Small Intestine Flashcards
How is chyme propelled through the small intestine?
Peristaltic waves
The presence of chyme in the SI stimulates the release of what?
secretin
Secretin is released from what cells?
S cells
S cells are found where?
In the duodenum
Secretin stimulates the release of what?
Bicarbonate and water
Secretin stimulates what cells to release bicarbonate and water?
Pancreatic acinar cells
Bicarbonate rich mucus is also released by what? Where?
Brunner’s glands
duodenum
The bicarbonate-rich mucus does what?
neutralizes the gastric acid and makes the pH alkaline,
Protects duodenal wall from highly acidic gastric juice
What else does secretin do?
Decreases gastric motility
The presence of fat in the duodenum stimulates the release of what?
CCK - cholecystokinin
CCK is release by which cells where?
I-cells duodenum
CCK causes what to contract?
The gallbladder
CCK causes what to relax?
Sphincter of Oddi
CCK causes what to be excreted into the duodenum?
bile
CCK also stimulates what?
The pancreas to release enzymes which aid in the digestion of fat, starches, and protein
What enzyme completes the breakdown of starch into maltose?
Pancreatic amylase
Further digestion is assisted by enzymes from where in the small intestine?
Brush border of the enterocytes
Maltose breaks down what? Into what?
Maltose
2 molecules of glucose
Lactase breaks down what? Into what?
Lactose
Glucose and lactose
Sucrase breaks down what? Into what?
Sucrose
Glucose and fructose
What enzymes are found in the brush border of the enterocytes?
lactase, maltase, sucrase
Glucose is actively transported into the intestinal cells by what?
Sodium-glucose transporter
There is also a small amount of _______ that digests fat.
Intestinal lipase
Some fat is absorbed into the _________ which drain into what?
Central lacteals
Thoracic duct
What digests the polypeptides?
Intestinal peptidases
What are the proteolytic pancreatic enzymes? What do they produce?
trypsin chymotrypsin proelastase carboxypolypeptidase Produce: amino acids
Amino acids are _____ transported from the lumen into the intestinal cells by what?
Actively
Sodium-amino acid carrier
Fat breaks down to what in the SI?
Fatty acids and glycerol
Starch, glucose, and lactose break down into what in the SI?
Glucose
Fructose
galactose
Proteins breakdown into what in the SI?
Amino acids
All the products broken down are absorbed by the SI and transported where? Except what and to where?
To the liver
Except some fat - to central lacteals which drain into thoracic duct
