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2010-08-24 20:15:31

Covers material for 1st test
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  1. Define physiology
    • Study of the logic of life
    • No longer just FUNCTION - understand how/why life works
  2. Define "Teleological"
    • Using purpose as a means of explanation
    • Ie, we breathe to oxygenate our bodies
  3. Define "Mechanistic"
    • Using cause and effect as a means of explanation
    • Ie, concentration gradients are created in capillary beds and drive exchange
  4. Define the key relationship for Quantity in mathematical terms
    • Quantity = Concentration x Volume
    • Volume can be exchanged for Flow
  5. Define the key relationship for Flow in mathematical terms
    • Flow = Force x Conductance
    • Flow = Force / Resistance
  6. Define Homeostasis
    • The property of an open system (organism) to regulate its internal environment to maintain a stable, constant condition
    • Accomplished by adjusting multiple dynamic equilibriums which are controlled by interrelated control mechanisms
  7. Relative ion concentrations of:
    • Positive > Negative
    • Na+ > Cl- >> K+
  8. Relative ion concentrations of:
    Interstitial fluid
    • Positive > Negative
    • Na+ > Cl- >> K+
  9. Relative ion concentrations of:
    Intracellular fluid
    • Negative > Positive
    • K+ > Cl- > Na+
    • Note: there are many negatively charged proteins
  10. How large is the volume of plasma?
  11. How large is the volume of the ISF?
  12. Name the organs used to maintain the ISF
    • Kidneys
    • Skin
    • Lungs
    • GI Tract
  13. How large is the volume of the intracellular fluid?
  14. How is water lost?
    • Urine
    • Insensible water
    • Feces
  15. How is water obtained?
    • Drink
    • Water content in food
    • Oxidative metabolism
  16. How much water is typically lost in a day?
  17. Describe the point of this experiment:
    • Osmolarity acts as a regulator of homeostasis
    • The increased amount of fluid into the system dropped osmolarity of the blood
    • This triggered increased renal filtration to re-establish proper levels
  18. What constitues the plasma membrane?
    • A lipid bilayer (hydrophobic in, hydrophilic out)
    • Proteins
  19. What is the fluid mosiac model?
    • Describes the motility/fluidity of the membrane
    • Proteins and lipids are free to diffuse around
    • Membrane can buckle and expand
  20. How does the PM act as a barrier?
    It is semipermeable based on molecule: size, polarity, and solubility
  21. What are the PM's functions?
    • Barrier
    • Cell Adhesion
    • Bearer of self-identity markers/transport proteins
  22. What are the two types of membrane proteins?
    • Extrinsic (perepheral)
    • Intrinsic (integral)
  23. What are the types of integral proteins?
    • Carrier - must change shape to permit passage
    • Channel - always open
  24. What are the types of unassisted membrane transport?
    • Diffusion
    • Osmosis
  25. What are the types of assisted membrane transport?
    • Carrier-mediated transport
    • Active transport
    • Vesicle transport
  26. What is diffusion?
    • Spreading of molecules based solely on their thermal energy
    • Move from high => low concentration
  27. What is the difference between Brownian motion and diffusion?
    • Diffusion only occurs down a concentration gradient (until uniformly dispersed)
    • BM describes the actual motion - when gradient is abolished, movement still occurs
  28. Factors that affect diffusion
    • Concentration gradient
    • Lipid solubility of molecule
    • Membrane surface area
    • Molecular weight of molecule
    • Membrane thickness
  29. How can membrane channels be selective?
    Residues within the "ion filter" portion selectively filter the correct ion
  30. What is the difference between diffusion and carrier-mediated transport?
    • Carrier-mediated requires conformational change of protein
    • Carrier-mediated may require energy input
    • Carrier-mediated reaches a saturation point (speed of which protein can change shape maxed)
  31. What factors affect speed of carrier-mediated transport?
    • Specificity
    • Saturation
    • Competition
  32. What are the types of active transport?
    • Primary - require direct use of ATP
    • Secondary - driven by ion concentration gradient established by a primary pump
  33. Does facilitated diffusion require energy input?
  34. What are the types of vesicular transport?
    • Endocytosis
    • Pinocytosis
    • Receptor-mediated
    • Phagocytosis
    • Exocytosis
  35. Which cells have a membrane potential?
    ALL cells
  36. How is a membrane potential established?
    Differences in charge are sequestered to opposite sides of the PM
  37. What is the resting membrane potential?
    • The separation of charge across the PM in all cells
    • Nerves maintain this when they are not firing an action potential
  38. What controls the membrane potential?
    Ion channels
  39. Approximate size of things:
    Pores' existance was postulated long before they were discovered (due to size)
  40. Describe the "ionic hypothesis"
    • The membrane potential is determined by the intracellular K+
    • Julius Bernstein
    • Used squid axon
  41. Describe the "sodium theory"
    • Membrane potential in nerves is based both on intracellular K+ and extracellular Na+
    • Hodgkin & Huxley
    • Had better instruments - could see action potential better
  42. What was incorrect about the "ionic hypothesis"?
    • Stated an AP was generated to due breakdown of membrane potential
    • Did not account for Na+
  43. What is the Nernst equation?
    • Em = ~(60/z) log10 [K+]outside / [K+]inside (mV)
    • For 1 ion
    • z = charge
  44. What does the Nernst equation describe?
    • At equilibrium, the force exerted by ion concentration is balanced by force exerted by charge
    • Chemical vs Electrical
  45. What is the Goldman-Hodgkin-Katz Constant Field Equation?
    • It accounts for numerous ions permeating the PM
    • Can simplify to Nernst when permeability of one ion >> other
  46. Define the relative permeabilities of ions during an AP
    • At rest, K >> Na
    • At peak AP, NA >> K
  47. What is a patch clamp?
    Allows researcher to analyze (hopefully) a single ion channel in a membrane
  48. Define depolarization
    The abolishment of a membrane potential
  49. Define repolarization
    The re-establishment of a membrane potential
  50. Define hypopolarization
    The further reduce (more negative) the membrane potential
  51. Define hyperpolarization
    To increase (make less negative) the membrane potential
  52. How to local anesthetics work?
    • As a weak base, they can cross membrane in uncharged state
    • Inside cell, the charged form can bind to voltage gated Na+ channels
    • Prevent generation of an AP
  53. What are the 3 major channels used in axons?
    • Leaky K+
    • Voltage gated Na+
    • Voltage gated K+
  54. What is crenation?
    The wrinkling of a cell (ie, RBC) due to a high salt solution
  55. How can water pass across PM?
    • By osmosis across bilipid layer (slow)
    • Thru aquaporins (fast)
  56. Describe the structure of aquaporins
    • 6 transmembrane segments that associate into an hourglass shape
  57. What are the two branches of aquaporins?
    • Orthodox - extremely selective to water
    • Cocktail set - homologs; will let similar molecules pass
  58. Define osmosis
    • The net diffusion of water down its concentration gradient
    • Thru a selectively permeable membrane impermeable to the SOLUTE
    • Moves from low => high SOLUTE CONCENTRATION
  59. When does osmosis reach equalibrium?
    When osmotic pressure = hydrostatic pressure
  60. Define Osmolarity
    • Measure of a solution's total solute concentration
    • Expressed in Osmoles/L
    • A colligative property
  61. What is a colligative property?
    • One that depends solely on the number of particles, not the nature of them
    • Ie, Osmolarity
  62. What is the normal osmolarity of body fluids?
    290-300 mOsm
  63. What is the van't Hoff limiting law?
    • π = RTΦic
    • Calculates osmotic pressure
    • "i" is the number of moeities the molecule dissolves into
    • "c" (molarity) can also be substituted for "m" (molality)
    • Φ is the osmotic coefficient
    • Closer to ideal the more dilute a solution is
  64. What is the osmotic coefficient (Φ) for some solutions?
    • Ideal = 1
    • Monovalent = 0.9-0.95
    • Multivalent < 0.9
    • Mono-/disaccharides ~ 1 (a little over)
  65. Determining net flow of water
    • Jv(net) = Kf (deltaPσdeltaπ)
    • σ is the reflection coefficient
    • Kf is the filtration coefficient
  66. What is the reflection coefficient (σ)?
    • σ = 1 - P(solute)/P(water)
    • Describes the permeability of the solute
    • σ = 1, impermeable
    • σ = 0, permeable
  67. What factors affect Kf?
    • Related to the size of the membrane
    • Related to relative conductivity of water thru the membrane
  68. Why do body cells not normally experience volume changes?
    The concentration of nonpenetrating solutes in the ECF is carefully regulated to match the osmolarity of the ISF
  69. Define tonicity
    The effect nonpenetrating solutes in a solution have on cell volume
  70. Describe the difference between tonicity and osmolarity
    • Osmolarity has units to describe concentration in each compartment
    • Tonicity is merely the relative concentration between two compartments
  71. Define Isotonic
    Equal solute concentrations between compartments
  72. Define Hypertonic
    [Solutes in ECF] > [Solutes in cell]
  73. Define Hypotonic
    [Solutes in ECF] < [Solutes in cell]
  74. What is the isotonic condition for RBCs?
    • 0.9% NaCl
    • 154mM
    • 308mOsm
  75. Can proteins penetrate capillaries?
  76. What is the mechanistic reason for molecule exchange in capillary beds?
    • Net blood pressure entering causes solutes to cross into tissues
    • Net osmotic pressure exiting causes the reverse
  77. What makes the capillary beds ideal for exchange?
    • Maximized surface area
    • Velocity of blood flow is relatively slow
  78. How to pass a capillary
    • Water soluble molecules can diffuse thru water-filled gaps
    • Lipid soluble can diffuse across endothelial PM
    • Proteins CANNOT diffuse across
  79. What drives the osmotic pressure in capillaries?
    • Proteins
    • Since all other solutes have a σ~0, and proteins are σ~1, only the proteins affect osmotic pressure
  80. What is the Starling equation?
    • Describes how net pressure on either end of the capillary beds drives molecule transport