The human digestive system

• A tissue is a group of cells with a similar structure and function.
• An organ is a group of tissues working together for a specific function.
• The stomach contains muscle tissue and also glandular tissue which releases enzymes.
• Organs are grouped into organ systems which work together to form organisms.
• Food contains three main nutrients: carbohydrates such as starch, protein, and lipids, also known as fats.
• Large food molecules are broken down into small molecules by enzymes during digestion.
• The human digestive system consists of the mouth, esophagus, stomach, small intestine, and large intestine.
• In the mouth, food is chewed and enzymes in the saliva begin to digest a starch into smaller sugar molecules.
• The food then passes down the esophagus into the stomach where enzymes begin the digestion of proteins and the stomach also contains hydrochloric acid which helps the enzymes to digest proteins.
• The food spends several hours in the stomach, churning action of the stomach muscles turns the food into a fluid increasing the surface area for enzymes to digest the fluid.
• The fluid passes into the small intestine where chemicals are released into the small intestine from the liver and pancreas.
• The pancreas releases enzymes which continue the digestion of starch and protein and start the digestion of lipids.
• The liver releases bile which helps to speed up the digestion of lipids and also neutralizes the acid released from the stomach.
• In the small intestine, the small food molecules are produced by digestion and absorbed into the bloodstream either by diffusion or by active transport.
• The fluid makes its way through the large intestine where water is absorbed into the bloodstream and finally the feces is released from the body.
• In the digestive system, large food molecules are digested into smaller molecules and then the products of digestion are absorbed into the bloodstream.
• The products of digestion are then used by the body to build new carbohydrates, lipids, and proteins.
• Some of the glucose produced is used in respiration.