Chapter 2 Flashcards
(33 cards)
what do electroencephalograph measure?
measures the electrical activity generated by the brain
what are event-related potentials?
EEG responses to a single stimulus (flash of light/loud sound)
- they have distinctive shape and time delay (latency)
what is a seizure?
wave of abnormally synchronous electrical activity in the brain
what is the disorder of epilepsy?
brain disorder characterized by seizures
what is the treatment for seizures?
neurosurgery was to locate and remove the source of a seizure before antiepileptic medications
what is the focus of neurophysiology?
it focuses on the electrical activity of neurons
- neurons are negatively charged
what are ion channels?
proteins that span the membrane and allow ions to pass through
what are the two types of ion channels?
- ungated ion channels (stays open all the time - K+ channels)
- gated ion channels (open and close in response to signals. - Na+ channels)
what is selective permeability?
property of a membrane that allows some substances to pass through but not others
- neurons have selective permeability by allowing K+ enter and leave freely but not Na+
what are the two opposing forces that drive ion movement?
- Diffusion w/ concentration gradient
- Electrostatic pressure causes ions to flow towards opposite charged areas
what is the equilibrium potential?
electrical charge that balances two opposing forces- corresponds to resting potential
what is the sodium-potassium pump?
pump that pumps three Na+ out for every two K+ in
- Neurons use a lot of ATP for this
what is the difference between local potentials and action potentials?
local potentials are graded changes in potential of membrane (they diminish as it moves away from point of stimulation)
action potentials are not graded and do not diminish as it travels down the axon
what is the difference between absolute refractory phase and relative refractory phase?
- absolute refractory phase means no action potential can be produced
- relative refractory phase means only a very strong stimulation can produce an AP
why do action potentials only travel in one direction?
because of the refractory state after an AP is fired
what is saltatory conduction?
it occurs only in myelinated axons (the ones that travel long distances)
- nodes of ranvier- small gaps in the insulating myelin sheath that contain Na+ channels and allow for saltatory conduction (potential traveling inside axon jump from node to node)
what is excitatory postsynaptic potentials (EPSP)?
increases the likelihood that the neurons will fire an AP b/c of Na+ channels opening
what is inhibitory postsynaptic potentials (IPSP)
decreases the likelihood of neurons firing an AP because of chloride ions rushing in, making cells more neg
what determines whether a synapse excites or inhibits the postsynaptic cell?
- the particular neurotransmitter released by presynaptic cell (glutamate excites while GABA inhibits)
- the particular postsynaptic receptor
what are ligands and receptors
- ligands are molecules that fit into receptors and activates/block (neurotransmitters are ligand that come from pre to post)
- receptors are what the ligand bind to (the receptor determines the action of the neurotransmitter)
what is the difference between spatial and temporal summation?
spatial is the summing of all potentials that reach the axon hillock from different spatial locations
temporal is summing of all potentials that reach axon hillock based on time
how do neurotransmitters disappear?
- degradation (breakdown and inactivation of the transmitter by enzyme)
- reuptake (transmitter cleared from synapse & absorbed back into presynaptic axon terminal)
what are the different types of synapses?
- axo-dendritic
- axo-somatic
- axo-axonic
- dendro-dentritic
what are axo-axonic synapses?
it is a synapse between two axons where they alter the amount of neurotransmitters being released
