Describe the process as food enters and exits the stomach. Are there glands that control this?

The human stomach is a muscular bag located in the upper
middle of the abdomen.  When empty, the stomach flattens out, leaving a small air bubble
in the upper portion, and with the walls of the main body and lower portion of the
stomach more or less touching one another.  The lining is thrown into folds that
disappear as the stomach distends with food.

Ingested food
and liquids pass down the esophagus to enter the stomach.  The esophagus has a sphincter
muscle at its junction with the stomach that can contract to slow or control the entry
of food into the stomach.  There are no glands controlling this process, however there
are pressure sensors involved.

Gastric (stomach) emptying
is a complex process and varies according to the nature of the ingested
food.

In the case of ingestion of a large quantity of
water, there is no need for the water to remain in the stomach for processing, and it
will pass rapidly through the stomach into the duodenum and small
intestines.

A Big Mack, on the other hand, is handled
differently from the water.  Pressure sensors will promote relaxation and expansion of
the stomach and delay emptying.  Glands in the duodenum and small intestine will relay
information back to the stomach to modulate the stomach’s contraction and emptying. 
Like the esophagus, the stomach has a sphincter muscle at its outlet that helps control
the rate of gastric emptying.  The food will remain in the stomach longer than the water
in order for the gastric pepsin and acid to begin digesting the
food.

The first reference refers to the dog’s stomach, but
is applicable to humans.  The second gives expanded information on human gastric
emptying.