Digestion

• What is Digestions Role

  To break down complex molecules in food into simple nutrients that can be absorbed into the blood, and then used by the body
• What does the digestive system depend on

  Muscular system

  Nervous and Endocrine (hormones)

  Circulatory system
• Muscular system

  Chewing, swallowing, Moving food along
• Nervous + Endocrine (hormones)

  Co-ordination of organs and release of enzymes
• Circulatory System 


  Transport of nutrients to the rest of the body
• Digestive processes

  1. Ingestion
  2. Digestion
  3. Absorbtion
  4. Egestion
• Ingestion 


  Eating/ Drinking
• Digestion

  Break down of food
• Physical/ Mechanically Digestion

  Breaking food into smaller pieces

  ex/ chewing
• Chemical Digestion

  Molecules are broken down by enzymes and other juices

  Ex/ proteins into amino acids
• Absorption

  Nutrient are taken into the blood stream
• Egestion

  Removal of undigested material from the digestive tract

  ex. Defecation
• GI tract

  gastrointestinal tract

  Log tube that starts at the mouth and proceeds through the pharynx (throat), esophagus, stomach, small intestine, and finally the large intestine

  Food passes through it
• Accessory glands

  help with mechanical digestion (teeth, tongue) or with chemical digestion (pancreas, liver, gull bladder, and salivary glands)
• Tour of the GI tract

  1. The Mouth
  2. The Pharynx (the throat)
  3. Esophagus
  4. The stomach
  5. Small Intestine
  6. The large intestine (AKA colon)
• The mouth - Hard Paleta 


  Separates the mouth + the nose
• The mouth - Soft Palete 


  Controls air flow + swallowing
• The mouth - Uvula 


  Swings back when you swallow in order to cover the nasal passage
• The Mouth - Salivary glands

  Produce Salivary amylase which begins the digestion of starches
• When does digestion start

  When the salivary glands produce salivary amylase
• Saliva production is under the control of the nervous system therefor the smell, thought, sight of food trigger salivation
• The Mouth - tongue

  Responsible for moving food around during chewing, and for taste
• What are the 5 basic tastes

  Sour, sweet, salty, bitter, Umami (savoury)

  A dry tongue can’t taste since taste buds require water to taste chemicals in the food

  Majority of taste comes from your nose
• The Pharynx (throat)

  Passage-way shared by both air and food
• Epiglottis 


  A muscular flap that moves down, when you swallow to cover your windpipe ( = no food in your lungs )
• Esophagus

  Muscular tube found behind the trachea

  25cm tube that connects the throat to the stomach

  Food that has been chewed + mixed with saliva is now called BOLUS

  the bolus moves down the esophagus by Peristalsis (involuntary muscle movement)