Cellular Neurophysiology Flashcards
neurons
info processing nerve cells
characteristics of neurons
elongated
separated by synapses
in a network
electrically active
lots of them
function of glia
support neurons physically and chemically
regulates blood flow and supply of nutrients to neurons
guides development
guides neural migration and produces chemicals to stop it
what do some glial cells contain
insulating myelin
what does the cell body contain
the cell nucleus
synonym for cell body
soma
dendrites
short network of thin projections from neuron cell body
RECEIVES signals from other neurons
axons
long projection from cell body
impulse travels down axon to axon terminals
SENDS signals to other neurons
what are axons covered in
myelin sheath - a fatty substance that serves as insulation for nerve impulses travelling along the axon
each myelin wrapper is a projection from…
a glial support cell
myelination
speeds up nerve conduction
happens over development
has functional consequences if disrupted
what makes up the white matter in the brain
axons
composed of axonal fibre tracts connecting different brain areas
what makes up the grey matter in the brain
cell bodies and dendrites
what creates the white colour of white matter in the brain
comes from fatty myelin sheaths around the axon
how can fibre tracts in the brain be traced
chemical methods or diffusion MRI imaging
at resting state what is the voltage of the cell
roughly -70mV
the cell is more negative on the inside than the outside because of different concentrations of negative and positive ions
when does an actional potential occur
when the inside of the cell reaches threshold (-55mV roughly)
what voltage is threshold for an action potential to occur
roughly -55mV
what pump maintains resting potential of the cell membrane
sodium-potassium pump
what is saltatory conduction
where the action potential jumps between the gaps in the myelin sheath known as nodes of ranvier
how do glial cells communicate
chemically
what is moved in and out due to the sodium potassium pump
3Na+ out for every 2K+ in
what powers the sodium potassium pump
energy produced from ATP -> ADP + Pi + energy
how is ADP formed for the sodium potassium pump to work
ATP -> ADP + Pi (inorganic phosphate) + energy
hydrolysis of ATP (adding a molecule of H20) creates ADP + an inorganic phosphate + energy
the energy is used to pump 3Na+ out and 2K+ in to the membrane
ligand gated ion channels
neurotransmitter gated ion channels
activated by the binding of a specific molecule (ligand)
a ligand can be a neurotransmitter, hormone, drug, etc
depolarisation
occurs when threshold is reached (-55mV)
sodium ion channels open and sodium ions enter the neuron
makes the voltage increase
repolarisation
occurs when roughly +30mV is reached
sodium ion channels close and potassium ion channels open and potassium ions enter the neuron
causes the voltage to decrease as the membrane is more permeable to potassium ions so they diffuse out of the neuron down the concentration gradient
hyperpolarisation and refractory period
potassium ion channels are delayed to close so the voltage goes below resting potential (below -70mV)
known as the refractory period as voltage goes below resting potential and then increases again to restore -70mV
what causes a neuron to fire
stimulation of a neuron with electric current can cause it to fire
more electricity = …
more electricity = more action potentials
describe process of synaptic transmission of neurotransmitters
presynaptic neuron excited by action potential
vesicles containing neurotransmitters bind to presynaptic membrane to release neurotransmitters
neurotransmitters released into synapse and diffuse across it
neurotransmitters bind to post synaptic receptors
this works via lock and key mechanism
this changes the polarisation of the cell
chemical activity either causes AP in next neuron or not
