natural/physical barriers

Question 1

name some of the constitutive barriers to infection

Answer 1

skin, mucous and commensal bacteria

Question 2

I what different ways does skin act as a barrier

Answer 2

physical = tightly packed, multi-layered cells, constantly being renewed
physiological = low pH 5.5, low O2 tension
glands = secrete hydrophobic oils, lysozyme, ammonia and antimicrobial peptides

Question 3

how does mucous act as a constitutive barrier

Answer 3

physical = line all body cavities and traps invading/foreign pathogens
contains enzymes that directly kill pathogens

Question 4

what are they and how do cilia act as a physical barrier

Answer 4

they are tiny hair-like structures found on the epithelium that trap pathogens and contribute to removal of mucous(assisted by coughing/sneezing)

Question 5

how do commensal bacteria act as barriers to infection

Answer 5

they live on epithelial surfaces and have a symbiotic relationship with the host(us), they compete with pathogens for scarce resources as well as producing fatty acids that inhibit growth of many pathogens