Large Intestine Flashcards
Why there is a richness in MALT in the large intestine?
Due to the large bacterial population in the large intestine
What is the name of the absorptive cell in the colon?
Colonocyte
Goblet cells producing lubricating mucus become more numerous where
along the
length of the colon and in the rectum.
What are the characteristics of Colonocyte
have irregular microvilli and dilated intercellular spaces indicating active fluid absorption.
What is significant component of the appendix
MALT
The serosa of the is characterized by
small pendulous pockets of adipose tissue .
Omentale appendices
The muscularis of the colon has longitudinal and circular layers but differs from that of the small intestine?
outer layer condensed in three separate
longitudinal bands called teniae coli.
What are the histological modification found in the appendix?
1- The intestinal glands i are less well developed, shorter, and often spaced
2- Diffuse lymphatic tissue in the lamina
propria is abundant and is present often in the submucosa.
3- Lymphatic nodules with germinal centers are numerous and highly characteristic of the appendix.
What is the epithelial transition between the rectum and the anal canal?
simple columnar mucosal lining of the rectum is
replaced by stratified squamous epithelium.
Which muscle form the internal anal sphincter?
the rectum’s muscularis
Which muscle form the external anal sphincter?
(levetor ani)
Defecation involves the action of which muscle?
external anal sphincter muscle
What is the anal columns, and what do they contain?
longitudinal folds of the mucosa and submucosa
include sinuses of the rectal venous plexus
The large intestine gland lck which cell?
Paneth cells
Histologic Differences Between the Small and Large Intestines (Colon)
- large intestine lacks plicae circulares and villi
- Intestinal glands are deeper (longer) and lack Paneth
- goblet cells are more numerous in the large intestine
- muscularis externa shows taenia coli.
- The contractions of taenia coli forms haustra.
- lamina propria of the large intestine contains many solitary lymphatic nodules, and lymphocyte accumulations.
Anorectal Junction transition
lamina propria of the rectum is replaced by dense irregular connective
internal hemorrhoidal plexus of veins (contenuation of submucosal veins in the rectum) becomes in the mucosa of the anal canal.
The intestinal glands become shorter and less in number then disappear completely.
Colorectal cancer
adenocarcinoma
develops from benign adenomatous polyps in the mucosal epithelium.
usually occur in epithelium of the rectum, sigmoid colon, or distal descending colon
more common in individuals with low-fiber diets,
which reduce the bulk of fecal material, and this in turn prolongs contact of the mucosa with toxins in feces.
Hemorrhoids:
Swollen blood vessels in the mucosa or submucosa of the anal canal
This common condition typically results from a low-fiber diet, constipation, prolonged sitting, or
straining at defecation, conditions that produce increased pressure on these blood vessels.
Diverticulosis:
Herniation or outpocketing of the mucosa and submucosa of the colon can occur between the teniae coli, forming bulges (diverticula) and a
condition called diverticulosis. This disorder can result from structural defects in the colon wall or from high intraluminal pressure or constipation. Fecal material
can become immobilized in the diverticula and cause localized inflammation or diverticulitis.
