Histo of colon, appendix, rectum, anal canal Flashcards
JP
Function of the Large Intestines
Absorb water from the remaining indigestible food matter and then past useless waste material from the body.
Hence why when the stool stays it the colon too long you are constipated cause the colon keeps absorbing the water so it eventually becomes hard
Length of the large intestines
4.9ft (1.5m)
1/5 of the whole length of the intestine
What are the large intestines comprised of
caecum
colon
rectum
anal canal
What is the epithelium of the large intestines?
Simple Columnar epithelium
Where are intestinal glands located
Extends through lamina propria to muscularis mucosae
In which intestine are globlet cells more abundant
Large intestines and produce mucus for lubricating the lumen
What is present in the lamina propria and submucosa
Lymphatic cells and lymphatic nodules
How does the large intestines differ from the small intestines in physical form?
Large intestine is wider
Outer longitudinal layer of the muscularis has been reduced to 3 strap-like bands known as the Taeniae Coli
How long does the large intestines take to finish the digestion of food
16hrs
What type of vitamins does the colon aborb
vitamin K. thiamine and riboflavin
What 2 ions does the large intestine secrete
K+ and Cl-
Where is the appendix attached
Inferior surface of the caecum
The appendix is apart of the mucosa-associated lymphoid tissue (MALT); True or False
True- plays an important role in immunity
What is Appendicitis?
Inflamed appendix due to a blockage that traps infectious materials in the lumen
The appendix can be removed with no apparent damage or consequence to the patient; True or False
True
There are no plicae circularis and villi in the rectum; True or False
True
How long is the rectum
12cm
Epithelium of the rectum is
Simple Columnar Epithelium; straight intestinal glands with goblet cells
Which part of the mucosa is squeezed between the intestinal glands
Lamina propria
Where is the anal canal located
At the terminal part of the large intestines
2-3cm in front and a little below the tip of the coccyx
Downwards ad backwards
Where does the anal canal open
Anal Orifice
Location of the Anal Orifice
4cm below and in front of tip of the coccyx
How long is the anal canal
2.5 - 4cm long
What separates the the upper 2/3 from the lower 1/3 of the anal canal
Pectinate aka Dentate Line
Which embryologically related area is above and below the pectinate line
Above; Endoderm
Below: Ectoderm
What does the mucosa and submucosa form ABOVE the pectinate line
Both layers form longitudinal folds called Columns of Morgagni
What joins the Columns of Morgagni together
Anal valves
Where are the anal sinuses located
Located in the submucosa above the valves
The pectinate lie is the level of the anal valves; True or False
True
What surrounds the anal canal
Inner involuntary smooth sphincters (continuation of circular layer of smooth muscle
Outer voluntary (Striated) sphincters
The anal canal is divided into 3 parts; name them:
-Zona Columnaris (Upper part, above pectinate line)
-Anal transitional zone (pectinate line)
Lower part, below pectinate line
What are the contents of the Zona Columnaris and which artery supplies it
Simple columnar epithelium with crypts continuous with rectal mucosa
Supplied by Superior rectal Artery (branch of inferior mesenteric artery)
Contents of the Anal Transitional Zone
Stratified Squamous non keratinized epithelium
This region is susceptible to various carcinomas
Blood supply of the Lower part
Supplied by Inferior rectal artery ( Branch of internal pudendal artery)
Name the 2 zones that the lower part of the anal canal is divided into
Intermediate zone (Between pectineal line and Hiltons line)-
Stratified squamous on keratinized epithelium without hair follicles, sebaceous glands
Between Hilton’s line and verge of anus- Stratified squamous Keratinized epithelium WITH sebaceous glands, hair follicles, sweat glands
How long is the upper muscular part of the anal canal
15mm
What embryological layer does the upper part of the anal canal originate from
Endodermal origin
What type of mucous membrane lines the upper part of the anal canal
Lined by semitransparent mucous membrane
-simple columnar
Injury to the upper muscular part of the anal canal is called
Anal fissure
Which area of the anal canal does 85% of diseases begin
Pectinate line
Colour contrast from upper part to intermediate area
Bluish pink mucosa above and black skin below
How long is the Anal verge
8mm
What kind of origin does the anal verge have
Ectodermal origin
What are the 3 parts of the External Anal Sphincters
Subcutaneous
Superficial
Deep
Name the 5 rectal arteries
Superior rectal artery
Internal iliac artery
Middle rectal artery
Internal Pudendal Artery
Inferior rectal artery
What is the venous drainage
Porto-Caval Anastomoses
Veins run with the arteries
Also have Internal and External rectal plexus
Lymphatic drainage above and below pectinate line
Above- Internal iliac lymph nodes
Below- Superior inguinal lymph nodes
Innervation above and below pectinate line
Above- Inferior Epigastric (autonomic fibres (visceral))
Below- inferior rectal (pudendal nerves)
