Mucosa of the Small Intestine
- simple columnar epithelium w/ goblet cells
- most cells are columnar absorptive cells
- enzymes attached to the microvilli = disaccharidases and dipeptidases
What are lacteals?
center of lamina propria
Do the numbers of goblets cells increase or decrease as you pass through the small intestine?
Increase
Even more found in the large intestine
What does secretin do?
decreases intestinal motility
What does CCK (cholecystokinin) do?
- stimulates enzymatic pancreatic secretion
- increases intestinal motility
What does serotonin do?
increases gut motility
Paneth Cells
- usually at base of gland
- only in ruminants, horses, and humans
- contain eosinophilic granules
- produce lysozyme = bacteriocidal protein
M cells
- special cells over GALT (gut associated lymphatic tissue)
- endocytose molecules from gut lumen
- antigens then travel across them to underlying lymphatic tissue
- only seen w/ special techiques
Mucosa of Large Intestine
- lacks villi
- thicker mucosa than small intestine
- crypts are more extensive and richer in goblet cells
Flat bands of longitudinal muscle found in the tunica muscularis of the large intestine of human, swine, and horses?
taeniae
3 parts of large intestine
- cecum (birds have two)
- colon
- rectum
3 types of glands of the anal region
- anal glands
- glands of the anal sacs
- glands of circumanal region
Anal glands
-near rectoanal junction
Don’t confuse with “anal sacs” = large sac like pockets in lining of anal canal that open to the lumen
glands of the anal sacs
apocrine and sebaceous glands open into anal sacs
glands of circumanal region (“perianal”)
- sebaceous and sweat glands assoc. w/ hairs
- hepatocyte-like “hepatoid glands”
- lack ducts
- often develop benign tumors in aged male dogs = “perianal adenomas”
Avain Digestive Tract
- buccal cavity = no lips or cheeks
- crop (ingluvies) = esophageal diverticulum
- proventriculus = true stomach
- ventriculus = muscular; gizzard
- small intestine
- cloaca
Proventriculus
- true stomach
- rugosal (mucosal) glands open to the surface
- subrugosal (submucosal) glands = more deeply located, open to surface via “papillae”
