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GI I Exam 1 > Histology of the SI and LI > Flashcards

Histology of the SI and LI Flashcards

1
Q

Small Intestine

A

duodenum, jejunum, and ileum

principle site for digestion of food and absorption of digestion products

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2
Q

Plicae circulares

A

transverse folds with a submucosal core
-cannot lay flat if distended
not in duodenum, visible in jejunum, less so in ileum
-foldings of the entire mucosa, and some submucosa
-covered with intestinal villi

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3
Q

Intestinal Villi

A

mucosal folds that project into lumen and cover surface of SI
- increase absorptive surface area

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4
Q

enterocytes

A

simple columnar cells that produce enzymes for digestion and absorption

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5
Q

goblet cells

A

provide mucus coat to shield from abrasion and bacterial invasion

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6
Q

lacteal

A

lymphatic structure in intestinal villi that is important for absorption

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7
Q

Villi

A

Finger like folds of mucosa projecting into the lumen

covered by microvilli

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8
Q

Enterocyte microvilli

A

striated border

  • provide amplification of luminal surface
  • glycocalyx coat assists in nutrient uptake
  • actin microfilament core anchors to other proteins and myosin 1 via terminal web
  • terminal web permits contraction of microvilli
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9
Q

Intestinal Glands

A

simple tubular glands lined by simple columnar epi.

1) enteroendocrine cells
2) paneth cells
3) intestinal stem cells
4) microfold (M) cells
- continuous w/ simple columnar that covers intestinal villi
- open onto the luminal surface of the intestine at the base of the villi

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10
Q

enteroendocrine cell

A

found throughout the intestinal glands
-secrete peptide hormones to control gut motility, regulate secretion of enzymes, HCL, bile and other components for digestion

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11
Q

Secretin

A

stimulates bicarbonate secretion by the pancreatic duct

it enhances insulin secretion by B cells of the islet of langerhans

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12
Q

Cholecystokinin

A

it slows down emptying of the stomach by acting on the pyloric sphincter
it stimulates bile release from the gallbladder and teh secretion of pancreatic enzymes

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13
Q

gastrin

A

it stimulates the secretion of the HCL by parietal cells
it stimulates insulin secretion by B cells of the islet of langerhans
also stimulates gastric motility and growth of the mucosal cells

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14
Q

Paneth Cells

A

pyramidal shaped cells at base of intestinal glands

  • funcitons in innate immunity by secreting antimicrobial substances (lysozyme, a-defensins, other glycoproteins)
  • regulate normal bacterial flora via antibacterial action and phago.
  • sometimes found in LI (just a lil)
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15
Q

Intestinal Stem Cells (ISCs)

A

reside in niche at crypt base, near paneth cells
repopulate epi lining
daughter cells move out of the crypts…differentiate into goblet cells, enterocytes, enteroendocrine cells

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16
Q

Microfold (M) cells

A

specialized cells that overlie peyer’s patches and other large lymphatic nodules
-has microfolds and thin glycocalyx
-has a deep pocket like recesss connected to extracellular space, houses dendritic cells, macrophages, and T and B cells
-internalize and transfer pathogens (e coli_ to immune cells
AG TRANSPORTING CELLS

17
Q

Gastroduodenal junction

A

pyloris: thick wall due to presence of the pyloric sphincter muscle. pyloric glands at base of each gastric pit
duodenum: abundant brunner’s glands in submucosa. DEEP to mm. secretory mucosa w/ villi

basically look at submucosa area..has brunner’s glands? ITS SI starting!

18
Q

Duodenum

A

initial segment of SI
BRUNNERS glands in submucosa
=tubuloacinar mucous glands…produce alkaline secretion which neutralize the acidic chyme
-collects bile and pancreatic secretions bia the hepatopancreatic ampulla
leaf like villi

19
Q

Jejunum

A

long finger like villi (typically longest)
-tubular intestinal glands
-villus core contains well developed lacteal
NO SUBMUCOSAL glands
-lymphoid nodules/follicles in the LP

20
Q

Ileum

A

PEYERS PATCHES!!! =mucosal lymphoid nodules specific to ileum
finger like villi shorter than jejunum typically
paneth cells found at base of intestinal glands

21
Q

Ileocecal junction

A

food is propelled from ileum into cecum through ileocecal valve
-abrupt transition from villi of SI to glandular epi. of LI
-valve has thickened extension of the MM.
(critical function is to limit reflex of colonic contents into ileum
-mus. externa is also somewhat thickened

22
Q

Large intestine

A

absorbs water, sodium, vitamins, will uptake sedatives, anesthetics, steroids
openings of tubular intestinal glands (crypts of LIERBURKUHN) are hallmark of MUCOSA
-hall mark: intestinal glands, goblet cells but no intestinal villi

23
Q

crypts of lierberkuhn

A

openings of tubular intestinal glands of the large intestine. they are the hallmark of the mucosa
-lined by a large number of GCs

24
Q

Hallmark of the colon

A

glands consisting of simple columnar epi. with numerous goblet cells

25
Q

Hirschprung’s disease

A

aganglionosis in the distal colon

  • mutations of the RET gene required for migration and differentiation of NCC
  • failure of NCC development in both plexuses of a bowel segment
26
Q

short segment disease

A

HIRSCHPRUNGS

85% of cases..confined to rectosigmoid region

27
Q

long-segment disease

A

HIRSCHPLUNGS
10% of cases
extends past rectosigmoid region –> splenic flexure

28
Q

Total colonic anganglionosis

A

HIRSCHPLUNGS
5% of cases
affects entire colon

29
Q

Hirschplungs disease presentation/diagnosis/treatment

A

presentation: constipation, poor feeding, and progressive abdominal distention
dx: delayed BM < 48 hrs after birth, rectal biopsy, barium enema
tx: surgical removal of the affected colon segment, pull through of ganglionic colon segments

30
Q

inflammatory bowel disease

A

includes ulcerative colitis and crohns disease

-characterized by diarrhea, pain, and periodic relapses

31
Q

Ulcerative colitis

A

affects the mucosa of the LI

32
Q

Crohns disease

A

affects any segment of the intestinal tract

  • chronic inflammatory process involving the terminal ileum, also obs. in LI
  • inflammatory cells produce cytokines that cause damage to the intestinal mucosa
  • infiltration of neutrophils into the crypts of lieberkuhn –> destruction of intestinal glands due to crypt abcesses –> progressive atrophy, ulceration
33
Q

Rectum proper

A

typical mucosa with tubular intestinal glands, transverse rectal folds

34
Q

Anal canal (lower part)

A

1) anal column- with mucosal folds
2) anal sinuses- depressions btwn columns
3) anal glands- extend into submucosa and muscularis externa

circumanal glands, large apocrine glands surrounding the anal orifice

35
Q

Colorectal zone of anal canal

A

simple columnar epi. identical to the rectum (upper 1/3)

36
Q

anal transition zone

A

simple columnar epi –> stratified squamous epi of perianal skin (middle 1/3)

37
Q

squamous zone

A

stratified squamous epi continuous w/ perianal skin (lower 1/3)

38
Q

internal anal sphincter

A

at the level of the anus, inner circular layer thickens to form the internal anal sphincter

GI I Exam 1 (4 decks)

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