Your digestive system is designed to draw water, electrolytes and nutrients from the food you eat for use by your body's systems. Your digestive tract runs from your mouth to anus and includes your esophagus, stomach and intestines. Your salivary glands, pancreas and biliary system are accessory digestive organs. The body goes through four basic processes of digestion: motility, secretion, digestion and absorption.
Motility
Gastrointestinal motility refers to the movement of your digestive tract. This contraction is often referred to as mechanical digestion. Your digestive tract exerts two primary movements -- propulsive and mixing. Propulsive movement is when food is pushed through your digestive tract. Mixing movement has two functions: to mix food with your digestive juices to aid digestion and to help your intestines absorb nutrients.
Secretion
To digest food, your digestive system secretes enzymes and digestive juices that break food into smaller segments. Once food is broken into smaller pieces, your intestines extract nutrients. Gastric liquids are primarily composed of water, mucus, electrolytes, hydrochloric acid and the enzyme pepsin, which helps break down proteins in food. Your body produces gastrin, a hormone that promotes gastric liquid secretion to assure that your digestive system can break down and use nutrients from food.
Digestion
Digestion refers to the process of breaking food into smaller segments. For example, when you eat carbohydrates, such as bread or pasta, the starch molecules are broken down into smaller molecules called maltose, then further reduced to glucose for blood absorption. Your body then uses the glucose as fuel. Sucrose, or table sugar, is a simpler form of sugar; your system breaks it down into glucose and fructose before it is transported to your blood for use.
Absorption
Absorption is the final stage of digestion. Your small intestine provides the final digestive action. Once the protein, fat and carbs you eat are broken down into nutrients, including vitamins and minerals, in your small intestine, they are transported to the cells for fuel and other uses. Once in your bloodstream, your red blood cells, which contain oxygen, transport oxygen and nutrients throughout your body. Your body uses the nutrients to perform bodily functions. For example, vitamin B-12, which is extracted from animal protein foods, is used to repair tissues and manufacture red blood cells.
