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35 Cards in this Set

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What are the GI regulatory and secretory substances released in the stomach?

Regulatory:
- Gastrin

Secretory:
- Intrinsic Factor
- Gastric acid
- Pepsin
- HCO3-
What are the GI regulatory and secretory substances released in the duodenum?
Regulatory:
- Cholecystokinin
- Glucose-dependent insulinotropic peptide
- Motilin
- Secretin
- VIP

Secretory:
- HCO3-
What are the GI regulatory and secretory substances released in the jejunum?
Regulatory:
- Cholecystokinin
- Glucose-dependent insulinotropic peptide
- Motilin
- VIP
What are the GI regulatory and secretory substances released in the ileum?
Regulatory:
- Motilin
- VIP
What is the source of Cholecystokinin?
I cells (duodenum and jejunum)
What is the source of Gastrin?
G cells (antrum of stomach)
What is the source of Glucose-dependent insulinotropic peptide?
K cells (duodenum and jejunum)
What is the source of Motilin?
Small intestine
What is the source of Secretin?
S cells (duodenum)
What is the source of Somatostatin?
D cells (pancreatic islets and GI mucosa)
What is the source of Vasoactive Intestinal Peptide (VIP)?
- Parasympathetic ganglia in sphincters
- Gallbladder
- Small intestine
What is the source of Intrinsic Factor?
Parietal cells in stomach
What is the source of gastric acid?
Parietal cells in stomach
What is the source of Pepsin?
Chief cells in stomach
What is the source of HCO3-?
- Mucosal cells in stomach, duodenum, salivary glands, pancreas
- Brunner glands in duodenum
What is secreted from I cells? Location? Action?
Cholecystokinin - duodenum and jejunum
- ↑ pancreatic secretion
- ↑ gallbladder contraction
- ↓ gastric emptying
- ↑ sphincter of Oddi relaxation
What is secreted from G cells? Location? Action?
Gastrin - antrum of stomach
- ↑ gastric H+ secretion
- ↑ growth of gastric mucosa
- ↑ gastric motility
What is secreted from K cells? Location? Action?
Glucose-dependent insulinotropic peptide - duodenum and jejunum
- Exocrine: ↓ gastric H+ secretion
- Endocrine: ↑ insulin release
What is the action of Motilin? Source?
Motilin - small intestine
- Produces migrating motor complexes (MMCs)
What is secreted from S cells? Location? Action?
Secretin - duodenum
- ↑ pancreatic HCO3- secretion
- ↓ gastric acid secretion
- ↑ bile secretion
What is secreted from D cells? Location? Action?
Somatostatin - pancreatic islets and GI mucosa
- ↓ gastric acid and pepsinogen secretion
- ↓ pancreatic and small intestine fluid secretion
- ↓ gallbladder contraction
- ↓ insulin and glucagon release
What is the action of Nitric Oxide in the GI tract?
↑ smooth muscle relaxation, including LES
What is the action of Vasoactive Intestinal Peptide (VIP)? Source?

Parasympathetic ganglia in sphincters, gallbladder, and small intestine:
- ↑ intestinal water and electrolyte secretion
- ↑ relaxation of intestinal smooth muscle and sphincters

What is secreted from Parietal cells? Location? Action?
Intrinsic Factor - stomach
- Vitamin B12 binding protein (required for B12 uptake in terminal ileum)

Gastric Acid - stomach
- ↓ stomach pH
What is secreted from Chief cells? Location? Action?
Pepsin - stomach
- Protein digestion
What is secreted from mucosal cells and Brunner glands? Location? Action?
HCO3-
- Mucosal cells in stomach, duodenum, salivary glands, and pancreas
- Brunner glands in duodenum

- Acts to neutralize acid
Which regulatory substance ↑ pancreatic secretion, ↑ gallbladder contraction, ↓ gastric emptying, and ↑ sphincter of Oddi relaxation? Source? Regulation? Other?
- Cholecystokinin (from I cells in duodenum and jejunum)
- Regulation: ↑ by fatty acids and amino acids
- CCK acts on neural muscarinic pathways to cause pancreatic secretion
Which regulatory substance ↑ gastric H+ secretion, ↑ growth of gastric mucosa, and ↑ gastric motility? Source? Regulation? Other?
- Gastrin (from G cells in antrum of stomach)
- Regulation: ↑ by stomach distention/alkalinization, amino acids, peptides, and vagal stimulation; ↓ if stomach pH <1.5
- Phenylalanine and troptophan are potent stimulators
- Gastrin ↑↑ in Zollinger-Ellison Syndrome
- Gastrin ↑ by chronic PPI use
Which regulatory substance ↓ gastric H+ secretion (exocrine) and ↑ insulin release (endocrine)? Source? Regulation? Other?
Glucose-dependent insulinotropic peptide (aka Gastric Inhibitory Peptide = GIP)
- From K cells in duodenum and jejunum
- Regulation: ↑ by fatty acids, amino acids, and oral glucose
- Oral glucose load is used more rapidly than the equivalent given by IV due to GIP secretion
Which regulatory substance produces migrating motor complexes (MMCs)? Source? Regulation? Other?
Motilin - from small intestine
- Regulation: ↑ in fasting state
- Motilin receptor agonists (eg, erythromycin) are used to stimulate intestinal peristalsis
Which regulatory substance ↑ pancreatic HCO3-, ↓ gastric acid secretion, and ↑ bile secretion? Source? Regulation? Other?
Secretin - from S cells in duodenum
- Regulation: ↑ by acid and fatty acids in lumen of duodenum
- ↑ HCO3- neutralizes gastric acid in duodenum, allowing pancreatic enzymes to function
Which regulatory substance ↓ gastric acid and pepsinogen secretion, ↓ pancreatic and SI fluid secretion, ↓ GB contraction, and ↓ insulin and glucagon release? Source? Regulation? Other?

Somatostatin - from D cells in pancreatic islets and GI mucosa
- Regulation: ↑ by acid and ↓ by vagal stimulation
- Inhibitory hormone
- Antigrowth hormone effects (inhibits digestion and absorption of substances needed for growth)

Which regulatory substance ↑ smooth muscle relaxation including that of the LES? Other?
Nitric Oxide
- Loss of NO secretion is implicated in ↑ LES tone of achalasia
Which regulatory substance ↑ intestinal water and electrolyte secretion and ↑ relaxation of intestinal smooth muscle and sphincters? Source? Regulation? Other?

Vasoactive Intestinal Polypeptide (VIP)
- Source: parasympathetic ganglia in sphincters, GB, and SI
- Regulation: ↑ by distention and vagal stimulation, ↓ by adrenergic input
- VIPoma: non-α, non-β islet cell pancreatic tumor that secretes VIP → copious Watery Diarrhea, Hypokalemia, and Achlorhydria = WDHA syndrome

What is WDHA syndrome?

Watery Diarrhea, Hypokalemia, and Achlorhydria:
- Caused by VIPoma, a non-α, non-β islet cell pancreatic tumor that secretes VIP
- VIP ↑ intestinal water and electrolyte secretion, as well as ↑ relaxation of intestinal smooth muscle and sphincters