Absorption of amino acids

Overall, it's a type of active transport- ATP is used in pumping sodium ions out of the cells into the lumen of the small intenstines, creating a higher concentration of sodium ions in the lumen than in the cells. This means sodium can freely diffuse back down its concentration gradient, from the lumen across the membrane carrying with it amino acids as a cotransport mechanism (and this bit would be 'facilitated diffusion').

Reply 2

OP

Thanks for answering endeavour, I wasn't sure anyone would bother cos the post was so long - so active transport into the small intestine cells from the lumen...and facilitated diffusion from the small intestine cells into the capillaries?

The text in the book is wrong, right?

Reply 3

wednesburywench

2

active transport apparently, my teacher picked up on the same thing n sed it was wrong in the small book but correct in the large main book. Ridiculous seein as its written by the same bloke

Reply 4

OP

wednesburywench

active transport apparently, my teacher picked up on the same thing n sed it was wrong in the small book but correct in the large main book. Ridiculous seein as its written by the same bloke

Thats brilliant thanks. Just as long as I know I'm revising the right thing.

Reply 5

Revenged

active transport uses carrier proteins in the membrane and ATP energy to move thigs against the conc gradient... right?

does faciliated diffusion also carrier proteins as well... what stops these productions from simply diffusing back out again?

and do these carrier proteins change shape when the substrate lands on the causing the substrate to be brought into the cell...

soz, it was ages ago i did unit 1

Reply 6

Cirsium

19

nah facilitated diffusion uses protein channels

Reply 7

Revenged

what exactly is the difference?

Reply 8

animaluvva

Thanks for answering endeavour, I wasn't sure anyone would bother cos the post was so long - so active transport into the small intestine cells from the lumen...and facilitated diffusion from the small intestine cells into the capillaries?

The text in the book is wrong, right?

i got confused wiv the same thing.
so is it active transport into the epithelial cells from the lumen for amino acid and glucose. im confused cos the book says that glucose and amino acid are different.

Reply 9

OP

ky1986

i got confused wiv the same thing.
so is it active transport into the epithelial cells from the lumen for amino acid and glucose. im confused cos the book says that glucose and amino acid are different.

Hey, from the answers I got on here and from what I have read I'd say yeah, active transport into the cell from the lumen and facilitated diffusion out the other side into the capillaries.

I'm still confused about the book saying that they're different because I don't know what the difference between glucose absorption and amino acid absorption could be. If anyone knows that'd be great?

Reply 10

idiopathic

I thought glucose and amino acids were absorbed in the same way too...

Reply 11

oxymoron

7

The mechanism you're talking about is normally referred to as a type of active transport as it does use energy from ATP hydrolysis to drive in amino acids to the cells against their concentration gradient.
The thing is, the mechanism relies of the facillitated diffusion of Na+ ions down their concentration gradient (which was set up by active transport) through a channel (cotransport) protein.

So in other words - it is active transport of amino acids using facillitated diffusion of Na+ ions.
There are several methods of glucose transport, but as far as I know - the one that happens in the human digestive system is the same as the above mechanism but relies of different channel proteins (as they are specific to the substrate).

Reply 12

oxymoron

The mechanism you're talking about is normally referred to as a type of active transport as it does use energy from ATP hydrolysis to drive in amino acids to the cells against their concentration gradient.
The thing is, the mechanism relies of the facillitated diffusion of Na+ ions down their concentration gradient (which was set up by active transport) through a channel (cotransport) protein.

So in other words - it is active transport of amino acids using facillitated diffusion of Na+ ions.
There are several methods of glucose transport, but as far as I know - the one that happens in the human digestive system is the same as the above mechanism but relies of different channel proteins (as they are specific to the substrate).

ohhhhhh thanks, so much clearer

Reply 13

every1 who is confused try this link.....
but its still different from the AQA A textbook tho

http://www.biologymad.com/Digestion/13%20-%20digestion_files/frame.htm

Reply 14

animaluvva

Hey, from the answers I got on here and from what I have read I'd say yeah, active transport into the cell from the lumen and facilitated diffusion out the other side into the capillaries.

I'm still confused about the book saying that they're different because I don't know what the difference between glucose absorption and amino acid absorption could be. If anyone knows that'd be great?

hey in the June 04 paper page 10, it shows the absorption of amino acid, which is same as described in the text book. check it out

http://www.aqa.org.uk/qual/gceasa/qp-ms/AQA-BYA6-W-QP-Jun04.pdf

Reply 15