Signalling in the Nervous System Flashcards
What are the names of the ‘gaps’ between myelin on axons of neurons?
Nodes of Ranvier
What are the names of the processes which stem from the cell body of neurons and receive input from receptors/other neurons?
Dendrites
Describe the Nernst equation for calculating equilibrium potential.
E = (RT/zF)ln ([ion outside cell] / [ion outside cell])
R = gas constant z = valence T = temperature (K) F = faraday constant
What is the typical resting membrane potential of a neuron?
Between -60mV to -70mV
What is equilibrium potential?
The membrane potential where there is no net movement of ions in or out of the cell
What is an action potential?
A very brief but dramatic change in membrane potential
Action potentials are an all or nothing response. T/F?
True
Depolarisation is due to the fast opening of voltage gated channels for which ion?
Sodium
Repolarisation is due to the slow opening of voltage gated channels for which ion?
Potassium
Lidocaine is a local anaesthetic. What is its mechanism of action?
Blocks sodium channel to prevent depolarisation
Lidocaine is a local anaesthetic which inhibits depolarisation by blocking sodium channels. What other class of drugs also works by blocking these channels?
Antiepileptic drugs
What factors determined the destination of current in a neuron?
The axon diameter
The number of open pores or channels in the membrane
Describe saltatory conduction in myelinated neurons
The action potential ‘jumps’ from node to node allowing faster transmission of the cell
What are the symptoms of Gullain-Barre syndrome?
Progressive motor weakness
Motor and sensory loss (mainly in the face, limbs, trunk and diaphragm)
Gullain-barre is an inflammatory disease which can be caused by a prior infection. T/F?
True
Describe the process of synaptic transmission in neurons
The action potential enters the presynaptic terminal, allowing calcium enter through voltage gated calcium channels. calcium causes docking of synaptic vesicles containing neurotransmitters which are then released by exocytosis. The neurotransmitter then binds to and activates receptors on the postsynaptic membrane. This causes an influx of either sodium (excitatory) or calcium (inhibitory) in the post-synaptic cell which causes, respectively, action potential firing or hyper polarisation to prevent depolarisation
Excitatory and inhibitory postsynaptic potentials are graded, threshold potentials which bring the resting membrane potential either closer to or further from threshold potential. T/F?
True
Give example of biogenic amine neurotransmitters?
Catecholamines, 5-hydroxytrytamine, serotonin
Glutamate is an amino acid neurotransmitter which is excitatory. Name an inhibitory amino acid neurotransmitter?
Gamma-aminobutyric acid (GABA)
Botulism results in skeletal muscle weakness and paralysis of the diaphragm. How is this achieved?
When the botulinum toxin is ingested from clostridium bacteria in contaminated food, this disrupts exocytosis to prevent ACh release
How do autoantibodies act in myasthenia gravis to cause severe muscle weakness?
These bind to and block ACh receptors in the postsynaptic membrane at the motor end plate
Which tissues are most affected by myasthenia gravis?
Eyelids Eyes Face Throat Limb muscles
What technique is used to investigate cognitive processes in response to a stimulus?
Electoencephalography (EEG)
How is PET used to locate brain activity while performing a task?
It measures blood flow via a small dose of radioactive material injected into the bloodstream
PET uses blood flow to locate brain activity while performing a task. What other imaging technique can be used similarly?
functional MRI
How is transcranial magnetic stimulation used to investigate Brian activity?
This uses electormagnetic stimuli to cause depolarisation or interrupted firing to interrupt brain activity while performing a task
