Hi,
I had a question regarding the last step of intestinal fat absorption. I understand that fats are broken down and then go through enterocyte where they are packaged up and formed into chylomicrons and then, are transported into the lacteal. After the chylomicrons get into the lacteal, does some of the "fat" go into the capillaries that are wrapped around the lacteal?
Chylomicron protein and lipid composition is apparently modified during passage through the lacteal - this seems to imply that some fat could be transferred to the capillaries surrounding the lacteal but I am not 100 % sure on this.
My other question is that if chylomicrons are going to the liver anyways, why can't they just go into the lacteal and then go into the capillary system surrounding the lacteal, rather than go all the way up into the thoracic duct and drain into the systemic circulation and then end up in the liver?
Chylomicrons are too large to enter into the blood capillaries, and consequently they are transported through the lacteal (lymph).
My next question is, does something happen to the chylomicrons when they are in the lymphatic system, such as change shape or polarity some how? I am just confused regarding chylomicrons ending up in the liver anyways, so why do they travel in the lymphatic system?
I think this kind of connects up to the first two questions - there are some compositional changes when the chylomicron enters and exits the lacteal. I am not sure as to the nature of those changes, perhaps chylomicrons become more hydrophobic upon entry into the lacteal and more hydrophilic upon exit to the subclavian vein. However, the main point is that they are too large to be transported through the capillaries, and must go through the lymph instead.
I hope this helps!
Katt