Week 6 Lecture Gut Flashcards
Question: What are the three main types of secretion in the gastrointestinal (GI) system?
Answer: The three main types of secretion in the GI system are fluid secretion, enzyme secretion, and hormone secretion.
Question: Which cells are primarily responsible for acid secretion in the stomach?
Answer: Parietal cells are primarily responsible for acid secretion in the stomach.
Question: Which endocrine cells regulate acid secretion in the stomach?
Answer: G cells (secreting gastrin) stimulate acid secretion, while D cells (secreting somatostatin) inhibit acid secretion.
Question: How is pancreatic enzyme secretion regulated?
Answer: Pancreatic enzyme secretion is regulated by exocrine acinar cells, which are influenced by hormones such as secretin and cholecystokinin (CCK) released from endocrine cells in the gut.
Question: Which hormones are involved in the regulation of acid and enzyme secretion in the GI tract?
Answer: Gastrin, somatostatin, secretin, and cholecystokinin (CCK) are key hormones involved in regulating acid and enzyme secretion in the GI tract.
Question: Describe the control mechanism of acid secretion in the stomach.
Answer: Acid secretion in the stomach is controlled by the interaction of parietal cells (acid production), G cells (gastrin release), and D cells (somatostatin release). Gastrin stimulates acid production, while somatostatin inhibits it.
Question: Identify the three main types of secretory cells in the GI tract and their functions.
Secretory epithelial cells: Produce mucus and enzymes.
Exocrine acinar cells: Secrete digestive enzymes (e.g., amylase, trypsin).
Endocrine cells: Release hormones like gastrin, somatostatin, and insulin.
Question: What are the main components involved in the control of acid secretion in the stomach?
Answer: The control of acid secretion involves several key cells: Parietal cells (secrete HCl), G cells (secrete gastrin), D cells (secrete somatostatin), and Enterochromaffin-like (ECL) cells (secrete histamine). These cells work together through hormonal and neural signals to regulate acid production.
Question: How do different secretory cells in the stomach interact to control acid secretion?
Answer: G cells release gastrin, which stimulates ECL cells to release histamine and directly stimulates parietal cells to secrete HCl. D cells release somatostatin, which inhibits gastrin release, thereby reducing acid secretion.
Question: How do transporters control acid secretion in parietal cells?
Answer: Parietal cells secrete acid (HCl) via the H+/K+ ATPase (proton pump) located on the apical membrane. Chloride ions (Cl-) are transported out of the cell via a Cl- channel, while K+ is recycled back into the cell through K+ channels, maintaining the electrochemical gradient necessary for HCl secretion.
Question: What controls the secretion of mucous in the stomach?
Answer: Mucous secretion is primarily controlled by goblet cells and is stimulated by prostaglandins and acetylcholine. The mucous protects the stomach lining from acid damage.
Question: How is pepsinogen secretion from chief cells regulated?
Answer: Chief cells secrete pepsinogen in response to signals like gastrin, histamine, and acetylcholine. Pepsinogen is converted to active pepsin in the acidic environment of the stomach, aiding in protein digestion.
Q: What controls fluid secretion in the exocrine pancreas?
A: Fluid secretion in the exocrine pancreas is controlled by Ca2+ and cAMP, which regulate the activity of channels and transporters, modulating ion movement across epithelial cells in the ducts.
Q: What is the role of Ca2+ in enzyme secretion in the exocrine pancreas?
A: Ca2+ release, modulated by G-protein coupled receptors, triggers the secretion of inactive enzymes from acinar cells, which are later activated in the gut.
Q: What controls insulin secretion in beta cells of the endocrine pancreas?
A: Insulin secretion in beta cells is controlled by Ca2+ influx through L-type Ca2+ channels and is modulated by G-protein coupled receptors.
