BIOL 155: Term 1

• Physiology


  Study of Body Function
• Anatomy


  Study of Function
• Trade-offs


  Occur when multiple competing function must be carried out by a single structure
• Homeostasis


  Ability to maintain a stable internal environment
• Components of homeostasis


  • Sensor
  • Integrator
  • Effector
• Allostasis


  Body's ability to adapt to our set point, or behaviour, to meet different conditions
• Types of allostasis


  • Physiological - set points automatically reset during specific states
  • Behavioural - we choose to perform behaviours that aren't currently needed (put on clothes)
• Negative Feedback Loop


  Variable returns back to set point
• Positive Feedback Loop


  Variable enhances moving further from set point
• Tumor


  When cell cycle regulation is disrupted, abnormal cell division occurs
• Cancer


  When boundaries of the tumor break through tissue and into bloodstream, attacking nutrients across body
• Properties of intercellular fluid

  • LOW Na + Cl
  • HIGH K
  • HIGH Viscosity
  • MORE Electronegativity
• Properties of extracellular fluid

  • HIGH Na + Cl
  • LOW K
  • LOW Viscosity
  • LESS Electronegativity
• Types of ion movement across membrane

  • Diffusion - NO protein assistance
  • No transport
  • Facilitated Transport - movement with help of membrane protein
• Types of facilitated transport

  • Passive Transport - Concentration Gradient [high] to [low]
  • Active Transport - Against Concentration Gradient [low] to [high]
• Types of active transport

  • Primary Active Transport: 'pump' protein uses ATP
  • Secondary Active Transport: cotransport protein (eg. Na drags protein when pumped)
  • Vesicular Transport: for larger particles
• Graded Potential


  Occurs in dendrites, small localized
• Factors affecting size of graded potential

  • # Ion Channels that Open - More Permeability
  • Direction + Amplitude
• Action Potential


  Occurs in axon, generated by opening and closing of Voltage-Gated Ion Channels
• Voltage-gated ion channels


  • Voltage-Gated Na Channel: RAPID
  • Voltage-Gated K Channel: SLOW
• Features of action potentials

  • All-or-None (Threshold)
  • Propagation: when they travel across axon it does not get weaker
  • Stereotyped Dimensions
  • All-or-None (Refractory)
• Types of refractory period

  • Absolute Refractory Period: a second AP CANNOT be triggered
  • Relative Refractory Period: a larger than normal stimulus can trigger 2nd AP
• Resting Membrane Potential


  The total resting membrane potential of all ions
• Equilibrium Potential Eion


  No Net Movement occurs across the membrane (Diffusion = Electro)
• Forces driving ion movement across membrane

  • Diffusive Forces: Uncharged molecule moves passively
  • Electromotive Forces: Charged molecules move
• Electrochemical Gradient


  Ions move across membrane according to Electrochemical Gradient (Diffusive + Electro Force)
• Mechanisms generating neuron transmembrane potential

  • Ion Channels - fastest
  • Cotransporter
  • ATP-Powered Pump - slowest
• Excitable cells


  • Neurons
  • Myocytes
• Types of ion channels

  • Non-Gated (Leak) Ion Channel: Always opened, Create Resting Membrane Potential
  • Gated Channels: Open and Close depending on 'Gating' Factors
• Gating factors for ion channels

  • Ligand-Gating - Binding of Neurotransmitters (eg. Ach)
  • Voltage Gating - Activation Gate, electrical change
  • Mechanical-Gating - Applied Pressure
• All new cells come from the division of preexisting cells
• During differentiation, cells specialize into different functions (epithelial, connective, muscle, neural)
• 4 Main Types of Tissue

  • Epithelial - line surfaces and spaces in the body
  • Connective - fills/stiffens spaces in your body
  • Muscle - contract/produce mechanical force
  • Nervous - specialized to send/receive info in the form of electromechanical signals
• Shared features of epithelial tissue

  • Epithelia
  • Glands
  • Cellular Polarity
  • Intercell Junctions
• Types of exocrine glands

  • Secrete sweat, substances, through ducts
• Endocrine glands


  Secrete hormones into bloodstream
• Surfaces of epithelial cells

  • Apical Surface - in contact with lumen
  • Basolateral Surface - in contact with interstitial fluid
  • Basement Membrane
• Types of intercell junctions

  • 'Leaky' Tight Junctions - allow water and solutes to pass through spaces
  • 'Tight' Tight Junctions - occur where apical surface turns to lateral
• Types of simple epithelial tissue

  • Squamous = square
  • Cuboidal = cubed
  • Columnar = columns
  • Pseudo-Stratified = look like multiple layers but 1
• Types of stratified epithelial tissue

  • Squamous
  • Cuboidal
  • Columnar