina propria contains - mucosal immunity in oral cavity
- macrophages
- dendritic cells
dendritic cells - mucosal immunity in oral cavity
- project dendrites into the epithelium
- uptake antigens
- migrate to secondary lymphoid tissue and draining lymph nodes
saliva contains
- lysozyme
- lactoferrin
- histatins
- salivary IgA
- myeloperoxidase
lysozyme - mucosal immunity in oral cavity
- cleaves bacterial cell walls
salivary IgA
- aggregates oral bacteria
- prevents formation of dental plaques
pemphigus vulgaris
- acontholytic (loss of intercellular connections) in persons aged 30-60
pemphigus vulgaris cause
- autoimmune attack of desmosomes
pemphigus vulgaris result
- formation of severe intraepidermal bullae starting in oral cavity and spreading to skin
- can be fatal
bullous pemphigold vs pemphigus vulgaris
- resembles pemphigus vulgaris but less severe
bullous pemphigold cause
- autoimmune attack of hemidesmosomes
bullous pemphigold result
- sub epidermal bulael with characteristic inflammatory infiltrate of eosinophils
diffuse lymphoid tissue located
- located in mucosa
- unless seen in submucosa known as Peyer’s patches
two forms of diffuse lymphoid tissue
- loose clusters of lymphoid cells
- lymphoid nodules
where are lymphoid nodules found
- in lamina propria of mucosa throughout gut
Peyer’s patches
- found in ileum
- large and press outward to submucosa
respiratory tract
- turbulent airflow and humidification causes large particles to land on mucosal surfaces
layer of mucus respiratory tract
- flows toward pharynx for expectoration or swallowing
swallowing is what kind of mechanism?
- cleansing mechanism
mucus clearance aided by
- coordinated secretion of mucin and proteins
- sufficient water for hydration
- beating cilia
- sneezing and coughing
protective antimicrobial factors in respiratory tract
- antioxidants
- defensins
- lactoferrins
- lysozyme
sentinel cell
- alveolar macrophage
- first line of defense
epithelium in vagina secretes
- epithelium secretes glycogen
normal flora in vagina
- convert glycogen to lactic acid
- creates acidic pH
- unfavorable for pathogens
normal urine
- sterile
normal urine pH
- bactericidal due to pH and urea
Tamm-Horsfall protein
- comes from kidney
- binds bacteria and prevents attachment to urinary tract lining
frequent urination
- rinses lower urinary tract with urine 4-8 times a day
- eliminates pathogenic organisms
pathogens that can bind to urinary tract epithelial cells
- N. gonorrhea
- E. coli
longer male urethra benefit
- passive protection
- longer route for bacterial to travel to bladder
Eye protections
- blinking
- lacrimal glands
- meibomian glands
- ciliary gland
- bacteriostatic/cidal tear film
lacrimal glands
- tears
meibomian glands
- sebaceous glands on eyelid
ciliary gland
- aporcrine sweat glands on eyelid
tear film comes from
- glandular secretions of conjunctiva and cornea
constant bathing of eyes with tears
- dilutes and clears foreign substances via tear ducts into nasal passage
tears contain
- lysozyme
lipid oil layer of eye
- lubricates and prevent evaporation
aqueous water layer of eye
- nourishes and protects cornea
mucin layer of eye
- adheres tear to eye
presence of innate immune defenses
- present intrinsically without previous stimulation
specificity of innate immune defenses
- limited specificity
innate immune defenses repeated exposure
- not enhanced by repeated exposure
diversity of expression of innate immune defenses
- limited diversity of expression