Negative  feedback  in  glucose
   homeostasis.
<P>
<Li> A  rise in blood glucose causes release of insulin from beta cells
the  pancreas,  promoting  glucose  uptake in cells and storage as
glycogen in the liver.
<Li> A  fall in blood glucose stimulates alpha cells in the pancreas to
secrete  glucagon,  which  causes the liver to break down glycogen
and release glucose.