Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Synapses
Uni of Notts, fundamentals of neuroscience, first year
| Question | Answer |
|---|---|
| Gap junctions | Connexin intercellular protein channels connecting certain brain cells & allowing small ions to pass bidirectionally between them without need of neurotransmitters or action potentials |
| Electrical synapses | Flow of electrical current from one cell to another by touching gap junctions. This is similar to a syncytium but only occurs in astrocytes & inferior olive so Golgi's theory is still used |
| Chemical synapses | Flow of electrical current using neurotransmitters to cause depolarisation by binding to receptors. The chemicals are stored in vesicles, held by docking proteins (SNARE) & released by the binding of calcium ions |
| Neurochemical experiment: Otto Loewi (1921) | Stimulated perfused frog heart with Vagus nerve to slow down heartrate. Sent perfusion liquid to 2nd perfused heart which slowed down proving a chemical (ACh) in the heart from the brain caused slowing |
| Post-junctional folds | Invaginations of the muscle membrane (sarcolemma) containing large surface area of chemical receptors & gated Na+ channels. This leads to more rapid & efficient depolarisation of the post-junctional membrane |
| Chemical synapse investigation: Henry Dale (1963) | Found specialised chemical synapses at the motor end-plate of neuromuscular-junctions, containing many post-junctional folds |
| End Plate Potentials (EPP) | Localised depolarisations at the neuromuscular junction which are graded but can be codified to cause certain responses characterised by time course and spatial distribution |
| Neuronal electrophysiology | Measuring EPPs by stimulating motor nerve with an extracellular electrode then measuring the change in potential across the membrane |
| Trend found by neuronal electrophysiology | A suprathreshold response is reached but slowly declines over 10-20ms further along the sarcolemma & gets progressively smaller the further from the endplate |
| Iontophoresis | Technique of delivering polar molecules through membranes by using a small current to repel charges on the molecule & force it through membranes |
| Nicotinic receptors | Ligand gated ionotropic channels which open in response to the binding of chemicals such as ACh & nicotine to allow an influx of sodium ions |
| Mode of action of botulinum toxin (Botox) | Binds irreversibly to SNARE proteins at neuromuscular-junctions to prevent docking of synaptic vesicles & the propagation of an action potential which causes paralysis of muscle fibres |
| Excitatory Post-Synaptic Potentials (EPSPs) | Opening of ligand gated channel to allow movement of ions with positive reversal potentials (e.g., Na+, Ca2+) to cause a positive subthreshold response. Mostly uses neurotransmitter glutamate |
| Inhibitory Post-Synaptic Potentials (IPSPs) | Opening of ligand gated channel to allow movement of ions with negative reversal potentials (e.g., K+, Cl-) to cause a negative subthreshold response. Mostly uses neurotransmitters glycine & GABA |
| Interaction of Post-Synaptic Potentials (PSPs) | Their summation on postsynaptic terminals will cancel each other out but contribute to the overall likelihood of an action potential being generated |
| How location of the synapse on a neurone affects likelihood of action potential propogation | Axon synapses with dendrite - likely excitatory Axon synapses with soma - likely inhibitory, more effective since closer to dendritic hillock Axon synapses with axon - causes efficient presynaptic inhibition or excitation using graded potentials |
Created by:
Beech47
Popular Neuroscience sets