Chapter 4: Neuronal Signaling Flashcards
what did Galviani study?
the reflexive responses of dissected frog legs to electrical responses
what are cations?
positively charged ions (sodium and potassium)
what are anions?
negatively charged ions (chloride)
voltage gradient
positive and negative ions will flow down their electrostatic gradients until positive and negative charges are equal everywhere
ungated channel
ions can cross a cell membrane through the appropriately shaped channel
gated channel
changes shape to allow the passage of substances when gates are open and to prevent passage when one or both gates are closed
what is the resting potential?
a store of negative energy inside the neuron membrane relative to the outside (-70mV)
what is the purpose of the sodium-potassium pump?
helps maintain resting potential in the cell by pumping Na+ from inside the cell and exchanges it for K+ from outside the cell
what causes hyperpolarization?
an efflux of K+, which makes the extracellular side of the membrane more positive, or an influx of Cl-
what causes depolarization?
an influx of Na+ through Na+ channels
how does an action potential start?
voltage-gated Na+ channels burst open a fraction sooner than gated K+ channels when the membrane receives enough stimulation, causing K+ ions to rush out of the cell
what is the all-or-nothing law?
the magnitude of the action potential remains consistent all the way down the axon terminal
what is saltatory conduction?
the current flow jumps over the nodes of ranvier, speeding up the conduction of the signal along the axon
excitatory postsynaptic potential
depolarizes the postsynaptic neuron
inhibitory postsynaptic potential
hyperpolarizes the postsynaptic neuron
deep brain stimulation
electrodes are implanted deep in the brain and stimulate targeted areas with a low-voltage electrical current to facilitate behaviour
what did Otto Loewi do?
stimulated the vagus nerve of a frog heart and measured the effects on heart rate.
discovered acetylcholine
what are the criteria for identifying neurotransmitters?
- chemical must be synthesized or present in the neuron
- when released, the chemical must produce a response in the target cell
- same receptor action must be obtained when the chemical is experimentally placed on the target
- there must be a mechanism for removal after the chemical’s work is done
presynaptic membrane
encloses molecules that transmit chemical messages
synaptic cleft
small space separating presynaptic terminal and postsynaptic dendritic spine
postsynaptic membrane
contains receptor molecules that receive chemical messages
microtubule
transport structure that carries substances to the axon terminal
synaptic vesicle
round granule that contains neurotransmitters
storage granule
large compartment that holds synaptic vesicles
postsynaptic receptor
site to which a neurotransmitter molecule binds
what are the steps of neurotransmission?
- synthesis
- release
- receptor action
- inactivation
what does calcium serve as?
the signal for vesicles to release their neurotransmitters into the axon terminal
what is the purpose of autoreceptors?
allows the neuron to keep track of how much neurotransmitter has been released and when to stop
what is the purpose of ionotropic receptors?
can depolarize or hyperpolarize the cell and can change the electrical charge in the receiving neuron
what is the structure of a metabotropic receptor?
embedded membraine protein with a binding site for a neurotransmitter but no pore
what is the purpose of a metabrotropic receptor?
activates a G-protein that can signal a second messenger
what do second messengers promote? what does this result in?
DNA transcription in pre and postsynaptic neurons. results in structural changes that strengthen the signals between two neurons
which neurotransmitter is present in the cholinergic system?
acetylcholine
which brain structures make up the cholinergic system?
midbrain and basal forebrain
what is the cholinergic system involved in?
learning and memory through its effects on attention
which neurotransmitter is present in the dopaminergic system?
dopamine
what are the two main pathways in the dopaminergic system?
mesolimbic pathway (nucleus accumbens) and nigrosriatal pathway (substantia nigra)
what is the mesolimbic pathway involved in?
reward; habit formation
what is the nigrostriatal pathway involved in?
moderates movement
which neurotransmitter is present in the noradrenergic system?
norepinephrine
what does the noradrenergic system control?
the sympathetic nervous system (fight or flight)
increases energy and heart rate
which neurotransmitter is present in the serotonergic system?
serotonin
what does the serotonergic system control?
mood and emotion, appetite and digestion, sleep cycles
what is GABA?
the most inhibitory neurotransmitter in the body. slows you down
what is glutamate?
the most numerous neurotransmitter in the body due to it being involved in so many things. most excitatory neurotransmitter in the body
