Karteikarten
Neuronal Communication
Karten in diesem Stapel (42)
- 1Electrical potential (voltage)Force exerted on charged particle
Greater electrical potential = greater the current - 2Equilibrium potentialvoltage required to balance ionic gradient
- 3Electrical conductanceRelative ability an electrical charge has to migrate from one point to another
- 4Leakage ion channelsAllows ions to pass through channel ANYTIME, irrespective of membrane potential
- 5Voltage gated channelsChannels only open in response to specific voltage
- 6Ligand gated channelsonly open in response to binding of ligand to its receptor
- 7Resting potential-70mV
Normal, unstilted conditions
Neurons always working to maintain resting potential - requires energy
Leaky channels release K+
Na+/K+ pump active - removes 3 Na+, takes in 2 K+ (ATP) - 8Voltage gated K+ channelsClosed during resting potential
Only open when membrane potential reaches +40mV
Allow K+ out of axon - 9Voltage gated Na+ channelsClosed during resting potential
Only open when membrane potential reaches -50mV (threshold)
Allow Na+ into axon - 10Threshold value-50mV
Stimulates an AP
Na+ move into - 11DepolarisationAn action potential
Opening of voltage gated Na+ channels
Makes inside of axon less -ive
Continues until membrane potential reaches +40mV - 12RepolarisationClosing of Na+ channels
Opening of voltage gated K+ channels
Outflow of K+, membrane potential lowered - 13Hyperpolarisation= too far
Too many K+ leave cell
Na+/K+ pump actively pumps Na+ out and K+ in to restore normal intracellular environment - 14Absolute refractory periodTime from depolarisation to repolarisation
Na+ channels are in an inactivated state and can't reopen again until resting potential restored - 15Propagation of signal from one neuron to anotherNo resistance loss because post-synaptic AP just as large as pre-synaptic AP
All APs are all-or-nothing
All neurons have to reach threshold to conduct an AP - 16Synapse= where neurons communicate with each other
Uses chemical messengers called neurotransmitters
Integration of signals determines the action of the post-synaptic neuron
- mainly excitatory = AP
- mainly inhibitory = no AP - 17Neurotransmission across synapseAP triggers opening of Ca2+ voltage gated channels - influx of Ca2+ at pre-synaptic membrane
Vesicles filled NTs fuse with pre-synaptic membrane and triggers exocytosis
NTs diffuse across synaptic cleft
bind to receptors on post-synaptic cell - 18Graded potentialChange in membrane potential of post-synaptic cell
Local change in membrane potential
Sum of the individual actions of the ligand gated channels - if large enough = AP - 19Excitatory synapseReceptor binding causes post-synaptic potential to be more +ive
Depolarisation
If it get above threshold, AP results
EPSP - 20Inhibitory synapseReceptor binding causes post-synaptic membrane to be more -ive
Hyperpolarisation
Less likely to reach threshold so no AP
IPSP - 21Excitatory NTse.g. glutamate
Make inside of neutrons LESS NEG.
Closer to threshold (-50mV)
Increased likelihood of an AP occurring - 22Inhibitory NTse.g. GABA
Makes inside of neuron MORE NEGATIVE
Further away from threshold - hyperpolarised
Less likely for an AP to occur - 23EPSPSynaptic potential that makes a post-synaptic neuron more likely to generate an AP
- 24Spatial summationWhen there are enough synapses close together to produce an AP in the next neuron
- 25Temporal summationWhen the post-synaptic membrane is depolarised in rapid succession
- 26IPSPSynaptic potential that makes a post-synaptic neuron less likely to generate an AP
- 27Fates of NTs1. bind to receptors on post-synaptic cell
2. destroyed by enzymes
3. re-uptake by pre-synaptic terminal
4. diffuse away
5. taken up by glia (astrocytes) - 28Synaptic delay~0.5 sec delay b/w arrival of AP at axon terminal and action at synapse
If a signal is being sent through many neurons, this delay can add up
-> use electrical synapse - 29Electrical synapsesWhere neutrons directly connect via gap junctions
Extremely rare: some brain sites, eye and PNS ganglia
APs ALWAYS TRANSMITTED TO POST-SYNAPTIC CELL
Efficient/fast but not versatile
Used for reflexes - 30Criteria for a molecule to be a NT1. must be synthesised and stored in the pre-synaptic neuron
2. must be released by the pre-synaptic axon terminal upon stimulation
3. when experimentally applied, must produce a response in the post-synaptic cell that mimics the response produced by the release of NT from the pre-synaptic neuron - 31Agonist NTstimulates the receptor
- 32Antagonist NTblocks/inhibits the receptor
- 33Amino acid NTse.g. glutamate (+), GABA (-), glycine (-)
Fast neurotransmitters - 34Classical/amine NTse.g. ACh (+/-), serotonin (-), NA (+)
Mainly slow neurotransmission - 35Neuropeptide NTse.g. substance P, opiods
Slow neurotransmission - 36Other Itse.g. nitric oxide, hydrogen sulfide, CO
Not packaged in pre-synaptic cell for release
Still released in activity dependent manner - 37Dale's PrincipleA neuron has a single NT
Classifies neutrons into groups of NT types
1. cholinergic (ACh)
2. catacholminergic (dopamine)
3. amino acidergic (GABAergic)
Most neurons release a single a.acid or amine NT
BUT many peptide neurons violate Dale's Principle - co-transmitters - 38Peptide NT synthesis and storage1. precursor peptide synthesised in rER
2. precursor protein split in Golgi to form active neurotransmitter
3. secretory vesicles containing peptide bud off Golgi body
4. secretory granules are transported down the axon (anterograde transport) to terminal where peptide is stored - 39Amine and amino acid NT synthesis and storage1. enzymes convert precursor molecules into NT molecules in the cytosol
2. transport proteins loss the NT molecules into synaptic vesicles in the terminal where they are stored - 40Ionotrophic NTFASTER - directly bind to and opens ion channel
Ligand-gated
Open and close in response to NT binding
No second messengers
Excitatory: glutamate, inhibitory: GABA - 41Metabolic NTSLOWER - acts via secondary messengers to activate effector proteins
Sense ligand-binding to receptor and activates a signaling cascade within the cell
G-COUPLED PROTEIN
Neither excitatory or inhibitory; but regulate the activity of excitatory and inhibitory neurotransmitters
2 major families of 2nd messengers:
1.Cyclic AMP (cAMP)
2. Inositol triphosphate (IP3) - 42—
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- Beschreibung
- Neuroscience Karteikarten am Neuronal Communication, erstellt von Maddi Thompson am 09/11/2017.
- Erstellt von
- Maddi Thompson
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