30 Questions
Where does almost all iron absorption occur in humans?
Duodenum
Which protein facilitates basolateral transport of iron out of enterocytes?
Hephaestin
What is the normal percentage of iron saturation in transferrin in the plasma?
35%
Which subtype of heme oxygenase removes Fe2+ from porphyrin in the cytoplasm?
HO-2
Where is most of the iron stored in the body?
Ferritin
Which protein is involved in binding Fe3+ to form transferrin?
Hephaestin
What is the normal plasma iron level in women?
$110 \ μg/dL$
In which part of the body does heme bind to an apical transport protein?
Enterocytes
What is the predominant form of iron in the body?
Fe2+ in hemoglobin
What is the function of apoferritin in the body?
Iron storage
Which enzyme can auto-catalytically activate trypsinogen?
Enterokinase
Where do some amino acids get liberated by aminopeptidases and endopeptidases?
Cytoplasm of mucosal cells
Which system transports dipeptides and tripeptides into enterocytes using H+?
PepT1 system
What is the final location where amino acids are digested into the bloodstream?
Cytoplasm of mucosal cells
Which deficiency results in protein malnutrition due to a congenital abnormality?
Enterokinase deficiency
Which enzyme hydrolyzes amino acids at the carboxyl ends of polypeptides?
Carboxypeptidase
What is the primary function of PepT1 system?
Transport dipeptides and tripeptides into enterocytes
Which of the following systems require Na+ for transport?
Na+-cotransport systems
Where do some free amino acids get liberated in the digestive process?
Intestinal lumen
Which enzyme is an exopeptidase that hydrolyzes amino acids at the carboxyl ends of polypeptides?
Carboxypeptidase
Where do M cells pass protein antigens to?
Lymphocytes
Which transporters are expressed on the apical membrane of enterocytes for nucleoside absorption?
Equilibrative and concentrative nucleoside transporters
Where are nucleotides split into nucleosides and phosphoric acid in the intestine?
Luminal surfaces of mucosal cells
Which cells secrete IgA in response to subsequent exposures to the same antigen?
Lymphocytes
What is the quantitative significance of lingual lipase and stomach lipase for lipid digestion?
Minor contributors to lipid digestion
Which transporter requires active transport for absorption of bases in the intestines?
Concentrative nucleoside transporter
Where are activated lymphoblasts initially released into following circulation?
Intestinal mucosa
In which species is lingual lipase secreted by Ebner glands?
Humans
What is the direct effect of free fatty acids generated by lingual and stomach lipase?
Signal to gastrointestinal tract parts
Which organ secretes pancreatic nucleases that split nucleic acids into nucleotides?
Pancreas
Test your knowledge on the absorption of amino acids in enterocytes and their transportation into the hepatic portal blood. Learn about the intracellular hydrolysis of peptides and the different transport systems involved in amino acid absorption.
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