Anatomy B/C

[SciBomb97]

Sure thing.
Oh I see, you're that person who's always adding to the wiki...
I understand the *evil look*

[mnstrviola]

Sure thing.
Oh I see, you're that person who's always adding to the wiki...
I understand the *evil look*

It's okay, it was more of a friendly evil look. If that's possible...

I am also taking a break from editing the digestive wiki cuz I need to practice for my actual events

[Kokonilly]

Kokonilly, will the notedump be for the digestive system?

I'm thinking respiratory.

[mnstrviola]

Kokonilly, will the notedump be for the digestive system?

I'm thinking respiratory.

Oh okay. Yeah that would be nice

[kappakun]

I have a question that recently came up that left me debating with my partner:
Where does fat digestion begin?
I have read many textbooks that say the mouth produces lingual lipase, which would imply that fat digestion begins in the mouth.
However, in class we were taught that fats are digested in the small intestine via pancreatic lipase, and this seems to be the correct answer among many online multiple choice tests I've taken. However I still would think that the answer should be the mouth because of lingual lipase.

Any thoughts on this?

[SciBomb97]

Ok, so this seems to be about the mouth producing lingual lipase.
Of what I've read out of the textbooks, lingual lipase is produced in the mouth and the digestion of fats begins in the mouth via saliva (triglycerides are broken down into simple glycerides and fatty acid chains). Now, the thing about lingual lipase is that it has an optimum pH of about 4.5-5.5 (and the pH of saliva is about 6.75-7), so digestion by lipase is continued in the stomach, which is what you probably learned in class. But digestion of fats does begin in the mouth.
I confirmed the textbook using Wikipedia http://en.wikipedia.org/wiki/Lingual_lipase.

[mnstrviola]

I have a question that recently came up that left me debating with my partner:
Where does fat digestion begin?
I have read many textbooks that say the mouth produces lingual lipase, which would imply that fat digestion begins in the mouth.
However, in class we were taught that fats are digested in the small intestine via pancreatic lipase, and this seems to be the correct answer among many online multiple choice tests I've taken. However I still would think that the answer should be the mouth because of lingual lipase.

Any thoughts on this?

Yeah, salivary lipase (or lingual lipase) starts the digestion of lipids. I believe most of the digestion of lipids, however, occurs in the small intestine.

[SciBomb97]

What mnstrviola said... most digestion of lipids occurs in the small intestine

[SciBomb97]

I was reading stuff about the oxygen-hemoglobin dissociation curve, and the wording is on a slightly higher level than I can understand.
Can anybody explain it in plain English?

[kappakun]

I was reading stuff about the oxygen-hemoglobin dissociation curve, and the wording is on a slightly higher level than I can understand.
Can anybody explain it in plain English?

The curve is a graphic representation of the factors that affect O2's affinity for hemoglobin.
The most important factor that determines the percent O2 saturation of hemoglobin is partial pressure of O2 (PO2). If you look at the dissociation curve, the partial pressure of O2 is on the x axis and % saturation is on the y axis.
This is the key relationship: When PO2 is high, hemoglobin has more affinity for O2. When PO2 is lower, there is less affinity for O2.

You may have seen examples of when the curves are shifting as well.
This illustrates the other factors that affect hemoglobin affinity for oxygen.
One such example is the Bohr effect (or Bohr shift). An increase in H+ causes O2 to unload from hemoglobin. So at lower blood pH (more H+), the curve pigeon to the right (or downward), demonstrating a lesser affinity. At higher pH, the curve shifts left (or upward), demonstrating the converse.
Here is a picture ref: http://chemistry.ewu.edu/jcorkill/biochem/fig_07_11.jpg
Another factor is temperature. As temperature increases, the amount of O2 released from hemoglobin increases too.
There's also a substance called BPG and is formed in red blood cells. The more BPG there is, the more O2 is unloaded from hemoglobin (having the same effect as an increase in temperature)
Hope that helped a bit!