5 - Gastrointestinal Absorption PPT Flashcards
Welcome back dedicated GI studiers! Your first question- what is the total amount of fluid in liters that should be absorbed by the intestines each day?
8.5 Liters
How do we get our 8.5L number?
Ingested fluid (1.5L) plus excreted fluid (7.0L)
Why is the stomach poor at absorption?
It do be lackin’ in villi doe
What makes the small intestine so highly absorptive?
It has many folds which increase the surface area
Where are these circular folds best developed?
In the duodenum and jejunum
What is the brush border?
Millions of villi that project from the surface of the mucosa
What is pinocytosis?
Cellular drinking
What contract rhythmically to keep the microvilli constantly moving?
Actin filaments
What absorbs carbs, fats, AAs, ions and water each day?
The small intestine
How is water absorbed and what laws must it obey?
Water is absorbed by diffusion and must obey the laws of osmosis.
How is sodium absorbed?
Active transport
Glucose is also absorbed by an active transport process. What mode is its absorption and what ion is involved?
- Co-transport mode
- Sodium takes it in
(TRUE/FALSE): Glucose and galactose utilize the same transport process.
(TRUE): Almost completely identical.
How does fructose differ from glucose and galactose as far as transportation?
Fructose is transported by facilitated diffusion
Proteins break down into di/tripeptides and AAs, and are cotransported with what ion?
Sodium
How do fats become soluble in chyme and thus able to penetrate the brush border to be absorbed?
They are taken in by bile micelles which are soluble in chyme
How many milliliters of chyme normally passes through the ileocecal valve into the large intestine?
1500ml
What can the rate of the chyme entering the large intestine indicate (slow vs fast)?
- Slow: not enough water, CONSTIPATION
- Fast: not enough liquid absorbed, DIARRHEA
Why did the proximal half of the colon get the name “absorbing colon”? Think reeeally hard
Because most of the absorption in the large intestine occurs in the proximal half of the colon!!!
What is the purpose of the distal colon?
It functions as FECES storage and is known as the storage colon
(TRUE/FALSE): The mucosa in the large intestine can actively absorb sodium.
(TRUE): Sodium is actively absorbed.
What hormone in large quantities enhances transport capability?
Aldosterone
What does the mucosa of the large intestine secrete while it absorbs chloride ions?
Bicarbonate ions
The combined absorption of sodium and chloride ions creates a __________ in the large intestine that causes __________ .
- Gradient
- Water absorption
