65 Questions
What stimulates parietal and chief cells in the stomach?
Acetylcholine released from enteric nerve endings
What primarily activates gastric secretion during the cephalic phase?
Vagal input
What is a key mechanism that terminates gastric secretion after a meal moves to the small intestine?
Buffering of gastric acidity by meal constituents
What provides energy to drive the proton pump in gastric parietal cells?
Mitochondria
What is released into the bloodstream alongside protons during gastric secretion?
Bicarbonate ions
What is of major importance in digestion in pancreatic juice?
Enzymes
Which hormone is responsible for stimulating pancreatic enzyme secretion?
Cholecystokinin
What is the main action of cholecystokinin (CCK) in relation to the gallbladder?
Contraction of the gallbladder
Which effect does cholecystokinin (CCK) have on gastric emptying?
Inhibits gastric emptying
Where are endocrine cells known as I cells located?
Upper small intestine mucosa
What stimulates the secretion of cholecystokinin (CCK)?
Contact of intestinal mucosa with digestion products
What is one of the locations where CCK is found, apart from I cells in the upper small intestine?
Brain
What is the primary role of gastric secretion in the stomach?
To protect the stomach from self-digestion
Which type of cells in the stomach secrete hydrochloric acid and intrinsic factor?
Parietal cells
What is the precursor of pepsin, an enzyme that initiates protein digestion?
Pepsinogen
Which hormone released by G cells in the antrum of the stomach triggers gastric secretion?
Gastrin
What is the main function of intrinsic factor secreted by parietal cells?
Absorbing vitamin B12
Which stimulus triggers parietal cell secretion in the stomach?
Histamine
What is the main function of bile in the body?
To dispose of cholesterol
Which component gives bile the golden yellow color?
Glucuronides of bile pigments
What are the main components of bile when considering it as a digestive secretion?
Bile acids
How are bile acids synthesized?
From cholesterol
What is responsible for the regulation of gastrointestinal functions after a meal?
Endocrine regulation
What is the enterohepatic circulation related to in the text?
Bile production
What is the role of ghrelin in the gastrointestinal system?
Stimulates growth hormone secretion
Which peptide is involved in increasing the motility of the small intestine?
Substance P
What is the function of the myenteric plexus in the gastrointestinal tract?
Motor control of smooth muscle layers
How does the enteric nervous system connect to the central nervous system?
Via parasympathetic and sympathetic fibers
Which component of the gastrointestinal tract is referred to as the 'little brain'?
Myenteric plexus
What effect does substance P have on the gastrointestinal tract?
Increases the motility of the small intestine
What is the primary function of the gastrointestinal tract?
Facilitate the absorption of nutrients and water into the body
Which gland produces saliva for initial digestion of starch?
Parotid gland
What is the composition of saliva mostly controlled by?
Parasympathetic branch of the autonomic nervous system
How does the sympathetic branch of the autonomic nervous system influence saliva composition?
By decreasing proteinaceous content
What is the function of saliva in the oral cavity?
Initiate digestion of starch
What is the pH nature of saliva in comparison to plasma?
Alkaline
Which organ secretes substances that aid in digestion along the length of the intestine?
Pancreas
What is the significance of the substantial surface area of the intestine?
It enhances absorptive function
Which phase of secretion in the stomach is quantitatively the most significant according to the text?
Gastric phase
What is one of the main functions of saliva as mentioned in the text?
Facilitating swallowing
How is the release of pancreatic enzymes controlled?
By hormonal control
What predominantly activates gastric secretion during the cephalic phase?
Vagal input
Why are most digestive enzymes in pancreatic juice released in inactive forms?
To avoid damage to the pancreas
What type of cells are packed with mitochondria to supply energy for the proton pump in the stomach?
Parietal cells
Which mechanism terminates gastric secretion after a meal moves from the stomach into the small intestine?
Somatostatin release
What is the significance of trypsin inhibitor in pancreatic secretion?
It prevents activation of trypsinogen
What is released into the bloodstream alongside protons during gastric secretion?
Bicarbonate ions
Which gastrointestinal secretion contributes to the digestion and absorption of fats?
Bile
How do granules containing digestive enzymes exit the cells in the pancreas?
By exocytosis
Which gastric phase reflex further amplifies secretion during digestion?
'Vago-vagal' reflexes
What effect does increased acid secretion have on further gastrin secretion?
Inhibits further secretion of gastrin
Where are endocrine cells known as I cells primarily located?
Mucosa of upper small intestine
How does ghrelin primarily influence growth hormone secretion?
By acting on receptors in the pituitary gland
Where are sensory neurons, interneurons, and motor neurons primarily located in relation to the gastrointestinal tract?
In the enteric nervous system
What does ghrelin primarily stimulate when it acts directly on receptors in the pituitary gland?
Growth hormone secretion
What is one of the strategic roles of ghrelin in the gastrointestinal system?
Regulation of food intake through central control
What is the primary role of the myenteric plexus in the gastrointestinal tract?
Innervation of smooth muscle layers
Which nerve fiber network is located between the outer longitudinal and middle circular muscle layers in the gastrointestinal tract?
Myenteric plexus
How many major networks of nerve fibers are intrinsic to the gastrointestinal tract based on the text?
Two
Which hormone is primarily secreted by the stomach and influences the central control of food intake?
Ghrelin
What is the approximate number of neurons in the enteric nervous system compared to those in the whole human spinal cord?
Equal
What is the trophic effect of CCK on the pancreas?
Enhances pancreas growth and maintenance
In addition to I cells, where else is CCK found in the body?
Distal ileum and colon
What triggers the increased secretion of CCK according to the text?
Contact of intestinal mucosa with digested peptides and amino acids
What is the primary effect of the peptide substance P in the gastrointestinal tract?
Increases small intestine motility
Test your knowledge on the composition and function of bile, including bile acids, bile pigments, and their role in disposing cholesterol. Learn about the secretion of bile, enterohepatic circulation, and reabsorption in the intestine.
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