GI Hormones and Physiology, C34 P199-203 Flashcards
OVERVIEW
Define the products of the following stomach cells:
Gastric parietal cells
P199
HCl
Intrinsic factor
OVERVIEW
Define the products of the following stomach cells:
Chief cells
P199
PEPsinogen (Think: “a PEPpy chief”)
OVERVIEW
Define the products of the following stomach cells:
G cells
P199
Gastrin, G cells are found in the antrum
Think: G = Gastrin
OVERVIEW
Define the products of the following stomach cells:
Mucous neck cells
P199
Bicarbonate mucus
OVERVIEW
What is pepsin?
P199
Proteolytic enzyme that hydrolyzes
peptide bonds
OVERVIEW
What is intrinsic factor?
P199
Protein secreted by the parietal cells that
combines with vitamin B12 and enables
absorption in the terminal ileum
OVERVIEW Name three receptors on the parietal cell that stimulate HCl release. P199
Think: “HAG”:
- Histamine
- Acetylcholine
- Gastrin
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
OVERVIEW
Where are most of the bile
acids absorbed?
P199
Terminal ileum
OVERVIEW How many times is the entire bile acid pool circulated during a typical meal? P200
Twice
OVERVIEW
What are the stimulators of
gallbladder emptying?
P200
Cholecystokinin, vagal input
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)
CHOLECYSTOKININ (CCK)
What is its source?
P200
Duodenal mucosal cells
CHOLECYSTOKININ (CCK)
What stimulates its release?
P200
Fat, protein, amino acids, HCl
CHOLECYSTOKININ (CCK)
What inhibits its release?
P200
Trypsin and chymotrypsin
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 productsSECRETIN
What is its source?
P200
Duodenal cells (specifically the argyrophilic S cells)
SECRETIN
What stimulates its release?
P200
pH < 4.5 (acid), fat in the duodenum
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 acidGASTRIN
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 fibersMISCELLANEOUS
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
