The document discusses two key aspects of the digestive system: 1. The swallowing process is initiated voluntarily but then proceeds automatically through a series of phases, beginning with mastication (chewing and crushing food) in the oral phase. 2. The regulation of gastric activity is controlled by the central nervous system and reflexes within the digestive tract walls, as well as hormones. Control occurs over three phases - the cephalic phase prepares the stomach for food, the gastric phase enhances secretions to break down the food, and the intestinal phase controls gastric emptying and triggers other organs.

1. THE DIGESTIVE SYSTEM
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2. The Swallowing (Deglutition) Process
A complex process that can be initiated voluntarily but
proceeds automatically once it begins. The process of
swallowing occurs in a series of phases:
STATION 19: let’s break it down!
Mastication, the
process of chewing
and crushing food,
occurs during the
oral phase!

3. The Regulation of Gastric Activity
The production of acid and
enzymes by the stomach mucosa
is controlled by the central
nervous system and is regulated
by reflexes within the walls of the
digestive tract and by hormones
of the digestive tract. Control of
gastric secretion proceeds in
three overlapping phases:
• Cephalic Phase – The sight, smell, taste, or
thought of food initiates the cephalic phase of
gastric secretion. This stage prepares the
stomach to receive food.
• Gastric Phase – Begins with the arrival of
food in the stomach. Secretions are enhanced
to homogenize and acidify the chyme.
• Intestinal Phase – Begins when chyme starts
to enter the small intestine. This phase
controls the rate of gastric emptying and
triggers other hormonal and neural events
that coordinate the activities of the intestinal
tract, pancreas, liver, and gallbladder.
STATION 19: let’s break it down!