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Bio /chem/cell > Membrane Potential W2 > Flashcards

Membrane Potential W2 Flashcards

(46 cards)

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1
Q

Why are membrane dynamic (3)

A

Growth
Movement
Proteins have a finite lifetime

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2
Q

Why are membranes excitable (4)

A

Communication
Movement
Contraction
Respond to stimulus

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3
Q

What causes membrane potential

A

Regulation of ion movement which causes a difference in charge

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4
Q

The ….. of membrane in positive

A

Outside

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5
Q

The …. of the membrane is negative

A

Inside

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6
Q

What is the resting membrane potential

A

Charge difference across a cell at rest (unstimulated)

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7
Q

Muscle resting membrane potential …. mV

A

-85

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8
Q

Nerve testing membrane potential ….mV

A

70

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9
Q

Membrane is said to be …… at rest

A

Polarised

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10
Q 
Inside cell:
Lots of....
Not much....
Compared to outside 
AT REST
A

K+

Na+

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11
Q

To cross lipid rich membrane

Ions need

A

Transport proteins

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12
Q

Proteins responsible for maintaining membrane potential (2)

A

Ion channels

Membrane bound enzymes

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13
Q

Example of ion channel

A

Sodium channels

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14
Q

What do sodium channels do

A

Allow sodium ions to flow down concentration gradients

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15
Q

Example of membrane bound enzymes

A

Sodium - potassium ATPase

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16
Q

What does Sodium - potassium ATPase pump do

A

Uses atp to pump ions through membrane against concentration gradient

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17
Q

….. …… form the basis of cell communication

A

Ion channels

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18
Q

Two types of ion channels

A

Non gated

Gated

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19
Q

When do gated ion channels open

20
Q

When do ligand gated ion channels open

Study These Flashcards
A

Open in response to chemical stimuli

21
Q

When to voltage gated ion channels open

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A

In response to chemical stimuli

22
Q

Two types of gated ion channels

Study These Flashcards
A

Ligand gated

Voltage gated

23
Q

Ion channel structure

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A

5 integral proteins joined together

24
Q

Which region of ion channels line inside of the protein

25
Which region of ion channels line outside of the protein
Hydrophobic
26
Ion Channels- what determines which ions may pass
The charge of the hydrophilic region of proteins that join together to make ion channel
27
How to ligand gated ion channels open - what do they have and process
Exposed receptor site for binding specific ligand molecules Molecule binds - changing shape of protein and allowing ions to flow through
28
Example of ligand gated ion channel opening
Muscle contraction -Acetylcholine bonds to Ligan gated sodium channel on surface of muscle fibre Sodium flows into cell causing depolarisation
29
Example of voltage gated ion channels opening closing process (Na+/K+)
Na+ flows into nerve cell causing depolarisation Voltage gated K+channels open causing repolarisation
30
K+/Na+ ATPase - how many molecules of ..... does it pump out of the cell
3 Na+ molecules
31
K+/Na+ ATPase - how many molecules of ..... does it pump into the cell
2K+
32
What two factors maintain the resting membrane potential
Leakage ion channels K+/Na+ ATPase pump
33
Passive ion diffusion is up/down the chemical gradient
Down
34
When ions move to a region of opposite charge they move ..... their electrical gradient
Along
35
How does membrane potential change | Via ......... or ......... - ....... ion channels
Voltage or ligand gated
36
Phases of ACTION potential
Initial stimulus - ligand gated ion channels open Voltage - gated Na+ channels open Voltage gated K+channels open
37
***1****Phases of ACTION potential -initial stimulus Describe Result
Ligand gated channels open allowing Na+ to flow into the cell down its concentration gradient Depolarises local area of cell to threshold (about -50mV)
38
***2***Phases of ACTION potential: Voltage - gated Na+ channels open Describe Result
Very brief Na+ rushes in down concentration gradient Initiates propagated action potential
39
***3***Phases of ACTION potential: Voltage - gated K+ channels open Describe Result
K+ rushes out of cell (slower rate than that of Na+rushing in before) Voltage gated Na+ channels begin to close Repolarisation
40
Describe the process of action potential
Rest-->depolarisation-->repolarisation-->rest ``` RESTING MEMBRANE POT atlases pump maintaining rest Most ion movement via leakage channels DEPOLARISATION stimuli(eg the opening of ligand gated Na+ ion channel) opens a voltage gated Na+ channel, depolarising the membrane potential REPOLARISATION voltage gated Na+ channels inactivated Voltage gated K+ channels activated RESTORING MEMBRANE POTENTIAL Na+/K+ ATPase works to restore Reston membrane potential (more Na+ outside that's inside and more K+ inside rather than outside) ```
41
Action potentials and skeletal muscle contraction process | Describe
An action potential arrives at neuromuscular junction Causing aCh to be released aCh binds to ligand gated sodium ion channels which initiates action potential in that cell This travels along t tubules And prompts the release of calcium ions Calcium ions bind to troponin --> moving tropomyosin away
42
Action potential and nerve conduction | Describe
In response to signal soma end of axon becomes depolarised Depolarisation spreads down the axon, meanwhile whilst the soma depolarises Action potential continues to travel down the axon
43
What determines how quickly action potentials can be repeated
Refractory period
44
Two types of refractory periods
Absolute | Relative
45
What does absolute refractory period mean Why is this so
Additional depolarising stimuli do not relish in new action potential Because Na+ channels are inactivated during this time
46
What does relative refractory period mean Why is this so
Only strong enough stimuli will result in action potential Because Na+ channels begin to recover but K+ channels have not closed yet So and efflux of Na+ ions will be balanced out but he efflux of K+ions unless it's big enough

Bio /chem/cell (13 decks)

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