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GI > Digestive system overview > Flashcards

Digestive system overview Flashcards

1
Q

muscosal protective system

A

MALT (mucosal associated lymphoid tissue)

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2
Q

regulation and coordination of digestion

A

via enteric neurons (intrinsic autonomic neurons) and hormones produced by endocrine cells in the mucosal epithelium

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3
Q

Role of coordinated effort of sympathetic/parasympathetic inputs

A

coordination of peristalsis, effects on blood vessels and glands

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4
Q

Layers of the digestive system, from lumen to mesentary

A

mucosa, submucosa, muscularis externa, serosa/adventitia

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5
Q

mucosa

A

epithelial layer, well-vascularized lamina propria (contains lymphocytes, plasma cells, macrophages), muscularis mucosae (smooth muscle)

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6
Q

submucosa

A

more dense connective tissue than muscosa, larger blood vessels, nerve plexi, glands, lymph nodes

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7
Q

muscularis externa

A

inner circularly and outer longitudinally arranged layers of smooth muscle and nerve plexes.

peristalsis and churning of lumen contents

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8
Q

serosa/adventitia

A

covering of squamous epithelial cells

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9
Q

esophagus

A

non-cornified squamous epithalium.
upper = skeletal muscle under voluntary control
midway = mix of skeletal/smooth muscle
lower 1/3 = smooth muscle

small, incomplete sphincter c maintained muscular contraction –| reflux

lacks thick mucous covering –> burning sensation on reflux, ulceration

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10
Q

3 histological regions of the stomach

A

cardia, fundus, pyloris

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11
Q

cardia

A

small area of mucus-secreting glands around the entry of the esophagus

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12
Q

fundus

A

main body of the stomach

secretes acid, peptic digestive products and mucus

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13
Q

pyloris

A

secretes mucus

endocrine cells –> gastrin

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14
Q

muscularis externa of the stomach

A

circular, longitudinal, and OBLIQUE layers

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15
Q

gastric pits

A

spaces between epithelial folds of the gastric epithelium

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16
Q

gastric glands

A

at bottom of mucus-secreting gastric pits

differentiated epithelial cells –> digestion of food at acidic pH

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17
Q

How often are surface cells of the gastric epithelium replaced?

A

every 3-5 days

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18
Q

rate of turnover for differentiated cells deep in the gastric glands

A

6-12 mo

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19
Q

location of gastric stem cells

A

upper neck region of gastric pit –> upward as mucus secreting cells, downward as gastric gland cells

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20
Q

surface mucous cells

A

secrete mucin and bicarbonate –> viscous protective layer

covered by glycocalyx (layer of glycoproteins)

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21
Q

chief cells

A

secrete pepsinogen

acid converts to pepsin (protease)

multiply through division or stem cells

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22
Q

parietal cells

A

pump H+ ions via H/K ATPase into lumen of the gastric glands –> pH of 1 - 1.5

energy-demanding –> increased mitochondria

secrete intrinsic factor –> B12 uptake

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23
Q

gastrin and histamine

A

stimulate acid secretion by parietal cells

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24
Q

excessive secretion of gastrin –> overproduction of HCl by parietal cells –> duodenal ulcers (increased acid cannot be neutralized)

A

Zollinger-Ellison syndrome

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25
Q

Enteroendocrine cells

A

one of the APUD (amine precursor uptake decarboxylation) cells

oriented toward the vascular side –> release to blood stream

26
Q

G cells

A

stomach and small intestine

gastrin secretion –> HCl secretion, contraction/relaxation of pyloric sphincter, proliferation of regenerative cells of stomach

27
Q

A cells

A

stomach and small intestine

Glucagon –> glycogenolysis by hepatocytes –> elevated blood glucose

28
Q

EC cells

A

stomach, small/large intestines

serotonin –> increased peristalsis

substance P

29
Q

D cells

A

stomach, small/large intestines

inhibits release of hormones by enteroendocrine cells in its vicinity

30
Q

I cells

A

small intestine

cholecystokinin –> release of pancreatic hormone, contraction of gall bladder

31
Q

K cells

A

small intestine

gastric inhibitory peptide –> inhibition of HCl secretion

32
Q

Mo cells

A

small intestine

Motilin –> increased intestinal peristalsis

33
Q

S cells

A

small intestine

secretin –> stimulates release of bicarb-rich fluid from pancreas

34
Q

relaxation of the pyloric sphincter

A

acidic chyme enters the duodenum

35
Q

digestion in the duodenum

A

result of pancreatic enzymes and surface enzymes of the intestinal mucosa (in glycocalyx)

36
Q

plicae circulares

A

transverse folds –> increased intestinal surface area –> better absorption

villi –> 8-fold increase in SA

best developed in jejunum

37
Q

enterocytes

A

absorptive/digestive epithelial cells

microvilli –> 30-fold increase in SA

take up fatty acids and monoglycerides from gut lumen –> di and triglycerides –> release to opposite side of enterocytes

38
Q

goblet cells

A

secrete mucous for protection/lubrication

ileum > jejunum > duodenum

39
Q

Crypts of Lieberkuhn

A

tubular glands continuous with surface epithelium

stem cells abundant in lower 1/3 –> mucous cells, enterocytes, Paneth cells

40
Q

Paneth cells

A

contain large, eosinophilic granules, which contain defensins (antibacterials), lysozymes and phospholipase

41
Q

Brunner’s glands

A

release bicarbonate into Crypts of Lieberkuhn –> neutralize acid from acidic chyme

also secrete mucins

Duodenum

42
Q

Lacteal

A

lymphatic vessel in lamina propria of intestinal villi –> larger lymphatics –> thoracic duct –> bloodstream

takes in fluid from the lumen of the intestine, and transports chylomicrons (lipoprotein droplets) exocytosed by enterocytes

43
Q

hepatic portal system

A

takes nutrients from gut capillaries to the liver

44
Q

immune response of the gut

A

M cells in Peyer’s patches = APCs –> present to lymphocytes and macrophages –> plasma cell IgA release –> IgA trancytosed to lumenal surface, where they serve as antibacterials

45
Q

pancreatic acinar cells

A

arranged at the end of a common duct

basal portion full of rough ER –> proteins for secretion

apical portion full of zymogen granules (require partial degradation to become active)

46
Q

exocrine pancreas

A

organized into clusters of pancreatic acinar cells

release trypsin, chymotrypsin, elastase, carboxypeptidase, triacylglycerol lipase

47
Q

activation of trypsinogen

A

proteolytic cleavage by enterokinase on epithelial enterocytes –> trypsin –> activation of other zymogens by proteolysis

48
Q

two enzymes released by the pancreas in ACTIVE form

A

amylase (degrades starch and glucose) and ribonuclease

49
Q

sphincter of Oddi

A

entry of pancreatic duct/common bile duct into the duodenum

50
Q

controls pancreatic secretion

A

secretin and cholycystokinin

51
Q

98% of pancreatic volume is dedicated to

A

exocrine function

52
Q

two major disaccharide products of amylase digestion

A

maltose and isomaltose (broken down by maltase and isomaltase –> glucose)

53
Q

cleaves lactose to glucose and galactose

A

lactase

54
Q

lack of lactase

A

bacteria utilize lactose –> bloating and diarrhea

55
Q

muscularis externa of small intestine

A

inner circular and outer longitudinal layers

innervated by myenteric nerve plexus of Auerbach

56
Q

Large intestine

A

smooth, lacks plicae and villi

57
Q

two cell types of large intestine

A

mucous-producing and absorptive cells

58
Q

main function of large intestine

A

recovery of water and salt during concentration of fecal matter

59
Q

3 main salivary glands

A

submandibular, sublingual, parotid

acinar design

60
Q

parotid gland

A

serous secretor

watery c amylase, RNase, DNase

61
Q

submandibular gland

A

mixed serous/mucous secretor

62
Q

sublingual gland

A

mucous secretor

lubricative and protective

GI (19 decks)

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