gi hormones l15?

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Questions and Answers

Which hormone primarily stimulates the exocrine secretions in the pancreas?

Cholecystokinin (CCK) (correct)

Gastrin

Secretin

Insulin

What is the primary role of secretin in the digestive process?

Promoting the secretion of bicarbonate by ductal cells (correct)

Inhibiting the release of digestive enzymes

Stimulating gastric acid secretion

Facilitating the absorption of nutrients

Which of the following factors directly influences the secretion of cholecystokinin (CCK)?

Presence of fatty acids in the duodenum (correct)

Activity of the vagus nerve

Release of glucagon

Acidity of the gastric contents

Which cells in the pancreas are responsible for secreting inactive precursors of digestive enzymes?

Acinar cells Signup and view all the answers

What type of signals predominantly regulate food intake within the gastrointestinal system?

Neurohumoral signals Signup and view all the answers

Which hormone is primarily responsible for stimulating the secretion of bicarbonate and water from bile ducts?

Secretin Signup and view all the answers

What effect does cholecystokinin (CCK) have on the gall bladder?

Constricts the gall bladder and relaxes the sphincter of Oddi Signup and view all the answers

What is the primary function of Brunner's glands in the duodenum?

Secrete mucus and bicarbonate Signup and view all the answers

Which of the following factors would decrease the secretion from Brunner's glands?

Sympathetic stimulation Signup and view all the answers

Which pathway is involved in the hypothalamic control of food intake?

Central neurohumoral signals Signup and view all the answers

Gastrin is primarily secreted in response to which of the following stimuli?

Protein digestion Signup and view all the answers

How does secretin influence the pH in the duodenum?

By increasing HCO3- secretion Signup and view all the answers

What is one of the key roles of motilin in the gastrointestinal system?

Regulating intestinal motility Signup and view all the answers

Which of the following hormones primarily inhibits gastric acid secretion through the secretion of somatostatin?

Secretin Signup and view all the answers

What is the primary site of release for Cholecystokinin (CCK)?

I cells in the upper small intestine Signup and view all the answers

Which hormone is responsible for stimulating insulin secretion in response to the presence of food in the small intestine?

Gastric inhibitory peptide (GIP) Signup and view all the answers

During which phase does gastrin release occur mainly due to vagovagal stimulation?

Cephalic phase Signup and view all the answers

What effect does Cholecystokinin (CCK) have on gastric acid secretion?

Inhibits gastric acid secretion Signup and view all the answers

Which hormone is released predominantly from D cells and acts to decrease motility and acid secretion?

Somatostatin Signup and view all the answers

Which of the following is a key action of Secretin?

Stimulates bicarbonate secretion from the pancreas Signup and view all the answers

What triggers the release of Secretin from S cells in the duodenum?

Decreased pH in the intestines Signup and view all the answers

Motilin is known for which specific physiological function?

Regulating migrating motor complex cycles Signup and view all the answers

Which additional factor increases the secretion of Gastrin during the gastric phase?

Breakdown of proteins to amino acids Signup and view all the answers

Which hormone has no known function in the gastrointestinal tract apart from stimulating insulin secretion?

Gastric inhibitory peptide (GIP) Signup and view all the answers

Which of the following hormones overlaps in function with Cholecystokinin (CCK) to increase gastric acid secretion?

Gastrin Signup and view all the answers

Which of the following hormones has a direct inhibitory effect on gastric motility?

Cholecystokinin (CCK) Signup and view all the answers

Which receptor does Gastrin primarily act upon to stimulate acid secretion?

CCK-2 Signup and view all the answers

What is the main difference and the shared features between gastrin and cholecystokinin (CCK)?

Shared: Common terminal, released at CCK receptors; Different: Length of peptide Signup and view all the answers

What does homology mean in the context of cholecystokinin (CCK) and gastrin?

They can act at each other's receptors. Signup and view all the answers

Where is the densest location of gastrin cells located? Additionally, gastrin cells do not extend beyond which structure?

Antrum of the stomach, Duodenum Signup and view all the answers

What stimulates gastrin release during the cephalic and gastric phases?

Mechanical distention of the stomach Signup and view all the answers

What stimulates the release of gastrin during the gastric and intestinal phases?

Breakdown of protein to amino acids Signup and view all the answers

Gastrin acts on CCK-2 receptors What is the primary role of gastrin?

Enhance secretion of gastric acid Signup and view all the answers

Gastrin is a trophic agent. What does that mean? How does it affect the stomach?

It stimulates the growth of gastric mucosa. Signup and view all the answers

Gastrin can increase which of the following? (Select all that apply)

Blood flow Signup and view all the answers

Describe the sequence of gastrin action on parietal cells.

Gastrin stimulates parietal cells to secrete hydrochloric acid. Signup and view all the answers

Where is cholecystokinin (CCK) released from?

I cells in the upper intestine Signup and view all the answers

Most CCK (cholecystokinin) actions occur in the...

Gallbladder and pancreas Signup and view all the answers

What are the two actions of CCK (cholecystokinin) cells on the parietal cells in the stomach?

Increase acid secretion alongside gastrin Signup and view all the answers

What are the two actions of CCK cells on the parietal cells in the stomach?

Increase acid secretion alongside gastrin Signup and view all the answers

What is the sequence of action of cholecystokinin (CCK) on the gastrointestinal system?

Stimulates bile secretion from the gallbladder Signup and view all the answers

Somatostatin responds to which of the following stimuli? (Select all that apply)

H+ Signup and view all the answers

H+, CCK, and ACh are stimulated by which of the following? (Select all that apply)

Increased blood glucose Signup and view all the answers

What action does somatostatin have?

Inhibits motility, acid secretion, and blood flow Signup and view all the answers

When is motilin released and how is it affected by meal ingestion?

Released in 90-minute cycles and inhibited by meal ingestion Signup and view all the answers

What does motilin cause?

Migration of the motor complex to clear foreign bodies Signup and view all the answers

The secretion of gastrin inhibitory peptide is stimulated by which of the following?

Food in the upper small intestine Signup and view all the answers

Where is GIP released from?

K cells in the duodenum and jejunum Signup and view all the answers

What is the major action of GIP?

Stimulates insulin secretion Signup and view all the answers

What type of serotonin is involved with vomiting from enterochromaffin cells?

5-HT3 Signup and view all the answers

What receptors does an anti-emetic block that is targeted at 5-HT3?

Serotonin receptors Signup and view all the answers

What receptors does the antiemetic agent block when targeting 5-HT3?

Serotonin receptors Signup and view all the answers

What are the endocrine secretions of the pancreas?

Glucagon and insulin Signup and view all the answers

What are the exocrine secretions of the pancreas? (Select all that apply)

Aqueous component Signup and view all the answers

What stimulates the exocrine secretions of the pancreatic ductal epithelial cells and the acinar cells respectively?

Cholecystokinin and secretin Signup and view all the answers

What do acinar cells produce? (Choose the correct option)

Enzymes rich in protein and a large volume of aqueous solution Signup and view all the answers

What is the aqueous solution predominantly made of?

Sodium (Na) and Bicarbonate (HCO3) Signup and view all the answers

Control of pancreatic secretions during the Cephalic & Gastric phases is primarily mediated by?

Vagal acetylcholine (ACh) Signup and view all the answers

How is pancreatic secretion controlled during the intestinal phase?

Stimulated by acids in the ductal cells, aimed to increase aqueous solution Signup and view all the answers

Bile is secreted by which of the following cells?

Hepatocytes Signup and view all the answers

Bile is released into which part of the digestive system?

Duodenum Signup and view all the answers

What is bile made of?

Bile salts and pigments Signup and view all the answers

What action does secretin have on the gallbladder?

Stimulates water and bicarbonate secretion Signup and view all the answers

What is the action of cholecystokinin (CCK) on the gallbladder?

Constricts the gallbladder and relaxes the sphincter of Oddi Signup and view all the answers

Which of the following functions is the vagus nerve involved in?

Gall bladder constriction Signup and view all the answers

What are Brunner's glands?

Mucous secreting glands in the early part of the duodenum Signup and view all the answers

What increases the secretions of the Brunner's Glands?

Presence of food in the duodenum Signup and view all the answers

What is true about secretin and CCK (cholecystokinin) in relation to the presence of food in the duodenum?

Secretin is released in response to acidic chyme, while CCK is released in response to fatty acids. Signup and view all the answers

What effect does sympathetic stimulation have on pancreatic secretion?

Inhibitory effect Signup and view all the answers

Where is the central regulation of food intake located?

Hypothalamus Signup and view all the answers

From where does the hypothalamus receive signals?

The brainstem Signup and view all the answers

Which two efferent pathways from the hypothalamus are associated with the inhibition of food intake and an increase in metabolism, as well as stimulation of food intake and inhibition of metabolism (orexigenic)?

Anorexigenic pathway and orexigenic pathway Signup and view all the answers

What is the inhibitory pathway from the hypothalamus related to the melanocortin pathway?

Agouti-related peptide (AgRP) Signup and view all the answers

Which of the following statements correctly describe the melanocortin pathway? (Select all that apply)

Pro-opiomelanocortin is released Signup and view all the answers

What is the stimulatory pathway from the hypothalamus involving neuropeptide Y (NPY)?

Enhanced food intake and energy storage Signup and view all the answers

How does neuropeptide Y (NPY) stimulate the pathway that leads to increased food intake?

By binding to Y1 receptors in the hypothalamus Signup and view all the answers

What's true of the following statements regarding the POMC and NPY pathways?

Two pathways are mutually exclusive: POMC pathway and NPY. Signup and view all the answers

What does galanin stimulation induce?

Satiety and inhibits feeding Signup and view all the answers

How can we eliminate satiety?

By blocking the vagal afferent Signup and view all the answers

How do pancreatic β-cells act on the hypothalamus?

They release insulin, which directly acts on the hypothalamus inducing satiety. Signup and view all the answers

What action of the following stimulates the POMC pathway and inhibits the NPY pathway?

Leptin released from adipocytes Signup and view all the answers

What effect does leptin released from adipocytes have on the POMC and NPY pathways?

Stimulates the POMC pathway and inhibits the NPY pathway Signup and view all the answers

Distension of the stomach stimulates vagal afferents and leads to which of the following outcomes?

Inhibition of feeding Signup and view all the answers

Cholecystokinin (CCK) is released due to what stimulus?

the presence of food in the small intestine and stimulates satiety. Signup and view all the answers

Peptide YY is released by which type of cells?

Entroendocrine L cells Signup and view all the answers

Which of the following accurately describes the action of peptide YY?

Direct inhibition of NPY orexigenic nerves Signup and view all the answers

Ghrelin is released from which of the following?

Oxyntic glands in the stomach Signup and view all the answers

Ghrelin stimulates the release of which hormone?

Growth hormone Signup and view all the answers

Ghrelin acts directly on which of the following?

Orexigenic NPY neurons Signup and view all the answers

Which statement is true regarding dopaminergic neurons in the ventral tegmental area (VTA) of the midbrain, particularly in reward pathways?

They play a significant role in the brain's reward system. Signup and view all the answers

What stimulates dopaminergic neurons?

Sight, smell, and taste of food Signup and view all the answers

What is true about peptide YY?

It decreases food intake by inhibiting NPY only. Signup and view all the answers

Secreting is released from which cells in the duodenum?

S cells Signup and view all the answers

Study Notes

Control of Pancreatic Secretion

The intestinal phase involves secretin and CCK as key regulators.
Secretin increases aqueous solution and bicarbonate (HCO3-) secretion, elevating pH in response to acidity.
CCK is stimulated by fats and proteins, promoting enzyme secretion from acinar cells.
Vagal afferent fibers facilitate CCK's effect through acetylcholine (ACh).

Gallbladder and Bile

Bile is produced by hepatocytes, stored in the gallbladder, and released into the duodenum.
Composed of water, bilirubin, cholesterol, bile salts, and fats, bile is essential for fat digestion.
Secretin enhances water and bicarbonate secretion from bile ducts.
CCK constricts the gallbladder and relaxes the sphincter of Oddi, facilitating bile acid release.
The vagus nerve also plays a role in gallbladder contraction.

Brunner’s Glands

Located in the early duodenum, Brunner’s glands secrete mucous and bicarbonate.
Protects the duodenum from stomach acid, with secretion influenced by food presence and vagal stimulation.
Secretin and CCK further stimulate their secretion, while sympathetic stimulation decreases it.

Gastrointestinal Hormones

Key hormones include gastrin, cholecystokinin (CCK), and secretin, among others.
These hormones influence pancreatic function, bile secretion, and Brunner’s gland activity.

Regulation of Food Intake

Central regulation occurs in the hypothalamus, influenced by neurohumoral signals from digestion and emotional states.
Two main efferent pathways:
- Suppression of food intake and increased metabolism.
- Hormonal inputs from gastrin and CCK.

Pancreatic Secretions

The pancreas has both endocrine (glucagon, insulin) and exocrine functions.
Exocrine components include enzyme-rich juice (from acinar cells) and aqueous solution (from ductal cells).
Enzyme precursors are secreted as inactive forms (trypsinogen, chymotrypsinogen) and activated in the duodenum.

Gastric Phases

Cephalic Phase: Triggered by sensory stimuli; stimulates gastrin release and secretion of mucous, HCl, and pepsinogen.
Gastric Phase: Activated by stomach distension, promotes peristalsis and gastric emptying.
Intestinal Phase: Inhibitory phase by CCK and secretin to slow gastric emptying.

Gastrin and CCK

Both are structurally related and act on CCK receptors; share similar C-terminal sequences.
Gastrin is densely located in the antrum, stimulated by receptors activated during cephalic and gastric phases.
Increases acid secretion from parietal cells and stimulates growth of gastric mucosa.

Cholecystokinin (CCK)

Released from I cells in the upper small intestine in response to proteins and fats.
CCK mainly affects gallbladder and pancreas but also has complex interactions with gastric acid secretion, depending on receptor type.
Involved in increasing blood flow to the splanchnic area.