Small and Large Intestine Flashcards by Maggie Eby

Primary site of absorption &
completion of digestion

Small intestine

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T/F: Small Intestine has modifications to increase
surface area

true

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Mucosa & submucosa
throughout small intestine
arranged in valve-like folds/
rings:

plicae circulares

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Mucosa & submucosa
throughout small intestine
arranged in valve-like folds/
rings, plicae circulares (=
valves of ___)

valves of Kerkring

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plicae circulares increase surface area, contain ____

submucosal core

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Mucosal surface made up of
____, ~1 mm long, contain
core of lamina propria

villi

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Mucosal surface made up of
villi, ~1 mm long, contain
core of l_____

amina propria

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Between villi are ____

crypts of
Lieberkuhn (extensions into lamina propria)

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(Villi) Epithelium supported by
connective tissue lamina
propria, containing capillaries
& lymphatics for _____

absorption
of nutrients

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Intestinal villi lined by _____ epithelium

simple
columnar

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(gluten
enteropathy or allergy
to the wheat protein
gluten)

Celiac disease

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Celiac disease causes:

causes villus
blunting, atrophy and
loss => malabsorption &
weight loss.

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Celiac Disease causes villus
blunting, atrophy and
loss => ___

malabsorption &
weight loss.

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____ is the
presence of lymphocytes
epithelial cells.

Intraepithelial
lymphocytes

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There are three functional zones in the epithelium of the small intestine:

1) Villi 2) crypts 3) Neck (where villi and crypts meet)

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Cells of the SI epithelium:

Enterocytes
Mucous cells
Paneth cells
Endocrine cells
Stem cells

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Mucosal cells of the small
intestine called ____, cover surface of villi

enterocytes
(E)

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Mucosal cells of the small
intestine called enterocytes
(E), cover _____

surface of villi

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Enterocytes: Apical/ luminal surface highly
folded, modified into 2-3000
_____(= striated or brush
border)

microvilli

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Microvilli on enterocytes ↑ surface area for absorption;
coated with _____ containing enzymes
important for digestion

protective
glycocalyx

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Microvilli on enterocytes ↑ surface area for absorption;
coated with protective
glycocalyx containing enzymes
important for ___

digestion

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Enterocytes separated from luminal surface by _____

desmosomes and tight junctions

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Interspersed among enterocytes
are mucus secreting ____ cells

goblet cells

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Mucous cells Usually found in the _____ of
the crypts

upper 2/3

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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:

1. Columnar cells 2. Mucous cells 3. Endocrine cells 4. 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