Protein digestion Flashcards
What proteases are released by which cells from the pancreas?
Acinar cells release, trypsinogen, chymotrypsinogen, proelastase, procarboxypeptidase A and B
What activates trypsinogen?
Enterokinase
What activates chymotrypsin, proelastase, procarboxypeptidase A and B?
Trypsin
What are the endopeptidases and where do they work on proteins?
trypsin breaks carboxyl group of basic AA (Arg and Lys). Chymotrypsin breaks carboxyl group of aromatic AA. Elastase breaks carboxyl group of aliphatic AA (Gly, ala, val, leu, ile, ser, thr, cys and met)
What are the exopeptidases?
act on carboxyl end of protein, releasing single AA. carboxypeptidase A: on aromatic or aliphatic side, release a single AA.
Carboxylpeptidase B acts on aa with basic side chain (Lys and arg)
What is mucosal hydrolysis?
brush border peptidases work on short peptides. Aminopeptidases that work on Amino end (A or N).
Di or tripeptidase work on di or tri peptides
What are the main VFAs produced for energy in the hindgut?
Acetic (C2), Propionic (C3) and butyric (C4)
What are the main differences in hindgut of swine and poultry?
In swine the colon is very long and cecum is short and cylindrical blind sac, has ileocecal valve, terminates in the rectum and passage time is slow.
In poultry: one short colon and 2 ceca (blind sacs), has ileocolonic valve, ends in cloaca and passage time is fast.
What is the histology of hindgut?
Similar to midgut but there are more goblet cells to secrete mucus so that the digesta can be mobilized, as it is drier than in the midgut
What are haustras?
Pouches in the colon that are used to retain fines and fluids for fermentation
What systems does the cloaca serves?
Digestive, urinary and reproductive
How is reverse peristalsis in poultry?
It evacuates cecal content into the colon and out of cloaca, it initiates in the cloaca and moves contents back into the ceca for fermentation and nutrient absorption
What fills the cloaca?
Coprodeum receives from colon
Urodeum receives urine from kidneys, ureters
Proctodeum receives from oviduct or sperm duct
How can the colon be divided in swine?
colon is very long (can be divided into ascending (most absorption), transverse and descending).
Why may the collection of excreta from poultry reflect only the unabsorbed nutrients from the GIT?
Because in poultry the digestive, reproductive and urinary system all end in the same place, the cloaca. Thus contents from the hindgut are excreted together with uric acid that comes from the uretra. therefore more nutrients may be present in the excreta than just undigested nutrients from GIT.
