GI III Flashcards
lacteal
lymphatic channels in core of the villus
where does fat absorption take place
through the alcteal and conveyed to the larger lymphatic structures
Function of smooth muscle within the lamina propria
contract and compress lacteal and move lymph from the lacteal to the lymphatic duct to the submucosa
What do the plasma cells in the lamina propria secrete?
antibodies, specifically IgA
What forms the intestinal glands (crypts of Liberkuhn)
epithelium invaginating into the lamina propria
Where is the stem cell niche in the intestinal gland, and what takes place there
base of the gland
mitotic events
Paneth cells
present at the bottom of the instinal glands
prominent acidophilic granules
granules contain lysozymes (which are bacteriolytic)
Brunner’s glands
hallmark feature of duodenum
secrete alkaline mucus and human epidermal growth factor
don’t exist in jejunum
human epidermal growth factor
stimulates cell proliferation
inhibits acid secretion from parietal cells
Ileum
is flat
plicae circulares deminish in size
presence of peyer’s patches
M cell
located in well-developed lymphatic nodules
involved in immune surveillance
Teniae coli
3 longitudinal bands of muscularis externa that are found in the external aspect of the muscularis externa
not found in the rectum
Haustra
present in the large intestine
Plicae semilunares
semilunar folds
Large intestine
lacks villi brush border poorly developed increased crypt density increased goblet cell density increased intestinal gland density paucity of lymphatic vessels
Mechanism of appendicitis
feaclith and intraluminal pressure
infection and mucosal ulceration
Appenidix
lamina propria is rich in lymphatic tissue
muscularis extern has circular layer and outer longitudinal layer
villi absent
Valves of houston/transverse rectal fold
3 permanent folds in the rectum
distal/inferior
middle
proximal/superior
What is the function of the valves of houston
support and suspend the fecal mass until you poop
What is the gut tube derived from ABOVE the pectinate line
hindgut
what is the gut tube BELOW the pectinate line derived from
the proctodeum
What is the innervation above the pectinate line
autonomic (no pain)
What is the innervation below the pectinate line
somatic
Where does cancer below the pectinate canal drain?
into the inguinal nodes
Layers of the anal canal from the lumen out
simple columnar epithelia w/large population of goblet cells
muscularis mucosae
submucosae
Submucosae of anal canal
contains internal hemorrhoidal (venous) plexus
plexus found in three anal columns called anal cushions
Anal columns
ridges projecting into lumen
What are the three anal cushions
left lateral
right anterior
right posterior
(named as if the patient is in a supine position)
Where do hemorrhoids develop
in the anal cushion
Bottom of columns join together and form a wall called what
anal valves
What is the name for the depressions at distal end of the columns
anal sinuses
Anal sinuses
glandular secretions accumulate here
glands here can become infected and cause an anorectal abscess
What are the epithelia transitions dital to the pectinate line
simple columnar
stratified squamous non-keratinized epithelia
stratified squamous keratinized epithelia
Interspincteric groove (white line of HIlton)
ring-like depression just below pectinate line
represents the border between the internal and external anal sphincters
What is the most common anorectal abscess
perianal
Anorectal abscess
gland secretions and/or fecal matter plugging up anal sinuses, leading to inflammation and infection. Pockets up pus (abscesses) accumulate
Fistula in ano
when anorectal abscesses develop in tubes which penetrate from anal canal to the skin of perineum.
What are locations of fistula in ano from most to least common
- intersphincteric
- transspincteric
- suprasphincteric
Colonic DIverticula
happens in large intestine only
found at sights of weakness between tenia coli
formed by out pouching of mucosa and submucosa
False diverticula involve _____ and ______
mucosa
submucosa
True diverticula involves _____
all layers
ex) Meckel’s diverticulum
What is a common site for polyps?
large intestine
Why do polyps develop
due to hyperproliferation of cells
Larger it is, more likely to be invasive
Lymphatic vessels in the lamina propria of the large intestine
are poorly developed
are better developed in the presence of inflammatory bowel disease
Ulcerative colitis
typically confined to large intestine
Crohn’s Disease
found anywhere along GI tract
much more likely to cause fissures and fistula
Hirschsprung’s disease will always involve what?
rectum
Hirschsprung’s disease (aka congenital megacolon)
neural crest cells do not migrate properly into involved segment of colon
Will show a lack of myenteric and submucosal plexus
causes area to remain constricted
