To survive, your body must have a system for transforming food and drink into
absorbable nutrients. Digestion begins when you see, smell, feel, or taste foods. The
hormonal and nervous systems signal the gastrointestinal tract that food is on the way.
Muscles flex and digestive secretions flow. A group of cooperating organs orchestrates
digestion including the mouth, esophagus, stomach, small and large intestines,
pancreas, liver, and gall bladder.
To get the nourishment you need, nutrients must successfully traverse the
gastrointestinal tract, or the GIT. The GIT is a long, hollow tube that extends from the
mouth to the anus. Foods contain macronutrients that are broken down during
digestion into smaller units that are absorbed by cells lining the small intestine.
Ultimately nutrients traverse absorptive cells and are released into the bloodstream or
lymph system and transported throughout the body.
Sometimes problems arise such as regurgitation of stomach contents into the
esophagus, ulcers in the stomach, a blocked bile duct, or insufficient enzymes. Knowing
more about the digestive process helps you avoid these problems and stay healthy.
Recognize the system of cooperating organs
Outline the contribution each organ makes to digestion
Identify simple sugars, amino acids, and fatty acids as products of digestion
Describe the role of the mouth, teeth, tongue, epiglottis, and esophagus in
chewing, lubricating, and delivering food and drink to the stomach
Explain the cause of heartburn or gastroesophageal reflux disease
Identify common sense habits that reduce esophageal damage
Discuss how the stomach is protected from the effects of acid and enzymes
Place stomach acid on a pH scale
Correlate stomach ulcers with known causes
Associate the small intestine and villi with their roles in transforming
macromolecules into small, absorbable units
Match types of absorption (passive, facilitated, active) with energy requirements