Lecture 5 - Control of Secretion Flashcards
Salivary glands are controlled by _____ reflexes throughout all three phases of digestion, which means the ____ is involved.
Long reflexes
CNS
The cephalic phase accounts for about 30% of ______ secretions during a single meal. Keep in mind while the vagus nerve innervates nerves of the enteric nervous system that stimulate Parietal, Mucosal Neck, G, and Chief cells, only ____ cells are stimulated with _____ while the others are stimulated via ACh.
Gastric
G-cells
GRP
Without CCK secretion from I-cells in the duodenum and without ______ secretion from S-cells in the duodenum, what is the character of Pancreas secretions in the Cephalic phase?
Keep in mind Vagovagal pathway only WEAKLY stimulates the pancreas.
No CCK –> Only Gastrin will bind CCK-1/A –> weak binding affinity causes limited stimulation of CCK-1/A receptors in duodenum and Pancreas –> little secretion from Acinar cells.
No secretin –> no stimulation of extralobular duct cells –> no HCO3- secretion from them –> low volume and high protein content Pancreatic secretions.
Build-up of luminal acid in the stomach depletes the mucosal buffering capacity and DIRECTLY inhibits ___-cells and STIMULATES ___-cells.
G-cells
D-cells
During the Gastric phase, the _____ plexus of the gut and the Long reflex are acivated by stretch/mechano receptors. What’s different about the way this Short reflex mech stimulates gastric digestion compared to the Long reflex mech?
Intrinsic plexus
The Short reflex nerves stimulate G-cells vis ACh, while the Vagovagal Long reflex used GRP to stimulate G-cells. All other stimulation is the same, accomplished via ACh on M3 receptors.
Chemoreceptors on Parietal cells stimulate acid secretion in response to ___, ___, and ____.
Chemoreceptors on G-cells stimulate Gastrin secretion in response to dietary ____ and small ____ from pepsin digests.
Ca++, Alcohol, and Caffeine
Dietary proteins
Peptides
During the Gastric phase, Pancreatic secretions are basically the same as during the _____ phase, and for all the same reasons.
Cephalic
Acid secretion from Parietal cells is stimulated in the stomach at pH > ___-___ but is inhibited at pH below that.
2-3
During the Intestinal phase, distention of the duodenum activates stretch/mechano receptors and binding of free Phe and Trp activate chemoreceptors that cause the secretion of ______ –> this hormone enhances acid secretion by parietal cells.
Keep in mind free Phe and Trp activate chemoreceptors on ___-cells in the duodenum to secrete _____ (there are fewer of these cells in the duodenum than in the stomach.)
Oxyntin
G-cells
Gastrin
Once most of the food is digested during the Intestinal phase, low pH stimulates _____ cells in the duodenum to secrete ______ –> this stimulates pancreatic duct cells to secrete HCO3- and it also INHIBITS ____-cells.
Also, lower pH stimulates _____-cells to secrete SST, which inhibits G-cells and Parietal cells.
S-cells
Secretin
G-cells
D-cells
Intestinal phase causes release of enterogastrones: hormones that inhibit acid secretion, Secretin being among them. Another one is _____, secreted from K cells of the small intestine –> it directly inhibits ____ and ___ cells, though it is a poor regulator of these cells. It also acts to amplify glucose-mediate release of ______ from the pancreas.
GIP
G and P cells
Insulin
Which phase are the Liver and Gallbladder mainly stimulated?
Intestinal
