Food moves through your GI tract by a process called peristalsis. The large, hollow organs of your GI tract contain a layer of muscle that enables their walls to move. The movement pushes food and liquid through your GI tract and mixes the contents within each organ.
The muscle behind the food contracts and squeezes the food forward, while the muscle in front of the food relaxes to allow the food to move. Food starts to move through your GI tract when you eat. When you swallow, your tongue pushes the food into your throat. A small flap of tissue, called the epiglottis, folds over your windpipe to prevent choking and the food passes into your esophagus.
Once you begin swallowing, the process becomes automatic. Your brain signals the muscles of the esophagus and peristalsis begins. Lower esophageal sphincter. When food reaches the end of your esophagus, a ringlike muscle—called the lower esophageal sphincter —relaxes and lets food pass into your stomach. After food enters your stomach, the stomach muscles mix the food and liquid with digestive juices.
The stomach slowly empties its contents, called chyme , into your small intestine. Small intestine. The muscles of the small intestine mix food with digestive juices from the pancreas, liver, and intestine, and push the mixture forward for further digestion. The walls of the small intestine absorb water and the digested nutrients into your bloodstream. As peristalsis continues, the waste products of the digestive process move into the large intestine. Large intestine. Waste products from the digestive process include undigested parts of food, fluid, and older cells from the lining of your GI tract.
The large intestine absorbs water and changes the waste from liquid into stool. Peristalsis helps move the stool into your rectum. The lower end of your large intestine, the rectum, stores stool until it pushes stool out of your anus during a bowel movement. Watch this video to see how food moves through your GI tract.
As food moves through your GI tract, your digestive organs break the food into smaller parts using:. The digestive process starts in your mouth when you chew. Your salivary glands make saliva , a digestive juice, which moistens food so it moves more easily through your esophagus into your stomach.
Saliva also has an enzyme that begins to break down starches in your food. After you swallow, peristalsis pushes the food down your esophagus into your stomach. Glands in your stomach lining make stomach acid and enzymes that break down food. Muscles of your stomach mix the food with these digestive juices. Your pancreas makes a digestive juice that has enzymes that break down carbohydrates, fats, and proteins. The pancreas delivers the digestive juice to the small intestine through small tubes called ducts.
Your liver makes a digestive juice called bile that helps digest fats and some vitamins. Lauren is a Registered Dietitian with over 6 years of experience in the field. She has experience in food service management, nutrition counseling, and WIC. You can see her writing work at www. Sydney Stein. Sydney is a graduate from the S. As the body digests the food you eat, it utilizes vitamins, minerals and macronutrients at different points along the digestive tract.
Video of the Day. Tip As your body digests the food you eat, it utilizes vitamins, minerals and macronutrients at different points along the digestive tract.
The Digestive System Process. Carbohydrates: This macronutrient is grouped into two categories: simple carbohydrates , which include sugars found in foods such as fruit, vegetables and milk, and complex carbohydrates , which consists of starches and fiber found in whole grain breads and cereals, starchy vegetables and legumes.
Protein: A macronutrient found in foods such as meat, eggs and beans, which your body digests into smaller molecules called amino acids. Fats: A macronutrient that's categorized into healthy fats , which consist of oils such as corn, canola, olive, safflower, soybean and sunflower, and less-healthy fats that are found in butter shortening and snack foods.
Vitamins: Micronutrients that are classified by the fluid in which they dissolve; water-soluble vitamins include all B vitamins and vitamin C, while fat-soluble vitamins include vitamins A , D, E and K. Minerals: Micronutrients that are elements in food that your body needs to function normally.
Some minerals that are essential for health include calcium, potassium, magnesium and iron. Skip to main content. Digestive System. Search for:. Absorption in the Small Intestine The absorption of nutrients occurs partially by diffusion through the wall of the small intestine. Learning Objectives Describe the role played by the small intestine in the absorption of nutrients.
Key Takeaways Key Points Digested food is able to pass into the blood vessels in the wall of the small intestine through the process of diffusion. The inner wall, or mucosa, of the small intestine is covered in wrinkles or folds called plicae circulares that project microscopic finger-like pieces of tissue called villi, which in turn have finger-like projections known as microvilli. Each villus transports nutrients to a network of capillaries and fine lymphatic vessels called lacteals close to its surface.
Key Terms villi : Tiny, finger-like projections that protrude from the epithelial lining of the intestinal wall.
Examples Examples of nutrients absorbed by the small intestine include carbohydrates, lipids, proteins, iron, vitamins, and water. Absorption of Monosaccharides, Amino Acids, Dipeptides, Tripeptides, Lipids, Electrolytes, Vitamins, and Water Glucose, amino acids, fats, and vitamins are absorbed in the small intestine via the action of hormones and electrolytes.
Learning Objectives Describe the process of absorption of nutrients in the small intestine. Key Takeaways Key Points Proteins are degraded into small peptides and amino acids di- and tripeptides before their absorption by proteolytic and digestive enzymes such as trypsin. Lipids fats are degraded into fatty acids and glycerol by pancreatic lipase.
Carbohydrates are degraded into monosaccharide or oligosaccharide sugars by the action of amylase. Carbohydrates, such as cellulose, pass through the human intestinal tract undigested. Water and some water-soluble vitamins are absorbed by diffusion. Some electrolytes and water non-soluble vitamins require an active uptake mechanism. Key Terms trypsin : A digestive enzyme that cleaves peptide bonds a serine protease.
Examples During breastfeeding, the lactase enzyme breaks down lactose milk sugar. Licenses and Attributions. CC licensed content, Shared previously.
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