Midterm 1 - Unit 1 Lecture 2 Flashcards
what is membrane potential
difference in distribution of ions(charged atoms) inside and outside the cell
what are elements inside the cell
potassium (K+)
sodium (Na+)
chloride (Cl-)
what are the elements outside the cell
Lots of Na+ & Cl-
Some K+
what is the distribution of ions at resting state
more negative ions inside than outside the neuron
what is the quantitative value for resting membrane potential
-70 mV
what is an action potential
very rapid change in the membrane potential that occurs when a neuron is stimulated.
what triggers and action potential
If membrane voltage reaches threshold
what happens during an action potential
Membrane potential goes from the resting potential to some positive value (approx. +30mV)
why does the membrane potential change during an action potential
Due to sodium channel opening to allow an influx of Na+ ions inside the cell (Depolarization)
what is depolarization
the rapid rise in potential, an all-or-nothing event that is initiated by the opening of sodium ion channels within the plasma membrane
what is hyperpolarization
a change in a cell’s membrane potential that makes it more negative.
what is myelin
fatty substance covering axons allows faster conduction of nerve impulses
what are the nodes of ranvier
axonal segments that lack myelin, allowing the action to jump from node to node
what is a synapse
small gap between two neurons, where nerve impulses are relayed by a neurotransmitter, from a presynaptic terminal of one axon to the postsynaptic receptors of another
what happens during neurotransmitter release
Vesicles release neurotransmitters across synaptic cleft onto other neurons
Released neuro- transmitters bind to postsynaptic receptors, which in turn open ion- channels
what happens after neurotrasmitter release
Stimulation of receptors on postsynaptic membrane causes generation of synaptic (local) potential
Are postsynaptic potentials positive or negative
can be both
what is an EPSP
synaptic inputs that depolarize the postsynaptic cell, bringing the membrane potential closer to threshold and closer to firing an action potential
what is an IPSP
synaptic inputs that hyperpolarize the postsynaptic cell, caused by the flow of negatively charged ions
EPSP’s must summate to produce an action potential. true or false
true
what are the two types of summations
spatial summation
temporal summation
what is spatial summation
occurs when several weak signals from different locations are converted into a single larger one
inputs from many presynaptic neurons at once
what is temporal summation
converts a rapid series of weak pulses from a single source into one large signal
input from one presynaptic neuron in quick succession
what is convergence
multiple neurons influencing one neuron
what is divergence
one neuron can influence multiple
how is a Postsynaptic potential terminated
through reuptake(taken back to axonal terminal that released it
having the neurotransmitters destroyed
cocaine blocks the reuptake of what neurotransmitter
dopamine
how do most drugs that affect behaviour
by affecting synaptic transmission
drugs can interfere with the opening/closing of these ion channels
can block or inhibit the postsynaptic effect OR can facilitate them
how does Ethanol (alcohol) affect synaptic transmission
facilitates postsynaptic (GABA) stimulation
keeps Cl- ions channels open for longer periods of time
i.e., larger or longer IPSP
