Membrane Potentials Flashcards
(24 cards)
What is a resting membrane potential?
It’s practically a membrane potential of an unstimulated,resting action potential
What is the all or none principle?
Where sodium,rushes to go into the the action potential until it reaches its peak then the sodium gate closes and if depolarization is not great enough to reach threshold then no impulse will be conducted
What are the two methods of propagating an action potential?
The continous and Saltatory propagation
What is Continuous propagation?
It is basically the action potential moving through an unmyelinated axon and depolarizing the adjacent region of the axon membrane this is a continous action
What is the saltatory propagation?
It is when an action potential moves through a myelinated axon and myelin limits movement of ions so it has to jump from node node which makes this propagation faster
What is Multiple sclerosis?
It is the unmyelination of the cns and usually causes weakness,visual abd speech disturbances and urinary incontinence
What is a synapse?
It is a region that transmits information from one neuron to the other
What is synaptic fatigue?
When the neurotransmitter cannot recycle fast enough to meet the demands if the fast stimuli
What are the 3 types of synapses?
Axodendric
Axosomatic
Axoaxonic
What is the diffrence between EPSP AND IPSP
Epsp-It is excitory and helps trigger the action potential
Ipsp-Is inhibitory and helps reduce neurons the ability to trigger the action potential
What happens when a membrane is polarized?
More negative ions move out of the membrane and it works like a bioelectric batteryv
What is ion equilibrium potential?
It is basically the movement of ions around a plasma membrane and the net flow of an ion type is equal to zero
The number of ions moving in is equal to the number if ions moving out of the membrane
What is depolarization?
This is when the membrane potential almost becomes zero and where the inside of the membrane becomes less negative and the chances if a ln impulse being produced increases
What is the course of the action potential?
It starts off with a slight depolarization then moves to the excitation period where depolarization occurs then repolarization followed by a brief hyperpolarisation then the action potential goes into the refractory period where there’s no depolarization
What are the two types of refractory periods?
The Absolute refractory period where no Na channels are open no matter the stimulus they will not reopen to let Na in
The relative refractory period where some Na channels are open but also threshold is higher that normal making it difficult to raise membrane potential to a point of exitation
What is hyperpolarisation?
It is the opposite of depolarization where the inside of the membrane potential becomes more negative and it increases and is away from zero there reducing the chances of an impulse being created
What are the two factors that affect Action potential propagation?
The diameter the longer the diameter the faster the propagation
The myelin sheath
Temperature
What is conduction velocity?
The conduction velocity is widely affected by the effect of the diameter a larger diameter will have less resistance to the current flow therefore faster velocity conduction
Then the effect of myelinated fibers where the fibers that are myelinated are alot faster, and these are in the saltatory period
What are the 3 groups of Axons?
A,B,C fibers
What are the type A fibers like?
They are myelinated
Move at a high speed
Have a large diameter
Are responsible for touch,balance and position
Carry information to and from the cns
What are the types B fibers?
That are myelinated
Medium speed and diameter
Immediate signals
The are responsible for sensory and peripheral effector
What are the type C fibers
Unmyelinated
Slow speed
Small diameter
Gland control and involuntary control
Carry slower information
What are the two types of conduction?
Othrodromic in a straight line
Antidromic in the opposite direction
The Axon diameter and speed effect?
Information is carried within the nervous system by propagated nerve impulses called action potentials the larger diameter and myelinated axons carry Information to aid in position,balance and vision
