Neurons Flashcards
(18 cards)
What charge is the intercellular fluid with respect to the extracellular fluid?
Negative
How many Na ions move out of the cell?
3
How many K ions move into the cell?
2
What moves the membrane potential away from 0:
hyperpolarisation or depolarisation?
Hyperpolarisation
What moves the membrane potential towards 0:
hyperpolarisation or depolarisation?
Depolarisation
At what voltage does a large depolarisation occur?
-55mV
How is polarisation reversed?
The membrane potential overshoots 0
What is the large change in membrane potential called?
Action potential
What is the ‘threshold’ voltage and what does it trigger?
-55mV
Triggers the opening of voltage gated Na+ channels
At what voltage do Na+ channels shut?
What open after?
35mV
K+ voltage gated channels open
What makes the membrane potential more negative after 35mV is reached?
K+ voltage gated channels are opened,
K+ ions leave the cells
What channels open at ‘threshold’ 55mV?
Where do the ions diffuse?
What does this cause:
depolarisation or repolarisation?
Na+ voltage gated channels open.
Na+ ions diffuse into cell.
Depolarisation
What channels close, and open at ‘peak’ 35mV?
Where do the ions diffuse?
What does this cause:
depolarisation or repolarisation
Na+ voltage gated channels close.
K+ voltage gated channels open.
K+ ion diffuse out of cell.
Repolarisation
What is the refractory period?
A period where the neuron cannot generate another action potential until the first one has ended.
What is the period where a neuron cannot generate another action potential until the first one has ended?
The refractory period
What increases axon AP conduction speed?
Myelination of axons
What are the sections called where the axon membrane is exposed to the extracellular fluid?
Nodes of ranvier
What are Nodes of ranvier?
What can occur at these points?
Sections where the axon membrane is exposed to the extracellular fluid.
Ion flow can occur to speed up AP conduction.
