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ANT 3100: Chapter 11 (PHYS)
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82
Anatomy
Undergraduate 1
10/24/2012

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Term
membrane potential
Definition
electrical potential difference across the cell membrane
Term
resting membrane potential
Definition
membrane potential in a cell at rest (not stimulated)
Term
millivolts of resting membrane potential
Definition
-40 to -80 mV in neurons
Term
resting membrane potential is established by 3 main ions
Definition
sodium, potassium, chloride
Term
[Na]i: intracellular sodium concentration
Definition
~ 15 mEq/L
Term
[Na]o: extracellular sodium concentration
Definition
~ 145 mEq/L
Term
permeability of sodium
Definition
.05 (at rest)
Term
[K]i: intracellular potassium concentration
Definition
~ 135 mEq/L
Term
[K]o: extracellular potassium concentration
Definition
~ 5 mEq/L
Term
permeability of potassium
Definition
1.0 (at rest)
Term
what plays the biggest role in determining resting membrane potential?
Definition
potassium
Term
[Cl]i: intracellular chloride concentration
Definition
~ 8 mEq/L
Term
[Cl]o: extracellular chloride concentration
Definition
~ 110 mEq/L
Term
permeability of chloride
Definition
.45 (at rest)
Term
2 Factors that dictate resting membrane potential
Definition
1) magnitude of the concentration gradients of ions
2) permeabilities of the membrane to ions
Term
What leaks passively into the cell during resting conditions?
Definition
Na+ (permeability = small) and Cl- (permeability = large)
Term
What leaks passively out of the cell during resting conditions?
Definition
K+ (permeability = large)
Term
Increase extracellular Na+
Definition
*Vm becomes more positive(depolarization)
increase the gradient for Na to leak into the cell
Term
Increase extracellular K+
Definition
*depolarization
decrease the gradient for K to leak out of the cell
Term
Increase extracellular Cl-
Definition
*causes Vm to become more negative (hyperpolarization)
increase the gradient for Cl to leak into the cell
Term
Decrease extracellular Na+
Definition
*hyperpolarization
decreases the gradient for Na to leak into the cell
Term
Decrease extracellular K
Definition
*hyperpolarization
increases gradient for K to leak out of the cell
Term
Decrease extracellular Cl-
Definition
*depolarization
decrease the gradient for Cl to leak into the cell
Term
Increase intracellular Na
Definition
*hyperpolarization
decreases the gradient for Na to leak into the cell
Term
Increase intracellular K
Definition
*hyperpolarization
increases the gradient for K to leak out of the cell
Term
Increase intracellular Cl
Definition
*depolarization
decrease the gradient for Cl to leak into the cell
Term
Decrease intracellular Na
Definition
*depolarization
increase the gradient for Na to leak into the cell
Term
Decrease intracellular K
Definition
*depolarization
decrease the gradient for K to leak out of the cell
Term
Decrease intracellular Cl
Definition
*hyperpolarization
increases the gradient for Cl to leak into the cell
Term
at rest, the cell is most permeable to
Definition
K+
Term
increase the permeability of Na+
Definition
increase the movement of Na into the cell = depolarization
Term
decrease the permeability of Na+
Definition
decrease the movement of Na into the cell = hyperpolarization
Term
increase the permeability of K+
Definition
increase the movement of K out of the cell = hyperpolarization
Term
decrease the permeability of K+
Definition
decrease the movement of K out of the cell = depolarization
Term
increase the permeability of Cl-
Definition
increase the movement of Cl into the cell = hyperpolarization
Term
decrease the permeability of Cl-
Definition
decrease the movement of Cl into the cell = depolarization
Term
action potential (location)
Definition
occurs solely in excitable cells
Term
action potential
Definition
local, very large and very rapid changes in resting membrane potential
Term
threshold
Definition
depolarized resting membrane potential that must be reached to elicit an action potential
Term
refractory period
Definition
period of time when a cell fails to respond to a stimulus of threshold intensity
Term
absolute refractory period
Definition
period of time when no action potential can be elicited
Term
absolute refractory period (when)
Definition
occurs during the repolarization phase due to the inactivation of Na+ channels
Term
relative refractory period
Definition
possible to elicit an action potential during this period of time even though a greater than threshold stimulus is needed
Term
relative refractory period (when)
Definition
occurs during the after-hyperpolarization phase [most Na+ channels begin to activate and most K+ channels can be opened or are still opened]
Term
action potential conduction
Definition
spread of action potentials along a membrane
Term
velocity in axons depends on
Definition
fiber diameter and myelin
Term
rate of conduction velocity
Definition
less than 2 meters/sec
Term
rate of saltatory conduction
Definition
3-120 meters/sec
Term
subthreshold stimulus
Definition
no action potential
Term
threshold stimulus
Definition
one action potential
Term
submaximal stimulus
Definition
many action potentials
Term
maximal stimulus
Definition
maximum number of action potentials
Term
supramaximal stimulus
Definition
no further increase in action potentials
Term
electrical synapses are formed by
Definition
two connexons
Term
a single connexon is formed by
Definition
6 connexins (proteins)
Term
2 functions of electrical synapses
Definition
1) synchronization between adjoining cells
2) rapid passage of info between two adjoining cells
Term
presynaptic membrane
Definition
membrane at the synapse that is carrying information
Term
postsynaptic membrane
Definition
membrane at the synapse that is receiving the information
Term
fate of neurotransmitter
Definition
reuptake by presynaptic membrane or astrocytes via endocytosis
Term
postsynaptic potential
Definition
resting membrane potential change in postsynaptic membrane due to the binding of neurotransmitter to postsynaptic membrane receptors
Term
excitatory postsynaptic potential (EPSP)
Definition
caused by depolarizing current through the postsynaptic membrane (influx of cations [K]or efflux of anions [Na])
Term
inhibitory postsynaptic potential (IPSP)
Definition
caused by hyperpolarizing current through the postsynaptic membrane (influx of anions(Na) or efflux of cations [K])
Term
summation of postsynaptic potential
Definition
integrated sum of EPSPs and IPSPs; determines Vm change
Term
temporal summation
Definition
when multiple postsynaptic potentials from the same synapse converge at about the same time
Term
spatial summation
Definition
when multiple postsynaptic potentials from different synapses converge at about the same time
Term
synaptic plasticity
Definition
ability of some component of a synapse to change
Term
synaptic plasticity can cause
Definition
1) decrease or increase in neurotransmitter release
2) decrease or increase in receptor sensitivity
3) decrease or increase in number of receptors
Term
3 types of memory
Definition
1) sensory memory
2) short-term memory
3) long term memory
Term
sensory memory (description)
Definition
short term retention of sensory input; information that is scanned, evaluated, and acted upon
Term
how long does sensory memory last?
Definition
less than a second
Term
how long does short term memory last?
Definition
seconds to minutes to hours
Term
sensory memory is _____ in nature
Definition
electrical
Term
shorter short term memory is _____ in nature
Definition
electrical
Term
longer short term memory is _____ in nature
Definition
synaptic
Term
long term potentiation causes (3)
Definition
1)enhanced neurotransmitter release
2)enhanced receptor sensitivity
3)increased number of receptors
Term
how long does long term memory last?
Definition
hours to a lifetime
Term
long term memory is _____ in nature
Definition
synaptic
Term
two types of long term memory
Definition
1) declarative/explicit
2) procedural/implicit
Term
declarative memory
Definition
retention of events, people, places, facts, etc
Term
where is declarative memory stored?
Definition
in various parts of the cerebellum
Term
procedural memory
Definition
conditioned reflexes
Term
where is procedural memory stored?
Definition
in cerebrum and cerebellum
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