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Any Biology buffs know about Bicarbonate ions and their role as a buffer?

E

Ender

Golden Member
I need to know how long it takes for Bicarbonate ions to take affect as a buffer...

Anyone know or have a link? I tried google but no luck 🙁
 
I couldn't find any specific reaction times just explanations that Bicarbonate Ions affect the Digestive system, which doesn't help me

I'm asking this because I want to know if the pH level of the small intestine would decrease slightly if the Bicarbonate ions don't have as much time to react in the duodenum due to increased peristalsis.
 
Originally posted by: caboob
Originally posted by: Ender
Originally posted by: Fenixgoon
H2O + HCO3 --> H2CO3 + OH-... OH- = hydroxide = base
Click to expand...

So it's an instantaneous reaction?
Click to expand...

Yes it is but it's an equilibrium, not a forward reaction.
HTH .🙂
Click to expand...

Hmm... so if there is a set amount of liquid required to be neutralized but that liquid moves faster than it normally does through a duct but the Bicarbonate secretions remain the same, would the neutralization have the same effect pH wise in both situations?

Wouldn't the Bicarbonate ions not have enough time to compeltely secrete? Or does the pancreas secrete a redundant amount of these ions?

Heh... I'm asking this because it's for a test mark and even my Biology teacher doesn't know -_-
 
The carbonate is a weak base and incompletely converts to bicarb and the amount that is converted is defined by its Ka. Well in this case, its Kb (a reaction constant).

So depending on whats entering the "system", the reaction moves in reaction to what's entering the system. So the presence of excess liquid (OH-?) in the system forces the conversion of bicarb to carbonate.

Conversely, dilution of this system (by adding water) drives the conversion from carbonate to bicarb. There is a discrete amount of buffer, keep in mind what state and proportion the buffer is in: conjugated salt or its weak base.

Hope this makes sense.
 
I don't know the chemistry behind any of this, I just wanted to know if the buffer would have time to completely neutralize all the liquid if the duodenum pushed the liquid out of the buffer site faster.
 
YOu've got to understand that digestion is much more than the body trying to buffer the acidic partly digested food from the stomach at the duodenum. The duodenum is also where bile, with its alkaline bile salts, and pancreatic juices, which have a pH of around 8.4-8.9, enter the digestive system. I'd think there is not enough time for bicarb, which is a very slow acting buffer in the body the way the body's system is set up in a negative feedback system, to try to buffer the digestive juices, nor would it want to at that early stage in the intestines due to the introduction of the aforementioned salts and such.
 
Well I argue that the pH may be just SLIGHTLY lower than it would if the duodenum didn't rush the chyme. Does that make sense? The difference between pH 8.9 and 8.8 is enough for me to be right and my teacher wrong 😀

edit: If I could get any sort of link that provides the reaction speed of Bicarbonate ions in an experiment or something... that would be great.
 
I'd agree with you in this case since the buffering action of bicarb is rate-limited by how fast it can diffuse through the physical space of the system. But after a sbort time the buffer eventually establishes equilibrium. To further complicate things, it depends what's entering the duodenum since amino acids liberated from digested protein also have buffering action.
 
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