SMHM 3 - DIGESTION,ABSORPTION& Introduction Tosurvive,...

DIGESTION, ABSORPTION, & TRANSPORTION OF NUTRIENTS
Introduction
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.
Learning Outcomes
• 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
• Identify chyme
• 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

• Connect the large intestine to its functions including conservation of water,
absorption of minerals, and concentration of digestive residues
• Outline the benefits of bacterial colonies in the large intestine
A System of Cooperating Organs
The gastrointestinal tract (GIT) is a long tube that extends from the mouth to the anus.
It consists of longitudinal and circular muscles that contract in waves to propel
substances along. Hormones and enzymes assist in the breakdown of food in a process
called digestion. The GIT includes the mouth, esophagus, stomach, small and large
intestines, rectum, and anus. Organs that provide substances needed for digestion
include the pancreas, gall bladder, and liver. Together, these organs form a system that
efficiently transforms the foods that you eat into the nutrients that you need to
maintain your body.