As a premed student, I had not taken any courses on human anatomy or physiology so medical school/prepping for the MCAT were my first instances of this information. And while studying, sometimes I would forget the big picture and just memorize small bits of information which did not translate to a good understanding of the information.

Blue = Clinical Significance

What the heck is bile and why do we need it?

Your liver (the big organ that sits on the right underneath your ribs and if you can feel it under the ribs then the liver is way too big) produces bile and that bile travels to the gallbladder to be stored. The bile kind of hangs out in the gallbladder until you eat a meal with lipids in it. Then, bile is released from the gallbladder and heads to the duodenum (first part of the small intestine) in order to help the lipids get digested. Lipids and bile acids combine to make a structure called a micelle (look this up if you don’t know what it is) and this micelle is easily digested by an enzyme released by your pancrease (pancreatic lipase). So if were not able to make bile for some reason (there are certain diseases which can inhibit production of bile), you would not be able to digest lipids properly. Also, it is important to know that bile is actually what gives poop it’s brown color. So if for some reason a patient came into the office and complained of stools that were lighter than normal, you would automatically know there was some problem with the bile.

Where does bile come from?

Bile is made from the precursor cholesterol. This is why it is so important that we get most of the bile out of our bodies, to get rid of that darn cholesterol.

How does the gallbladder know when to release bile from its stores?

Let’s start from the beginning, you eat a very fatty and greasy slice of pizza. This goes through your stomach and when it ends up at the duodenum, the duodenum releases a hormone called Cholecystokinin (I don’t think you need to know the name of the hormone for the MCAT but in case you do, it is also known as CCK). CCK goes to the gallbladder and says “hey there is lipid that needs to be digested come on down.” The gallbladder contracts and releases bile which goes to the duodenum to make micelles with the lipids that need to be digested. So now if someone did not have bile in the gallbladder, not only would stools be lighter in cool since bile gives poop that dark brown color, but also the stools would be fatty and greasy looking because the lipids were not properly digested.