Nervous System Flashcards
(14 cards)
What does the sensory neurone do
Carry impulses from receptor cells to the coordinater (the cns)
Depolarisation
Stimulus of an axon result in a brief reversal of potential difference across membrane from -70 to +40mv
What are voltage gated sodium channels stimulated by
The rapid change of potential difference ( action potential)
When is the axon depolarised
Once it reaches 40 mv
Repolarisatuon
Instantly after depolarisation voltage gated k+ channels open and they diffuse out down the conc gradient which starts to repolarise the membrane
What happens after hyperpilarisation
The voltage gated k+ channels close and the sodium potassium pump restarts and restores resting potential
What is it called when it goes below resting potential
Hyperpolarisation
What happens at threshold
All voltage gated sodium channels open and it reaches +40mv
What is threshold
-55mv
What is the concentration gradient for ions called
Electrochemical gradient
What is the refractory period
Nerve impulses can’t travel backwards because sodium channels are deactivated for a certain period of time
What is propergation
Sodium ions move along the axon by local circuits which causes next set of voltage gated sodium ion channels to open causing depolarisation to move down the neurone
Where does propagation happen
In unmylenated neurones
What does mylenation cause
Saltatory conduction-
