Nutrition

• When analysing markets, a range of assumptions are made about the rationality of economic agents involved in the transactions
• The Wealth of Nations was written

  1776
• Rational


  (in classical economic theory) economic agents are able to consider the outcome of their choices and recognise the net benefits of each one
• Consumers act rationally by


  Maximising their utility
• Producers act rationally by


  Selling goods/services in a way that maximises their profits
• Workers act rationally by


  Balancing welfare at work with consideration of both pay and benefits
• Governments act rationally by


  Placing the interests of the people they serve first in order to maximise their welfare
• Rationality in classical economic theory is a flawed assumption as people usually don't act rationally
• Marginal utility


  The additional utility (satisfaction) gained from the consumption of an additional product
• If you add up marginal utility for each unit you get total utility
• Mycorrhiza


  Symbiotic association between fungi and the roots of vascular plants
• Mycorrhiza


  • Serves as an extension of the root system
  • Enhances phosphorus uptake
  • Transfers nutrients like zinc and copper
• Parasitism


  A parasitic plant depends on its host for survival
• Parasitic plants


  • Dodder
• Predation


  An insectivorous plant has specialized leaves to attract and digest insects
• Insectivorous plant


  • Venus flytrap
• Heterotrophs


  Organisms that consume organic molecules from other organisms for nutrition
• Animal dietary categories


  • Herbivores
  • Carnivores
  • Omnivores
  • Detritivores
• Detritivores


  Heterotrophs that obtain nutrients from decaying bodies of plants and animals called detritus by breaking them into smaller sizes before decomposition acts on them
• Intracellular digestion


  Food is processed inside the cell (for single-celled organisms)

  
• Extracellular digestion


  Food particles are broken down into smaller components outside the cell (for most multicellular organisms)
• Animals with extracellular digestion

  • Hydra
  • Flatworms
  • Coelenterates
• Feeding mechanisms in animals

  • Substrate-feeders
  • Filter-feeders
  • Fluid-feeders
  • Bulk-feeders
• Substrate-feeders


  • Earthworms
  • Caterpillars
• Filter-feeders

  • Whales
  • Coelenterates
• Fluid-feeders


  • Mosquitoes
  • Leeches
  • Head lice
  • Aphids
• Bulk-feeders


  • Snakes
  • Cats
  • Humans
• Stages of food processing in animals

  • Mechanical processing/ingestion
  • Secretion of enzymes and other digestive aids
  • Enzymatic hydrolysis
  • Absorption
  • Elimination
• Mechanical processing/ingestion


  The act of eating or taking in food via the mouth cavity
• Enzymatic hydrolysis


  The process that converts food substances into living matter
• The human digestive system is important for the absorption of nutrients in the body</b>

  
• Human digestive system


  1. Food enters mouth

  2. Saliva amylase softens food

  3. Teeth break down food

  4. Tongue moves bolus to esophagus

  5. Peristalsis moves food to stomach

  6. Food stays in stomach for 2-6 hours

  7. Food enters small intestine

  8. Bile and enzymes continue digestion

  9. Nutrients absorbed by small intestine

  10. Undigested food enters large intestine

  11. Water and minerals absorbed

  12. Solid waste (feces) expelled

  
• Nutrients needed by animals to maintain homeostasis

  • Water
  • Carbohydrates
  • Proteins
  • Fats
  • Minerals
  • Vitamins
• Water


  Natural solvent that helps digest food, eliminate waste, regulate body temperature, maintain blood pH, and keep skin/respiratory surfaces moist
• Carbohydrates


  Major energy source for cells
• Proteins


  Building materials for cell structures, muscles, and bones
• Fats


  Used to build cell membranes, steroid hormones, and other cellular structures; also used to insulate nervous tissues and as an energy source
• Minerals


  Needed to maintain homeostasis, e.g. calcium for bones/teeth, trace minerals like iodine, cobalt, zinc, etc.
• Vitamins


  Organic molecules required in small amounts for normal metabolism, e.g. fat soluble A, D, E, K and water soluble B vitamins
• A balanced diet containing the right amounts of different nutrients is needed to maintain a healthy body