digestion

Examples of digestion in the following topics:

• Invertebrate Digestive Systems

  • Invertebrates can be classified as those that use intracellular digestion and those with extracellular digestion.
  • The simplest example of digestion intracellular digestion, which takes place in a gastrovascular cavity with only one opening.
  • The alimentary canal is a more advanced digestive system than a gastrovascular cavity and carries out extracellular digestion.
  • Because the food has been broken down exterior to the cells, this type of digestion is called extracellular digestion.
  • Their food is broken down in their digestive tract (extracellular digestion), rather than inside their individual cells (intracellular digestion).

• Chemical Digestion of Carbohydrates, Proteins, Lipids, and Nucleic Acids

  • Chemical breakdown of macromolecules contained in food is completed by various enzymes produced in the digestive system.
  • The digestive enzymes, however, are secreted mainly as their inactive precursors, the zymogens.
  • Sucrose digestion yields the sugars fructose and glucose, which are readily absorbed by the small intestine.
  • Digestion of certain fats begins in the mouth, where lingual lipase breaks down short chain lipids into diglycerides.
  • Complete digestion of one molecule of fat (a triglyceride) results in three fatty acid molecules and one glycerol molecule.

• Digestion and Absorption

  • Mechanical digestion refers to the physical breakdown of large pieces of food into smaller pieces which can subsequently be accessed by digestive enzymes.
  • Different organs play specific roles in the digestive process.
  • Digestive enzymes are found in the digestive tracts of animals.
  • The digestion of carbohydrates begins in the mouth.
  • Digestion of carbohydrates is performed by several enzymes.

• Digestive Systems

  • Animals use the organs of their digestive systems to extract important nutrients from food they consume, which can later be absorbed.
  • During digestion, food particles are broken down to smaller components which will later be absorbed by the body.
  • The digestive system is one of the largest organ systems in the human body.
  • The functions of the digestive system can be summarized as follows: ingestion (eat food), digestion (breakdown of food), absorption (extraction of nutrients from the food), and defecation (removal of waste products).
  • This diagram shows a generalized animal digestive system, detailing the different organs and their functions.

• Vertebrate Digestive Systems

  • Vertebrates have evolved more complex digestive systems to adapt to their dietary needs.
  • Humans and many animals have a monogastric digestive system .
  • The process of digestion begins with the mouth and the intake of food.
  • 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.

• Processes and Functions of the Digestive System

  • Digestion is necessary for absorbing nutrients from food, and occurs through two processes: mechanical and chemical digestion.
  • Here we will be looking at the importance of two main functions of the digestive system: digestion and absorption.
  • The digestive system is comprised of the alimentary canal, or the digestive tract, and other accessory organs that play a part in digestion - such as the liver, the gallbladder, and the pancreas.
  • Digestion begins in the mouth.
  • There are at least five major digestive hormones in the gut of mammals that help process food through chemical digestion.

• Hormones of the Digestive System

  • There are five main hormones that aid and regulate the digestive system in mammals.
  • There are five main hormones that aid in regulation of the digestive system in mammals.
  • Cholecystokinin (CCK) is in the duodenum and stimulates the release of digestive enzymes in the pancreas and stimulates the emptying of bile in the gall bladder.

• Aging and the Digestive System

  • Aging can result in changes of the digestive system due to decreased nerve sensitivity, loss of muscle, 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, along with changes in neurosensory feedback regarding enzyme and hormone release, and diminished response to internal sensations and pain.
  • malabsoration of nutrients due to a variety of causes, including inflammatory bowel diseases, radiation enteritis, digestive failure, and malnutrition.
  • Several aspects of the digestive tract are labeled in this cartoon.

• Digestive System: Mouth and Stomach

  • The extensive chemical process of digestion begins in the mouth.
  • A large part of digestion occurs in the stomach .
  • Further protein digestion takes place in the small intestine.
  • Digestion of food begins in the (a) oral cavity.
  • Enzymes in the saliva begin to digest starches and fats.

• Digestive Processes of the Small Intestine

  • The small intestine uses different enzymes and processes to digest proteins, lipids, and carbohydrates.
  • The small intestine is where most chemical digestion takes place.
  • The three major classes of nutrients that undergo digestion are proteins, lipids (fats), and carbohydrates.
  • Other carbohydrates pass undigested into the large intestine, where they are digested by intestinal bacteria.
  • Some carbohydrates, such as cellulose, are not digested at all, despite being made of multiple glucose units.