Lecture A1 - The Mucosal Surfaces and the Human Microbiota and Pathogens Flashcards
Name the three main mucosal surfaces of the human body?
Respiratory tract
Gastrointestinal tract
Urogenital tract
What is the first of the two contradictory functions of the major mucosa?
Facilitate exchanges between the inside of the body and the outside world.
Form an efficient barrier to microbes/pathogens.
What cells separate the inside from the outside of the body?
Epithelial
Describe simple squamous epithelial cells.
Lines blood vessels and air sacs of lungs.
Permits exchange of nutrients, wastes and gases.
Describe simple cuboidal epithelial cells.
Lines kidney tubules and glands.
Secretes and reabsorbs water and small molecules.
Describe simple columnar epithelial cells.
Lines most digestive organs.
Absorbs nutrients, produces mucus.
Describe stratified squamous epithelial cells.
Outer layer of skin, mouth, vagina.
Protects against abrasion, drying out, infection.
Describe stratified cuboidal epithelial cells.
Lines ducts of sweat glands.
Secretes water and ions.
Describe stratified columnar epithelial cells.
Lines epididymus, mammary glands, larynx.
Secretes mucus.
What is the second of the two contradictory functions of the major mucosa?
Hosts the largest fraction of the human microbiota.
Efficiently deal with pathogens.
Why are mucosal surfaces good sites for pathogens to invade and colonise?
They are in continuous, intense and dynamic contact with the outside world that allow for interactions with microorganisms.
What are the three levels of mucosal defences?
Immediate innate immunity.
Induced innate immunity.
Induced adaptive immunity.
Describe immediate innate immunity.
Epithelial cells - mechanical and chemical defences.
Microbial - microbiota direct and indirect and roles in defence.
Describe induced innate immunity.
Pathogens induced responses by epithelial cell, innate lymphoid cells, neutrophils and other immunocytes.
Describe induced adaptive immunity.
Pathogens cellular (ILC and T cell) and antibody-based responses (B cells).
What are the two barriers preventing crossings of infectious agents into the body?
High rate of tissue regeneration so epithelial cells always shedding releasing infected cells.
Muscle contractions that induce mucus movements that eliminate pathogens.
What is eubiotic microbiota?
Optimal functional configurations promoting health.
What is dysbiotic microbiota?
Pathological functional configurations promoting disease.
What are the indirect mechanisms of barrier functions mediated by the microbiota?
Stimulate activity and production of mucus.
Stimulates IL-1b processing and secretion.
Indirect induction of AMP released by epithelial cells.
Direct stimulation of antimicrobial production.
T-cell differentiation.
Induction of B cells and regulating the secretion of SIgA.