Physio Exam 1 Review

  1. list 3 factors that determine the rate of flux
    • 1. number of transporters in the membrane
    • 2. extent of transporter saturation (transporter affinity and ligand concentration)
    • 3. rate of transporter confirmational change
  2. how does a hypotonic solution change a cell?
    cell swells
  3. how does a hypertonic solution change a cell?
    cell shrinks
  4. how does an isotonic solution affect a cell?
    no change
  5. what is the difference between isotonic and isosmotic?
    • isotonic: non-penetrating solutes
    • isosmotic: non-penetrating plus penetrating solutes (non-penetrating: ions, penetrating: urea)
  6. 1 mole of NaCl is how many osmoles?
    2 osmoles (Na + Cl)
  7. how many osmoles is 1 mole of glucose?
    1 osmole
  8. what is the osmolarity of extracellular fluid?
    300 mOsm
  9. define equilibrium potential
    • when there is a concentration difference but no voltage difference, i.e. both sides have the same net charge
    • "The equilibrium potential is the voltage across a cell membrane that exactly balances the force in the concentration gradient of a permeable ion"
  10. define the nernst equation
    Ex = (58/z)log10 ([X1]/[X2]) where X1 = extracellular concentration, X2 = intracellular concentration and z = valence electron (eg. Ca = 2). The nernst equation yields the equilibrium potential of a single ionic species
  11. define the log10 of 0.1, 1, 10 and 100
    • 0.1: -1
    • 1: 0
    • 10: 1
    • 100: 2
  12. define diffusion potential
    a transient charge due to certain ions diffusing faster than other ions. this charge dissapears as the equilibrium potential is reached.
  13. true/false: [K] is always greater inside the cell than outside
  14. define the resting potential
    it is not a transient diffusion potential. it is a steady potential due to ions having moved across the membrane.
  15. define depolarization
    (aka hypopolarization). membrane potential moves toward 0 mV
  16. define repolarization
    membrane potential moving away from 0 mV in the negative direction
  17. define hyperpolarization
    membrane potential more negative than the resting value
  18. what would happen if the Na/K ATPase pump did not work?
    the membrane potential would slowly reach 0 mV
  19. list the steps of an action potential
    • 1. increase in Na permeability driven by electrical and concentration gradients
    • 2. membrane moves closer to 0 mV
    • 3. Voltage gated Na channels open causing more Na channels to open via positive feedback (rising stage)
    • 4. potential overshoots reaching 40 mV causing voltage gated K channels to open and K leaves the cell
    • 5. falling phase - first driven by concentration gradient then by electrical gradient. Na channels close (voltage gated) leading to Na inactivation
    • 6. hyperpolarization
    • 7. resting potential
  20. define absolute refractory period
    brief period after the AP when a second threshold stimulus or suprathreshold stimulus cannot elicit a second AP due to voltage gates being closed.
  21. why type of stimulus will not cause an AP?
    a stimulus that is applied slowly--"Adaption"
  22. define Adaption
    a property of the neuron and is due to accomodation of ion channels
  23. define rheobase
    magnitude of the lease intense stimulus that can elicit a response
  24. define utilization time
    duraction required to elicit a response by a stimulus with a rheobase magnitude
  25. define chronaxie
    duration required to elicit a response from a stimulus that has a magnitude that is twice the rheobase magnitude
  26. a drug that makes a cell more excitable will shift the graph which direction?
    to the left
  27. define electrotonic currents
    passive currents that do not propagate
  28. what prevents an AP from traveling backwards along an axon?
    Na inactivation
  29. list the events that occur during an AP in a motorneuron to an AP in the sarcolemma of a muscle cell
    • 1. AP reaches presynaptic terminal causing an influx of Ca
    • 2. ACh is released into the synapse
    • 3. ACh binds AChR in postsynaptic motor endplate
    • 4. chemically regulated Na and K channels open causing Na influx and K efflux across the motor endplate
    • 5. Endplate potential is generated and opens voltage-regulated Na channels in the sarcolemma immediately surrounding the motor endplate causing an AP in the sarcolemma
  30. list 5 characteristics of End Plate Potentials (EPPs)
    • 1. only occur following an AP in a motorneuron
    • 2. not spontaneous
    • 3. confined to endplate region
    • 4. amplitude: 10 mV
    • 5. lead to an AP in adjacent region of the membrane
  31. list 6 characteristics of Miniature EPPs
    • 1. occur at rest
    • 2. spontaneous
    • 3. confined to endplate region
    • 4. follow release of the contents of one synaptic vesicle
    • 5. amplitude 1-2 mV
    • 6. undergo summation
  32. what are the products of ACh metabolism?
    • acetate: enters circulation
    • choline: taken up by presynaptic terminal to form ACh again
  33. what effect does curare have?
    binds to AChR so ACh cannot bind. Muscle AP does not occur
  34. what effect does botulinum toxin have?
    blocks ACh release causing flacid paralysis
  35. what effect does organophosphatase have?
    blocks the action of ACh, muscle cannot relax causing spastic paralysis leading to suffocation followed by flacid paralysis due to ATP depletion.
  36. define Titin
    largest protein. stretches when filaments contract. Runs from Z-line to M-line and stabilizes thick filaments
  37. define Nebulin
    runs along entire length of thin filament and acts as a scaffold
  38. what areas of the sarcomere change length during contraction?
    I and H change in length but the filament length does not change during contraction.
  39. list 3 characteristics of Type I myosin
    • 1. slow contraction
    • 2. small diametere
    • 3. less fatigue
  40. list 4 characteristics of Type IIA fibers
    • 1. smaller than IIB
    • 2. use oxidative metabolism
    • 3. less fatigue
    • 4. slower than IIB
  41. list 3 characteristics of type IIB fibers
    • 1. use glycolytic metabolism
    • 2. largest diameter
    • 3. fast
  42. what type of function do Type I fibers serve?
    maintaining posture
  43. what type of functions do Type II fibers serve?
    perform tasks rapidly with a lot of dexterity
  44. describe the orientation of transverse tubules in cardiac vs. skeletal muscle
    • cardiac: run parallel to fibers
    • skeletal: run perpendicular to fibers
  45. what is special about myosin heavy chain alpha?
    expressed only in the heart and masseter
  46. what is special about Troponin I?
    a unique isoform only expressed in the heart
  47. is nebulin in cardiac muscle?
  48. what is the significance of a long refractory period in cardiac muscle?
    prevents the heart from undergoing a tetanic contraction, which would be life threatening.
  49. list the steps in a ventricular action potential
    • Phase 0: Na influx
    • Phase 1: K influx, Na efflux
    • Phase 2: Ca influx, K efflux
    • Phase 3: K influx, Ca efflux
    • Phase 4: no net current flow
  50. list 2 sources of calcium in the heart
    • 1. interstitial space
    • 2. SR
  51. list 3 methods of removal of Ca in the heart
    • 1. SR removes Ca via Ca-ATPase pump
    • 2. Membrane bound Ca-ATPase pump pumps Ca out of the cell
    • 3. Na/Ca Exchanger (Secondary active transport mechanism) to pump out Ca and pump in Na, the Na/K ATPase pump maintains the Na concentration
  52. list the steps in smooth muscle contraction initiation
    • 1. Increase in cytosolic Ca
    • 2. Ca + calmodulin
    • 3. Ca/calmodulin + MLCK
    • 4. Phosphorylation of myosin cross bridges
    • -Activation results when MLCK activity is greater than the phosphatase activity
  53. what is special about the inward flow of positive charged ions in smooth muscle?
    uses Ca instead of Na during rising phase of the action potential
  54. list 4 mechanisms that control smooth muscle activation
    • 1. some cell spontaneously generate APs (resting potential is never steady)
    • 2. no NMJ in smooth muscle. motor neuron endings release neurotransmitters in the vicinity of smooth mucles cells
    • 3. hormones can act as NTs
    • 4. local factors such as pH, O2 level, NO and stretching can affect smooth muscle activation
  55. explain the difference between the two types of smooth muscles
    • Single-Unit: gap junctions, all cells work together, spontaneously activated, stretch-activated
    • Multi-Unit: each cell activated independently, no spontaneously activated
  56. list the jaw opening muscles
    digastric, lateral pterygoid
  57. list the jaw closing muscles
    masseter, temporalis, medial pterygoid
  58. what type of fibers predominate in the deep and superficial masseter?
    slow fibers, amount of slow fibers increase from bruxing
  59. what general pattern exists among all jaw closing muscles
    greater amounts of slow myosin in deep vs. superficial and anterior vs. posterior
  60. what type of efferent nerve fibers are in a muscle spindle?
    gamma fusimotor fibers (most common) and beta fusimotor fibers (rare: 1/3 of all spindles)
  61. what type of sensory nerve fibers are in muscle spindles
    • Ia afferent: primary endings
    • II afferent: secondary endings
  62. what type of muscle fibers are in muscle spindles?
    • 1. nuclear bag intrafusal (2-3/spindle)
    • 2. nuclear chain intrafusal (4-6/spindle)
    • - most fibers in a muscle are extrafusal fibers which do the work assoc. with muscle contractions
  63. what is the role of gamma motor neurons in muscle spindle?
    sensitivity in shortened muscles. gamma motor neurons cause polar regions of intrafusal fibers to shorten --> stretch of equatorial regions --> restoration of sensitivity
  64. what is the golgi tendon organ?
    receptors in skeletal muscles. they are located at the junction between muscle fibers and tendons. they generate signals proportional to the amount of force generated by the extrafusal muscle fibers. Basically tells you how much force the muscle is doing so you don't throw a tea cup over your shoulder when you pick it up.
  65. explain the muscle relationships between carnivores, herbivores and omnivores
    • Carnivores: large temporalis, jaw closers express superfast myosin
    • Herbivores: Large masseter, jaw closers express alpha cardiac myosin, no superfast myosin
    • Omnivores: unspecialized.
  66. what are the three masticatory phases?
    • Preparatory: transport into the mouth
    • Reduction: breakdown of food
    • Preswallowing: bolus formation
  67. what sensory nuclei control mastication?
    • Trigeminal Sensory Nucleus: projects to cerebellum
    • Trigeminal Mesencephalic Nucleus: cell bodies of spindle afferents from jaw closers, mechanoreceptors in PDL, gingiva and palate
  68. what are the motor nuclei involved in mastication
    • Trigeminal Motor Nucleus: alpha and gamma motor neurons of jaw closers
    • Hypoglossal Motor Nucleus
    • Facial Motor Nucleus
  69. motor, sensory, and premotor cortex are active during voluntary clenching, but the premotor cortex is not active during what?
    gum chewing
  70. explain the jaw-closing reflex
    afferent fibers from muscle spindles, cell bodies in mesencephalic nucleus synapse on alpha motor neurons in trigeminal motor nucleus. very fast with basically no modulation from higher centers
  71. explain the jaw-opening reflex
    stimulus (touch, pressure) excites afferents that terminate in the spinal trigeminal tract which synapse on interneurons which in turn synapse on alpha motor neurons in trigeminal motor nucleus to innervate jaw openers. polysynaptic reflex, highly modulated for specific stimulus.
  72. explain the difference between facultative group and obligate group of muscles in terms of swallowing
    • facultative: variable group involved with preparatory and oral phases
    • obligate: muscles used in the pharyngeal phase of swallowing
  73. list 4 mechanisms that prevent aspiration of food
    • 1. respiration is inhibited
    • 2. larynx and upper esophageal sphincter elevate
    • 3. intrinsic muscles of glottis move vocal cords toward each other
    • 4. bolus moves through sinuses to pharynx
  74. list the sensory and motor nuclei involved in swallowing
    • Sensory: nucleus tractus solitarius, trigeminal sensory
    • Motor: nucleus ambiguus, facial, trigeminal and hypoglossal nuclei
  75. what are the different interneurons involved in swallowing and what do they do?
    • Dorsal Interneurons: initiation and timing of swallowing
    • Ventral Interneurons: distribute the excitation to the swallowing motor nuclei
  76. what motorneurons are inhibited during the oral and pharyngeal phase of swallowing?
    esophageal motorneurons
Card Set
Physio Exam 1 Review
overview of physiology for exam 1