CPPS 303_Function & Regulation in Gastric Digestion_Feb 28 & March 3_2025 Flashcards
What are the three general functions of the stomach?
- Storage
- Digestion
- Protection
These functions allow the stomach to manage food intake, break down food components, and protect against pathogens.
How much food can an adult stomach store?
Roughly one liter
This storage capacity is essential for managing food intake before digestion.
What is gastric accommodation associated with?
Vagovagal reflex
This reflex helps the stomach adjust its volume to accommodate food intake.
What is the typical time required to empty stomach contents?
2 to 4 hours
This duration can vary based on the type of food consumed.
What enzyme is responsible for breaking down proteins in the stomach?
Pepsin
Pepsin acts as an endopeptidase, breaking peptide bonds of nonterminal amino acids.
What is the role of gastric lipase in digestion?
Responsible for approximately 30% of fat digestion without bile
It works alongside lingual lipase to initiate fat breakdown.
What is the function of acidic gastric juice in digestion?
- Unfolding of proteins
- Conversion of pepsinogen into pepsin
Acidic conditions are crucial for activating digestive enzymes.
What type of bacteria can survive the acidic gastric environment?
Helicobacter pylori
This bacterium is associated with gastric and duodenal ulcers.
What two body systems regulate gastrointestinal functions?
- Neural regulation
- Hormonal regulation
These systems work together to coordinate digestive processes.
What is the enteric nervous system often referred to as?
Brain of the gut
It contains millions of neurons that control gastrointestinal functions.
What type of neurons does the enteric nervous system consist of?
- Motor neurons
- Interneurons
- Sensory neurons
These neurons regulate motility, secretion, and sensory feedback.
What is the role of the vagus nerve in gastrointestinal function?
Supplies parasympathetic fibers to most parts of the GI tract
This innervation enhances GI secretion and motility.
What effect does sympathetic nervous innervation have on GI functions?
Causes a decrease in GI secretion and motility
It also increases sphincter tone by inhibiting enteric neurons.
What are the three main types of cells that produce gastric secretions?
- Mucous neck cells
- Parietal cells
- Chief cells
Each cell type has a specific role in digestion and secretion.
What hormone is released by G cells in the stomach?
Gastrin
Gastrin stimulates gastric acid secretion and is part of the hormonal regulation of digestion.
What initiates the cephalic phase of gastric acid secretion?
Sensory stimuli such as smell, sight, taste, thought, and swallowing of food
This phase prepares the stomach for food intake.
What is the role of histamine in gastric acid secretion?
Enhances the release of HCl by binding to H2 receptors on parietal cells
Histamine works synergistically with gastrin and ACh.
What is the pH range for pepsinogen conversion to pepsin?
Between 3.0 to 5.0
Conversion occurs more rapidly when pH is less than 3.
What phase of gastric secretion accounts for approximately 30% of total acid secretion?
Cephalic phase
This phase occurs before food enters the stomach.
What cells produce somatostatin (SST)?
Delta cells
SST inhibits gastrin release and thus regulates gastric acid secretion.
What happens during the gastric phase of acid secretion?
Food entry distends the gastric mucosa, activating vagovagal and local enteric reflexes
These reflexes stimulate further gastric acid secretion.
What do G cells release?
Gastrin
G cells are located in the gastric mucosa and play a key role in regulating stomach acid secretion.
What type of cells are ECL cells?
Enterochromaffin-like cells
ECL cells release histamine and are found near parietal cells in the stomach.
What initiates the gastric phase of acid secretion?
Entry of food into the stomach
The gastric phase is characterized by two primary stimuli: distension of the gastric mucosa and the presence of food.
