Flashcards in Drug Absorption #2 Deck (94)
secrete gastrin (which in turn controls the secretion of HCl)
About ___L/day of fluids are secreted by the stomach
Would you anticipate significant absorption from the stomach? Why?
-no, almost no drug is absorbed by the stomach
-drugs do not stay in the stomach long enough and the stomach has a small surface area
Where is the site of most absorption of drug?
small intestine due to the large membrane surface area
What is the pH of the stomach? with food?
food neutralizes the stomach--> pH goes up to around 4,5, or 6
What are the 3 segments of the small intestine?
-duodenum: connected to the pylorus (upper)
T/F Each segment of the small intestine have regional differences
TRUE. transporter proteins are located at specific sites in the intestine
What components help tribute to the large surface area of the small intestine?
-folds of kerckring (increase 3x)
-villi (increase 30x)
-microvill (increase 600x)
Is stored in the _______; made by the _____
gall bladder; liver
gall bladder empties bile into the duodenum (ph ~6)
Why does the pH change from 2 when it leaves the stomach and go up to 6?
bicarbonate ion-->neutralize acidic fluid that is emptying from the stomach
What is the primary function of the large intestine? pH?
storage of waste; pH 5.5-7
T/F There are vili present in the Large Intestine.
FALSE; no villi present leading to absorption being poorer
_____ are present in the large intestine. What is a downfall of having this there?
microflora--> if a drug makes it to the large intestine it may destroy the bacteria that is already there and the bacteria could absorb the drug and metabolize it
As pH varies from a weak acid or base... so does
the degree of ionization
Summary of pH in GI tract
-stomach (fasting): less than 2
-stomach (fed): 2-6
-large intestine: 5.5-7
T/F Solids and liquids are emptied the same way from the stomach
FALSE; emptied differently
What do you think is a major factor affecting stomach emptying?
Fed mode of the stomach (3)
-one type of pattern
-regular, frequent contractions
-grinding and mixing occurs as long as food is present
_____ and ___ will empty from the stomach and leave in a FIRST order process
liquids and particles less than about 5-10 mm
Liquids empty the stomach _____. High Volume--> _____
immediately; faster emptying
_____ leave in a ZERO order process, it is converted at a ______ rate
What are the 4 phases of the fasting mode in the stomach?
II: increase in tone and activity (few contraction of different magnitudes)
III: strong contractions--> HOUSEKEEPER
IV: decline in activity
The housekeeping stage of the fasting mode....
sweeps anything left in the stomach out
How long does it take for material to move through the entire small intestine?
T/F Solution, pellets, and single units move through the small intestine at about the same rate
TRUE-> it does not depend on the presence of food
Absorption _____ occur in the stomach--> but the ____ of emptying of the stomach does effect drug absorption
DOES NOT; RATE
What factors affect gastric emptying? (11)
-hydrogen ion concentration
Fats, proteins, and carbs typically have _____ emptying if they are the same caloric value. The presence of these _____ emptying
____ (food) have the greatest effect on emptying on a molar basis
fats: they are harder to digest