Introduction to the neurone L1 Flashcards
do dendritic trees differ in the CNs>
yep
can you remember the nernst equation?
At rest, the membrane is principally permeable to ___, so the resting potential is close to the __ Nernst potential.
At rest, the membrane is principally permeable to K+, so the resting potential is close to the K+ Nernst potential.
internal chloride conc is ….
low
the equilibrium potential for Chlorine is …..
negative
teh equilibrium for calcium is
positive
is chlorine actively extruded from the neurone?
what does this mean for the Cl- resting potential?
in most neurons, Cl- is also extruded by secondary active processes:
- coupled to K+
- and to the sodium- dependent influx of HCO3- ions
means cl- resting pot is more negative than the resting potential
in wihcih neurones is intracellular Cl- raised?
In developing neurons (and adult olfactory receptor neurons) inward Na+/K+-coupled Cl- transport (NKCC1) raises intracellular chloride concentration so that opening of chloride channels at the resting potential instead allows an outward (excitatory) flow of chloride ions.
how is Ca2+ powerfully extruded from the neurones?
- an ATP-fuelled Ca2+ pump
- secondary active transport via a sodium- calcium exchange,
is calcium and intracellular messenger?
yep
describe an Action potential
what are gap junctions?
allow ions and small molecules to pass freely.
form of synapse
problems with gap junctions compared to chemical synapses?
- require large presynaptic terminal
- almost all bidirectional
- no flexibiltiy by using differetn transmitters
where are gap junctions used
normally used when it is necessary to synchronise the activity of large populations of cells, as in the developing embryo, or within the heart.
vesicles of transmitter:
Fusion is induced by ………. proteins contained within the vesicle and presynaptic terminal membranes.
Fusion is induced by v-SNARE and t-SNARE proteins contained within the vesicle and presynaptic terminal membranes.
whats the calcium sensory at the presynaptic terminal
The vesicle-associated protein synaptotagmin acts as the Ca2+ sensor.
describe the process of exocytosis of the vesicle containing transmitter
- vesicle docks
- vesicle primed by close association between v and t SNAREs
- Calcium binds synaptotagmin
- membranes fuse
3 criteria for a neurotransmitter
- must be present within the presynaptic terminal, or mechanisms exist for its synthesis.
- Second, it must be released in adequate quantity on stimulation.
- Finally, added transmitter must have the same effect as stimulation.
Neurotransmitters can act either directly on _______ receptors which are themselves ionic channels, or indirectly on ________ receptors which achieve their effects via second messenger cascades.
Neurotransmitters can act either directly on ionotropic receptors which are themselves ionic channels, or indirectly on metabotropic receptors which achieve their effects via second messenger cascades.
gaps
glutamate, the primary ____ transmitter in the CNS
glutamate, the primary excitatory transmitter in the CNS
GABA and glycine, the major ______ transmitters in brain and spinal cord.
GABA and glycine, the major inhibitory transmitters in brain and spinal cord.
advantages of ionotropic receptors?
- rapid
- some cases - allow Ca2+ influx
The most important excitatory ionotropic receptors in the CNS are those which respond to the amino acid transmitter ______.
The most important excitatory ionotropic receptors in the CNS are those which respond to the amino acid transmitter glutamate.
There are two distinct classes of ionotropic glutamate receptor
what are they
There are two distinct classes of ionotropic glutamate receptor: NMDA and non-NMDA receptors
non-NMDA receptors can divide into….. (another 2 subcategories)
divide into into AMPA and kainate receoptors
describe AMPA current voltage relationship
linear - ohmic.
mostly impermeable to divalent cations
are NMDA receptors permeable to Ca2+?
yep
are NMDA receptors permeable to Ca2+ at negative potentials?
at negative potentials they are blocked by extracellular Mg2+ ions trying to enter the channel.
When the membrane is depolarized this block is relieved, so that Na+ and Ca2+ ions can pass through the channel.
label
label regarding NMDA receptors
big advantage of metabotropic receptors?
amplification
lots of 2nd messenger molecules
g protein
adenylyl cyclase response + others
Nitric oxide acts directly on its effector enzyme, …..
Nitric oxide acts directly on its effector enzyme, soluble guanylyl cyclase.
obvious
fat
mamba
