As

soon as the person tastes the pizza, irrespective of how much digestion

happens, the taste receptors in the tongue send a signal via the use of nervous

system.

As

the person eats the pizza, the endocrine system regulates the release of the

hormone gastrin, which is responsible for breaking down the fat in the pizza.

As

the person eats the pizza, the cheese in the pizza is broken down primarily by

the enzyme maltase.

The

digestion of  fatty food takes in the

order of several hours, so it will likely be that the person feels full only

after several hours.

As

the person eats the pizza, the protein in the pizza is broken down primarily by the

enzyme lipase.

As

the person eats the pizza, the endocrine system regulates the release of the

hormone gastrin, which is responsible for breaking down the protein in the

pizza.