Week 2 Learning progressions

• What is a protein?


  Molecule made up of amino acids. Essential macronutrient important for structure, function and regulation of the body.

  • transporters, receptors
  • different shapes = various functions
• What are ion channels?


  Protein molecules that span across the cell membrane allowing passage of ions from one side of the membrane to the other
• Transport proteins

  1). Carrier proteins

  • open all the time

  2). Gated channels

  • opens to particular stimulus/require something to occur first!
  • Mechanical-gated, voltage gated, ligand-gated
  • Gated does NOT mean it requires energy
• What are ions?

  Atom or group of atoms that have an electric charge

  • Ions with positive charge = cations
  • Ions with negative charge = anions

  Ex. Ca+, Cl-, K+, Na+
• Mechanical gated channel


  physical change on cell membrane

  • triggers gated channel to open
• Voltage gated channel


  electrical change

  • triggers gated channel to open
• Ligand gated channel


  chemical binds to protein

  • triggers gated channel to open
• How do ions contribute to membrane potential?

  Sodium (Na+) and chloride (Cl-) ions are at high concentrations in extracellular region and low in intracellular regions. Chemical gradients drive the movement of ions in and out of call (high to low) .
• What forces promote Na+ to leak into the cell?

  1. Chemical gradient (Na+ from high to low concentration)
  2. Electrical gradient (positive/negs attract)
• What forces promote K+ to leak out of the cell?

  1. Chemical gradient (K+ goes from high inside to low outside)
• Active transport

  energy driven process where membrane proteins transport molecules across cells

  • low —> high = required energy

  ex. sodium potassium pump

  
• Facilitated diffusion

  • Polar
  • Ion
  • Big
  • Requires help
  • high —> low = no energy

  
• Simple diffusion

  • non-polar/hydrophobic
  • small
  • high —> low = no energy

  
• How are ions repelled to eachother?


  Repelled by like-charges
• Neurons


  structural and functional unit of the nervous system. Receive and pass on information
• Cells in nervous system

  • Neurons
  • Glial cells
• Dendrites


  part of neuron that receives information
• Cell body


  contains the nucleus and other organelles
• Axon hillock


  where action potential begins
• axon


  where action potential occurs
• myelin sheath


  helps to make action potential happen faster
• terminal branches


  part that passes the message to another cell
• Resting membrane potential


  Na+ on outside

  K+ inside

  • negatively charged inside
  • establishes chemical disequilibrium
  • differ in charges establish electrical equilibrium

  
• Action potential graph

  1. Resting membrane potential
  2. Stimulus
  3. Depolarization
  4. Repolarization
  5. Hyperpolarization

  
• Once you pass threshold, action potential will be triggered. (All or nothing, THINK: toilet flushing).
• What occurs during depolarization?

  Voltage gated sodium channels open
• What occurs during repolarization?

  At peak, voltage gated sodium channels close. Voltage gated potassium channels open.
• What occurs during hyperpolarization?

  Voltage gated potassium channels close