PNB 2274 EXAM 2 QUESTIONS AND ANSWERS
All steps that of skeletal muscle contraction
Starting with action potential traveling down motor neuron axon
Note gating mechanisms - answers :a.p down motor neuron axon
Voltage gated ca2+ channels open --> ca2+ flows into presynaptic cell
Vesicles then fuse with synaptic knob and release neurotransmitter (ach) into synapse
Ach binds to ach receptors (ligand gated) on motor plate of muscle fiber
Ach receptor is ionotropic --> opens nonselective voltage gated cation channels, allow
na+ flow in / k+ flow out
(at synapse reuptake and ache terminate signal)
Epsp to threshold --> action potential in muscle fiber --> travels down t-tubule
Voltage gated dhp receptor conformational change opens
Dhp mechanical pulls block from ryr on sarcoplasmic reticulum
Open ryr --> ca2+ flows into sarcoplasm
Ca2+ binds to tropononin and move tropomyosin from actin binding site
Myosin head binds and releases a p
Power stroke
Release adp, leaving spot for atp to bind and release myosin head
Atp hydrolyzes to adp + p
Opposite charges ______ and like charges ________ according to ___________. -
answers :attract; repel; coulombs law
If you decrease the distance between a particle what happens to the force - answers
:increases
What membrane quality prevents passage of charge - answers :insulator
,What membrane quality can allow charge passage (via ion channels - answers
:conductor
Membranes are - answers :typically insulators, can be conductive, exhibit passive and
active behaviors
The potential inside the cell relative to the outside potential is known as - answers :vm
(membrane potential)
Inside the cell is about _____ mv?
Outside the cell is assumed to be _____ mv? - answers :-70, slightly negative
0
What contributes to membrane potential - answers :unequal distribution of ions and
unequal permeability of ions (ek and there permeability)
Relative concentrations inside and outside for the following ions at rest:
K+
Cl-
Na+ - answers :k+ high inside
Cl- high outside
Na+ high outside
[na+] is _____ outside the cell - answers :higher
Wants to flow in due to charge and concentration
What contributes to negative charge inside cell - answers :dna, atp, rna negatively
charged and can't leave cell
Ion distributions and concentrations are maintained by - answers :pumps and selective
permeability (ion leaky channels)
Nernst equilibrium tells us - answers :voltage at which an ion diffuses in one direction
balanced by electrostatic attraction in another
Eionx = rt/zf ln ([x]outside/ [x]inside)
What effects the nernst - answers :temperature
, Concentration
Note: z = ion charge
What is equilibrium potential - answers :when ion net flow is 0, requires no e
The membrane potential at which the flux of a given ion type reverses from inward to
outward - answers :reversal potential
What happens to the nernst if concentration is equal inside and outside cell?
What is this called? - answers :ln(1) = 0
Therefore: e ion = 0
Equilibrium potential
Eionx = rt/zf ln ([x]outside/ [x]inside)
Increase temp what happens to nernst? - answers :increase
In what cases is the nernst irrelevant (we can't use it)? - answers :ion not permeable
Chemical is uncharged
Resting membrane potential (vm) is
What does this mean - answers :-70 mv
The cell potential at which all ions net flux is 0 (steady state)
Example:
K+ is concentrated high inside cell
If ek > vm what will happen to k+
Flow in
Flow out
No change - answers :flow out
Example:
K+ is concentrated high inside cell
If ek < vm what will happen to k+
Flow in
Flow out
All steps that of skeletal muscle contraction
Starting with action potential traveling down motor neuron axon
Note gating mechanisms - answers :a.p down motor neuron axon
Voltage gated ca2+ channels open --> ca2+ flows into presynaptic cell
Vesicles then fuse with synaptic knob and release neurotransmitter (ach) into synapse
Ach binds to ach receptors (ligand gated) on motor plate of muscle fiber
Ach receptor is ionotropic --> opens nonselective voltage gated cation channels, allow
na+ flow in / k+ flow out
(at synapse reuptake and ache terminate signal)
Epsp to threshold --> action potential in muscle fiber --> travels down t-tubule
Voltage gated dhp receptor conformational change opens
Dhp mechanical pulls block from ryr on sarcoplasmic reticulum
Open ryr --> ca2+ flows into sarcoplasm
Ca2+ binds to tropononin and move tropomyosin from actin binding site
Myosin head binds and releases a p
Power stroke
Release adp, leaving spot for atp to bind and release myosin head
Atp hydrolyzes to adp + p
Opposite charges ______ and like charges ________ according to ___________. -
answers :attract; repel; coulombs law
If you decrease the distance between a particle what happens to the force - answers
:increases
What membrane quality prevents passage of charge - answers :insulator
,What membrane quality can allow charge passage (via ion channels - answers
:conductor
Membranes are - answers :typically insulators, can be conductive, exhibit passive and
active behaviors
The potential inside the cell relative to the outside potential is known as - answers :vm
(membrane potential)
Inside the cell is about _____ mv?
Outside the cell is assumed to be _____ mv? - answers :-70, slightly negative
0
What contributes to membrane potential - answers :unequal distribution of ions and
unequal permeability of ions (ek and there permeability)
Relative concentrations inside and outside for the following ions at rest:
K+
Cl-
Na+ - answers :k+ high inside
Cl- high outside
Na+ high outside
[na+] is _____ outside the cell - answers :higher
Wants to flow in due to charge and concentration
What contributes to negative charge inside cell - answers :dna, atp, rna negatively
charged and can't leave cell
Ion distributions and concentrations are maintained by - answers :pumps and selective
permeability (ion leaky channels)
Nernst equilibrium tells us - answers :voltage at which an ion diffuses in one direction
balanced by electrostatic attraction in another
Eionx = rt/zf ln ([x]outside/ [x]inside)
What effects the nernst - answers :temperature
, Concentration
Note: z = ion charge
What is equilibrium potential - answers :when ion net flow is 0, requires no e
The membrane potential at which the flux of a given ion type reverses from inward to
outward - answers :reversal potential
What happens to the nernst if concentration is equal inside and outside cell?
What is this called? - answers :ln(1) = 0
Therefore: e ion = 0
Equilibrium potential
Eionx = rt/zf ln ([x]outside/ [x]inside)
Increase temp what happens to nernst? - answers :increase
In what cases is the nernst irrelevant (we can't use it)? - answers :ion not permeable
Chemical is uncharged
Resting membrane potential (vm) is
What does this mean - answers :-70 mv
The cell potential at which all ions net flux is 0 (steady state)
Example:
K+ is concentrated high inside cell
If ek > vm what will happen to k+
Flow in
Flow out
No change - answers :flow out
Example:
K+ is concentrated high inside cell
If ek < vm what will happen to k+
Flow in
Flow out
