Digestion and Metabolism: Organs from stomach to duodenum Flashcards
What causes PANS stimulation of the vagus nerve?
Sight, smell, taste, and even thoughts of food can
What does stimulation of the vagus nerve cause?
innervation of the stomach cells to release mucus, HCl, pepsinogen, ghrelin, and gastrin
When does the gastric phase begin?
At the arrival of food in the stomach
What happens during the gastric phase?
Stretch receptors activation enhance gastrin secretions, and gastrin is released into the bloodstream
What happens when gastrin is released into the bloodstream
Protein digestion, powerful contractions called mixing waves, and stimulates gastric motility
What does Gastric Lipase do?
digests fat
What is the function of Intrinsic factor?
vitamin B12 absrorption
What is the function of HCl
Creates an acidic environment that is necessary for the cells that secrete pepsinogen, kills most microorgansims ingested, denatures proteins, inactivates most food and salivary enzymes, and helps break down plant cell walls.
If the volume of food in the stomach increases, what else increases?
The activity of stretch receptors which increases intragastric pressure, which increases gastric emptying
How does osmotic pressure affect gastric emptying?
The greater the osmolarity = the less gastric emptying as stomach contents are diluted.
How does nutrient density affect gastric emptying?
The greater nutrient density = less gastric emptying.
For carbs, CHO effect is exterted via duodenal osmoreceptors
For Fats & Proteins, CCK
How does particle size affect gastric emptying?
The greater the particle size, the lesser gastric emptying.
What is the sieving mechanism?
heavier particles collecting in the lower part of the stomach
How does viscosity affect gastric emptying?
Soluble fiber needs more water to be drawn in which activates appetite suppresants.
What are insoluble fibers?
Fibers that swell in water found in outer skin of plants and are the main component of plant cell walls and cereal grains
What are soluble fibers?
Fibers that thicken in water that are found in fleshy part of fruits and endosperm of grain, legumes, nuts and seeds.
How do insoluble fibers treat constipation?
Increases stool bulk and reduce transit time by promoting movement of material through colon
Where are short chain fatty acids produced and why aare they important?
Produced in the colon by bacterial fermentation of dietary fiber. It also dilutes carcinogens reducing the risk of colon cancer
How do soluble fibers work in the digestive system?
They increase viscosity of stomach contents, bind to bile and reduces the reabsorption which reduces circulating cholesterol.
What is the function of vomiting?
Reflex to remove toxins/poisons from the upper GI tract.
How does vomiting work?
Sensations of irritation of the upper GI tract relaxes both pyloric and LES sphincters and peristaltic was discharge duodenal contents into stomach and then eventually out of mouth.
What are Gastric Ulcers?
Damage of the lining of the digestive tract from stomach acid
What causes ulcers and how are they treated?
NSAIDs, Helicobacter pylori, cause ulcer and are treated by antibiotics.
When does the intestinal phase begin and what is its function?
When chyme enters the duodenum; It controls emptying and secretions of the digestive tract
What does distention of the duodenum cause?
Inhibition of gastrin production and gastric contractions.
Stimulates contraction of pyloric sphincter to reduce further discharge of chyme
What is secreted during the intestinal phase?
Alkaline mucus, Cholecystokinin (CCK), Gastric inhibitory peptide (GIP), Secretin
What is alkaline mucus triggered by?
Vagal stimulation
What is the trigger and function of Cholecystokinin (CCK)?
Triggered by proteins and fats in chyme;
Constricts the pyloric sphincter
Stimulates pancreatic enzyme secretion
Increases bile synthesis in the liver
Stimulates gallbladder contraction to release bile
What is the trigger and function of Gastric inhibitory peptide?
Triggered by carbohydrates in chyme;
Stimulates release of insulin from pancreas in a glucose dependent manner
promotes growth and survival of pancreatic beta cell
stimulates adipogenesis
What is the trigger and function of Secretin?
Triggered by decreased pH (acidity);
Stimulates pancreatic buffers
protects duodenum from acidic chyme
Increases mucus secretion in duodenum
Neutralizes pH in duodenum by optimizing functionality of pancreatic amylase and pancreatic lipase.
What organs comprise the small intestine and what do they do?
Duodenum, ileum, and jejunum; they control secretions, digestion and absorption
What is the role of the large intestine?
Water absorption, feces formation and expulsion
