Digestive system ppt. V

The Rectum
?Forms last 15 cm of digestive tract
?Is an expandable organ for temporary storage of feces
?Movement of fecal material into rectum triggers urge to defecate
?AnusIs exit of the anal canal
?Has keratinized epidermis like skin [anus]
?[The rest of the rectum is columnar or nonkeratinizedstratified squamous]
Anal canal:
superiorepitheliumissimplecolumnar;inferiorepitheliumisstratifiedsquamous.
•Internal anal sphincter(smooth muscle)
•External anal sphincter(skeletal muscle)
•Hemorrhoids: Vein enlargement or inflammation
Anal Sphincters
?Internal anal sphincter:
?circular muscle layer of muscularis externa
?has smooth muscle cells, not under voluntary control
?External anal sphincter:
?encircles distal portion of anal canal
?a ring of skeletal muscle fibers, under voluntary controlK. Salivary Glands-three pairs
–1. Parotid: largest.
–a.Serous.
–b. Parotid ductenters the oral cavity adjacent to the 2ndupper molar
–2. Sublingual: smallest.
–a.Mixed, but primarily mucous.
–b.Eachhas 10-12 ducts that enter the floor of the oral cavity.
–3. Submandibular: mixed,
–a.Posteriorhalf of inferior border of mandible.
–b.Ductenters oral cavity on either side of lingu