This process is also referred to as motility and the partially digested food is propelled by the wave-like action called peristalsis. Ring-like muscular valves called sphincters prevent the back flow of partially digested food and digestive juices. There are sphincters between the esophagus and stomach esophageal sphincter , between the stomach and small intestine pyloric sphincter and small intestine and colon ileocecal sphincter.
The chemical process of digestion involves the release of water, acid, bicarbonate and enzymes to be mixed with the food to further break it down into smaller subunits. Chemical breakdown starts in the mouth where enzymes break down complex carbohydrate. In the stomach, water and acid are released to begin the breakdown of protein. A mucus lining protects the stomach from the corrosive acid. The mixture, also known as chyme, enters the small intestine where bicarbonate is introduced to neutralize the acid and enzymes are added to break chemical bonds.
Most small intestine digestive enzymes are produced in the pancreas and small intestine. Our nervous system and hormones control digestion. The nervous system consists of the central nervous system, and the peripheral nervous system. Our brain and spinal cord make up the central nervous system while the peripheral system lies outside the skull and vertebral column. There are two components to the peripheral system: the somatic system that supplies the skin and muscle, and the autonomic system which supplies smooth muscle, cardiac muscle, and glands.
The PSNS supplies signals to maintain normal function and conserve body processes. The SNS provides signals to accelerate the process. Our gastrointestinal tract receives signals from the central and autonomic systems as well as sends signals to these systems.
Hormones are also involved in regulating digestion. Your digestive tract secretes hormones to control the release of digestive enzymes and juices. Here is a table of some hormones. Our appetite and hunger are controlled by a complex process that involves many signals. Here is a brief overview of that process. Decide whether you want to consume pre- and probiotic foods to benefit your health.
Visit the websites below to help in your decision-making process. Defend your decision scientifically. Skills to Develop Sketch and label the major organs of the digestive system and state their functions. From the Mouth to the Stomach There are four steps in the digestion process Figure 2.
From the Stomach to the Small Intestine When food enters the stomach, a highly muscular organ, powerful peristaltic contractions help mash, pulverize, and churn food into chyme. The stomach has three basic tasks: To store food To mechanically and chemically break down food To empty partially broken-down food into the small intestine The length of time food spends in the stomach varies by the macronutrient composition of the meal.
Video 2. Kefir There has been significant talk about pre- and probiotic foods in the mainstream media. From the Large Intestine to the Anus After a few hours in the stomach, plus three to six hours in the small intestine, and about sixteen hours in the large intestine, the digestion process enters step four, which is the elimination of indigestible food as feces.
Processes of Digestion Digestion involves two processes - physical and chemical. Regulation of Digestion Our nervous system and hormones control digestion. The digestive tract begins at the mouth and ends at the anus. It is like a long muscular tube, up to 10 metres long, with digestive organs attached along the way.
A large reservoir of microbes, such as bacteria, live within the large intestine and, to a lesser degree, in vthe rest of the digestive system. These bacteria play an important role in healthy digestion. The exact types of bacteria are particular to each person. Other factors that influence the type of bacteria in your digestive system include where you live in the world, what health conditions you have and what medications you have received.
Digestion begins in the mouth. The food is ground up by the teeth and moistened with saliva to make it easy to swallow. Saliva also has a special chemical, called an enzyme, which starts breaking down carbohydrates into sugars. Once swallowed, muscular contractions of the oesophagus massage the ball of food down into the stomach.
The food passes through a sphincter, or small muscle ring, into the stomach. Here it is mixed with gastric juices. The stomach is a muscular bag and it churns the food to help break it down mechanically as well as chemically. The food is then squeezed through a second sphincter into the first part of the small intestine, called the duodenum.
Once in the duodenum, the food is mixed with more digestive enzymes from the pancreas and bile from the liver. Proteins , fats , carbohydrates , vitamins , minerals , and water are nutrients. Your digestive system breaks nutrients into parts small enough for your body to absorb and use for energy, growth, and cell repair. MyPlate offers ideas and tips to help you meet your individual health needs. Each part of your digestive system helps to move food and liquid through your GI tract, break food and liquid into smaller parts, or both.
Once foods are broken into small enough parts, your body can absorb and move the nutrients to where they are needed. Your large intestine absorbs water, and the waste products of digestion become stool. Nerves and hormones help control the digestive process. 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. Fats break down into into fatty acids and glycerol. The waste parts of food that the body can't use are what leave the body as feces. How Does Digestion Work? The small intestine is made up of three parts: the duodenum pronounced: due-uh-DEE-num , the C-shaped first part the jejunum pronounced: jih-JU-num , the coiled midsection the ileum pronounced: IH-lee-um , the final section that leads into the large intestine The inner wall of the small intestine is covered with millions of microscopic, finger-like projections called villi pronounced: VIH-lie.
The large intestine has three parts: The cecum pronounced: SEE-kum is the beginning of the large intestine. The appendix , a small, hollow, finger-like pouch, hangs at the end of the cecum. Scientists believe the appendix is left over from a previous time in human evolution.
It no longer appears to be useful to the digestive process. The colon extends from the cecum up the right side of the abdomen, across the upper abdomen, and then down the left side of the abdomen, finally connecting to the rectum. The colon has three parts: the ascending colon and the transverse colon, which absorb fluids and salts; and the descending colon, which holds the resulting waste.
Bacteria in the colon help to digest the remaining food products. The rectum is where feces are stored until they leave the digestive system through the anus as a bowel movement. It takes hours for our bodies to fully digest food.
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