Metabolism Integration

Stanford Metabolic Map

https://mededucation.stanford.edu/pathways-download/

Role of the Liver

Central processing facility and metabolic hub

Determines what dietary nutrients and metabolic fuels are sent to peripheral tissues

Glucose regulator that:

• Removes excess glucose from blood when carbohydrate levels are high. Stored as glycogen.

• Releases glucose when glucose levels are low.

• Controlled by insulin and glucagon signaling

Portal vein directly delivers nutrients from small intestine and inactivates toxins from the diet. - “first pass effect” for food and IV medication

Glucose-6-P fates

Monosaccharides from food are converted to Glucose-6-P by hexokinase & glucokinase

Fate of Glucose-6-P depends on metabolic needs of the liver balanced with other organs

Most Glucose-6-P is used to generate glycogen.

But if other tissues (the brain) need glucose, Glucose-6-P can be dephosphorylated and released to the bloodstream.

If the liver needs NADPH, the Glucose-6-P is used by pentose phosphate pathway

Can also by used in glycolysis to generate Acetyl-CoA, for a variety of purposes

Pancreas

produces insulin and glucagon

also secretes digestive proteases for digestion in small intestine: Trypsin, Chymotrypsin, Elastase