The Dynamic Neuron Flashcards
When information supposedly is processed only in one direction called?
Polarization
Describe the structure of the neuron (3)
An outer membranes of neurons, made of fatty substances
Draped around a cytoskeleton that is built up of rods of tubular and filamentous proteins that extend out into dendrites and axons alike
Dendrites change shape sprouting new ___________ and ___________ others
Connections
Withdrawing
Axons grow new _______
Endings
What are inside neurons?
Many inner compartments
Tiny protuberances that stick out from the dendrites called _________ ______
Dendritic spines
Where do incoming axons make most of their connections?
Dendritic spines
What do the end-points of the axons also respond to?
Growth factors
What do growth factors do? (3)
Taken up inside and then transported to the cell body
Where they influence the expression of neuronal genes and hence
The manufacture of new proteins
What does “synapse” mean in Greek?
To clasp together
What are the junctional spots when dendrites receive contacts from incoming axons?
Synapses
What are the communication between nerve cells at synapses called?
Synaptic transmission
Where are most synapses located in the cerebral cortex?
On the dendritic spines, sticking out like little microphones
What are currents that come into the cell called?
Excitation
What are currents that move out of the cell called?
Inhibition
The axons of neurons transmit electrical pulses called:
Action potentials
How do action potentials move along nerve fibers? Why?
Like a wave travelling down a skipping rope
Axonal membrane contains ion channels
What do ion channels do?
They can open and close to let through electrically charged ions
What do the ion channels let in?
Some let in sodium ions (Na+) while others let through potassium ions (K+)
What happens when ion channels open?
The Na+ or K+ flow down opposing chemical and electrical gradients, in and out of the cell
The Na+ or K+ flow down opposing chemical and electrical gradients, in and out of the cell, in response to:
Electrical depolarisation of the membrane
What is the first channels to open when an action potential starts at the cell body?
Na+ channels
Step 1 (when an action potential starts at the cell body) (2)
Na+ channels open
A pulse of sodium ions flashes into the cell and a new equilibrium is established within a millisecond
Step 2 (when an action potential starts at the cell body)
In a trice, the transmembrane voltage switches by about 100mV
Flips from an inside membrane voltage that is negative to one that is positive
