BIOL203 Lesson 3

• Atom


  Anything that takes up space and has mass
• Molecule


  Formed of multiple atoms joined together
• Compound

  2+ different elements
• Subatomic particles

  Protons, electrons, neutrons
• Electron shell

  The 1st-8th shells, with the 3rd shell being the valence shell containing valence electrons
• Covalent bond


  Formed by sharing electrons
• Solution


  Homogenous mixture of 2 or more compounds, where the minor component is dispersed in the major component
• Aqueous solution


  Water is the solvent
• Electronegativity

  Ability of an atom to attract electrons in a bond
• Polar molecule

  Has a partial positive and partial negative charge in different parts
• Hydrogen bond

  Formed between a hydrogen atom bonded to a highly electronegative atom and another highly electronegative atom
• Solubility

  Simple carbohydrates (sugar) dissolve in water, other substances (fat) are insoluble
• Starch


  Glucose particles packed into tight dense granules by plants
• Enzyme

  Protein catalyst that facilitates chemical reactions without being changed
• pH

  Measure of concentration of hydrogen ions (H+), scale of 0-14
• pH of saliva 6.4, stomach 1.0, small intestine 8.0
• Enzymes in digestive system are controlled by pH of solution they are suspended in
• Digestive system

  Set of organs that work cooperatively to digest food and deliver nutrients
• Types of tissues in digestive system

  • Epithelial
  • Connective
  • Blood
  • Neural
  • Muscle
• Organs in digestive system

  • Mouth
  • Pharynx
  • Esophagus
  • Stomach
  • Small intestine
  • Large intestine
  • Rectum
  • Anus
• Accessory organs in digestive system

  • Salivary glands
  • Liver
  • Pancreas
  • Gallbladder
• Transit time of food

  24-72 hours
• Functions of digestive system

  • Digestion
  • Absorption
  • Elimination
• Substances released in digestive system: enzymes, hormones, mucus
• Chyme

  Food mixed with stomach secretions
• Small intestine

  Has circular folds and finger-like projections lined with epithelial cells to help absorb nutrients
• Absorption


  Transfer of nutrients from gastrointestinal tract into blood and lymph vessels
• Hepatic portal vein

  Delivers absorbed nutrients from intestines to the liver
• Elimination


  Solid waste eliminated through large intestine with help of gut microbes
• Circulatory system

  Network of blood vessels: arterioles, arteries, capillaries, venules, veins