GI Hormones and Physiology, C34 P199-203 Flashcards by Tiggee R

OVERVIEW
Define the products of the following stomach cells:
Gastric parietal cells
P199

HCl

Intrinsic factor

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OVERVIEW
Define the products of the following stomach cells:
Chief cells
P199

PEPsinogen (Think: “a PEPpy chief”)

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OVERVIEW
Define the products of the following stomach cells:
G cells
P199

Gastrin, G cells are found in the antrum

Think: G = Gastrin

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OVERVIEW
Define the products of the following stomach cells:
Mucous neck cells
P199

Bicarbonate mucus

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OVERVIEW
What is pepsin?
P199

Proteolytic enzyme that hydrolyzes

peptide bonds

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OVERVIEW
What is intrinsic factor?
P199

Protein secreted by the parietal cells that
combines with vitamin B12 and enables
absorption in the terminal ileum

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OVERVIEW
Name three receptors on the
parietal cell that stimulate
HCl release.
P199

Think: “HAG”:

Histamine
Acetylcholine
Gastrin

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OVERVIEW
What is the enterohepatic
circulation?
P199

Circulation of bile acids from the liver
to the gut and back to the liver via the
portal vein

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OVERVIEW
Where are most of the bile
acids absorbed?
P199

Terminal ileum

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OVERVIEW
How many times is the entire
bile acid pool circulated
during a typical meal?
P200

Twice

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OVERVIEW
What are the stimulators of
gallbladder emptying?
P200

Cholecystokinin, vagal input

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OVERVIEW
What are the inhibitors of
gallbladder emptying?
P200

Somatostatin, sympathetics (it is impossible
to flee and digest food at the same time),
vasoactive intestinal polypeptide (VIP)

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CHOLECYSTOKININ (CCK)
What is its source?
P200

Duodenal mucosal cells

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CHOLECYSTOKININ (CCK)
What stimulates its release?
P200

Fat, protein, amino acids, HCl

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CHOLECYSTOKININ (CCK)
What inhibits its release?
P200

Trypsin and chymotrypsin

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CHOLECYSTOKININ (CCK)
What are its actions?
P200

Empties gallbladder
Opens ampulla of Vater
Slows gastric emptying
Stimulates pancreatic acinar cell growth
    and release of exocrine products

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SECRETIN
What is its source?
P200

Duodenal cells (specifically the
argyrophilic S cells)

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SECRETIN
What stimulates its release?
P200

pH < 4.5 (acid), fat in the duodenum

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SECRETIN
What inhibits its release?
P200

High pH in the duodenum

SECRETIN
What are its actions?
P200

Releases pancreatic bicarbonate/enzymes/
    H(2)O
Releases bile/bicarbonate
Decreases lower esophageal sphincter
    (LES) tone
Decreases release of gastric acid

GASTRIN
What is its source?
P200

Gastric antrum G cells

GASTRIN
What stimulates its release?
P201

Stomach peptides/amino acids
Vagal input
Calcium

GASTRIN
What inhibits its release?
P201

pH < 3.0

Somatostatin

GASTRIN
What are its actions?
P201

Release of HCl from parietal cells
Trophic effect on mucosa of the stomach
and small intestine

SOMATOSTATIN What is its source? P201

Pancreatic D cells

SOMATOSTATIN What stimulates its release? P201

Food

SOMATOSTATIN What are its actions? P201

Globally inhibits GI function

MISCELLANEOUS What is the purpose of the colon? P201

Reabsorption of H(2)O and storage of stool

MISCELLANEOUS What is the main small bowel nutritional source? P201

Glutamine

MISCELLANEOUS What is the main nutritional source of the colon? P201

Butyrate (short-chain fatty acid)

MISCELLANEOUS Where is calcium absorbed? P201

Duodenum actively, jejunum passively

MISCELLANEOUS Where is iron absorbed? P201

Duodenum

MISCELLANEOUS Where is vitamin B12 absorbed? P201

Terminal ileum

``` MISCELLANEOUS Which hormone primarily controls gallbladder contraction? P201 ```

CCK

``` MISCELLANEOUS What supplement does a patient need after removal of the terminal ileum or stomach? P201 ```

Vitamin B12

MISCELLANEOUS Name the main constituents of bile. P202

Water, phospholipids (lecithins), bile | acids, cholesterol, and bilirubin

MISCELLANEOUS What are most gallstones made of? P202

Cholesterol

MISCELLANEOUS How do opiates affect the bowel? P202

By stimulating sodium absorption and inhibiting secretion in the ileum as well as decreasing GI motility by incoordinated peristalsis (Therefore, place patients on stool softeners when dispensing pain medication)

``` MISCELLANEOUS Which type of muscle fibers, smooth or striated, does the esophagus contain? P202 ```

``` Both: Upper third—striated muscle control of motor nerves Middle third—mixed Lower third—smooth muscle, primarily under control of vagal motor fibers ```

MISCELLANEOUS Which electrolytes does the colon actively absorb? P202

Na+, Cl⁻

MISCELLANEOUS Which electrolyte does the colon actively secrete? P202

HCO⁻(3) (plays a role in diarrhea causing the patient to have a normal anion gap acidosis)

MISCELLANEOUS Which electrolyte does the colon passively secrete? P202

K⁺

MISCELLANEOUS What is the gastrocolic reflex? P202

Increased secretory and motor functions of the stomach result in increased colonic motility

MISCELLANEOUS What is the blood supply to the liver? P202

75% from the portal vein, rich in products of digestion 25% from the hepatic artery, rich in O2 (but each provide for 50% of oxygen)

MISCELLANEOUS What are Peyer patches? P202

Nodules of lymphoid tissue with B and T lymphocytes in the small intestine that selectively sample lumenal antigens found in the terminal ileum