Action potential Flashcards
If the membrane is made permeable to a specific Ion the membrane potential move towards what
The equilibrium potential
When voltage gated sodium channels open it flows down what
Concentration gradient
and a electrochemical gradient
Each action potential increases the sodium concentration in the axon by
40 µM
Compare the speed of potassium and sodium channels opening
Potassium channels cause hyper polarisation and open slowly and take longer to close
sodium channels called depolarisation open quickly and close quickly
What timeframe is an action potential occur
2 ms
3 confirmations a sodium channel can exist in
Closed, open, inactivated
Relative Refractory period
Sodium channels are recovering from inactivation, the excitability returns was normal as a number of channels in the inactivated state decreases and as the number of open voltage-gated potassium channels close
Voltage-gated sodium channel how many sections of alpha subunit
1 alpha subunit with Four secitions
Voltage-gated sodium channel where is the inactivation particle and its role
Found between domain three and domain four, can block the pore
Voltage-gated sodium channels and potassium channels out of the six transmembrane domains which domain is positively charged
Four
Potassium voltage gated channels how many alpha domains
For
Which form of the anaesthetic is membrane permeable
Unprotonated
lipophillic
membrane permeable
What form of anaesthetic is membrane impermeable
Protonated
membrane permeable
Local anaesthetics block axles in what order
Small myelinated axons
un myelinated axons
large myelinated axons
How does Axon diameter affect velocity
Large axon faster velocity
Ideal membrane properties
Low capacitance - voltage changes more readily in response to current
high resistance- change in voltage spread further along the axon
Longer the distance the faster the conduction
What kind of conductance does myelinated axons do
Saltatory
Why is statutory conduction faster
Action potential jumps from node to node allowing us faster conductance velocity. Action potential only occurs at the notes
What are the symptoms of Multiple Sclerosis caused by
Breakdown or damage of the myelin sheath
Depolarisation causes inactivation of what channels and opening of what channels
Inactivation voltage gated sodium channels
opening of voltage gated potassium channels
Define neuromuscular junction
Synapse between the nerve and escalator muscle fibre
What happens at the nerve terminal when action potential is initiated
Opens for dedicated calcium channels
calcium influx due to moving towards calcium’s equilibrium potential
increased calcium concentration
increasing calcium promotes exocytosis of the vesicels
Both sodium and calcium Portuguese channels can have additional subunits describe the function
Can have additional beta gamma delta subunits as well as glycosylation and phosphorylations
Fine tune the properties and enable correct regulation of channel activity
Compare the relative speed of opening of sodium gated channels and calcium forged gated channels
Voltage-gated calcium channels activate more Sony than voltage-gated sodium channels
Calcium voltage gated channels can exist inactivated or inactivated forms explain how this occurs
Inactivation is calcium dependent
During the vesicel fusion calcium binds to what to bring the school close to membrane
Siynaptotagim
What allows the vesicel fusion with the membrane
SNARE complex
The nicotinic acytly choline receptor is what kind of channel
Ligand gated ion channel, allows sodium and potassium to move through
More sodium is true as is a greater distance from sodium is equally potential while potassium is very close to the tacit equilibrium potential
A depolarisation at the end plate leads to
At the adjacent sodium channels due to local spread of charge causing muscle action potential
Competitive blockers of nicotinic acetly choline receptors
d-tubocurarine
The polarising blockers of nicotinic ACh receptors
Succinylcholine
How do you depolarising nicotinic ACh blockers work
Maintain end plate depolarisation
all felt activate adjacent sodium channels because they will be inactivated
Nicotinic ACh receptors produce a vast depolarisation because they are work on a channel
Looking gated ion channel
