Hormones and Gastric Secretions Flashcards
Gastrin
- What cells/organ secrete this hormone?
- What is the stimulus that causes the release of this hormone?
- What are its targets?
- What are its effects?
- G cells in stomach (antrum)
- Peptides, distension, Input from CNX that causes release of gastric releasing peptide (GRP) onto G cells
- Targets –> effects:
- GI smooth muscle –> (+) gastric emptying and motility
- Parietal cells –> (+) HCl and intrinsic factor
- Enterochromaffin-like (ECL) cells –> (+) secretion of histamine which will increase HCl also
Cholecystokinin
- What cells/organ secrete this hormone?
- What is the stimulus that causes the release of this hormone?
- What are its targets?
- What are its effects?
- I cells of duodenum
- Peptides and fatty acids
- Targets –> Effects:
- Gallbladder –> (+) contraction to release bile into duodenum
- GI smooth muscle –> (-) gastric motility and (+) intestinal motility
- Pancreatic acinar cells –> (+) pancreatic enzyme secretion
Secretin
- What cells/organ secrete this hormone?
- What is the stimulus that causes the release of this hormone?
- What are its targets?
- What are its effects?
- S-cells of duodenum
- Protons from gastric acid reaching duodenum or fatty acids in duodenum
- Targets –> Effects:
- GI smooth muscle –> (-) gastric motility and secretion and (+) intestinal motility
- Pancreatic duct cells –> (+) pancreatic duct secretion (water and bicarb)
Glucose dependent insulinotropic Peptide (GIP)
- What cells/organ secrete this hormone?
- What is the stimulus that causes the release of this hormone?
- What are its targets?
- What are its effects?
- K-cells in duodenum and jejunum
- Carbs
- Targets –> Effects:
- GI smooth muscle –> (-) gastric motility, (+) intestinal motility
- Parietal cells –> (-) HCl secretion
- Pancreatic beta cells –> (+) insulin secretion
Motilin
- What cells/organ secrete this hormone?
- What is the stimulus that causes the release of this hormone?
- What are its targets?
- What are its effects?
- M cells in duodenum
- Fasting
- Targets –> Effects:
- GI smooth muscle –> (+) gastric motility (+) small bowel motility
What are the important neurocrine factors to know? What is a neurocrine factor?
VIP
GRP
Endorphins
These are synonymous with neurotransmitters (see image for example)
VIP
- Leads to production of what compound?
- Effect on GI and vascular smooth muscle?
- Effect on secretion?
- NO
- Relaxation
- (+) pancreatic and intestinal secretion
GRP
- Where is this released from?
- What does it stimulate?
- Released from post-ganglionic fibers of Vagus nerve
- Stimulates gastrin release from g cells
Endorphins / Enkephalins
- When are these released
- What do they do
- How are they used clinically
What are the 2 important paracrine factors to know for GI system?
Histamine
Somatostatin
Histamine
- Source
- Stimulus
- Function
- ECL cells
- Gastrin and Ach
- (+) H+ secretion from parietal cells
Somatostatin
- Source
- Stimulus
- Function
- (1) D-cells in stomach and duodenal mucosa (2) pancreas
- Protons
- Inhibit gastric motility and acid secretion
In the region of the stomach circled in blue in the image:
- What are the major secretions?
- What are the glands called?
- Decribe the motility happening in region.
- Mucus and HCO3-
- Cardiac glands
- Prevention of reflux of stomach contents, entry of food
In the region of the stomach circled in yellow in the image:
- What are the major secretions?
- What are the glands called?
- Decribe the motility happening in region.
In the region of the stomach circled in green in the image:
- What are the major secretions?
- What are the glands called?
- Decribe the motility happening in region.
Mucus glands:
- Location?
- Secretion?
- Throughout stomach
- Mucus, HCO3-
Chief cells:
- Location?
- Secretion?
- Fundus and body of stomach
- Pepsinogen
Parietal cells:
- Location?
- Secretion?
- Fundus and body
- HCl, intrinsic factor
ECL cells:
- Location?
- Secretion?
- Near parietal cells
- Histamine
D cells:
- Location?
- Secretion?
- Throughout GI tract (stomach, intestines, pancreas)
- Somatostatin
G cells:
- Location?
- Secretion?
- Antrum and duodenum
- Gastrin
Describe the composition of gastric juice.
What are the major stimulatory regulators of Gastric secretion?
Gastrin
GRP
Histamine
Ach
What are the major inhibitory regulators of Gastric secretion?
Somatostatin
GIP
Secretin
CCK
How do parietal cells produce acid?
Have carbonic anhydrase in cell that makes H+ and HCO3-. HCO3- is secreted into blood, H+ is moved into vesicles which are then trafficked to apical membrane to release H+ when signaled to do so by gastrin, histamine and Ach. When bicarb is moved to blood, Cl- enters cell –> this is secreted with H+ into stomach as HCl
When acid is present in the antrum of the stomach, […] will act to decrease gastrin release and acid secretion.
Somatostatin
When acid is present in the duodenum, […] will act to decrease gastrin and acid secretion.
Secretin
When fats and peptides are present in the duodenum, […] will be released to decrease acid secretion.
CCK
When carbohydrates are present in the duodenum, […] will be released to decrease gastrin and acid secretion.
GIP
How do the following OTC drugs lead to inhibition of gastric acid secretion:
- Zantac
- Prilosec
- Tums
