Lecture 3 Flashcards

1
Q

sensory stimulus

A

activation of cutaneous mechanoreceptors by skin deformation

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2
Q

neural code

A

action potential, post-synaptic potential

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3
Q

interpretation/action

A

flexor withdrawal reflec

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4
Q

extracellular and cytosolic fluid

A

-neurons are in an extracellular milieu that is water-based
-ions: atoms or molecules with a net electrical charge

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5
Q

the concentration gradient is the product of:

A
  1. the imermeability of the plasma membrane to the movement of ions
  2. the presence of proteins that maintain actively the gradient of concentration
  3. the presence of proteins that allow ions to passively cross the membrane (into or out of the cell)
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6
Q

ion channels

A

control of resting and action potentials

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7
Q

receptors-channels

A

neurotransmitters and post-synaptic potentials

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8
Q

metabotropic receptors

A

neurotransmitters and neuromodulators

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9
Q

ion pumps

A

-producers of electrochemical gradients
-formed by transmembrane proteins
-catalyze ATP for energy (active transport)
-push ions against the concentration gradient (from more diluted to concentrated)
-produces the ion concentration gradients (neuronal signaling)

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10
Q

proteins-channels

A

-voltage dependent
-polar R groups
-non polar R groups
-transmembrane domains
-ion selectivity
-mechanism of activation (gating)

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11
Q

Na/K ATPase ion exchange pump

A

-catalyze ATP into ADP
-drives 3 Na+ out, brings 2 K+ in
-forms a concentration gradient of more Na outside and more K inside

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12
Q

K+ equilibrium potential

A

-80mV

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13
Q

Na+ equilibrium potential

A

62mV

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14
Q

Ca2+ equilibrium potential

A

123mV

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15
Q

Cl- equilibrium potential

A

-65mV

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16
Q

diffusion

A

-dissolved ions redistribute in a homogenous manner
-ions diffuse along their concentration gradient when the channels are permeables to ions and there is a concentration gradient across the membrane

17
Q

electrical potential (V)

A

-pressure exerted on ions
-influences the movement of ions

18
Q

electric current (I)

A

movement of ions according to Ohm’s law:
V=R x I or I=V x G

19
Q

electric conductance (G)

A

= ease by which I can flow through

20
Q

resistance (R)

A

capacity to block I
R=1/G

21
Q

equilibrium potential

A

-each ion has a potential at which the net ionic flow is 0
-I.e. membrane potential at which the movement of the inside (i) to the outside (o) is the same as in the other direction
-difference in electrical potential that counters the diffusive force due to the concentration gradient

22
Q

is the membrane potential determined solely by the concentrations of K+?

A

No

23
Q

structure of K+ channels

A

-4 transmembrane subunits
-hairpin pore endows selectivity and permeability to K+ ions
-mutations of K+ channels (hereditary neurological disorders –> epilepsy)