bio study

• Nutrition


  Process by which organisms obtain and utilize their food
• Nutrition

  1. Ingestion

  2. Digestion
• Ingestion


  Process of taking food into the digestive system so that it may be hydrolized or digested

  
• Digestion


  The breakdown of food (either chemically or mechanically) in order to utilize nutrients
• Types of Nutrients

  • Micronutrients (vitamins, minerals and water)
  • Macronutrients (proteins, lipids, carbohydrates)
• GI (gastrointestinal) tract

  Alimentary canal

  
• Ingestion

  1. Mouth

  2. Mechanical digestion

  3. Chemical digestion

  
• Mouth


  • Break up food
  • Digest starch
  • Kill germs
  • Moisten food
• Bolus


  Lump of food formed with saliva and the tongue
• Swallowing (and not choking)

  1. Epiglottis closes trachea

  2. Peristalsis moves food along

  
• Types of digestion(eg)


  • Chewing a saltine
  • Saliva breaking down saltine into glucose
  • Teeth tears/grinds the hamburger
  • Pepsin breaking down hamburger into amino acids
• Pharynx


  Back of the throat, approximately 15cm long
• Digestive Glands


  Groups of specialized secretory cells found in the lining of the alimentary canal or accessory organs

  
• Stomach


  • Food storage
  • Disinfect food (HCl, pH 2)
  • Chemical digestion
  • Mechanical digestion

  
• The stomach is made of protein, but it doesn't digest itself because of mucus secreted by stomach cells that protects the lining
• Gastric Juices


  • Acidic (pH 1.5-2.5, HCl)
  • Pepsin enzyme breaks down proteins
• Accessory Organs


  • Pancreas
  • Gall Bladder
  • Spleen
• Gall Bladder


  Pouch structure near the liver that concentrates and stores bile
• Bile


  Emulsifies lipids (breaks apart fats)
• Pancreas


  Organ that secretes digestive enzymes and hormones

  
• Pancreatic Juice


  • Digests proteins, starch, and fats
  • Buffers acid from stomach to maintain pH 7-8

  
• Liver


  Produces bile to break up fats
• Small Intestine


  • Major site of chemical digestion and absorption
  • Lined with villi to increase surface area
• Duodenum


  First section of small intestine where food from stomach mixes with digestive juices

  
• Absorption in Small Intestine


  • Occurs through villi and microvilli
  • Almost 90% of daily fluid intake is absorbed
• Ileum


  • Adapted for efficient absorption with long length, villi, and microvilli
• Large Intestine (Colon)


  Reabsorbs water, not enough leads to constipation, too much leads to diarrhea
• Bacteria in the large intestine produce vitamins and gases
• Appendix


  Vestigial organ
• Digestive Homeostasis Disorders


  • Ulcers
  • Appendicitis
  • Gallstones
  • Heartburn
• 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
• Rational agents will select the choice which presents the highest benefits
• 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