DIGESTIVE SYSTEM

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DIGESTIVE SYSTEM

• Function
• Digestion, absorption and eliminate waste.
• Changing food so that they can be absorbed and
  used by cells.

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Type of Digestion

• Mechanical digestion
• Chewing, swallowing, peristalsis etc. break food
  into tiny particles, mix them well with the
  digestive juices and move them along the
  digestive tract.
• Chemical digestion
• Breaks down large food molecules into smaller
  molecular by digestive enzymes.

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Reference http//www.ama-assn.org/ama/pub/categor
y/7155.html
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Digestion processes

• Mouth (mechanical and chemical digestion teeth
  and salivary gland)
• esophagus (mechanical peristalsis)
• stomach (chemical enzyme)
• small intestine (chemical enzyme)
• bile gallbladder liver
• pancreatic juice pancreas
• large intestine

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Food

• Food is used as collections of nutrients in a
  form which is eaten, digested and metabolized to
  provide energy and materials that build and
  maintain the structure, regulate the function of
  the body.
• Major nutritional sources
• Organic compounds carbohydrates
• proteins
• lipids
• vitamins
• Inorganic compound water H2O
• Minerals Na, K, P, S, Ca, Fe etc.

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• Energy balance
• 3040 of energy are used for normal growth,
  development and activity. The rest is used for
  maintain body temperature.
• Food and Nutrition Board recommend
• female 2,000 Kcal
• male2,700 Kcal
• 1Kcal energy required to raise the temperature
  of 1 liter of H2O from 1516C
• Energy producing food
• protein 4 Kcal/g
• carbohydrate 4 Kcal/g
• fat 9 Kcal/g

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• Organic Compounds
• Carbohydrate
• suggest intake 50100 g/day
• primary energy source
• eg. Sugar, starch
• Lipid
• 6090 g/day
• fat containing compounds
• fat soluble vitamins A, D, E, K
• Vitamin A vision, bone, teeth, anticancer
• Vitamin D control optimal blood level of Ca, P
• Vitamin E antioxidant agent
• Vitamin K blood clot
• Essential fat (lipid) linoleic acid

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• Proteins
• 4060 g/day, but in USA about 100 g/day
• Essential amino acid
• eg. Lysine, leucine, isoleucine and tryptophan
• Complete proteins from animal sources
• Incomplete proteins from plants
• eg. Peas and beans are good lysine source but low
  in trptophan nuts, seeds and cereals are good
  source in tryptophan but low in lysine
• Complementary diet is important for vegetarians

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Body Mass Index (BMI)

• BMI of 25 is ideal
• Less than 25 is great
• 30 and above is very unhealthy