Lecture 47- Digestive System Part 2 Flashcards
What does the gastric phase begin with?
The arrival of food in the stomach
The activation of what type of receptors enhance gastrin sections from the cephalic phase?
Stretch receptors
What three things happen when gastrin is released into the bloodstream?
- Protein digestion
- Powerful contractions (mixing waves)
- Stimulation of gastric motility
What is the role of intrinsic factor in the gastric phase of digestion?
Intrinsic factor is a glycoprotein secreted in the stomach that facilitates the absorption of vitamin B12 in the small intestine.
What is the role of gastric lipase?
Digests fat
How is pepsin increased in order to break down proteins?
Pepsinogen is converted into pepsin due to acidic environment
What type of environment is essential for the function of cells that secrete pepsinogen?
Acidic environment
What are the five main roles of HCl function?
- Acidic environment to secrete pepsinogen
- Acidic environment to kill microorganisms
- Denatures proteins
- Inactivates most of the enzymes in food
- Helps break down plant cell walls/connective tissues in meat
What 5 main factors determine gastric emptying?
- Volume
- Osmotic pressure
- Nutrient density
- Particle size
- Viscosity
How does an increase in volume affect the rate of gastric emptying?
How does this occur?
Increases rate
Increased volume=increased activity of stretch receptors=increase intragastric pressure=increased rate
How does an increase in osmolarity affect the rate of gastric emptying?
How does this occur?
Decreases rate
When the stomach is more salty in needs time to dilute it first which decreases the rate
How does an increase in nutrient density affect the rate of gastric emptying?
How does this occur?
Decreases rate
Can be done with carbs, fats, proteins. Needs more fluid to offset nutrients which takes more time and decreases rate
How does an increase in particle size affect the rate of gastric emptying?
How does this occur?
Decreases rate
Have to sieve through large/small particles and the larger particles collect at lower part of stomach
How does an increase in viscosity affect the rate of gastric emptying?
How does this occur?
Decreases rate
Soluble fiber requires more water to be drawn in and activates appetite suppressants
What is the only determinant of gastric emptying that will increase the rate, proportional to increasing the factor?
Volume
How does insoluble fiber water react in water?
Swells
How does soluble fiber water react in water?
Thickens
What part of the plant is insoluble fiber found in?
Skin
What part of the plant is soluble fiber found in?
Flesh
How does insoluble fibers treat constipation
Insoluble fibers treat constipation by adding bulk to stool, making it softer and easier to pass, and by stimulating the muscles in the intestines to move waste along more efficiently
How does insoluble fibers reduce the risk for colon cancer?
Bacterial fermentation of dietary fiber dilutes carcinogens for cancer
How does soluble fibers treat constipation
Increases water due to more viscosity which will make the stool softer
How does soluble fibers reduce cholesterol levels?
Binds bile which reduces the reabsorption of bile acids
How does soluble fibers help diabetics?
Viscosity entraps sugars which slows glucose absorption/lowers spikes in glucose levels
How does vomiting reflex work?
-Pyloric sphincter relaxes
-Peristaltic waves discharge small intestine contents to stomach
-Gastroesophageal sphincter relaxes
-Stomach contents through esophagus, pharynx, and mouth
What are the six consequences of habitual purging?
- Esophagus damage
- Scar tissue formation
- Affects peristalsis
- Tooth decay
- Cardiac irregularities
- Death
How does gastric ulcers occur?
When stomach acid damages the lining of the digestive tract
What does the intestinal phase begin with?
Begins when chyme first enters the duodenum
What is the primary role of the intestinal phase?
Controls emptying and secretions in the GI tract
What three things does the distension (stretching) of the duodenum do?
- Inhibits gastrin production
- Inhibits gastric contractions
- Stimulates the contraction of the pyloric sphincter which prevents further discharge of chyme
What are the four secretions of the intestinal phase?
- Alkaline mucus
- CCK- Cholecystokinin
- GIP- Gastric inhibitory peptide
- Secretin
How does CCK affect the pyloric sphincter? What does this do to gastric emptying and satiety?
-Constricts the pyloric sphincter
-Inhibits gastric emptying
-Triggers satiety by inhibiting food intake
CCK ______ pancreatic enzyme secretion
Stimulates
CCK _______ bile synthesis in the liver
Increases
CCK ________ gallbladder contraction to release bile
Stimulates
What does GIP stimulate the release of?
What needs to be dependent for this to happen?
Insulin
Glucose-dependent
What does secretin stimulate the release of? What is their function?
Pancreatic buffers
Protects the duodenum from acidic chyme
Secretin _________ mucus secretion in the duodenum
Increases
Secretin neutralizes the pH in the duodenum by optimizing the function of what two pancreatic enzymes?
Lipase and amylase
In the small intestine, what is released if the pH is low?
Secretin
In the small intestine, what is released if there is an increased amount of carbohydrates?
GIP
In the small intestine, what is released if there is an increased amount of lipids/proteins?
CCK
What do GIP, CCK, and secretin all have negative inhibition on?
Gastric secretions in the small intestine
What are the two main inhibition processes of GIP on gastric secretion?
- Insulin release
- Increase of fat synthesis and storage
What are the four organs CCK has an effect on during gastric secretion inhbition?
Liver, pancreas, pyloric sphincter, and gallbladder
What is the function at the liver, gallbladder, pancreas, and pyloric sphincter during CCK inhibition of gastric secretion?
Liver- increase bile synthesis
Gallbladder- release bile
Pancreas- digestive enzymes
Pyloric Sphincter- constriction
What organ does secretin affect/what is the function?
Pancreas- mixture of bicarbonate and water to increase pH so digestive enzymes can function
What is the function of pancreatic alpha amylase?
Breaks down carbs and starches
What is the function of protease?
Breaks down proteins into amino acids
What is the function of pancreatic lipase?
Breaks down fats in the pancreas
What is the function of nucleases?
Break down RNA or DNA
What are the four pancreatic enzymes?
- Pancreatic alpha amylase
- Protease
- Pancreatic lipase
- Nucleases
