BIOL 2420 Lecture Notes - Lecture 31: Portal Vein, Ileocecal Valve, Hepatic Portal System
9 Mar 2018
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Unit 4: digestive system physiology (f: motility of si: Excess sugar is stored as fat because fat is lighter: vldl (very low density lipoproteins) = triglycerides and proteins (good way of carrying them because triglycerides are hydrophobic) Glucose is converted into triglycerides, which get transported in vldls. The vldls exit the liver and enter the capillary. Note: inside the vldls, the triglycerides are broken down again into their constituent parts (fas & a monoglyceride) The vldls cannot exit the capillary because they"re so large, so lipoprotein lipase cuts the vldls and the small hydrophobic substances (the fas) can easily diffuse into the tissue. The free fatty acids diffuse across, but the monoglyceride (has polarity) simply re- enter the liver: vldls do not penetrate the capillaries. The chylomicron passes by the tissues and there are enzymes there to break it apart: absorbed aas, aas are taken up by hepatocytes (liver cells)
