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Physiology > GI > Flashcards

GI Flashcards

1
Q

Gastrin

A

From: G cells (antrum/duodenum, jejenum)
Target: entero-chromaffin-like cell (ECL) and parietal cells
Action: 👆🏽 gastric acid secretion, 👆🏽gastric mucosal growth
Inhibitor: somatostatin
Activator: AA in stomach, distention, gastrin releasing peptide

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2
Q

CCK (cholecystikinin)

A 
From: I cells of SI
Target: secretion in circulation
Action: motility of gallbladder, delivery of chyme from stomach, 👆🏽pancreatic secretions (relaxes sphincter of Oddi), 👆🏽satiety, 👇🏽 gastric motility
Inhibitor: somatostatin
Activator: FA, AA, distention
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3
Q

Secretin

A 
From: S cells of SI
Target: pancreas and stomach
Action: 👇🏽gastric acid, 👆🏽HCO3- from pancreas (👆🏽cAMP in ductal cells), neutralizes acid delivered to duodenum, optimum pH for intestinal enzymes
Inhibitor: somatostatin
Activator: acid in SI
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4
Q

Ghrelin

A 
From: X cells of stomach
Target: hypothalamus and stomach
Action: 👆🏽gastric acid, gastric motility, 👆🏽food intake (hunger)
Inhibitor: stomach distention
Activator: hypoglycemia or low body wt
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5
Q

Motilin

A 
From: M cells of duodenum/jejunum
Target: Smooth m. of antrum and duodenum
Action: 👆🏽migrating motor complex, 👆🏽gastric and intestinal motility
Inhibitor: food
Activator: fasting
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6
Q

Somatostatin (SST)

A

From: D cells (antrum)
Action: 👇🏽 gastric acid secretion
Activator: 👆🏽acid secretion in stomach

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7
Q

Pyloric Stenosis

A

Hypertrophe of pyloric sphincter
ROS: projectile vomiting, dehydration, olive-shaped mass in RUQ, child is always hungry
Dx: string/kirklin/mushroom sign on imaging

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8
Q

Dumping Syndrome

A

Dissension of proximal SI (rapid gastric emptying causes hypertonic fluid draws fluid into abd)
ROS: diarrhea, abd pn, flushing, palpitations, tachycardia, sweating and hypotension

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9
Q

HCl

A

From: parietal cells
Action: activates pepsin (cleaves pepsinogen), kills bacteria, denatures proteins
Activator: Gastrin, ACh, Histamine

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10
Q

Intrinsic Factor (IF)

A

From: parietal cells
Action: Binds w/ Vit. B12 to enable its absorption in ileum
Activator: Gastrin, ACh, Histamine

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11
Q

Pepsinogen

A

From: chief cells
Action: Oncel cleaved into pepsin, digests protein
Activator: ACh, gastric acid, secretin

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12
Q

Gastric Lipase

A

From: chief cells
Action: fat digestion, need acidic pH
Activator: ACh, acid, secretin

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13
Q

Mucus

A

From: mucus neck cells
Action: lubrication, motility, barrier btwn acid lumen and gastric mucosa
Activator: ACh, mucosal irritation

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14
Q

Bicarbonate (HCO3-)

A

From: mucus neck cells
Action: buffers gastric acid damage to epithelium, gastric mucosal barrier

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15
Q

Histamine

A

From: enterochromaffin-like cell (ECL)
Action: 👆🏽acid secretion
Activator: ACh and Gastrin

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16
Q

Peptic Ulcer Dz (PUD)

A

Chronic (extends to muscularis)
ROS: recurrent/episodic epigastric pn related to food intake, anemia, perforation
Tx: eradicate H. Pylori w/ abx

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17
Q

NSAID induced Ulcers

A

NSAIDs block PGE synthesis (PGE helps maintain mucosal barrier)

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18
Q

Duodenal ulcers

A

Distal to pylocric sphincter

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19
Q

Trypsin

A

From: exocrine pancreas
Action: protease - degrades proteins (basic aa’s)

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20
Q

Chymotrypsin

A

From: exocrine pancreas
Action: protease - degrades proteins (aromatic aa’s)

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21
Q

Lipase

A

From: exocrine pancreas
Action: degraded TGs into FA and glycerol

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22
Q

Carboxypeptidase

A

From: exocrine pancreas
Action: protease - removes terminal acid group from protein

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23
Q

Elastases

A

From: exocrine pancreas
Action: degrades elastin and some other proteins

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24
Q

Nucleases

A

From: exocrine pancreas
Action: degrades nucleic acids

25
Q

Pancreatic amylase

A

From: exocrine pancreas
Action: degrades starch, glycogen and most other CHOs (humans cannot degrade cellulose)

26
Q

Pre-Hepatic Jaundice

A

👆🏽 production of bilirubin from increased breakdown of RBCs
LFT: 👆🏽free unconjugated (indirect) bilirubin in lasma
E.g. - Hemolytic dz of newborn

27
Q

Hepatic Jaundice

A

Cause: destruction of hepatocytes
LFTs: 👆🏽conjugated (direct) bilirubin levels in plasma
ROS: no formation of stercobilin (pale stools), dark urine bc bilirubin is being filtered by kidneys

28
Q

Post-Hepatic Jaundice

A

Cause: obstruction of bile ducts - conj bili cannot be secreted into bile and it reflexes back into systemic circulation
LFTs: 👆🏽conjugated (direct) bilirubin in plasma
ROS: pale stools, steatorrhea, dark urine
E.g. - gallstones, ca of head of pancreas

29
Q

Hepatic Bile

A

900ml/day

Alkaline fluid to neutralize acidic chyme, H2O follows passively

30
Q

Gallbladder Bile

A

450 mL/day

Stored, adicified, concentrated, removes H2O and NaCl

31
Q

Contracting Segment (SI)

A

Circular m. contraction, longitudinal m. relaxation

+ by ACh and Substance P

32
Q

Receiving Segment (SI)

A

Circular m. relaxes, longitudinal m. contracts

+ by NO and VIP

33
Q

Stool H2O

A

Only about 100mL should make it into stools

6.5L R. in SI, 1.9L R. in colon

34
Q

Max colon R. capacity

A

= 5L, so if > 5L enters colon pt will have diarrhea

35
Q

Cholera and E.Coli (VIP, Histamine and PGEs)

A

Secretory diarrhea b/c of 👆🏽intracellular cAMP activating the apical CFTR channel (so more H2O moves basolaterally to apical lumen)

36
Q

C. Diff (ACh, 5-HT and Bradykinin)

A

Secretory diarrhea b/c of 👆🏽intracellular [Ca2+] causing more Cl- secretion (H2O moves basolaterally to lumen)

37
Q

Nutrients Absorbed in upper SI

A

CHO, Fe3+ and Ca2+

38
Q

Nutrients absorbed throughout SI

A

Protein, fat, salt, H2O

39
Q

Nutrients absorbed in distal ileum

A

Bile acids, vit. B12 (cobalamin)

40
Q

GLUT5

A

Fructose absorbed via facilitated diffusion from lumen

41
Q

SGLT1

A

Glucose (and galactose) absorbed from lumen; Na+ dependent

42
Q

GLUT2

A

SI: secretion of glucose/fructose/galactose into blood
Pancreas: absorb glucose (to 👆🏽insulin release)
Liver: not insulin-dependent

43
Q

Achalasia

A

Failure of relaxation of LES due to loss of Auerbach (myenteric) plexus
ROS: dilation of esophagus, progressive dysphagia, uncoordinated/absent peristalsis; Bird’s beak” on barium swallow

44
Q

Gastrocolic (duodenocolic) Reflex

A

Stimulus: food in stomach/duodenum
Response: mass movements
Requires: ENS + extrinsic nerves

45
Q

Gastroileal Reflex

A

Stimulus: stomach distention
Response: ileal motility increased and relaxing IC valve
Requires: extrinsic ANS n., gastrin and CCK

46
Q

Ileogastric Reflex

A

Stimulus: stretch of ileum
Response: decreased gastric motility
Requires: ENS and ANS control

47
Q

Ileal Brake

A

Stimulus: delivery of nutrient (esp. lipid) to ileum
Response: decreased gastric/SI motilin
Requires: GLP-1 and PeptideYY

48
Q

Migrating Motor Complex (MMC)

A

Stimulation: motilin
Response: propels indigestible matter (every 90 min post-prandial)
Requires: ENS

49
Q

GERD

A

👇🏽resting LES pressure

ROS: esophagitis

50
Q

Peristaltic reflex

A

Circular muscle upstream contracts and longitudinal relaxes (pushes bolus), downstream the circular relaxes (receptive relaxation) and longitudinal contracts

51
Q

Defecation

A

External (and internal) sphincter relaxes, rectal smooth m. contracts
*urge when rectum filled to 25% capacity

52
Q

Pancreas damage w/ lipid digestion intact

A

80-90% can be lost before lipid digestion will be affected

53
Q

Pancreatitis

A

ROS: steatorrhea
Cause: decrease in pancreatic enzymes

54
Q

Bile Duct Obstruction

A

👆🏽conjugated bilirubin in serum and urine, could have slightly increased unconjugated bilirubin

55
Q

Cholelithiasis

A

Slightly increased unconjugated bilirubin, increased serum and urine conjugated bilirubin

56
Q

SCFAs in Colon

A

Protective effect, makes colonic fluid acidic to decrease bacterial overgrowth, increase colonic blood flow

57
Q

Gastrinoma

A

Tumor of non-B-cell pancreas, secretes gastrin

ROS: PUD, steatorrhea, diarrhea

58
Q

Most absorption of SCFAs produced by bacteria occurs where?

A

Colon

Physiology (4 decks)

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