149 Questions
What stimulates the secretion of gastric inhibitory peptide (GIP)?
Glucose and fat in the duodenum
Which hormone stimulates insulin secretion when administered at blood levels comparable to those produced by oral glucose?
Glucose-dependent insulinotropic peptide (GIP)
What is the effect of somatostatin on the secretion of gastrin?
Inhibits gastrin secretion
Which hormone is responsible for producing contractions in smooth muscle in the stomach and intestines between meals?
Motilin
What type of receptors does motilin act on in the duodenum and colon?
G-protein–coupled receptors
Which hormone's secretion is stimulated by acid in the lumen and inhibits the secretion of gastrin?
Somatostatin
What triggers substantial release of gastrin and activates stretch receptors in the stomach?
Physical presence of the meal
What enzyme is responsible for moving H+ ions out of parietal cells?
H+/K+/ATPase
Which phase activates 'vago-vagal' and local reflexes that amplify secretion during gastric secretion?
Gastric phase
What is the key mechanism that terminates gastric secretion after a meal moves into the small intestine?
Buffering of gastric acidity
What is the major function of pancreatic juice?
Digestion
Which cell in the stomach is packed with mitochondria to supply energy for proton pump activity?
Parietal cells
What is the main reason for the alkaline feature of saliva?
To neutralize gastric secretions
Which gland secretes saliva that is hypotonic compared with plasma?
Parotid gland
Which branch of the autonomic nervous system plays the most prominent role in controlling salivary secretion?
Parasympathetic branch
What is the primary function of saliva in relation to taste buds?
To serve as a solvent for taste bud stimulation molecules
During which phase does the stomach significantly add digestive juices to the meal?
Gastric phase
How does sympathetic branch input affect the composition of saliva?
By increasing proteinaceous content
What is the main action of cholecystokinin (CCK) in the body?
Inhibits gastric emptying
Where is cholecystokinin (CCK) primarily secreted from?
I cells in the upper small intestine
What effect does CCK have on the gallbladder?
Causes gallbladder contraction
How does CCK influence acid secretion in the body?
Inhibits acid secretion
Where is CCK also found, besides the intestinal mucosa?
Brain, especially cerebral cortex
What stimulates the increased secretion of cholecystokinin (CCK)?
Contact of intestinal mucosa with digestion products
What is the primary route by which the body disposes of cholesterol?
Conversion to bile acids
Which components of bile are responsible for its golden yellow color?
Bile pigments
What is the primary function of bile acids in digestion?
Emulsifying fats
What is the process by which some components of bile are reabsorbed in the intestine and excreted again by the liver?
Enterohepatic circulation
Which modality for gastrointestinal regulation involves the release of hormones associated with a meal?
Endocrine regulation
What substance in bile resembles pancreatic juice and contains bile acids and bile pigments?
An alkaline electrolyte solution
What is the primary function of the gastrointestinal tract?
Serve as a portal for nutrient absorption
Which organ does NOT secrete substances that aid in digestion along the gastrointestinal tract?
Kidneys
Which gland produces saliva for initial digestion of starch?
Parotid gland
What does saliva primarily mediate the digestion of?
Starch
Which segment of the gastrointestinal tract has a substantial surface area crucial for absorption?
Jejunum
Where do glandular structures mainly deliver secretions into the lumen along the length of the intestine?
Stomach and mouth
What is the primary function of intrinsic factor in gastric secretion?
To aid in the later absorption of vitamin B12
Which cells in the stomach are responsible for producing pepsinogens and gastric lipase?
Chief cells
What is the role of gastrin in gastric secretion?
Trigger parietal cell secretion
Which hormone acts as a trigger of parietal cell secretion by binding to H2-receptors?
Histamine
What is the precursor of pepsin, an enzyme that initiates protein digestion?
Pepsinogen
Which of the following glands in the stomach contains parietal cells and chief cells?
Glands in the fundus or body
What is the principal physiologic action of gastrin?
Stimulation of the growth of stomach mucosa
How is gastrin secretion affected by the presence of amino acids in the stomach?
It increases due to direct action on G cells
What is the role of acid in the antrum with regard to gastrin secretion?
It inhibits gastrin secretion through somatostatin release
What is the function of enteric nervous system in the intestinal system?
Regulates sensory and secretomotor neurons autonomously
How do some mediators differ from stable hormones in their mode of action?
They alter cell function locally in a paracrine manner
Which factor does NOT influence gastrin secretion?
Concentration of lipids in the intestines
How is the secretion of pancreatic juice primarily controlled?
By gastrointestinal hormones like secretin and CCK
What consequences can result from the activation of digestive enzymes within the pancreas?
Digestion of the pancreas
Why are most digestive enzymes released in inactive forms by the pancreas?
To avoid damaging pancreatic cells
What is the role of tryptin inhibitor secreted by the pancreas?
Preventing activation of trypsin within the pancreas
Which substance is NOT involved in neutralizing gastric acid by pancreatic juice, bile, and intestinal juices?
Trypsin
What is the primary function of bile acids in digestion?
Absorption of fats
What is the role of secretin in digestion?
Increases secretion of bicarbonate by pancreas and biliary tract
How does the release of secretin by acid illustrate feedback control?
Neutralizes acidic stomach content
Where is secretin primarily secreted from?
S cells in the upper small intestine mucosa
What triggers the increased secretion of secretin?
Acid bathing the upper small intestine mucosa
What is a unique characteristic of secretin's metabolism?
Little is known about its metabolism
How does secretin contribute to digestion?
Increasing bicarbonate secretion by pancreas and biliary tract
What is the primary function of cholecystokinin (CCK) in the body?
Enhances gallbladder contraction
Where is cholecystokinin (CCK) secreted from?
I cells in the upper small intestine
Which of the following is NOT an action of cholecystokinin (CCK)?
Inhibit gastric acid secretion
What stimulates the increased secretion of cholecystokinin (CCK)?
High levels of peptides and amino acids in digestion
Which hormone is found in nerves in the distal ileum and colon, besides being secreted by endocrine cells?
Cholecystokinin (CCK)
What is the key mechanism that terminates gastric secretion after a meal moves into the small intestine?
Presence of somatostatin
What initiates substantial release of gastrin and activates stretch receptors in the stomach?
Physical presence of the meal
What is the primary function of the pancreatic juice?
Contain enzymes for digestion
What is the role of mitochondria in gastric parietal cells?
Supply energy for proton pump
What is released into the bloodstream along with protons from parietal cells?
Bicarbonate ions
What triggers the 'vago-vagal' as well as local reflexes that amplify secretion during the gastric phase?
Stretch receptors activation
What is the primary route for disposing of cholesterol in the body?
Conversion to bile acids
Which component is responsible for the golden yellow color of bile?
Bilirubin
What represents the most important component of bile when considering it as a digestive secretion?
Bile acids
What is the process by which some components of bile are reabsorbed in the intestine and excreted again by the liver?
Enterohepatic circulation
Which modality is NOT involved in gastrointestinal regulation according to the text?
Metabolic regulation
Which gastrointestinal modality involves the release of hormones that travel through the bloodstream to affect distant segments of the tract?
Endocrine regulation
What is the primary mode of action for some mediators that differ from stable hormones?
Direct action on cells in the local area where they are released
What is the primary factor that influences gastrin secretion?
Acidic contents of the stomach
How is gastrin secretion affected by the rate of discharge of the vagus nerves?
Inhibits gastrin secretion
Which cells in the stomach directly produce gastrin?
G cells
What is the primary effect of acid in the antrum on gastrin secretion?
Activates somatostatin release
Which factor is NOT involved in regulating gastrin secretion through a negative feedback loop?
Presence of amino acids in the small intestine
What is the role of ghrelin in the gastrointestinal system?
Stimulates growth hormone secretion
Which nerve plexus is primarily concerned with motor control in the gastrointestinal tract?
Myenteric plexus
What is the function of Substance P in the gastrointestinal system?
Increases motility of the small intestine
Why is the enteric nervous system sometimes referred to as the 'little brain'?
Contains as many neurons as the whole spinal cord
Which gastrointestinal peptide is primarily secreted by the stomach and affects food intake regulation?
Ghrelin
How are the myenteric plexus and submucous plexus different in their location within the gastrointestinal tract?
Submucous plexus is located outside the muscle layers while myenteric plexus is inside
Gastrin is primarily secreted by D cells in the antral portion of the gastric mucosa.
False
The enteric nervous system controls only the sensory functions of the gastrointestinal tract.
False
Acid in the antrum stimulates gastrin secretion solely through direct action on somatostatin.
False
Blood borne factors have no effect on gastrin secretion.
False
Parietal cells in the stomach secrete hydrochloric acid and intrinsic factor.
True
Cholecystokinin (CCK) stimulates insulin secretion when administered at blood levels similar to those produced by fructose.
False
The primary physiological action of gastrin is the inhibition of pepsin secretion.
False
Chief cells in the stomach produce pepsin and gastric lipase.
False
Gastrin is a hormone released by D cells in the antrum of the stomach.
False
Histamine triggers parietal cell secretion by binding to H1-receptors.
False
Intrinsic factor is important for the absorption of vitamin B12.
True
Lipase in the stomach initiates the digestion of dietary proteins.
False
Acetylcholine released from enteric nerve endings in the fundus primarily stimulates parietal and chief cells.
True
Gastric secretion during the cephalic phase is predominantly activated by vagal input.
True
Stretch receptors in the stomach provoke vago-vagal as well as local reflexes that inhibit secretion during the gastric phase.
False
Parietal cells contain mitochondria that supply energy to drive the apical H+/K+/ATPase that moves H+ ions into the parietal cell.
False
The release of protons by parietal cells is not accompanied by the release of bicarbonate ions into the bloodstream.
False
Pancreatic juice does not contain enzymes that are of major importance in digestion.
False
Ghrelin is primarily secreted by the intestine.
False
Substance P is found only in nerve cells in the gastrointestinal tract.
False
The enteric nervous system contains fewer neurons than the spinal cord.
False
The myenteric plexus is primarily involved in sensory control.
False
The enteric nervous system cannot function autonomously without connections to the CNS.
False
Submucous plexus is located between the outer longitudinal muscle layer and the mucosa.
False
Gastric inhibitory peptide (GIP) is the only hormone that stimulates insulin secretion when administered at blood levels similar to those produced by oral glucose.
True
Somatostatin 14 and somatostatin 28 are both forms of somatostatin and both are secreted.
True
Motilin stimulates the relaxation of smooth muscle in the stomach and intestines during the period between meals.
False
Somatostatin secretion is stimulated by glucose and fat in the duodenum.
False
Gastrin, CCK, secretin, and glucagon all stimulate insulin secretion when administered at blood levels comparable to those produced by oral glucose.
False
Motilin acts on G-protein–coupled receptors on enteric neurons in the colon to stimulate motility during digestion.
True
Saliva is hypertonic compared with plasma.
False
The sympathetic branch has a significant influence on the volume of saliva produced.
False
Parasympathetic branch of the autonomic nervous system plays the most prominent role in controlling salivary secretion.
True
Gastric secretion is primarily controlled by hormonal factors.
False
The stomach readies itself to receive the meal during the cephalic phase after taking in the meal.
False
Intestinal phase of gastric secretion is the most quantitatively significant phase.
False
Saliva is produced by two pairs of salivary glands that drain into the oral cavity.
False
Saliva contains amylase, which primarily mediates the digestion of proteins.
False
The gastrointestinal tract encountered by a meal includes, in order, the colon before the stomach.
False
The primary function of the gastrointestinal tract is to eliminate waste products from the body.
False
The parts of the gastrointestinal tract that are encountered by the meal include the liver and spleen.
False
Glandular structures deliver secretions into the lumen particularly in the stomach and large intestine.
False
The majority of digestive enzymes in pancreatic juice are released in their active forms.
False
The pancreas secretes a trypsin inhibitor to prevent the activation of enzymes that could digest itself.
True
Bile, an important secretion for gastrointestinal function, originates from the pancreas.
False
Bile acids play a crucial role in the digestion and absorption of proteins.
False
Pancreatic juice is primarily under neural control rather than hormonal control.
False
Intrinsic factor is essential for the absorption of vitamin C.
False
Bile is the only route by which the body can dispose of cholesterol.
True
Bile pigments are responsible for the dark green color of bile.
False
Bile acids are synthesized from proteins and secreted into the bile.
False
Endocrine regulation of gastrointestinal functions involves hormones traveling through the lymphatic system.
False
The pancreas plays a vital role in endocrine regulation during digestion.
True
The release of hormones by triggers associated with a meal is an example of endocrine regulation.
True
Substance P is mainly secreted by the pancreas and stimulates growth hormone secretion.
False
The enteric nervous system can function autonomously without connections to the central nervous system.
True
The enteric nervous system is sometimes referred to as the 'big brain' due to its complexity.
False
Ghrelin, primarily secreted by the stomach, plays a key role in controlling food intake.
True
The myenteric plexus innervates the outer longitudinal muscle layers and is primarily involved in sensory function.
False
Cholecystokinin (CCK) inhibits gallbladder contraction and the absorption of glucose.
False
Test your knowledge on the activation of gastric secretion during the cephalic phase, triggered predominantly by vagal input. Learn about the release of gastrin, stretching of the stomach, and the reflexes involved in amplifying gastric secretion.
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