Lesson 12.2 The Digestion Process

• Nutrition - The consumption of food from these sources and the processes that convert food substances into living matter.
• Ingestion - intake of food through the mouth.
• Digestion - process of mechanical and chemical breakdown, in which large food molecules are broken down into simpler molecules that can be absorbed by the body cells.
• Absorption - process in which digested food materials are absorbed by the body cells.
• Assimilation - transport and use of absorbed nutrients, such as the food's conversion into new protoplasm to provide energy.
• Elimination - removal of undigested material out of the digestive tract.
• Physical digestion - is the mechanical breakdown of food into smaller particles.
• Chemical digestion - is the breakdown of complex molecules, such as proteins, starch, and fats, into simple soluble molecules through hydrolytic reactions catalyzed by digestive enzymes.
• Mouth - Food intake starts in the mouth, which leads to the mouth cavity.
• Pharynx - is a common passage for food and air.
• Esophagus - smooth muscles force food into a narrow, muscular tube called esophagus or gullet.
• Stomach - The partially digested food now enters a J-shaped organ called stomach
• Food absorption - is the process by which digested food materials are absorbed by the cells.
• Small Intestine

  consists of three parts:

  • duodenum, jejunum, ileum
• Large Intestine - Undigested food leaves the small intestine and enters the large intestine, which is shorter but broader than the small intestine.
• Amino Acids - are also used for the formation of anzymes and hormones.
• Glucose is used by all cells for energy production.
• Liver - is the second largest organ and the largest gland in the human body.
• Pancreas - is a soft, triangular gland lying between the small intestine and the stomach.
• A greenish-yellow bag attached to the liver called the gallbladder.
• Digestive System

  A) Mouth

  B) Esophagus

  C) Stomach

  D) Pancreas

  E) Large Intestine

  F) Rectum

  G) Anus

  H) Small Intestine

  I) Gallbladder

  J) Liver