mechanical digestion

Examples of mechanical digestion in the following topics:

• Digestion and Absorption

  • In order for nutrients (carbohydrates, lipids, vitamins) to be absorbed for energy, food must undergo chemical and mechanical digestion.
  • Digestion is the mechanical and chemical break down of food into small organic fragments.
  • Mechanical digestion refers to the physical breakdown of large pieces of food into smaller pieces which can subsequently be accessed by digestive enzymes.
  • Digestive enzymes are found in the digestive tracts of animals.
  • Mechanical and chemical digestion of food takes place in many steps, beginning in the mouth and ending in the rectum.

• Processes and Functions of the Digestive System

  • Digestion is necessary for absorbing nutrients from food and occurs through two processes: mechanical and chemical digestion.
  • Many different organs have essential roles in the digestion of food, from the mechanical breakdown of food by the teeth to the creation of bile (an emulsifier) by the liver.
  • This mechanical and chemical breakdown encompasses the process of digestion.
  • Mechanical digestion: Larger pieces of food get broken down into smaller pieces while being prepared for chemical digestion; this process starts in the mouth and continues into the stomach.
  • Enzymes in saliva then begin the chemical breakdown of food; teeth aid in the mechanical breakdown of larger food particles.

• Digestion in the Mouth, Pharynx, and Esophagus

  • Digestion is the mechanical and chemical breakdown of food into smaller components that are more readily absorbed into the bloodstream.
  • Digestion is the mechanical and chemical breakdown of food into smaller components so that it can be more readily absorbed into the bloodstream.
  • When food enters the mouth, digestion begins with the action of mastication, a form of mechanical digestion, and with the contact of saliva.
  • It cleans the oral cavity, moistens the food, and contains digestive enzymes.
  • The mechanism for swallowing is coordinated by the swallowing center in the medulla oblongata and pons.

• Mechanisms of Chemical Digestion

  • Proteins and polypeptides are digested by hydrolysis of the C-N bond .
  • In the absence of stomach pepsin, digestion in the small intestine proceeds with difficulty.
  • Stomach pepsin digests about 20% of the proteins, the rest is digested by pancreatic and small intestine enzymes.
  • Fats are digested by lipases which hydrolyze the glycerol-fatty acid bonds.
  • Proteins and polypeptides are digested by hydrolysis of the C-N bond.

• Mouth

  • The mouth receives and mechanically breaks down food, produces saliva, and is the first portion of the alimentary canal.
  • While its primary function is to begin the process of mechanically and chemically digesting food, the mouth is also the beginning of the alimentary canal—a larger digestive tube.
  • In the digestive process, the mouth's purpose is to prepare food for further digestion in the stomach and the small intestine.
  • This process begins with the mechanical breakdown of food by the teeth, which fit into the alveolar arches.
  • Describe the features of the mouth that play a role in digestion

• Aging and the Digestive System

  • Aging can result in changes in the digestive system due to decreased nerve sensitivity, muscle loss, and increased infection rate.
  • The changes associated with aging of the digestive system are largely caused by decreased nerve sensitivity, loss of muscle tone, and increased susceptibility to bacterial infection because of a weakened immune system.
  • Thus, changes include loss of strength and tone of muscular tissue and supporting muscular tissue, decreased secretory mechanisms, decreased motility of the digestive organs, changes in neurosensory feedback regarding enzyme and hormone release, and diminished response to internal sensations and pain.
  • Malabsorption of nutrients due to inflammatory bowel disease, radiation enteritis, digestive failure, and malnutrition.
  • Several aspects of the digestive tract are labeled in this diagram, including the mouth, large intestine (colon), rectum, anus, ileum, small intestine, stomach, and esophagus.

• Hormonal Responses to Food

  • This is controlled by a negative feedback mechanism.
  • In the duodenum, digestive secretions from the liver, pancreas, and gallbladder play an important role in digesting chyme during the intestinal phase.
  • Foods high in lipids (fatty foods) take a long time to digest.
  • Understanding the hormonal control of the digestive system is an important area of ongoing research.
  • Hormones, such as secretin and cholecystokinin, play important roles in digestive processes.

• Ingestion

  • Mastication, or chewing, is an extremely important part of the digestive process, especially for fruits and vegetables, as these have indigestible cellulose coats which must be physically broken down.
  • Also, digestive enzymes only work on the surfaces of food particles, so the smaller the particle, the more efficient the digestive process .
  • While the food is being mechanically broken down, the enzymes in saliva begin to chemically process the food as well.
  • Describe the process of ingestion and its role in the digestive system

• Vertebrate Digestive Systems

  • Humans and many animals have a monogastric digestive system .
  • The process of digestion begins with the mouth and the intake of food.
  • The stomach of birds has two chambers: the proventriculus, where gastric juices are produced to digest the food before it enters the stomach, and the gizzard, where the food is stored, soaked, and mechanically ground.
  • The digestive enzymes of these animals cannot break down cellulose, but microorganisms present in the digestive system can.
  • This is the site where the roughage is fermented and digested.

• Organs of the Digestive System

  • The organs of the digestive system can be divided into upper and lower digestive tracts.
  • The human body uses a variety of mental and physiological cues to initiate the process of digestion.
  • Our digestive system is like a long tube, with different segments doing different jobs.
  • When we take a bite of food, the food material gets chewed up and processed in the mouth, where saliva begins the process of chemical and mechanical breakdown.
  • This diagram shows the relationship between the various organs of the digestive system.