"Digestion is the breakdown of large insoluble food compounds into small water-soluble components so that they can be absorbed into the blood plasma."
The process by which nutrients are broken down and absorbed by the body.
Digestive system: Understanding the structure and functions of the digestive system is necessary when studying digestion and absorption. This topic covers organs involved in digestion such as the mouth, esophagus, stomach, small intestine, large intestine, liver, pancreas, and gallbladder.
Enzymes: Digestive enzymes play a vital role in breaking down food into smaller molecules that the body can absorb. This topic covers different types of enzymes and their functions in the digestive process.
Carbohydrates: Carbohydrates are a vital source of energy for the body. This topic covers the digestion and absorption of carbohydrates, including the role of enzymes, dietary fiber, and glucose regulation.
Proteins: Proteins are essential for the growth and maintenance of tissues in the body. This topic covers the digestion and absorption of proteins, including the role of enzymes, amino acids, and protein synthesis.
Fats: Fats provide energy, help to insulate and cushion the body, and are essential for the absorption of fat-soluble vitamins. This topic covers the digestion and absorption of fats, including the role of enzymes, bile acids, and lipoprotein metabolism.
Vitamins and minerals: Vitamins and minerals are essential for various bodily functions and play a vital role in maintaining good health. This topic covers the digestion and absorption of vitamins and minerals, including their dietary sources, bioavailability, and roles in the body.
Digestive disorders: Digestive disorders, such as gastroesophageal reflux disease (GERD), inflammatory bowel disease (IBD), and celiac disease, can affect the digestive process, nutrient absorption, and overall health. This topic covers the causes, symptoms, and treatments of these disorders.
Nutrient metabolism: Nutrient metabolism involves the conversion of nutrients into energy or other biomolecules that the body needs. This topic covers the biochemical pathways involved in the metabolism of digestible nutrients such as glucose, amino acids, and fatty acids.
Gut microbiome: The gut microbiome plays a vital role in the digestion and absorption of nutrients, as well as in maintaining gut health. This topic covers the composition, functions, and interactions of the microbiome with the host.
Nutritional requirements: Understanding the nutritional requirements of the body is essential for meeting the body's needs for growth, maintenance, and repair. This topic covers the recommended dietary allowances (RDAs), dietary guidelines, and nutrient composition of foods.
Mechanical digestion: This is the physical breakdown of food into smaller pieces that can be easily digested.
Chemical digestion: This is the chemical breakdown of food through the actions of enzymes.
Enzymatic digestion: This involves the breaking of large molecules into smaller ones with the help of enzymes.
Absorption: The process by which nutrients are taken into the bloodstream from the digestive tract.
Secretion: The release of enzymes from the digestive organs.
Elimination: The process by which undigested food is removed from the body as waste.
Gastric digestion: This involves the breakdown of food in the stomach by stomach acid and enzymes.
Intestinal digestion: The breaking down of food in the small and large intestines, including the absorption of nutrients and water.
Microbial digestion: This is the process by which bacteria in the digestive tract break down complex molecules that cannot be digested by humans.
Enteral nutrition: The delivery of nutrients directly into the GI tract, often through a feeding tube.
Parenteral nutrition: The delivery of nutrients directly into the bloodstream, bypassing the digestive tract.
Cellulose digestion: The process by which herbivores break down the tough, fibrous plant material that they consume.
Fat digestion: This involves the breakdown of fats into fatty acids and glycerol, which can be absorbed into the bloodstream.
"Digestion is often divided into two processes based on how food is broken down: mechanical and chemical digestion."
"The term mechanical digestion refers to the physical breakdown of large pieces of food into smaller pieces which can subsequently be accessed by digestive enzymes."
"Mechanical digestion takes place in the mouth through mastication and in the small intestine through segmentation contractions."
"In chemical digestion, enzymes break down food into the small compounds that the body can use."
"Mechanical digestion of the food starts by the action of mastication (chewing), a form of mechanical digestion, and the wetting contact of saliva."
"Saliva, a liquid secreted by the salivary glands, contains salivary amylase, an enzyme which starts the digestion of starch in the food; the saliva also contains mucus, which lubricates the food, and hydrogen carbonate, which provides the ideal conditions of pH (alkaline) for amylase to work, and electrolytes (Na+, K+, Cl−, HCO−3)."
"About 30% of starch is hydrolyzed into disaccharide in the oral cavity (mouth)."
"It will then travel down the esophagus and into the stomach by the action of peristalsis."
"Gastric juice mainly contains hydrochloric acid and pepsin. In infants and toddlers, gastric juice also contains rennin to digest milk proteins. As the first two chemicals may damage the stomach wall, mucus and bicarbonates are secreted by the stomach."
"The stomach provides a slimy layer that acts as a shield against the damaging effects of chemicals like concentrated hydrochloric acid while also aiding lubrication. Hydrochloric acid provides acidic pH for pepsin."
"At the same time protein digestion is occurring, mechanical mixing occurs by peristalsis, which is waves of muscular contractions that move along the stomach wall. This allows the mass of food to further mix with the digestive enzymes."
"Pepsin breaks down proteins into peptides or proteoses, which is further broken down into dipeptides and amino acids by enzymes in the small intestine."
"When the pyloric sphincter valve opens, partially digested food (chyme) enters the duodenum."
"Digestive enzymes from the pancreas and bile juice from the liver mix with the chyme in the duodenum, and then the digestion process continues in the small intestine."
"95% of nutrient absorption occurs in the small intestine."
"Water and minerals are reabsorbed back into the blood in the colon (large intestine) where the pH is slightly acidic (about 5.6 ~ 6.9)."
"Some vitamins, such as biotin and vitamin K (K2MK7) produced by bacteria in the colon, are also absorbed into the blood in the colon."
"Absorption of water, simple sugar, and alcohol also takes place in the stomach."
"Waste material is eliminated from the rectum during defecation."