Secretin is an enzyme formed by the upper intestinal layer and gets transported by blood to the PANCREAS which it stimulates: causing the flow of pancreatic juice, also the flow of bile and intestinal juice but to a lesser extent.
Alongside Gastrin, Secretin is one of the hormones of the Gastrointestinal tract; but their functions differ
A major factor in determining the mode of nitrogen excretion is the availability of water in the environment. Generally, aquatic animals excrete mostly ammonia, whereas terrestrial animals excrete either urea or uric acid.
