Secretions (Gastric, Salivary, Pancreatic, Bile) Flashcards
What are the main secretions of the stomach?
The main secretions of the stomach include hydrochloric acid, pepsinogen, intrinsic factor, and mucus.
What cells produce hydrochloric acid in the stomach?
Hydrochloric acid in the stomach is produced by parietal cells.
What is the function of hydrochloric acid in gastric secretion?
Hydrochloric acid creates an acidic environment that activates pepsinogen to pepsin and helps in protein digestion.
Which cells in the stomach secrete intrinsic factor?
Parietal cells secrete intrinsic factor in the stomach.
What is the role of intrinsic factor in gastric secretion?
Intrinsic factor is necessary for the absorption of vitamin B12 in the ileum.
Describe the composition and function of pepsinogen.
Pepsinogen is an inactive precursor of pepsin, composed of proteolytic enzymes.
How is pepsinogen converted into pepsin?
Pepsinogen is converted into pepsin by the action of hydrochloric acid.
What is the function of pepsin in gastric secretion?
Pepsin is an enzyme that breaks down proteins into smaller peptides.
What hormone stimulates gastric acid secretion?
Gastric acid secretion is stimulated by the hormone gastrin.
How does histamine contribute to gastric acid secretion?
Histamine stimulates gastric acid secretion by activating H2 receptors on parietal cells.
What is the role of gastrin in gastric acid secretion?
Gastrin is a hormone released by G cells in the stomach that stimulates gastric acid secretion.
Describe the regulation of gastric acid secretion by the vagus nerve.
The vagus nerve stimulates gastric acid secretion in response to cephalic and gastric stimuli.
What is the cephalic phase of gastric secretion?
The cephalic phase of gastric secretion is the initial response to the sight, smell, or taste of food.
How does the cephalic phase of gastric secretion occur?
The cephalic phase is mediated by the vagus nerve, leading to the release of gastrin and stimulation of acid secretion.
What is the gastric phase of gastric secretion?
The gastric phase of gastric secretion occurs when food enters the stomach.
What triggers the gastric phase of gastric secretion?
Gastric distension and the presence of peptides and amino acids trigger the gastric phase.
Describe the mechanisms of regulation in the gastric phase.
Gastric phase regulation involves neural, hormonal, and paracrine mechanisms to modulate acid secretion.
What is the intestinal phase of gastric secretion?
The intestinal phase of gastric secretion occurs when chyme enters the duodenum.
What inhibits gastric secretion during the intestinal phase?
Gastric secretion is inhibited by factors such as low pH, fatty acids, and peptides in the duodenum.
How do somatostatin and prostaglandins regulate gastric acid secretion?
Somatostatin and prostaglandins inhibit gastric acid secretion by acting directly on parietal cells.
What are the three pairs of salivary glands?
The three pairs of salivary glands are the parotid, submandibular, and sublingual glands.
What are the primary constituents of saliva?
Saliva consists primarily of water, electrolytes, mucus, and enzymes.
What enzymes are present in saliva and what are their functions?
Saliva contains enzymes such as salivary amylase (ptyalin) for carbohydrate digestion and lingual lipase for fat digestion.
How does saliva contribute to digestion?
Saliva moistens food, facilitates swallowing, and initiates carbohydrate digestion.
What is the role of salivary amylase in digestion?
Salivary amylase begins the digestion of starches into maltose in the mouth.
How does saliva protect the oral cavity?
Saliva protects the oral cavity by lubricating and cleansing the teeth and oral mucosa.
What is the composition of pancreatic juice?
Pancreatic juice is composed of water, electrolytes, bicarbonate, and digestive enzymes.
What enzymes are present in pancreatic juice and what are their functions?
Pancreatic juice contains enzymes such as pancreatic amylase, lipase, trypsin, chymotrypsin, and carboxypeptidase.
How does the pancreas regulate pancreatic secretion?
Pancreatic secretion is regulated by neural and hormonal signals, including secretin and cholecystokinin (CCK).
What is the role of secretin in pancreatic secretion?
Secretin stimulates the pancreas to release bicarbonate-rich fluid, neutralizing acidic chyme.
How does secretin stimulate pancreatic secretion?
Secretin is released in response to acidic chyme entering the duodenum, stimulating pancreatic bicarbonate secretion.
What is the function of pancreatic amylase?
Pancreatic amylase continues the digestion of carbohydrates in the small intestine.
What role does lipase play in pancreatic secretion?
Lipase breaks down triglycerides into fatty acids and monoglycerides for absorption.
Describe the function of trypsin in pancreatic secretion.
Trypsin digests proteins into smaller peptides and amino acids.
What is the function of chymotrypsin in pancreatic secretion?
Chymotrypsin hydrolyzes peptide bonds, further breaking down proteins.
What activates trypsinogen into trypsin?
Trypsinogen is activated into trypsin by enteropeptidase in the duodenum.
What is the function of pancreatic bicarbonate?
Pancreatic bicarbonate neutralizes acidic chyme, creating a suitable pH for enzymatic digestion.
How does the liver contribute to digestion?
The liver contributes to digestion by producing bile, which aids in fat digestion and absorption.
What is bile composed of?
Bile is composed of bile salts, cholesterol, phospholipids, bilirubin, and electrolytes.
What is the primary function of bile?
The primary function of bile is to emulsify fats, increasing their surface area for digestion by lipases.
How is bile secretion regulated?
Bile secretion is regulated by neural and hormonal signals, including cholecystokinin (CCK) and the vagus nerve.
What is the role of bile salts in digestion?
Bile salts em ulsify large fat globules into smaller droplets, aiding in their digestion and absorption.
How do bile salts aid in the digestion of fats?
Bile salts help in the digestion of fats by emulsifying them into smaller droplets, increasing their surface area for enzyme action.
What is the enterohepatic circulation of bile acids?
The enterohepatic circulation of bile acids involves the recycling of bile acids from the intestine back to the liver via the portal vein.
What is the function of bile pigments?
Bile pigments, such as bilirubin, give bile its characteristic color and are waste products of heme metabolism.
How does bile help in the absorption of fat-soluble vitamins?
Bile helps in the absorption of fat-soluble vitamins (A, D, E, K) by facilitating their solubilization and transport.
Describe the process of emulsification by bile salts.
Emulsification by bile salts involves the breakdown of large fat droplets into smaller droplets, increasing the efficiency of fat digestion by lipases.
How does bile flow from the liver to the small intestine?
Bile flows from the liver to the small intestine through the bile duct system, including the common bile duct and cystic duct.
What stimulates the release of bile from the gallbladder?
Bile release from the gallbladder is stimulated by cholecystokinin (CCK) in response to the presence of fatty acids and amino acids in the duodenum.
How does bile secretion change in response to a fatty meal?
Bile secretion increases in response to a fatty meal to aid in the emulsification and digestion of dietary fats.
