30 Questions
Where are amino acids transported out of the enterocytes?
Basolateral borders
At what rate is absorption of amino acids in the duodenum and jejunum?
Rapid
Where is there little absorption of larger peptides?
Ileum
What is the source of approximately 50% of the digested protein?
Ingested food
Where does almost all of the protein in the stools come from?
Bacteria and cellular debris
What happens to undigested proteins in infants?
They are absorbed in moderate amounts
Where does almost all iron absorption occur in humans?
Duodenum
Which protein facilitates basolateral transport of iron out of enterocytes?
Hephaestin
What is the plasma iron level in men under normal conditions?
130 μg/dL
Which protein converts Fe2+ to Fe3+ in the plasma?
Transferrin
What is the main function of apoferritin in the body?
Iron storage
Where does heme bind to initiate transport into enterocytes?
Apical transport protein
What is the main function of cholesterol esterase?
Hydrolysis of cholesterol esters
How do fats in the small intestine become emulsified?
By the action of bile acids, phosphatidylcholine, and monoglycerides
What happens to lipids when bile acid concentration is high in the intestine?
Interact with bile acids to form micelles
Which components are generally found in the hydrophobic centers of micelles?
Fatty acids, monoglycerides, and cholesterol
How do lipids move to the brush border of mucosal cells for absorption?
Diffuse out of micelles through the unstirred layer
What is the role of micellar formation in lipid digestion and absorption?
Solubilize lipids and provide a transport mechanism to enterocytes
What type of immunoglobulins are largely present in maternal colostrum?
IgAs
How do protein antibodies in maternal colostrum enter the circulation of infants?
By transcytosis from the mammary epithelium
What process is responsible for the absorption of intact proteins from the intestine?
Endocytosis
What may provoke the formation of antibodies when foreign proteins enter the circulation?
Formation of antibodies
What is a common factor in susceptibility to individual food allergies?
Genetic component
Which of the following foods are mentioned as common offenders causing allergic responses?
Crustaceans, mollusks, and fish
How is glucose transported into the interstitium for absorption?
Through GLUT2
What provides the energy for glucose transport into the enterocytes?
Active transport of Na+
What happens when the Na+/glucose cotransporter is congenitally defective?
Severe diarrhea
Which transporter is responsible for transporting fructose into enterocytes?
GLUT5
What is the role of insulin in the intestinal transport of sugars?
Has little effect
Why is it important to promptly remove glucose and galactose from the diet in cases of a defective Na+/glucose cotransporter?
To prevent severe diarrhea
Test your knowledge on the transmission of secretory immunoglobulins (IgAs) from maternal colostrum to infants, providing passive immunity. Learn about the process of transcytosis, endocytosis, and exocytosis involved in the absorption of antibodies. Explore how infants benefit from these antibodies and the changes in protein absorption post-weaning.
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