Digestion

• Digestion

  Occurs in the alimentary canal/digestive tract which is a muscular tube that is open at both ends
• Upper digestive tract

  • Mouth
  • Esophagus
  • Stomach
• Lower digestive tract


  • Small intestine
  • Large intestine
  • Rectum
  • Anus
• Accessory organs


  • Salivary glands
• Digestive process


  • Mechanical digestion
  • Chemical digestion
• Mechanical digestion

  • Food is physically broken down into smaller pieces
  • Can choke
  • Easier for nutrients to get absorbed
  • Increases surface area of food particles
• Chemical digestion


  • Chemical bonds are broken by enzymes via hydrolysis
• The 4 Major Stages of digestion

  1. Ingestion - taking in nutrients
  2. Digestion - physical & chemical breakdown of macromolecules
  3. Absorption - distribution of digested nutrients to cells 4. Elimination - removal of undigested solid waste
• Ingestion

  • Mechanical and chemical digestion begin in the mouth

  Mechanical Digestion

  teeth , palate, tongue
• • Chemical Digestion:
  • Saliva is produced by 3 pairs of salivary

  glands
• Saliva contains amylase which breaks down starch
• Nutrition

  • Our cells, body and blood contain mostly water and thousands of different molecules and ions
• 
  

  * Minerals - sodium nerve impuls compression, iron blood, calcium for strong bones

  * Water - Vital nutrient required by the body

  • Transport dissolved nutrients
  • Regulates body temp.
  • Major component of body fluids
  • Eliminates waste materials.
• Immunoglobulin: Antibody (protein)

  Insulin: Protein, regulates Sugar amount in blood

  Nucleic Acids - Encode, transmit and

  express genetic info

  2 Types:

  1. DNA (deoxyribonucleic)
  2. RNA (ribonucleic)

  * Important micronutrients: vitamins A, C, P
• 1. Water soluble type
  2. fat soluble

  These are two types of vitamins.

  Vitamins are not a source of energy
• Nutrition Label Activity.

  Acceptable # of calories from macronutrients:

  = 25% from fat

  = 15% prom protein

  = 60% from carbohydrates
• Enzymes

  Enzymes are proteins that act as biological catalysts

  • Catalysts help speed up the rate of chemical ractions without being consumed
• what are enzymes?

  • Enzymes catalyse all the biochemical reactions necessary to life
  • Highly specific. Each reaction in the body has a different set of enzymes that control it
  • Each enzyme acts on only one type of reactant moledule or substrate
• The large intestine, also known as the large bowel, is the last part of the gastrointestinal tract and of the digestive system in tetrapods. 
• Water is absorbed in large intestine and the remaining waste material is stored in the rectum as feces before being removed by defecation.
• The colon is the longest portion of the large intestine. The large intestine has the cecum, colon, rectum, and anal canal.
• In the large intestine, bacteria break down any proteins and starches in chyme that were not digested fully in the small intestine. When all of the nutrients have been absorbed from chyme, the remaining waste material changes into semisolids that are called feces.
• As it travels through the ileum, the thin liquid appearance of chyme begins thickening as an increasing amount of nutrients and some fluids are absorbed into the body. Finally, the chyme moves from the small intestine into the colon (large intestine).
• The four section of the large intestine is the cecum, colon, rectum and anus
• The cecum receives chyme from large intestine and it absorbs fluids and salts
• Chyme is important because it breaks down food and provides nourishment for the body.
• The colon helps with reabsorption of water and absorption of vitamins
• The rectum stores feces until elimination occurs
• The anus is where waste exits the body
• The main functions of the large intestine is production of vitamins and absorption of water and absorption of vitamins and salts
• Production of vitamins is not made by us, but it’s made by bacteria in our large intestine
• Aerobic bacteria means without oxygen and they live in an oxygen free area
• Where does feces go after the rectum?

  It goes through the anus when it can be eliminated from the rectum
• What does defecation mean?

  Expulsion of feces from rectum through anus
• How many anal sphincters are there?

  2
• What are the types of anal sphincters?

  Internal and external.
• What does the internal anal sphincter do?

  • Controls defecation
  • makes sure that the rectum does not open when you are sleeping
  • involuntary control
  • Controlled by autonomic nervous system
  • Keeps rectum closed when not ready for bowel movement; relaxes with adequate pressure
• What does the external anal sphincter do?

  • in the anus
  • voluntary control
  • Thick muscle
  • Can be clenched/unclenched (e.g., holding a bowel movement until you reach a restroom)
  • Conscious activation allows stool to pass from the body
• what type of cell is in the anus?

  mucus
• What does mucus do?

  • Protects stomach from acid
  • helps lubricate