Small and Large Intestine Flashcards
Primary site of absorption &
completion of digestion
Small intestine
T/F: Small Intestine has modifications to increase
surface area
true
Mucosa & submucosa
throughout small intestine
arranged in valve-like folds/
rings:
plicae circulares
Mucosa & submucosa
throughout small intestine
arranged in valve-like folds/
rings, plicae circulares (=
valves of ___)
valves of Kerkring
plicae circulares increase surface area, contain ____
submucosal core
Mucosal surface made up of
____, ~1 mm long, contain
core of lamina propria
villi
Mucosal surface made up of
villi, ~1 mm long, contain
core of l_____
amina propria
Between villi are ____
crypts of
Lieberkuhn (extensions into lamina propria)
(Villi) Epithelium supported by
connective tissue lamina
propria, containing capillaries
& lymphatics for _____
absorption
of nutrients
Intestinal villi lined by _____ epithelium
simple
columnar
(gluten
enteropathy or allergy
to the wheat protein
gluten)
Celiac disease
Celiac disease causes:
causes villus
blunting, atrophy and
loss => malabsorption &
weight loss.
Celiac Disease causes villus
blunting, atrophy and
loss => ___
malabsorption &
weight loss.
____ is the
presence of lymphocytes
epithelial cells.
Intraepithelial
lymphocytes
There are three functional zones in the epithelium of the small intestine:
1) Villi 2) crypts 3) Neck (where villi and crypts meet)
Cells of the SI epithelium:
- Enterocytes
- Mucous cells
- Paneth cells
- Endocrine cells
- Stem cells
Mucosal cells of the small
intestine called ____, cover surface of villi
enterocytes
(E)
Mucosal cells of the small
intestine called enterocytes
(E), cover _____
surface of villi
Enterocytes: Apical/ luminal surface highly
folded, modified into 2-3000
_____(= striated or brush
border)
microvilli
Microvilli on enterocytes ↑ surface area for absorption;
coated with _____ containing enzymes
important for digestion
protective
glycocalyx
Microvilli on enterocytes ↑ surface area for absorption;
coated with protective
glycocalyx containing enzymes
important for ___
digestion
Enterocytes separated from luminal surface by _____
desmosomes and tight junctions
Interspersed among enterocytes
are mucus secreting ____ cells
goblet cells
Mucous cells Usually found in the _____ of
the crypts
upper 2/3
Mucous cells synthesize ____
stored in membrane-bound
granules; lubricates & protects
epithelium
mucinogen (=> mucus),
Least frequent in the duodenum,
frequency increases into the
jejunum and ileum (most)
Mucous cells (goblet cells)
_____ found at
base of crypts; contain
large eosinophilic
granules
Paneth cells
Paneth cells found at
base of crypts; contain
large eosinophilic
granules—produce
antibacterial proteins
called _____, and
enzymes, including
______
defensins and lysozymes
Small #’s of enteroendocrine
(APUD) cells scattered
throughout but mainly in the
_____ of the crypt
lower third of crypt
Regulate GI motility & secretion
Enteroendocrine cells
“S” cells secrete secretin
(stimulate release of
_______)
bicarbonate from pancreas
“I” cells secrete
________
(stimulates pancreatic
secretion & contraction of
gallbladder)
cholecystekinin, or CCK
“I” cells secrete
cholecystekinin, or CCK
(stimulates ______)
pancreatic
secretion & contraction of
gallbladder
A” cells secrete ___
glucagon
glucagon effects
increase blood sugar
“K” cells secrete ______
(gastric
inhibitory peptide)
Actively dividing stem cells located :
at base of crypts
Stem cells migrate up ____, mature and are ___
Cells migrate up villus, mature, & are shed
Entire epithelial lining replaced roughly every ___ days
every 3-5 days
Lamina Propria: Most clearly seen in _____ but also surrounds and supports the
glands’ crypts
core of villi
Collagen, reticular fibers, fibroblasts & GAGs.???
Lamina propria
MALT located in lamina propria &
_____
submucosa of small intestine
Lots of lymphocytes (T), plasma
cells, eosinophils, macrophages &
mast cells– secrete ____
Sec IgA
Epithelium contains enlarged “M”
cells (microfold) —squamoid
enterocytes modified for ____
Ag
sampling, uptake of
macromolecules
Lamina propria of Small intetsine–May also see ___,
dome-shaped areas grossly visible
on surface of mucosa, project into
lumen
Peyer’s patches
Duodenum: Characterized by presence of
_____ in submucosa
Brunner’s glands
Brunner’s Glands: Secrete ______; unique
to duodenum
mucus & zymogens
Main function of duodenum—
_______,
assisted by pancreas & gallbladder
neutralize gastric acid & pepsin
Secrete an alkaline
mucus (8.0-9.5) which
may protect against
acidic stomach
contents entering the
duodenum
Brunner’s Glands
T/F: Alkaline mucus sec by brunner’s glands–This brings duodenal
contents closer to the
pH at which pancreatic
enzymes are most
effective
True (only found in duodenum)
Large intestine—modifies fluid content of
____. Specialized for mucous secretion
and salt & water absorption.
feces
_____—modifies fluid content of
feces. Specialized for mucous secretion
and salt & water absorption.
Large intestine
(Large intestime) Lining is a
mixture of absorptive and mucous
cells:
- Columnar cells
- Mucous cells
- Endocrine cells
- Stem cell
Includes cecum, appendix; ascending,
transverse, descending, & sigmoid
colon, & rectum
Large intestine
Large intestine lacks ____
villi & plicae
circulares
primary function of colon
1’ function, H2O & electrolyte
resorption
(Colon) 1’ function, H2O & electrolyte
resorption; also produces ____
for elimination of undigested food
& waste
mucus
(Colon) –large #’s of goblet cells in
epithelium & _____ in
submucosa—but no Brunner’s
glands
colonic glands
T/F: Villi are present in the colon
false
T/F: plicae circulares are present in the colon
false
Mucosal epithelium similar to small
intestine, but Paneth cells are:
generally
absent in adults
At the base of the glands the cell
population is a combination of
uncommitted stem cells (S),
goblet cells (G), columnar cells
(C), and the occasional pale-
staining endocrine cell (E).
**
Columnar cells – absorb soluble
salt and way=ter. No brush border
enzymes.
**
Mucous cells are present
throughout the colon but the
type of mucus ___
can change
T/F: MALT in large intestine does not form
domed Peyer’s patches
true
T/F: No lacteals present in lamina propria
true
T/F: Large #’s of commensal bacteria
(“coliforms”) present in large intestine
true
Outer longitudinal M layer in
muscularis externa is reduced or
incomplete—forms 3 longitudinal
strips, _____
taenia coli
taenia coli Responsible for formation of ____,
sacculations of large intestine
haustra
sacculations of large intestine
haustra
—small, blind-ended
sac, 2-13 cm in length distal
to ileo-cecal junction
Appendix
____ used for
bacterial digestion in
herbivores
Vestigial cecum;
Vestigial cecum; Contains large amounts of
____, active in
children
submucosal MALT
Appendix: If inflamed => ____
Tx—Sx removal,
appendectomy
appendicitis
Polyps—_____
* Any mass arising from the wall of the colon that protrudes into the
lumen
* Generally asymptomatic; most common sign, rectal bleeding
* Tx: Sx removal
adenoma
Colon cancer—_______
* ↑ roughage & fiber in diet ↓ colon cancer by ↓ transit time & ↑ GI
motility
* Tx: Surgical removal; if extensive, may require resection of portion of
colon
* New test kits for early detection; detect tumor Ab; also colonoscopy
screening over 50
adenocarcinoma
Short, dilated, terminal portion of large intestine
rectum
Rectum Contains _____ and large #’s of mucus glands
transverse rectal folds
Rectum: Transition of mucosa from simple columnar epithelium to stratified
squamous epithelium at ____
anal canal
Anal canal contains longitudinal folds called ____
anal columns
Within anal canal, ____ extend into submucosa & muscularis
externa (branched, straight, tubular glands—secrete mucus)
anal glands
Rectum: Surrounding Mm forms internal & external ______ (external—
voluntary, skeletal Mm; internal—involuntary, smooth Mm)
anal sphincters
Rectum: Occasional enlargement & irritation of submucosal Vv ~ anal canal =>
_____ (like varicose Vv)
hemorrhoids
—external opening; exit of GI tract
Anus
Swollen veins in anus and lower
rectum, similar to varicose veins.
hemorrhoids
Hemorrhoids can develop inside the
____ (internal hemorrhoids) or
_____
(external hemorrhoids)
rectum; under the skin around the anus
Difference in _______ of internal vs external hemorrhoids
referred pain
(Referred Pain for Hemorrhoids) Internal – follows _____, diffuse
* External ____, sharp on well-
localized
autonomics; somatic pain
