1-5-A Neuronal Action Potential Flashcards Preview

PHYSIOLOGY Exam 1 > 1-5-A Neuronal Action Potential > Flashcards

Flashcards in 1-5-A Neuronal Action Potential Deck (15):
1

1) Refraction Periods = (time it takes for neuron_________) is ______ [Fast/slow] so that ________

2) Cardiac Ventricle Refractory period is ______[shorter/Longer] than others. Why is this?

3) Name the 3 Cells that have Refractory Periods?

1) Refraction Periods (time it takes for neuron to start from resting potential and get back to resting potential) is FAST so that 1 AP can occur before the next starts!

2) Cardiac Ventricle Refractory period is longer to protect heart from additional electrical activity

3) Occurs in Motor Neurons / Skeletal Muscle / Cardiac Ventricle

2

1) [Subthreshold local responses] = small responses to ________ ________ that ________

2) When cell is depolarized to threshold = ______ ______ OCCURS! ---> ___ Channels open and ___ rushes INTO cell ______[passively/Actively]

1) [Subthreshold local responses] = small responses to depolarizing currents that bring neurons closer to [AP threshold]

2) When cell is depolarized to threshold = ACTION POTENTIAL OCCURS! ---> Na+ Channels open and Na+ rushes INTO cell passively

3

A: [Space Length Constant] = distance a ______ ______ can travel to the ______ before ______

B: LARGE Diameter axons= ______[higher/lower] internal and membrane resistance = ______ [longer/shorter] wavelength = ______[faster/slower] conduction

B2: ______ resistance decreases more than ______ resistance
So if you DEC ______ resistance you will INCREASE wavelength

A: [Space Length Constant] = distance a subthreshold depolarization can travel to the next membrane segment b4 dying out

B: LARGE Diameter axons= LOW internal and membrane resistance = LONGER wavelength = faster conduction

B2: {Ri} decreases more than {Rm}.
So if you DEC {Ri} you will INC wavelength

4

1) At Rest: INNER CELL = ______[positive/negative] and the Outer Cell = ______ [positive/negative]

2) Once a PART of the membrane is depolarized it becomes ______ from ______ state. What does this result in?

3) Local current flow= activates ______ channels to ______ the next membrane segment ---> ______ ______ in the resting membrane

4) ______ ______ are [ALL OR NONE RESPONSE]. What does this mean?

1) At Rest: INNER CELL = negative - - - - -
outer cell = + + + "positively cold outside"

2) Once a PART of the membrane is depolarized it becomes reversed from resting state and potential difference between the 2--->[local current flow] .

3) [Local current flow= activates Na+ channels to depolarize the next membrane segment --->AP in the resting membrane

4) Action Potentials are [ALL OR NONE RESPONSE] = A stimulus will either {elicit} an AP or {fail to elicit} an AP...no inbetween

5

A: UPSTROKE of AP comes from INC in ______ ---> ______ rushes into Cell and Cell becomes more ______ [+/-]
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B: REPOLARIZATION of AP comes from 2 things. What are they?
In this case ___ rushes OUT of the Cell and Cell becomes more ______[+/-]
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C: ______ can ONLY be closed/DEactivated by repolarization of the membrane potential

D: When channels are open, Na+ and K+ enter/leave cell ______ because they're going down their gradient

A: UPSTROKE of AP comes from INC in [Na+ channels opening]= Na+ rushes in = Cell becomes more POSITIVE
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B: REPOLARIZATION of AP comes from
1. [Na+ channels CLOSING] = "inactivation"
2. delayed INC of [K+ channels opening]
= K+ rushes OUT = Cell becomes more negative
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C: [K+ channels] can ONLY be closed/DEactivated by repolarization of the membrane potential

D: When channels are open, Na+ and K+ enter/leave cell PASSIVELY because they're going down their gradient

6

[M Gate] and [H-gate] regulate ____ movement!

*Resting : M Gate = ______ / H-gate = ______
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* Activated: M Gate = ______ / H-gate = ______ -->___ influx
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*INactivated: M Gate = ______ / H-gate = ______
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B: [Repolarization/____[+/-] membrane voltage] is what allows these channels to ___________

[M Gate] and [H-gate] regulate Na+ movement!

*Resting : M Gate = closed / H-gate = OPEN
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* Activated: M Gate = OPEN / H-gate = OPEN -->Na+ influx
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*INactivated: M Gate = OPEN / H-gate = closed
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B: [Repolarization/(-) membrane voltage] is what allows these channels to RESET from Inactivated --(back to)---> Resting

7

*[Na+ channels] are both ______ and ______ -dependent activated

2) Regenerative Depolarization= Na+ rushing into cell down both its ______ and ______ gradient to depolarize membrane potential to ______--(leads to)--->_____ channels opening and ______ feedback

3)What is the basis for refractory periods

*[Na+ channels] are both Time and Voltage -dependent activated

2) Regenerative Depolarization= Na+ rushing into cell down both its CONCENTRATION and ELECTRICAL gradient to depolarization membrane potential to it specific electrical potential--(leads to)--->more Na+ channels opening/positive feedback

3) Voltage-dependent INactivation of Na+ channels is the basis for refractory periods

8

A:[T or F]
Different neuronal cells have different K+ channels

B: [T or F]
K+ channels have multiple INactivation parameters

A: TRUE
Different neuronal cells DO have different K+ channels

B: FALSE
K+ channels have NO INactivation gate

9

A: K+ channels are ______ selective channels made of ___ ______. Although they exhibit ______ and ______-dependent ACTIVATION they do NOT have any ______ ______. This means that (unlike __) once open K+ channels remain OPEN until they're deactivated with ______

B: [K+ channels] are activated/opened when ______ from ______ occurs . = ______- dependent

C: When K+ ______ rushes ______ of cell---> toward its specific potential this eventually causes ______

A: K+ channels are HIGHLY selective channels made of 4 subunits. Although they exhibit time and voltage-dependent ACTIVATION they do NOT have any INactivation gates----> (unlike Na+) once open K+ channels remain OPEN until they're deactivated with repolarization

B: [K+ channels] are activated/opened when [AP upstroke] from Depolarization occurs . = Voltage- dependent

C: When K+ PASSIVELY rushes out of cell---> toward its specific potential = hyperpolarizes

10

______-dependent activation of K+ channels is Delayed/Slower than Na+

Voltage-dependent activation of K+ channels is Delayed/Slower than Na+

11

A: What's the difference between Absolute and Relative Refractory Period?

B: Refractory periods are based on ______-dependent features of ______ channels! ______ channels inactivate at ______ voltages and become unavailable = ______ Refractory Period

After REpolarization ______ channels recover from INactivation and become available again but requires STORNG stimulus = ______ Refractory Period

C: C: H-gate is ______[open/closed] during Absolute Refractory Period

Absolute Refractory Period (ARP): TIME in which a stimulus can NOT create another Action Potential

vs.

Relative Refractory Period(RRP:) TIME during which ONLY A STRONG stimulus can elicit another Action Potential but will be weak!

B: Refractory periods are based on voltage-dependent features of Na+ channels! Na+ channels inactivate at POSITIVE voltages and become unavailable = ARP

After REpolarization Na+ channels recover from INactivation and become available again but requires STORNG stimulus = RRP

C: H-gate is CLOSED!! During ARP!

12

A: Ca+ modulates Na+ channel activity by altering ______ ______ ______

B: Name the 2 conditions that can metabolically cause HYPERREFLEXIA


C: Blowing off [-CO2] ---> ______ plasma Ca+---> ______ extracellular membrane Positivity--> DEC [___ channel ______] ---> ______[easier/harder] neuronal excitability!

A: Ca+ modulates Na+ channel activity by altering membrane surface charge

B: HYPERREFLEXIA
1.HYPERventilation
2. HypOcalcemia

blowing off [-CO2] ---> DEC plasma Ca+--->DEC extracellular membrane Positivity--> DEC [Na+ channel activation threshold level] --->easier neuronal excitability!

13

A: Ca+ modulates Na+ channel activity by altering ______ ______ ______

B: Name the 2 conditions that metabolically cause hypOreflexia

HIGH [-CO2](______ acidosis)----> ______ Plasma Ca+--->extracell membrane is MORE ______[+/-] ---> INC [___ channel ______]--->__-gate closes and ___channels are less available -----> ______[easier/harder] to excite neurons :-(

A: Ca+ modulates Na+ channel activity by altering membrane surface charge

B: hypOreflexia

1.hypOventilation
2. Hypercalcemia

HIGH [-CO2](respiratory acidosis)----> INC Plasma Ca+--->extracell membrane is MORE + ---> INC [Na+ channel activation threshold level]--->H-gate closes and Na+ channels are less available -----> HARDER to excite neurons :-(

14

*Normal Extracellular K+ levels is between ____

2) HYPERkalemia ---> _____ Positivity of Resting Membrane Potential ---> ___-gate closes and ____ channels are less available

3) HYPERkalemia causes Conduction to go ______[Faster/slower]. Name 2 sx

*Normal Extracellular K+ levels is between 3 and 5

2) HYPERkalemia ---> INC Positivity of Resting Membrane Potential ---> H-gate closes and Na+ channels are less available

3) HYPERkalemia causes Conduction to SLOW =
•muscle weakness
•slow mentation

15

A: ______ axons are 100 x bigger in Diameter than ______ axons.

B: DESPITE THIS... ______ AXONS HAVE BETTER CONDUCTION VELOCITY because _______________

C: Saltatory Conduction = "______" from [__ ______ concentrated] ______ to ______

D: Internodal distance between 2 ______ = ____ mm

E: THERE ARE NO [___ channels] UNDER MYELIN SHEATH

A: UNmyelinated axons are 100 x bigger in Diameter than myelinated axons.

B: DESPITE THIS...MYELINATED AXONS HAVE BETTER CONDUCTION VELOCITY because myelin sheath INC membrane resistance

C: Saltatory Conduction = "jumping" from [Na+ channel Rich] [Node of Ranvier] to [Node of Ranvier]

D: Internodal distance between 2 [Node of Ranvier] = 1-2 mm

E: THERE ARE NO [Na+ channels] UNDER MYELIN SHEATH