Where does digestion end?

[Persistence101]

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In the liver or small intestines? This was an MCAT question last year and a lot of us couldn't agree on one answer.

 

[Aptamer]

Remember, almost all of digestion occurs in the small intestine. (Some digestion occurs in the mouth with amylase and some in the stomach by pepsin and H+ but most in the small intestine.) The liver main function, in digestion, is to produce bile which is then stored in gall bladder. It is then released when stimulated by cholecystokinin. Within the small intestine, most of the digestion is done in the duodenum via enzymes. The digested products are then absorbed in the ileum and jejenum.

 

[Kry]

I think (s)he might be referring to protein digestion.

 

[Persistence101]

Originally posted by Kry
I think (s)he might be referring to protein digestion.

yes, you are right...

 

[Unda Presha_TX]

Originally posted by Persistence101
In the liver or small intestines? This was an MCAT question last year and a lot of us couldn't agree on one answer.

This has got to be a trick question, but if I was down to either liver or small intestine then I'm going with small intestine. That's where most of the real digestion takes place. However, given the answer choice of large intestine (colon), I'd go with large intestine because if I'm not mistaken in the colon some water is withdrawn from chyme (that sweet, that nasty, that gushy stuff). I could be wrong, but I consider that removal of water as a form of digestion. Also, the large intestine is near the end of the GI tract.

So, where does digestion end? What's the answer?

 

[Persistence101]

Originally posted by Unda Presha_TX
So, where does digestion end? What's the answer?

I dunno...you tell me.






Anyone???

 

[beastmaster]

For god's sake.

Protein digestion begins in the stomach, continutes mostly in the duodenum, and ends in the jejunum, where all of the protein is broken down to amino acids (no longer considered protein) no larger than a tri-peptide and is absorbed into the bloodstream.

 

[Aptamer]

First, the definition of digestion is the catabolism of biomolecules (proteins, fats, nucleic acids, and carbohydrates) into absorbable units. Second, if we're following digestion of proteins then here it is:

Stomach - Proteins broken down to polypeptides and peptides by pepsin and hydrolysis by H+.

Small Intestine - In the duodenum, endopeptidases (trypsin, the chymotrypsins, and elastase) breaks interior peptide bonds. Also in the duodenum, exopeptidases (carboxypeptidase and aminopeptidase) hydrolyzes amino acids at the ends of the polypeptide chain. The di- and tri- peptides are transported into the intestinal cells and hydrolyzed by intracellular proteins.

Absorption (not digestion) occurs rapidly in the duodenum and jejunum but slow in the ileum. (Some amino acids actually enter the colon but then utilize by microbes.)

Amino acids are then enter the hepatic portal vein which leads into the liver which then initiates amino acid metabolism:
-Transamination, amination, and deamination for conversion of AAs for the common metabolic pool.
-Conversion to body protein (hair, nails, etc)
-Excretion via urine
-Creatine
-Nucleotide biosynthesis
-Hormones and Neurotransmitters
-Urea


By looking at the flow of proteins to amino acid metabolism (included because the OP brought up the liver and protein digestion) and the definition of digestion listed above, digestion ends at the duodenum where almost all proteolysis occurs.

But I could be wrong.

 

[Aptamer]

Beastmaster had the more succinct answer.

 

[indo]

Entry: succinct
Function: adjective
Definition: brief
Synonyms: blunt, boiled down, breviloquent, brusque, compact, compendiary, compendious, concise, condensed, curt, laconic, pithy, short, summary, terse

 

[HIIC]

At the city waste management plant after its left your house's septic tank...

HAHA.... I KILL ME

peace out my nizzles

 

[PublicHealth]

Originally posted by Aptamer
First, the definition of digestion is the catabolism of biomolecules (proteins, fats, nucleic acids, and carbohydrates) into absorbable units. Second, if we're following digestion of proteins then here it is:

Stomach - Proteins broken down to polypeptides and peptides by pepsin and hydrolysis by H+.

Small Intestine - In the duodenum, endopeptidases (trypsin, the chymotrypsins, and elastase) breaks interior peptide bonds. Also in the duodenum, exopeptidases (carboxypeptidase and aminopeptidase) hydrolyzes amino acids at the ends of the polypeptide chain. The di- and tri- peptides are transported into the intestinal cells and hydrolyzed by intracellular proteins.

Absorption (not digestion) occurs rapidly in the duodenum and jejunum but slow in the ileum. (Some amino acids actually enter the colon but then utilize by microbes.)

Amino acids are then enter the hepatic portal vein which leads into the liver which then initiates amino acid metabolism:
-Transamination, amination, and deamination for conversion of AAs for the common metabolic pool.
-Conversion to body protein (hair, nails, etc)
-Excretion via urine
-Creatine
-Nucleotide biosynthesis
-Hormones and Neurotransmitters
-Urea


By looking at the flow of proteins to amino acid metabolism (included because the OP brought up the liver and protein digestion) and the definition of digestion listed above, digestion ends at the duodenum where almost all proteolysis occurs.

But I could be wrong.

Poop.

 

[Unda Presha_TX]

Originally posted by Aptamer
First, the definition of digestion is the catabolism of biomolecules (proteins, fats, nucleic acids, and carbohydrates) into absorbable units. Second, if we're following digestion of proteins then here it is:

Stomach - Proteins broken down to polypeptides and peptides by pepsin and hydrolysis by H+.

Small Intestine - In the duodenum, endopeptidases (trypsin, the chymotrypsins, and elastase) breaks interior peptide bonds. Also in the duodenum, exopeptidases (carboxypeptidase and aminopeptidase) hydrolyzes amino acids at the ends of the polypeptide chain. The di- and tri- peptides are transported into the intestinal cells and hydrolyzed by intracellular proteins.

Absorption (not digestion) occurs rapidly in the duodenum and jejunum but slow in the ileum. (Some amino acids actually enter the colon but then utilize by microbes.)

Amino acids are then enter the hepatic portal vein which leads into the liver which then initiates amino acid metabolism:
-Transamination, amination, and deamination for conversion of AAs for the common metabolic pool.
-Conversion to body protein (hair, nails, etc)
-Excretion via urine
-Creatine
-Nucleotide biosynthesis
-Hormones and Neurotransmitters
-Urea


By looking at the flow of proteins to amino acid metabolism (included because the OP brought up the liver and protein digestion) and the definition of digestion listed above, digestion ends at the duodenum where almost all proteolysis occurs.

But I could be wrong.

Crap!

 

[Wilford Brimley]

Originally posted by Aptamer
First, the definition of digestion is the catabolism of biomolecules (proteins, fats, nucleic acids, and carbohydrates) into absorbable units. Second, if we're following digestion of proteins then here it is:

Stomach - Proteins broken down to polypeptides and peptides by pepsin and hydrolysis by H+.

Small Intestine - In the duodenum, endopeptidases (trypsin, the chymotrypsins, and elastase) breaks interior peptide bonds. Also in the duodenum, exopeptidases (carboxypeptidase and aminopeptidase) hydrolyzes amino acids at the ends of the polypeptide chain. The di- and tri- peptides are transported into the intestinal cells and hydrolyzed by intracellular proteins.

Absorption (not digestion) occurs rapidly in the duodenum and jejunum but slow in the ileum. (Some amino acids actually enter the colon but then utilize by microbes.)

Amino acids are then enter the hepatic portal vein which leads into the liver which then initiates amino acid metabolism:
-Transamination, amination, and deamination for conversion of AAs for the common metabolic pool.
-Conversion to body protein (hair, nails, etc)
-Excretion via urine
-Creatine
-Nucleotide biosynthesis
-Hormones and Neurotransmitters
-Urea


By looking at the flow of proteins to amino acid metabolism (included because the OP brought up the liver and protein digestion) and the definition of digestion listed above, digestion ends at the duodenum where almost all proteolysis occurs.

But I could be wrong.

Holy Cow!

 

[Rudy1223]

#2

 

[Wilford Brimley]

In a toilet bowl.

 

[indo]

what about the bacteria that continue digesting the "solids"?