Gastric response to a meal Flashcards
(37 cards)
Which part of the stomach is responsible for mixing, grinding, sieving?
Antrum and pylorus
When is gastric acid secretion greatest and lowest (circadian)?
Greatest at night and lowest in the morning
How many hours after ingestion of food is the rate of H secretion the highest?
approx. 3 hours (secretion is high but concentration is low)
After ingestion of food, when is [H] the lowest?
approx. 3 hours (concentration is low but secretion is high
What is alkaline tide?
it is the rise in pH of the capillaries near parietal cells due to excess bicarbonate being absorbed into the blood
How does Cl enter the cell from the basal side to make HCl in the lumen
Cl/HCO3 anion exchanger
What enzyme is required to combine H2O and CO2?
Carbonic Anhydrase
Why is no acid produced in the resting parietal cell?
Because the proton pump is kept away from the luminal surface until the cell is stimulated.
Acetylcholine has what effect on HCl secretion? Using which receptors?
ACh increases acid secretion via M3 receptors (calcium dependent)
What effect does somatostatin have on acid secretion? using which receptors?
Somatostatin reduces acid secretion via SSTR1 receptors (cAMP dependent)
What type of signaling pathway does Histamine use when stimulating parietal cells?
cAMP dependent
When HCl secretion is high, what happens to [Na]
[Na] decreases because the total volume increases.
Which two neurotransmitters increase mucus and bicarb secretion in the stomach?
ACh and Prostaglandins
Which cells secrete pepsinogen?
Chief cells
What is secreted by parietal cells?
HCl and intrinsic factor
What converts pepsinogen to pepsin?
HCl
What degrades the mucus barrier?
Pepsin degrades the mucus barrier by attacking the unglycosylated core..
H.Pylori causes ulcers. How is a person tested for the presence of H.pylori
- Patient is given carbon-13 urea which is broken down by the bacterial UREASE. The product carbon13 dioxide is exhaled. A breath test is given to determine the presence of C13O2. If present, patient is positive for H.pylori
- Biopsy of antral mucosa for RAPID UREASE TEST, histology, culture.
What effect does gastrin have on smooth muscle tone of the LES?
increases muscle tone (antireflux)
What effect does motilin have on smooth muscle tone of the LES?
increases muscle tone (antireflux)
What effect does atylcholine (vagus) have on smooth muscle tone of the LES?
increases muscle tone (antireflux)
What effect does CCk have on smooth muscle tone of the LES?
decreases muscle tone
What effect does secretin have on the smooth muscle tone of the LES?
decreases muscle tone
What effect does beta-adrenergics have on the smooth muscle tone of the LES?
decreases muscle tone
