The process of digestion begins in the mouth with the intake of food. The rise in obesity and the resulting diseases like type 2 diabetes makes understanding the role of diet and nutrition in maintaining good health all the more important. Taking in more food energy than is used in activity leads to storage of the excess in the form of fat deposits. One of the challenges in human nutrition is maintaining a balance between food intake, storage, and energy expenditure. This happens by both physical means, such as chewing, and by chemical means. During digestion, food particles are broken down to smaller components, which are later absorbed by the body. The conversion of the food consumed to the nutrients required is a multistep process involving digestion and absorption. Animals must convert these macromolecules into the simple molecules required for maintaining cellular function. However, the food consumed consists of protein, fat, and complex carbohydrates. At the cellular level, the biological molecules necessary for animal function are amino acids, lipid molecules, nucleotides, and simple sugars. While plants can obtain nutrients from their roots and the energy molecules required for cellular function through the process of photosynthesis, animals obtain their nutrients by the consumption of other organisms. Describe how excess carbohydrates and energy are stored in the bodyĪll living organisms need nutrients to survive.Describe the essential nutrients required for cellular function that cannot be synthesized by the animal body.Describe the ways in which organs work together to digest food and absorb nutrients.Explain the specialized functions of the organs involved in processing food in the body.Explain the processes of digestion and absorption.Computed tomography (CT) or magnetic resonance imaging (MRI) scans: These check for conditions such as cancer.By the end of this section, you will be able to:.Intestinal ultrasound: This tests for symptoms of conditions such as inflammatory bowel disease.Upper gastrointestinal X-ray: This X-ray examination of the upper GI tract (which involves the esophagus, stomach, and duodenum) after the ingestion of a contrast medium such as barium allows for a clear view of the small intestine and other structures.Endoscopy: This involves a scope with a camera that allows surgeons to view the inside of the small intestine through a very small incision.Ova and parasite test: This is a microscopic examination of stool to test for the presence of parasites or eggs, a common cause of diarrhea.Fecal occult blood test (FOBT): This test involves taking a stool sample to test for blood that cannot be seen by the naked eye.It can also pick up a bleeding ulcer, as well as treat it by injecting drugs to stop the bleeding. Esophagogastroduodenoscopy (EGD): This procedure involves a scope that is used to examine the small intestine, get a fluid sample for culture, or obtain a biopsy.Also, fluid levels in the small intestine can be viewed to make sure there is no obstruction. Abdominal X-ray: This looks at the diameter of the small intestine to see if it is dilated.Bacterial culture: This may be done on stool to look for infectious organisms.Medications that cause injury or impairment of the small intestine, such as NSAIDs, antimicrobials, proton pump inhibitors, or chemotherapy drugs.Small bowel diverticula, which are small sac-like protrusions of the wall of the large or small intestine.Intestinal obstructions, or blockages, such as small bowel obstructions.Intestinal bleedingwhich can occur with ulcers, inflammation, or cancer.Intestinal cancer, such as duodenal cancer.Intestinal infections that may be caused by viruses or bacteria.Peptic ulcers, which are open sores located along the stomach or duodenum.Small bowel bacterial overgrowth (SIBO), or excessive gut bacteria in the small intestine.Irritable bowel syndrome (IBS), a common condition related to a signaling issue between the brain and the gut that leads to gastrointestinal symptoms.Crohn’s disease, a long-term condition that causes painful inflammation along the digestive tract.Celiac disease, an autoimmune disease in which eating gluten triggers white blood cells to attack the lining of the small intestine.

Does the large intestine absorb water