What is the main site of carbohydrate absorption?
Jejunum
What is the route of absorbed monosaccharides?
Portal circulation to the liver
What are the mechanisms of carbohydrate absorption?
Which sugars are absorbed by facilitated diffusion?
Which transporter absorbs fructose in the intestine?
GLUT-5
Is fructose absorption sodium dependent?
No, it is sodium independent.
What type of transport is SGLT-1?
Secondary active transport
Which sugars are absorbed by SGLT-1?
What ions are required for SGLT-1 function?
Sodium ions
How does sodium facilitate glucose absorption?
Sodium moves down its gradient allowing glucose to move against its gradient.
What maintains the sodium gradient required for glucose absorption?
Na+/K+ ATPase pump
Which transporter moves glucose from enterocyte to blood?
GLUT-2
Where is GLUT-2 located in intestinal cells?
Basolateral membrane
What happens if Na+/K+ ATPase is inhibited?
Glucose absorption decreases
Which drug inhibits Na+/K+ ATPase and reduces glucose absorption?
Ouabain
What are alpha-glucosidase inhibitors?
Competitive inhibitors of enzymes that digest carbohydrates.
What is the clinical use of alpha-glucosidase inhibitors?
Treatment of type 2 diabetes mellitus
How do alpha-glucosidase inhibitors lower blood glucose?
By delaying carbohydrate digestion and absorption.
What is Phlorhizin?
A compound that inhibits glucose binding to its carrier.
How do flavonoids reduce carbohydrate absorption?
By inhibiting GLUT-2.
Where are flavonoids commonly found?
Fruits and vegetables
What is lactose intolerance?
Deficiency of lactase enzyme
What is the result of lactase deficiency?
Accumulation of lactose in the intestine.
What happens to undigested lactose in the intestine?
It is fermented by bacteria.
What are the products of lactose fermentation?
Acids and gases.
Why does lactose intolerance cause osmotic diarrhea?
Increased osmotic pressure due to unabsorbed lactose.
What are the main symptoms of lactose intolerance?
What is the treatment of lactose intolerance in infants?
Lactose-free milk.
What is the treatment of lactose intolerance in adults?
Lactose-free diet and yogurt.
What is sucrase deficiency?
A rare condition causing inability to digest sucrose.
At what age does sucrase deficiency usually present?
Early childhood.
What happens to fructose and galactose after absorption?
They are converted into glucose in the liver.
What is the fate of absorbed glucose?
Uptake by tissues, utilization, storage, or excretion.
Which tissues take up glucose without insulin?
What happens to excess glucose in the body?
Converted to glycogen or fat.
When does glucose appear in urine?
When blood glucose exceeds the renal threshold.
What is the renal threshold for glucose?
Approximately 180 mg/dL.
What are the mechanisms of carbohydrate absorption?
How does sodium facilitate glucose absorption?
Sodium moves down its gradient allowing glucose to move against its gradient.
How do alpha-glucosidase inhibitors lower blood glucose?
By delaying carbohydrate digestion and absorption.
Why does lactose intolerance cause osmotic diarrhea?
Increased osmotic pressure due to unabsorbed lactose.
What happens to fructose and galactose after absorption?
They are converted into glucose in the liver.
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