Changes

*Prevents dessication of the mucosal epithelium

*Prevents dessication of the mucosal epithelium

*Contains antimicrobial substances

*Contains antimicrobial substances

*Immunoglobulin - IgA

*Immunoglobulin - [[IgA]]

**IgA produced by mucosal plasma cells

**[[IgA]] produced by mucosal plasma cells

**IgA can attach to specific pathogen antigens (viruses, bacteria) trapping them in the mucus for clearance

**[[IgA]] can attach to specific pathogen antigens (viruses, bacteria) trapping them in the mucus for clearance

*Lysosyme

*Lysosyme

**Direct action on bacterial cell walls

**Direct action on bacterial cell walls

***Pharynx - pharyngitis

***Pharynx - pharyngitis

**Type

**Type

***Grossly many inflammatory processes (eg: response to viral or bacterial infection) in the URT will begin as a serous discharge, and then progress to a catarrhal exudate, and then to purulent/pseudomembranous/haemorrhagic as [[Neutrophils - WikiBlood|neutrophils]] are recruited

***Grossly many inflammatory processes (eg: response to viral or bacterial infection) in the URT will begin as a serous discharge, and then progress to a catarrhal exudate, and then to purulent/pseudomembranous/haemorrhagic as [[Neutrophils|neutrophils]] are recruited

***Serous - transparent fluid exudate (acute inflammation)  

***Serous - transparent fluid exudate (acute inflammation)  

***Catarrhal - mucous exudation (acute to subacute inflammation)

***Catarrhal - mucous exudation (acute to subacute inflammation)

====Parasitic infections ====

====Parasitic infections ====

*''Oestrus ovis'' larvae in the nasal cavity of sheep and goats = Nasal bots

*''Oestrus ovis'' larvae in the nasal cavity of sheep and goats = Nasal bots