PSYC340 Study Guide - Final Guide: Feces, Gastrointestinal Tract, Mechanoreceptor
24 Jun 2018
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Chapter 24: The Digestive System
1. Identify the organs of the digestive system and the six basic processes they perform.
A. Digestion
Digestive system - The organs involved in the breakdown of food
B. Gastrointestinal (GI) tract or alimentary canal
C. The gastrointestinal (GI) tract, or alimentary canal, is a continuous tube that
extends from the mouth to the anus through the thoracic and abdominopelvic
cavities. Organs of the gastrointestinal tract include the mouth, most of the
pharynx, esophagus, stomach, small intestine, and large intestine.
D. The wall of the GI tract contains two major types of sensory receptors: (1)
chemoreceptors, which respond to certain chemicals in the food present in the
lumen, and (2) mechanoreceptors, such as stretch receptors, that are activated
when food distends (stretches) the wall of a GI organ.
E. Accessory digestive organs - The accessory digestive organs include the teeth,
tongue, salivary glands, liver, gallbladder, and pancreas.
F. Basic processes
F.I. Ingestion - This process involves taking foods and liquids into the mouth
(eating).
F.II. Secretion
F.III. Each day, cells within the walls of the GI tract and accessory digestive
organs secrete a total of about 7 liters of water, acid, buffers, and
enzymes into the lumen (interior space) of the tract.
F.IV. Mixing and propulsion
F.V. Alternating contractions and relaxations of smooth muscle in the walls of
the GI tract mix food and secretions and move them toward the anus.
This capability of the GI tract to mix and move material along its length is
called motility
F.VI. Digestion- Mechanical and chemical processes break down ingested food
into small molecules.
F.VII. Mechanical digestion
F.VII.a. In mechanical digestion the teeth cut and grind food
before it is swallowed, and then smooth muscles of the stomach
and small intestine churn the food to further assist the process. As
a result, food molecules become dissolved and thoroughly mixed
with digestive enzymes
F.VIII. Chemical digestion
F.VIII.a. In chemical digestion the large carbohydrate, lipid,
protein, and nucleic acid molecules in food are split into smaller
molecules by hydrolysis. Digestive enzymes produced by the
salivary glands, tongue, stomach, pancreas, and small intestine
catalyze these catabolic reactions. A few substances in food can
be absorbed without chemical digestion. These include vitamins,
ions, cholesterol, and water.
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Document Summary
Identify the organs of the digestive system and the six basic processes they perform: digestion. Ingestion - this process involves taking foods and liquids into the mouth (eating). Each day, cells within the walls of the gi tract and accessory digestive organs secrete a total of about 7 liters of water, acid, buffers, and enzymes into the lumen (interior space) of the tract. Alternating contractions and relaxations of smooth muscle in the walls of the gi tract mix food and secretions and move them toward the anus. This capability of the gi tract to mix and move material along its length is called motility. Digestion- mechanical and chemical processes break down ingested food into small molecules. In mechanical digestion the teeth cut and grind food before it is swallowed, and then smooth muscles of the stomach and small intestine churn the food to further assist the process. As a result, food molecules become dissolved and thoroughly mixed with digestive enzymes.
