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  • 1.
      • Biology G10
      • Chapter 13: Heterotrophic Nutrition
  • 2. Heterotrophic Nutrition
    • Autotrophic organisms can make their own food
    • Heterotrophic organisms must take in food from enivron.
    • Heterotrophic nutrition is the breaking down of complex organic molecules into smaller, soluble molecules
      • These are absorbed to provide energy and nutrients for survival and growth
    • There are four types of heterotrophic nutrition
      • Holozoic
      • Saprobiontic
      • Parasitic
      • Mutualistic
  • 3. Heterotrophic Nutrition
    • Holozoic involves digesting food inside the body
      • Humans, mammals
    • Saprobiontic feeds on dead organic matter, digestion takes place externally
      • Bacteria, fungi
    • Parasitic obtains food from another organism by living inside it
    • Mutualistic involves two way nutritional gain for two different org's
  • 4. A Balanced Diet in Humans
    • A balanced diet provides enough of all nutrients to maintain good health
      • Carbohydrates and lipids for energy
      • Proteins for growth and repair
      • Vitamins, mineral ions and water
      • Fibre for digestions
        • Not classified as nutrient because not digested and absorbed
    • Amount of each nutrient varies by age, gender, activity level and pregnancy
      • Dietary reference value table used to estimate
      • Only a guideline
  • 5. Components of Human Diet
    • Energy is needed for the following:
      • Growth and maintenance of body tissues
      • Maintain body temperature
      • Muscle action (walking, exercise)‏
      • Involuntary muscle action (heartbeat)‏
    • Energy balace requires comparing food energy in with energy used by these activities
    • If more food energy is brought in than is used by activities an person will gain weight as stored energy
    • If less food energy is brought in than is used a person will loose weight by using stored energy
    • By adjusting diet and activity a balance can be attained
  • 6. Components of Human Diet
    • Carbohydrates are the main source of energy
      • Sugars and starchs (potato, rice)‏
    • Starch and disacharride sugars are broken down into monosacharrides (mostly glucose)‏
    • Glucose is used in respiration to general energy
    • Cellulose is not digested but it is the main type of fibre
      • Fibre is important for maintaining health digestion and digestive tract
  • 7. Components of Human Diet
    • Lipids are also a source of energy and other functions
      • Excess lipids are stored under the skin and around organs
      • Provides energy store and thermal/mechanical insulation
    • Lipids also used to make cell membranes
    • Essential fatty acids must be obtained from diet and cannot be synthesised in the body
    • Excess amounts of saturated fatty acids can cause heart disease and buildup in arteries
    • Replacing unsaturated fatty acids reduces this risk
  • 8. Components of Human Diet
    • Proteins are essential for growth and repair
      • Broken down into amino acids which are then used to build up new tissure and repair damaged tissues (4% per day)‏
      • Enzymes and hormones must be replaced
    • Body requires 20 different amino acids
      • 9 are essential amino acids (cannot be made in the body)‏
    • If essential amino acids are missing from the diet certain enzymes cannot be synthesised properly
    • First-class proteins have many amino acids
      • Meat, eggs
    • Second-class proteins have few amino acids
      • Wheat, rice
  • 9. Components of Human Diet
    • Water is essential part of body fluids
      • Blood, aqueous chemical reactions in cells
  • 10. Components of Human Diet
    • Vitamins and mineral ions are required for
      • Vision
      • Respiration
      • Connective tissue
      • Teeth and bones
      • Nerve function
      • DNA
      • Haemoglobin
  • 11. The Digestive System
    • The sequence of processes as food passes through the digestive system
      • Mechanical digestion
        • Food broken down into small particles with large surface area
      • Chemical digestion
        • Digestive enzymes break down food molecules to be absorbed
      • Absorption
        • Digested materials are taken into the bodies cells
      • Assimilation
        • Absorbed food materials are converted to new protoplasm
    • Must first understand the organs and tissues
  • 12. The Alimentary Canal
    • One long continuous tube from the mouth to the anus:
  • 13. Mouth and Pharynx
    • Mouth
      • Food first enters the body
      • Mechanically ground smaller by teeth
      • Tongue rolls food into a bolus for easy swallowing
      • Saliva lubricates and starts to digest food
    • Pharynx
      • Connects the mouth and oesophagus: “throat”
      • Air and food both use this passage
      • Larynx moves up during swallowing to prevent food from entering the airway (trachea)‏
  • 14. Mouth and Pharynx
  • 15. Oesophagus
    • Long, narrow, muscular tube that connects the pharynx to the stomach
    • Peristalsis moves bolus quickly to stomach
    • Ends at cardiac sphincter stopping backflow from stomach
    • No villi/microvilli
  • 16. Stomach
    • Muscular, stretchable bag with many muscles
    • Food is mixed with enzymes and gastric juices
    • Food becomes semi-liquid “chyme”
    • The pyloric sphincter stops the food from entering the small intestine until ready (2 – 6 hours)
    • No villi/microvilli
  • 17. Small Intestine
    • Most of digestion occurs here
    • Three main parts:
      • In duodenum pancreas adds juices
      • Jejunum coils for 2 meters
      • Ileum coils for 4 – 6 meters
    • Very long to allow
    • enzymes to digest food
    • Food absorption occurs here
    • Ileum connects to large intestine
  • 18. Absorption / Adaptions
    • Small intestine has special adaptations to increase surface area for absorption
      • Single layer epithelium layer
      • Inner walls shaped as transverse, circular folds
      • Along folds are finger-like villi sticking out
      • Along villi are microscopic microvilli on each cell
    • Well supplied with capillaries and lymphatic capillaries (fat soluble products)‏
  • 19. Adaption for Absorption
  • 20. Large Intestine
    • Larger in diameter but much shorter (1.5 m)‏
    • The main purpose is to absorb water and mineral salts
    • No digestion occurs here
    • Faeces (undigested food) is stored in rectum before being expelled through anus
    • Bacteria living here produce vitamins (K)‏
  • 21. Liver
    • Dark red, made of five lobes
    • Makes bile – alkaline liquid with bile salts
      • Helps break down fats
      • Stored until needed in the gall bladder
    • Bile emptied into duodenum
  • 22. Pancreas
    • Secretes pancreatic juice through bile duct into duodenum
    • Digestive enzymes and insulin added
      • Responsible for blood sugar regulation
  • 23. How is Food Digested - Mouth
    • Mechanical digestions?
    • Chemical digestion is breaking food down into simple, soluble substances
    • Saliva in the mouth mixes with the food
      • Mucin softens the food for rolling
      • Amylase starts to break starch into maltose
  • 24. In the Stomach
    • Mechanical digestion?
    • Chemical digestion
      • Hydrochloric Acid (HCl)‏
        • Stops amylase
        • Kills bacteria, germs, parasites
        • Provides optimum pH for enzymes
        • Activates digestive enzymes so they don’t eat stomach cells
          • Pepsinogen -> pepsin
          • Prorennin -> rennin
  • 25. In the Stomach
    • Pepsin digests proteins to polypeptides
    • Rennin clots/curdles milk proteins to keep them in the stomach to be digested
  • 26. In the Small Intestine
    • Pancreatic and intestinal juices are alkaline
      • Nuetralizes acid from stomach
    Intestinal Juice Pancreatic Juice Maltase Pancreaic amylase Lactase Trypsinogen Sucrase Pancreatic lipase Erepsin Enterokinase Intestinal lipase
  • 27. Small Intestine - Carbohydrates
    • Starch digested to maltose in mouth
    • Pancreatic amylase digests remaining starch
    • Lactase and sucrase digests other carbohydrates
  • 28. Small Intestine - Proteins
    • Undigested protein is digested by trypsin into polypeptides
    • Erepsin breaks polypeptides into amino acids
  • 29. Small Intestine - Fats
    • Fats must first be emulsified to be digested
      • Bile and bile salts break apart fats making an emulsion
    • Lipases digest fats to fatty acids and glycerol
  • 30. The Absorption Process
    • By the end of digestion in the ileum:
      • All carbohydrates are monosaccharides (mostly glucose)‏
      • All proteins are amino acids
      • All lipids are fatty acids and glycerol
    • Glucose and amino acids absorbed through villi into cappilaires
    • Fatty acids and glycerol absorbed into lymph system
  • 31. Saprobiontic Nutrition
    • Obtain nurtrients and energy from dead organic matter and organic waste (faeces)‏
    • Enzymes are secreated onto food to digest outside org.
      • Extracellular digestion
    • Soluble products are absorbed into organism
    • Many bacteria and fungi are saprobionts
    • Rhizopus (pin mold) grows on stored foods
      • Branches called hyphae grow out of food
      • No divisions between cells: continuous cytoplasm
      • Small round pin heads are sporangia (spore case)‏
      • Enzymes are secreated onto the food substrate
  • 32. Saprobiontic Nutrition
  • 33. Parasitic Nutrition
    • Obtains nutrients from living organisms (host)‏
      • Can live on or in another species
    • Tapeworm lives in pigs and transfers to humans
      • Flat, ribbon-like body made up of segments
      • Head (scolex) is embedded into intestine wall
      • Eggs are developed and pass out in faeces
      • Pigs are infected from faeces, eggs hatch inside pig
      • Worms live in muscle tissue of pigs which is eaten by humans
    • Long thin shape allows food to pass without major problems
  • 34. Parasitic Nutrition
  • 35. Adaptations of Tapeworm
    • Attachement structure to hold worm inside intestine
    • Living in intestine provides constant supply of food
    • Protective cuticle protects it from digestive enzymes
    • Can survive in low oxygen environment
    • Reduction of sense organs (lives in the dark)‏
    • Hermaphroditic can reporoduce by itself
    • Each segment produces eggs so that huge numbers of eggs are released each cycle
  • 36. Mutualistic Nutrition
    • Close relationship between organisms of different species where both gain a nutritional advantage
      • Bacteria live in human large intestine
      • Microorganisms live in cow/sheep stomachs help digestion
      • Lichens are combination of algae and fungi
    • Rhizobium (bacteria) live among the roots of legumes
      • Attracted by hormone secreated by plant roots
      • Nodules develop on the roots that contain the bacteria
      • Bacteria convert nitrogen into ammonia
      • Ammonia is then used by plant for protein synthesis
      • Bacteria is supplied with sugars from the plant
  • 37. Mutualistic Nutrition