B. The 1st Line of Defense of Innate Immunity

Question 1

fn of 1st line of innate defense

Answer 1

keeps pathogens from colonizing the host surfaces and from entering the host tissues. system includes physical and chemical factors

Question 2

how is skin a physical barrier

Answer 2

has a tough outer layer that is an effective barrier if intact. outer layer of epidermis consist of dead epithelial cells filled w/tough protection called keratin

Question 3

how is skin a chemical barrier

Answer 3

sweat glands secret sweat contains NaCl, which lowers aw, and lysozyme, which can lyse the peptidogylcan of gram +ive bacteria. sebaceous glands secrete sebum contains fatty acids that lower pH of skin

Question 4

what are mucous membranes

Answer 4

epithelial tissue covered w/a layer of sticky glycoproteins called mucus

Question 5

how are mucous membranes a physical barrier

Answer 5

traps particles including pathogens and prevent them from reaching and adhering to epithelium. tears rinse eyes and saliva rinses teeth.

Question 6

how are mucous membranes a physical barrier in the nose

Answer 6

in nose there are structures that cause turbulent air flow causing particle to get stuck in the mucous. part of the nasal cavity, trachea and bronchi are ciliated. cilia moves mucus and any trapped particles toward the throat where it is swallowed

Question 7

how is mucous membrane a chemical barrier

Answer 7

tears, saliva, mucus contain lysozyme, lactoferrin and antimicrobial peptides

Question 8

how do antimicrobial peptides like defensins work

Answer 8

+ively charged peptides. can bind to -ive;y charged membranes, disrupt them and be taken up into the cell. in the cytoplasm, can inhibit the activity of cellular components. disruption of outer membrane of gram -ive bacteria gives lysozyme access to peptidoglycan

Question 9

where are defensins also found

Answer 9

in lysosomes of phagocytes