Fig. 3.

Insulin actions on many tissues. Insulin is secreted from the pancreas from the β-cells of the islets of Langerhans and circulated throughout the body via the bloodstream. The released insulin acts on insulin receptors located on the plasma membrane of target tissues (i.e., skeletal muscle, liver, adipose tissue and heart). In skeletal muscle, cardiac muscle, and liver, insulin promotes glucose uptake and storage as glycogen or TG. In adipose tissue, insulin promotes conversion of glucose to TG by increasing lipid synthesis.