70 Questions
What accompanies the secretion of protons in the gastrointestinal system?
Release of bicarbonate ions
What disrupts the barrier that prevents autodigestion of the mucosa by gastric secretions?
Infection with Helicobacter pylori
Which of the following drugs can lead to gastric and duodenal ulceration?
Aspirin
What is a primary cause of ulceration in the Zollinger-Ellison syndrome?
Hypersecretion of acid
Where are most gastrinomas found in patients with Zollinger-Ellison syndrome?
Pancreas
What is commonly used to combat pain and treat arthritis, but can contribute to ulceration?
NSAIDs
What is the purpose of releasing trypsin as an inactive precursor?
To prevent digestion of the pancreas
Why does the pancreas secrete a trypsin inhibitor?
To prevent the activation of trypsin
What is the primary control mechanism for the secretion of pancreatic juice?
Hormonal control
Why are bile acids important in the digestion and absorption of fats?
To facilitate fat digestion and absorption
What is the function of bile in the body?
To dispose of cholesterol
What gives bile its golden yellow color?
Bilirubin and biliverdin
What is the role of Substance P in the gastrointestinal tract?
Increasing the motility of the small intestine
Where are the two major nerve fiber networks intrinsic to the gastrointestinal tract located?
Between the outer longitudinal and middle circular muscle layers
How many sensory neurons, interneurons, and motor neurons are found in the human gastrointestinal system?
More than in the spinal cord
What is the principal physiological action of gastrin?
Stimulation of gastric acid and pepsin secretion
What is the enteric nervous system sometimes referred to, and why?
The little brain for its size
How is gastrin secretion affected by the presence of protein digestion products in the stomach?
Stimulates gastrin secretion
How does Substance P affect growth hormone secretion?
Indirectly affects it through receptors in the pituitary
Which cells in the gastric mucosa produce gastrin?
G cells
What are the functions of the myenteric plexus (Auerbach plexus) within the gastrointestinal tract?
Controls muscle movements between certain layers
How does acid in the antrum affect gastrin secretion?
Inhibits gastrin secretion
What are hormones or paracrines in the gastrointestinal system primarily secreted by?
Nerve cells and gland cells
How do gastrointestinal hormones like gastrin primarily act in the body?
Paracrine and endocrine fashion
Which plexus is primarily involved in the control of intestinal secretion?
Submucous plexus
Which neurotransmitter is NOT mentioned as part of the gastrointestinal system?
Dopamine
The gastrointestinal system evolved to permit controlled nutrient uptake in __________ organisms.
Multicellular
Which component of bile is essential in the chemical alteration of meal components for absorption?
Enzymes
What is the primary function of the myenteric plexus?
Motor control of smooth muscle layers
Which gas is mentioned as part of the neurotransmitters in the gastrointestinal system?
Nitric oxide
What is the main action of gastrin in the gastrointestinal system?
Stimulating pancreatic enzyme secretion
Which stimuli inhibit gastrin secretion in the gastrointestinal system?
Somatostatin
Where are endocrine cells secreting cholecystokinin (CCK) found?
In the upper small intestine
What is the primary function of CCK in the gastrointestinal system?
Promoting bile flow
Which neurotransmitter is involved in increasing gastrin secretion through vagal discharge?
Cholecystokinin releasing peptide (GRP)
What is the effect of luminal peptides and amino acids on gastrin secretion?
Increase gastrin secretion
What is the primary function of bile acids in the digestive process?
Facilitate the absorption of vitamins
Which of the following is NOT a modality for gastrointestinal regulation mentioned in the text?
Intrinsic motility
How does endocrine regulation differ from paracrine regulation in gastrointestinal function?
Endocrine signals target distant organs, while paracrine signals act locally
Which component of the gastrointestinal system has extensive neural connections to both the central nervous system and an autonomous nervous system?
Intestinal system
What is the main function of the enteric nervous system within the gastrointestinal tract?
Coordinate sensory and secretomotor neurons
How do gastrointestinal hormones differ from paracrines in their mode of action?
Hormones act via the bloodstream, while paracrines act locally
What is the main function of Substance P in the gastrointestinal tract?
Increasing motility of the small intestine
Which nervous system is sometimes referred to as the 'little brain' due to its autonomous function in regulating gastrointestinal activities?
Enteric Nervous System
How many major networks of nerve fibers are intrinsic to the gastrointestinal tract?
Two
What is the collective term for the approximately 100 million neurons found in the gastrointestinal system?
Enteric Nervous System
What stimulates parietal and chief cells in the stomach?
Acetylcholine released from enteric nerve endings
During which phase is gastric secretion predominantly activated by vagal input?
Cephalic phase
What serves as a feedback inhibitory signal to shut off gastric secretion?
Release of somatostatin
What is the key mechanism that terminates gastric secretion after a meal moves from the stomach to the small intestine?
Presence of meal constituents
What is the primary function of mitochondria in gastric parietal cells?
Supplying energy for the proton pump
What plays a crucial role in buffering gastric acidity and terminating gastric secretion post-meal?
Presence of meal constituents
What is the primary function of gastrin in the gastrointestinal system?
Stimulating growth of the stomach mucosa
How is gastrin secretion affected by the presence of amino acids in the stomach?
It activates G cells to secrete more gastrin
What is the effect of acid in the antrum on gastrin secretion?
Inhibits gastrin secretion
Which factors affect the secretion of gastrointestinal hormones like gastrin?
Rate of discharge of the vagus nerves
What is the role of somatostatin in relation to gastrin?
Inhibits gastric acid and pepsin secretion
How do hormones and paracrines function within the gastrointestinal system?
By acting in a paracrine manner and sometimes entering circulation
What is the primary function of the myenteric plexus within the gastrointestinal tract?
Primarily involved in motor control
Which neurotransmitter is NOT mentioned as part of the gastrointestinal system?
Endorphin
What is the main role of the submucous plexus in the gastrointestinal system?
Innervates glandular epithelium and controls intestinal secretion
What activity describes the function of digestive secretions in the gastrointestinal system?
Breaking down macromolecules for absorption
Which neurotransmitter contributes to gastrointestinal regulation by affecting smooth muscle contractions?
Nitric oxide (NO)
How are some peptides released by the gastrointestinal system different from others?
Serving as hormones
What is the evolutionary advantage of the gastrointestinal system being functionally continuous with the outside environment?
Enhanced nutrient absorption
Which component is NOT found in digestive secretions that chemically alter meal components?
Macronutrients
How do paracrine factors differ from hormones in their role within the gastrointestinal system?
Act on nearby cells
Which gas molecule serves as a neurotransmitter involved in gastrointestinal regulation?
Nitric oxide (NO)
What is the primary purpose of digestive secretions in relation to meal components?
Chemically alter components for absorption
How do neurotransmitters like serotonin differ from ATP in their influence on gastrointestinal activities?
Control muscle contraction differently
Explore the function and regulation of hormones and paracrines in the gastrointestinal system. Learn about biologically active polypeptides secreted by nerve cells and gland cells, and their impact on gastrointestinal secretion and motility.
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