Lecture 19 & 20 - Avian GI anatomy, physiology & disease Flashcards
what structures in the oral cavity normally found in mammals are absent in birds?
lips
teeth
soft palate
no distinct separation between oral cavity and pharynx = oropharynx
no true intrinsic muscles in avian tongue
Name 1 airborne ruminant (there arent many)
hoatzin
what is the choana?
median fissure in palate connecting oropharynx and nasal cavity
what is tongue supported by?
the hyobranchial (hyoid) apparatus
where are salivary glands most prominant?
around the choanal slit, glottis and base of tongue
describe the action of swallowing
- pellet of food is seized by beak and moved by tongue to palate
- choanal opening reflexlively closed by muscular action - stops food entering nasal cavity
- rapid rostro-caudal movements of tongue move bolus into caudal part of oropharynx aided by caudally directed papillae
- infundibular cleft and glottis are reflexively closed
- propulsive action continued by laryngeal mound, etc.
describe the action of drinking
- fluid enters mouth by rapid rostro-caudal movements of tongue and accumulates in floor of oropharynx, caudal to tongue
- simultaneously larynx moves rostrally to lie close to choana
- head is raised and fluid flows around larynx and into esophagus mainly by gravity
common problems seen in oral cavity
hypovitaminosis A bacterial microabsceses candidiasis trichomoniasis capillariasis coccidosis
describe the internal surface of the esophagus
is longitudinally folded to increase distensibility of tube
abundant subepithelial mucus glands to lubricate food passage
describe location of esophagus
most of cervical esophagus is on the RIGHT side of the neck
what is another name for the crop?
ingluvies
where is the crop located?
dilatation of the esophagus
is the crop present in all species?
no!
are there mucus glands in the crop?
no!
describe the internal surface of the crop
its aglandular with a thin muscularis
innervation to the crop and esophagus is mediated by what nerve?
the vagus!
the esophagus and crop of granivores/omnivores have primarily what type of bacteria?
Gram (+) bacteria