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Chapter 13 Heterotrophic Nutrition 1210745399273844 9

Chapter 13 Heterotrophic Nutrition 1210745399273844 9






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    Chapter 13 Heterotrophic Nutrition 1210745399273844 9 Chapter 13 Heterotrophic Nutrition 1210745399273844 9 Presentation Transcript

        • Biology G10
        • Chapter 13: Heterotrophic Nutrition
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • Components of Human Diet
      • Water is essential part of body fluids
        • Blood, aqueous chemical reactions in cells
    • Components of Human Diet
      • Vitamins and mineral ions are required for
        • Vision
        • Respiration
        • Connective tissue
        • Teeth and bones
        • Nerve function
        • DNA
        • Haemoglobin
    • 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
    • The Alimentary Canal
      • One long continuous tube from the mouth to the anus:
    • 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)‏
    • Mouth and Pharynx
    • 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
    • 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
    • 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
    • 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)‏
    • Adaption for Absorption
    • 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)‏
    • 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
    • Pancreas
      • Secretes pancreatic juice through bile duct into duodenum
      • Digestive enzymes and insulin added
        • Responsible for blood sugar regulation
    • 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
    • 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
    • In the Stomach
      • Pepsin digests proteins to polypeptides
      • Rennin clots/curdles milk proteins to keep them in the stomach to be digested
    • 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
    • Small Intestine - Carbohydrates
      • Starch digested to maltose in mouth
      • Pancreatic amylase digests remaining starch
      • Lactase and sucrase digests other carbohydrates
    • Small Intestine - Proteins
      • Undigested protein is digested by trypsin into polypeptides
      • Erepsin breaks polypeptides into amino acids
    • 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
    • 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
    • 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
    • Saprobiontic Nutrition
    • 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
    • Parasitic Nutrition
    • 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
    • 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
    • Mutualistic Nutrition