GI 2 Flashcards
What structures of the stomach are anterior?
the cardia, fundus, body
What structures of the stomach are posterior
antrum (pyloric region), pyloric sphincer
What are the functional regions of the stomach
proximal (reservoir), distal (pump, grinder)
Structures that support the unique functions of the stomach
rugae and the oblique layer
What is the luminal secretion of the LES and the cardia
mucus and bicarb
What is the purposes of the LES and the cardia motility
Prevention of reflux, entry of food, regulation of belching (burping)
What do the fundus and the body of the stomach secrete?
H+, intrinsic factor, mucus, HCO3-, pepsinogens, lipases
What is the motility of the fundus and the body?
reservoir, tonic force during emptying
What do the antrum and the pylorus secrete?
mucus and HCO3-
What is the motility of the antrum and pylorus?
mixing, grinding, sieving, regulation of emptying
What are the different gastric secretions?
gastrin secretion, acid secretion, paracrine secretion, enzyme secretion (PAGE)
Acid is secreted by…
parietal cells in gastric glands
What is important about the tubulovesicular membrane (on a parietal cell)
it expresses H+,K+ pumps
What happens in parietal cell activation?
once the tubulovesicular membrane is activated, it will merge with the intracellular canaliculus (the fusion create a larger openning in the cell in which the H+/K+ pumps are found due to the fusion and it allows the cell to pump protons out-> the creation the HCl)
Acid secretion is stimulated by…
gastrin, ACh, histamine
Acid secretion is inhibited by…
prostaglandin E2 and somatostatin
What is motility?
the ability of the muscles of the digestive tract to contract
Would injecting VIP or ACh into the LES be an effective way to alleviate heart burn? Why?
By injecting ACh; ACh is a smooth muscle contractor, VIP is a smooth muscle relaxer= GERD is caused by relaxation, so to treat a symptom you would want to treat heartburn with ACh to increase smooth muscle motility
HCl secretions increase when ___ binds to its receptor by increasing intracellular calcium levels
ACh, or gastrin (Gq-R)
What is on the apical side of the parietal cell (in terms of pumps, channels)
H+/K+ pump, Cl- channel
What happens to the blood pH after a meal?
the blood pH rises; because you are adding bicarb into the blood in order to secrete HCl-, this is referred to so the alkaline tide
G cells are located…; and this tells us what about its secretions?
deep in the pits; they secrete gastrin into the blood (endocrine)
Gastrin secretions are triggered by…
vagus nerve stimulation (through GRP); amino acids
Gastrin secretions are inhibited by
acid, somatostatin
What is the function of gastrin?
acts on parietal and ECL cells to stimulate acid release and stimulate mucosa growth in stomach, small and large intestine
What are the 3 major paracrine secretions?
histamine, intrinsic factor, and somatostatin
Histamine is secreted by…
ECL cells
Histamine is stimulated by
gastrin and ACh
Intrinsic factor is produced by…
parietal cells
Somatostatin is secreted by
D cells
Why is somatostatin important?
it is the primary feedback signal
What are the two major enzymes secreted?
pepsin and gastric lipase
pepsin is secreted by…
chief cells (as pepsinogen)
pepsin is activated by…
acid or pepsin
gastric lipase
breaks down lipids; cosecreted with pepsin
receptive relaxation
relaxation of stomach muscles as food moves through the esophagus and enters stomach (getting ready for the food before it makes contact)
adaptive relaxation
relaxation of stomach muscles when filled (food makes stomach relax)
storage occurs where
in the proximal portion
mixing/ peristalsis occurs where
in the distal portion of the stomach
The stomach wall is not specialized for…, but it is specialized for… (how so)
not specialized for absorption, is specialized for protection (thick, alkaline mucus, tight junctions between epithelial cells, rapid replacement by GI stem cells)
What is a gastric ulcer?
destruction of the lining of the gastric mucosa
Taking what can provide relief for patients with stomach ulcers (to help with excess acid secretion)
Antacid
What can treat ulcer patients that have H. pylori
antibiotics (Warren and Marshall’s study)
What is cAMP’s effect on acid secretion?
cAMP increases acid secretion
