neutral structure and neural communication Flashcards
what are the five features of a typical neuron?
dendrites, terminal buttons, myelin sheath, axon (inside myelin sheath), and soma (cell body)
what is an action potential
- when a neuron fires and is caused by changes in low of charged molecules across the neuron’s cell membrane.
- term refers to rapid change in membrane potential of neuron
what are the ions involved in action potentials
Sodium (Na+), chloride (Cl-), potassium (K+)
what happens at rest membrane potential
neuron is polarised at -70mV
what happens when the Na+ ions flow
membrane potential depolarises (moves from -70mV to 0mV)
when will action potential be triggered
-50mV
what happens when action potential is finished
- refractory period where membrane potential is hyperpolarised
what does it mean for a membrane to be hyperpolarised
- it is even further from the threshold of activation and the neuron will be less likely to trigger another action potential untol the membrane potential has returned to the resting potential (-70mV)
what does the influx of positive ions in action potential initiate?
- increases the charge within the neuron, reducing difference in charge between the inside and outside of the neuron (going from -70mV to -40mV)
- depolarisation
what are the 6 steps of action potentials
- Na+ channels open, Na+ begin to enter cell
- K+ channels open, K+ being to leave cell
- Na+ channels become refactory, no more Na+ enters cell
- K+ continues to leave cell, causes membrane potential to return to resting level
- K+ channels close, Na+ channels resent
- Extra K+ outside diffuses away
what is the propagation of action potentials
- ions are only able to flow in and out across the neuron membrane in the gaps between the myelin, causing the actions potential to move faster
what is the rate law of action potentials
- neuron firing is “all or none” so frequency of firing determines the strength of the neural signal
- strong stimulus > leads to faster threshold for activation > more frequent action potentials
what are the 5 key structural details of a synapse
- terminal button
- synaptic cleft
- pre and post synaptic membrane
- synaptic vesicles
- microtubles
what do synapses enable
communications between neurons
what are neurotrasmitters
chemicals that are synthesised within the brain/neurons and are often called “chemical messangers”
where does the action potential stop and what does that mean
- stops at the end of an axon so the presynaptic neuron can only influence the post-synaptic neuron through the release of neurotransmitters across the synapse
steps for the neurotransmitter
- an action potential in the pre-synaptuc cell triggers synaptic vesicles to move toward the cell membrane
- this is followed by a fusio of the two membranes
- neurotransmitter molecules are then released
- neurotransmitter then flows into the synaptic cleft where it is available to bind to receptors on the post-synaptic membrane
what happens when the neurotransmitter releases
- when synaptic vesicles merges with the presynaptic membrane the contents are released into the synaptic cleft
- sometimes referred to as “kiss and run”
what happens in the neurotransmitter reuptake
- synapse has the capacity to recycle and reuse neurotransmitter molecules after they have been released
- endocytosis
what is the process of reabsorption into synapse
endocytosis
what doe excitatroy postsynaptoc potentials (EPSPs) do
- depolarise the postsynaptic cell membrane
- increase likelihood that an action potential will be triggered in the postsynaptic neuron
what is the primary excitatory neurotransmitter
glutamate
what do the inhibitory postsynaptic potentials (IPSPs) do
- hyperpolarise the postsynaptic cell membrane
- decrease the likelihood that an action potential will be triggered
what is the primary inhibitory neurotransmitter
Gamma-aminobutyric acid (GABA)
what is the combined effect of EPSPs and IPSPs
neural integration
how do neurotransmitters cause an effect on the post-synaptic neuron
- chemical message received by attaching to the binding site of a receptor sensitive to that neurotransmitter
- opening an ion channel is one example of the effect caused by neurotransmitter binding to the receptor
what is the action of neurotransmitters at receptor
- receptors are very selective (lock and key)
- each receptor can generally only be activated by one neurotransmitter
- each receptor has a specific function/action
- when a neurotransmitter binds to the receptor this will trgger the same event each time
what is the action of drugs on receptors
- drugs work by mimicking the chemical structure of the natural compound (perfectly or partially)
what is the action of drugs at the receptor
- can act as antagonists - activating the receptor like the natural compound
- can act as an antagonist - blocking the receptor and preventing the natural compound from activating it
drugs can only impact one function of the neurotransmitter. true or false
FALSE - they can impact every stage of neurotransmitter function from synthesis to release to receptor binding
how do drugs work
- by mimicking/triggering the same biological responses triggered by naturally occurring substances
do psychological events directly impact the biological processes
yes! Remembering things requires neurons to fire and chemical messages to be sent across neurons
