BIO 12D Lecture Notes - Lecture 12: Taenia Coli, Muscularis Mucosae, Falciform Ligament
15 May 2020
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Document Summary
Rectum muscular tube that readily expands to store accumulated fecal material prior to defecation. 3 thick, transverse folds of rectum called rectal valves. Ensure fecal material retained during passing of gas terminates at anal canal. Anal canal last few centimeters of large intestine. Anal columns thin longitudinal ridges in internal lining of anal canal. Anal sinuses small depressions located between anal columns. Pressure exerted on anal sinuses cause their cells to release excess mucin which lubricates anal canal during defecation. Base of canal are internal and external anal sphincters close off opening to anal canal and relax (open) during defecation internal = involuntary. Mucosa lined w/ simple columnar epithelium and goblet cells. Unlike small intestine, large intestine mucosa lacks intestinal villi. Contains numerous intestinal glands that extend to muscularis mucosae. Many lymphatic nodules and lymphatic cells in lamina propria. Muscularis of colon and cecum has 2 layers of smooth muscle.
