The Gastro-intestinal System 2 Flashcards
What are the main functions of the Stomach?
- Stores ingested food
- Secretes gastric juice (acid, mucus & intrinsic factor,
- digestive enzymes - pepsin, lipase)
- Mixes food with gastric juice
- initiates digestion of proteins & fat
- kills bacteria
What is Chyme?
Partially digested food
Where is the chyme moved into?
The duodenum
What is hydrochloric acid function and where can it be found?
- Hydrolysis; Sterilisation of meal
- Found in the Parietal cell
What is the function of intrinsic factor and where can it be found?
- Vitamin B12 absorption
- Parietal cell
What is the function of intrinsic Pepsinogen and where can it be found?
- Protein digestion
- Found in the chief cell
What is the function of mucus, bicarbonate and where can it be found?
- Gastroprotection
- Found in Surface mucous cell
What is the function of Trefoil factors and where can it be found?
- Gastroprotection
- Surface mucous cells
What is the function of histamine and where can it be found?
- Regulation of Gastric secretion
- Found in ECL cells
What is the function of Gastrin and where can it be found?
- Regulation of Gastric secretion
- G cells
What is the function of Gastrin Releasing Peptide (GPR) and where is it found?
- Regulation of Gastrin Secretion
- Found in the nerves
What is the function of Acetylcholine (ACh) and where can it be found?
- Regulation of Gastric Secretion
- Found in the Nerves
What is the function of somatostatin and where can it be found?
- Regulation of Gastric Secretion
- Found in the D cells
What are the 3 Phases of Gastric Secretion?
- Cephalic (“Head”) phase
- Gastric Phase
- Intestinal Phase
What is the cephalic phase?
- Triggered by factors arising before food enters the stomach – thought, smell, sight or taste of food
What is the Gastric Phase?
- Triggered by factors resulting from the presence of food in
the stomach
What is the Intestinal Phase?
- Triggered by factors resulting from movement of food
from stomach into duodenum
What are Carbohydrates digested by?
Salivary Amylase
What are proteins partially digested by?
By Pepsin in the Antrum
What does the Gastric Mucosal Barrier do?
Protects the stomach from damage
Describe how the Gastric Mucosal Barrier protects the stomach from damage?
- Cell membranes of gastric mucosal cells are impermeable to
HCl on the luminal side - Tight junctions between adjacent gastric mucosal (epithelial)
cells are impermeable to HCl - The HCO3– : rich mucus serves both as protective physical
barrier & as chemical barrier that neutralizes acid close to
gastric mucosa - Rapid rate of cell division – entire stomach lining replaced in
3 days - Prostaglandins inhibit acid secretion & promote alkaline
mucus secretion
What are the functions of the Small Intestine?
- Main site for digestion & absorption of ingested food
Secretes aqueous salt & mucus solution for lubrication
& protection - Utilizes segmentation & peristaltic contractions to mix
& propel chyme, and facilitate absorption - Digestion occurs via action of bile, pancreatic enzymes
& intestinal (brush-border) enzymes - Absorption occurs along the entire length – but largely
in the duodenum & jejunum
List the small intestine structure and how it relates to its function
- Mucosal surface thrown into permanent circular folds —>
3-fold Increase in surface area - Microscopic finger-like projections (villi) project from circular
folds —> 10-fold Increase in surface area - Villi are covered by epithelial cells
- Epithelial cells have numerous smaller, hair-like projections,
called microvilli or brush border —> 20-fold Increase in surface area - 3 types of digestive enzymes are expressed on the
membranes of microvilli or brush border – enteropeptidase,
disaccharidases & aminopeptidases
