The duodenal lumen (and pancreatic proteases like CHYMOTRYPSIN) is the site where pancreatic enzymes (“endopeptidases”) cleave large polypeptides into smaller bits (=dipeptides,tripeptides). It is at the BRUSH BORDER where the smallest kinds of peptides (dipeptides,tripeptides) are broken down into their amino acids, which finally can be co-transported with Na+ into the intestinal cell.
I think about it this way:
One of the Doctors in Training videos talked about absorption of nutrients, and specifically mentioned that dipeptides and tripeptides are cotransported with hydrogen into the Intestinal mucosal cells while single AAs are cotransported with Na+. So not only do dipeptides and tripeptides make it into the intestinal mucosa before being broken down, they actually get in faster than single AAs do.
Me: I am sorry to say but because of the consequences of your DM we will have to amputate your leg Patient: okay, but I have one question Me: yes? Patient: is fructose broken down in intestinal lumen or intestinal mucosa? Me: ..... Patient: ..... Me: I think its intestinal lumen
This question broke me more than the peptides.
Why is duodenal lumen incorrect? I thought pancreatic enzymes (chymotrypsin, carboxypeptidase) would be located here.
theres a zanki card in the GI deck from costanzo showing luminal side H+/dipeptide and H+/tripeptide co-transporters. Then inside the intestinal mucosa, the di and tripeptides are broken down into amino acids where a basal side transporter puts them into the blood stream
Heres a link showing that:
Di- and Tri- peptides can enter into enterocytes via PepT1 transporters and be broken down to amino acids within the enterocytes. Hence why the lumen is not the best answer
The semantics of this question made me vomit blood.
At least one day a patient will look me in the eyes and ask " where are tripetides broken down at". I will smile at them and say "the intestinal mucosa and not the duodenum". They'll smile back and then i'll then i'll walk away and think of this moment as I jump from the window.
submitted by ∗seagull(1933)
The semantics of this question made me vomit blood.
One day a patient will look me in the eyes and ask, "Where are tripetides broken down?" I will smile at them and say, "the intestinal mucosa and not the duodenum." They'll smile back and I'll walk away and think of this moment as I jump from the window.