Physiology 1: Neurones, Nerve Conduction and Synaptic Transmission Flashcards
electrical information starts and ends in what areas of the neuron?
apical dendrites to axon
do dendrites convey electrical signals actively or passively to the cell body (soma)?
passively
where does the cell body deliver the electrical information it has received to?
axon hillock
what does a passive electric signal mean?
incoming signals do not create an AP they just cause a graded change
highest density of voltage activated Na channels is located where? what is the significance of this?
axon hillock
most likely place for an AP to be generated
transport of materials between the soma and presynaptic terminal is an example of ___ transport
anterograde
transport of materials from the presynaptic terminal to the soma is an example of ___ transport
retrograde
what form of transport is most often exploited by viruses to infect the neuron?
retrograde
a multipolar neuron is classed as having _ or more neurites
3
what is a pseudounipolar neuron?
a neuron with 1 neurite that bifurcates
give an example of a pseudounipolar neuron
dorsal root ganglion neurone
give an example of a multipolar neuron
lower motor neuron
name the 4 functional regions of a neuron from superior to inferior
input
integrative
conductile
output
what is a golgi type 1 neuron?
a neuron that has a long axon that begins in the grey matter of the CNS
threshold is defined as?
the mP required to activate voltage activated Na channels
define overshoot
brief period when polarity is reversed to positive (i.e when mP reaches 0)
where does neuron AP tend to peak?
+40mV
what is Na’s equilibrium potential?
+60mV
why does the mP of the AP never reach Na’s equilibrium?
K+ channels start to open
when will K+ channels close?
when the neuron mP goes back to its resting potential (-70mV)
why do you get undershoot in an AP?
K+ channels close slowly so makes it go a bit more negative than the resting potential
how do electrical signals stay strong over long distances eg to provide signals to the leg?
action potentials regenerate to keep the signal strong
action potentials have a constant __
amplitude
the nerve cell membrane is leaky T or F
T
describe ohm’s law
I (current) x R (membrane resistance)
mP change is a ___ proces that decays exponentially with distance T or F
passive
T
the lamda value of an axon is the….
length constant (the determinant of how far a local current can spread)
increasing what increases lamda’s value?
membrane resistance/axonal resistance aka rm/ri
the longer the length constant the further…..
the local current spread
a difference in mP will cause what flow?
local current flow
if lamda is large…
the speed at which the AP moves along the axon is quicker
how can you increased passive current spread though an axon?
decrease axon diameter (ri)
increase rm by adding an insulating material
these insulating cells form many layers around a SINGLE axon
schwann cell (PNS) think swiss roll
these insulating cells form a single layer around MANY axons
oligodendrocytes (CNS)
why is myelin a good insulator?
it’s a fatty substance so doesn’t conduct
the AP jumps from one __ _ ___ to the next
node of ranvier
what is the node of ranvier?
a gap in the myelin sheath of a neuron between schwann cells
name a neurotransmitter that is degraded by an enzyme, what is this enzyme
ACh
acetylcholinesterase
most common type of synapse location
axodendritic (between an axon and dendrite)
how do synaptic potentials differ from action potentials?
they are graded
glutamate and glycine are examples of…
amino acids
what substance(s) are released from synaptic vesicles?
ACh
amino acids
amines (all the A’s)
what substance(s) are released from secretory vesicles?
peptides
name the only substance that CANNOT activate GPCRs
glycine
