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physio > Skeletal muscles > Flashcards

Skeletal muscles Flashcards

1
Q

What is membrane potention?

A

is the voltage or potential inside of a membrane relative to the outside

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2
Q

resting potential

A

its when the Vm is at rest

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3
Q

depolarization

A

It’s a positive change in membrane potential. influx of cations in or anions out.

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4
Q

hyperpolarization

A

its a negative change. Either cations out or anions in

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5
Q

repolarization

A

a negative change in membrane potential. Brings the membrane back to resting potential

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6
Q

Is K+ high or low inside the cell

A

High concentration of potassium inside the cell

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7
Q

Concentration of Na+ and Ca2+ inside the cell relative to outside

A

low concentration

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8
Q

what determines resting membrane potential?

A
  1. ion concentration gradient

2. membrane permeability

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9
Q

chemical force?

A

ions traveling along the concentration gradient

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10
Q

what is electrical force?

A

Relation to the charge- where the cations and anions want to travel

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11
Q

what is the electrochemical force

A

its the sum of the chemical and electrical force

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12
Q

equilibrium potential

A

where the chemical and electrical force are equal to each other, no ions are traveling through the membrane

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13
Q

what are some factors that help a cell maintain resting potential/ Vm?

A

Na+/K+ ATPase
and
K+ channels

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14
Q

how does the Na+/K+ ATPase work?

A

3 Na out and 2K in.

  1. Maintains concentration gradient for Na+ and K+.
  2. Stabilizes resting membrane potential

produces a -1 charge inside the cell

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15
Q

K+ channels- how do they work?

A
  1. re-polarization after AP (a negative change in membrane potential-in this case Cation K+ is out the cell)
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16
Q

when a membrane potential is NOT at equilibrium- describe the forces, net force, force strength

A
  1. Net force is not at zero
  2. The further away the membrane potential is from membrane equilibrium the net force increases
  3. net force acts on an ion to reach membrane equilibrium
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17
Q

How does net force work?

A

it works to bring the cell to membrane equilibrium

its influenced by chemical and electrical force

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18
Q

The resting membrane potential for neurons is close to which cation?

A

to K+

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19
Q

Ion channels are ___ or ____

A

active or passive transport

20
Q

voltage gated ion channels have

A

alpha - pore formining subunit

beta and gamma- accesory subunits

21
Q

ligand gated ion channels

A

ligand bind to the channel, acts on it

the ligand can be either intracellular or extracellular

22
Q

stretch activated channels

A

mechanic force/physical force opens the channel

ex: cochlea

23
Q

what are two types of ion channels based on permeability

A
  1. specific- voltage gate

2. non-specific/promiscuous- ACh receptors allows several ions to pass through

24
Q

extracellular channel ex

A

voltage gated Na+ channels- located on the plasma membrane, exposed to the extracellular space

25
Q

intracellular channel ex

A

ryanodine receptors

located within the cell

26
Q

what is graded potential? list characteristics

A

a small change in membrane potential
decremental
magnitude varies depending on the stimulus

can be either excitatory or inhibitory
can lead to an AP at the axon hillock

27
Q

axon hillock

A

AP starts here

28
Q

Action potentials!

A

all or nothing
arent decremental like graded potential
travel along the PM
travels in one direction

29
Q

what is absolute refractory period?

A
  • channels open or close. Even if they are closed they can not be reopened by a second stimulus
  • depolarization and repolarization occur
  • NO AP CAN BE GENERATED whatsoever
30
Q

relative refractory period

A

AP can occur but the stimulus has to be very strong to create a second one

  • Na channels can be reopened - but it currently is hyperpolarized-requires a lot of energy
  • voltage-gated K+ channels open and repolarize the cell
31
Q

voltage gated channel- activation gate

A

responds to change in membrane potential

32
Q

synaptic transmission

A

neuronal AP initiates depolarization of muscle PM

33
Q

excitation-contraction coupling

A

chemical energy/AP is converted into mechanical energy

sarcomeres shorten- contraction

34
Q

what neurons (general term) control skeletal muscles

A

somatic motor neurons

35
Q

what are the voltage gated Na channels

A
  1. activation gate

2. inactivation gate

36
Q

activation gate

A

responds to change in membrane potential

depolarization occurs, both activation gate and inactivation gate open

37
Q

inactivation gate

A

its a function of time - ball and socket

inactivation gate closes first and then the activation gate- this allows the membrane to go back to resting membrane potential

38
Q

steps for depolarization to occur starting at axon hillock

A

Graded potential–> axon hillock –>AP down the membrane –> Ca channels open, influx of Ca causes ACh vesicles to fuse at the synaptic cleft –> ACh binds to ACh receptors at NMJ –> Na+ and K+ flow through the channel –> depolarization occurs and Na+ channels open along the sarcolema –> DHP receptor on the T-tubule open and ryanodine receptors open

39
Q

what is a TRIAD

A

sarcoplasmic reticulum plus t-tubule

40
Q

what is the conformation of myosin when ATP is absent

A

myosin head is bound to actin filament, needs ATP to be released

41
Q

conformation of myosin with ATP present

A

myosin/actin are weakly bound

42
Q

during contraction- which direction does myosin travel

A

the plus end- barbed end

43
Q

what happens during muscle relaxation

A

ACh release decreases and eventually is removed from the NMJ

44
Q

what enzyme removes ACh from the NMJ

A

acetylcholinesterase

45
Q

how does acetylcholinesterase work

A

it breaks down ACh , recycles choline back to the synaptic cleft

46
Q

What is SERCA ?

A

its a Ca2+ ATPase pump, pumps Ca2+ back into the SR.

47
Q

what does calsequstrin do?

A

binds to Ca2+ to concentrate ions

physio (6 decks)

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