GUT- Functions of the Alimentary tract Flashcards
what is systemic immunity
bone marrow, spleen, thymus, lymph system, blood circulation
innate - prevents and avoids infection non-specific no memory mediated my macrophages, epithelial barriers, secretions
adaptive
responds to infection and prevents disease
highly specific response to targeted microbes
memory
mediated by Lymphocytes, antibodies
what is mucosal immunity
mucous membranes - eyes, nose, mouth, lungs, gut, genitourinary tract
all sites are usually colonised by microbes
main route of entry for microorganisms
large surface specialised for absorption
what are the innate and adaptive mechanisms involved in mucosal immunity
innate: mucin peristalsis antimicrobial peptides proteins (lysosomes, lactoferrin phagocytes)
adaptive:
mucosal / secretory system
must discriminate between harmful pathogens and harmless antigens - food and commensal bacteria
how is the mucosal barrier involved in innate immunity
natural barriers mucin peristalsis proteolysis microvillus membrane / squamous cells immunological - secretory IgA / IgM/ IgG
how is the oral cavity involved in innate immunity
saliva gingival fluid (leukocytes)
how to lymphoid cells contribute to mucosal immunity
there are lymphocytes intraepithelial-ly
scattered in the lamina propria - the dendritic cells extend arms up the sample the environment - acts as a pre-warning
what are peyers patches
collections of white blood cells
how are peyers patches involved in immunity
covered in M cells - these sample fluid from the gut
these then produce b cells which migrate from the m cells to the:
salivary glands, lachrymal glands, genitourinary system, lungs, small intestine
what features of secretory antibodies have
a component (secretory component) which stops degradation allowing it to survive in mucosal secretions
dimer
better at agglutination - 4 sites
mucous trapping
outline the concept of oral tolerance
active state where ingested food proteins do not elicit an immunological response
orally delivered antigens can supress systemic immunity - natural mechanism to prevent immune reactions to food and useful commensals
this means that an antigen first encountered through the mucosal immune system could produce an unresponsive systemic response to the antigen
what are the practical considerations of oral tolerance
tolerance to dietary foods
breakdown of food allergy
oral vaccination and safety
treatment and prevention of autoimmune disease
where can IgA be found
breast milk secretions - provides passive immune protection in new-born infants
