Neuroanatomy|Neurons Flashcards
What are dipoles?
Charge distributions at the synapses that create measurable electrical potentials
What is volume conduction?
How electrical currents get from the brain to the scalp. Body tissues have capacity for conduction or spread of electricity.
What part of the neuron receives messages from other neurons?
Dendrites
What part of the neuron is covered with myelin?
Axon
What term refers to the cell body of a neuron?
Soma
What type of cells provide maintenance and support for neurons?
Glial cells
What types of neurons carry sensory information from the periphery to the central nervous system?
Afferent (Sensory) neurons [Afferent Arrives]
What types of neurons carry motor signals from the CNS to the peripheral nervous system?
Efferent (Motor) neurons [Efferent Exits]
What do descending nerves do?
Transmit motor impulses from the brain to the peripheral nervous system
What do ascending nerves do?
Transmit sensory impulses to the brain
Nerve cells produce signals that are called what?
Action Potentials
What are LTP and LTD?
Long-Term Potentiation and Long-Term Depression
LTP and LTD are terms that refer to what?
Neuroplasticity
What do brainwaves measure?
EPSPs and IPSPs- not a direct measure of action potentials. These are graded potentials that occur at and near the synapses.
What is the max rate a neuron can produce action potentials?
About 1000 per second
What 2 terms define the process of making brain waves?
Excitatory post-synaptic potential (EPSP) and Inhibitory post-synaptic potential (IPSP)
What does an excitatory neurotransmitter do?
Increases depolarization and the likelihood of an action potential
What does an inhibitory neurotransmitter do?
Increases polarization and decreases the likelihood of an action potential.
What are sensory-evoked potentials (EPs)?
Electric responses generated by the CNS when sensory receptors in the brain are stimulated by auditory, visual, or somatosensory activity. For example, flashes of light generate visual evoked potentials and matching brain wave frequencies.
What are event-related potentials (ERPs)?
Similar to EPs but more generally reflect responses to mental, motor, or psychophysiological tasks. For example, some ERPs are triggered by novel or unexpected stimulation.
What are slow cortical potentials (SCPs)?
Shifts in the DC or standing polarity of the cerebral cortex. Negative shifts occur when the brain is preparing to do a cognitive task. Positive shifts occur and can be recorded when the brain is executing a cognitive task. They are considered slow because they may continue for several seconds in a frequency range usually less than 2 hz.
A negative slow cortical potential has what effect on cortical excitability?
It increases excitability
What focal site measures the max amplitude of SCPs?
Cz
What effect would the self-regulation of SCPs at Cz likely have?
Improved cognitive performance
What determines whether a neuron is considered part of the central or peripheral nervous system?
Location of its soma (cell body)
In what order does neural information travel through parts of a neuron?
Neural information flows from dendrites to the cell body, to the axon hillock, down the axon, and ends at the synaptic terminal. Synaptic terminals can send information to either the dendrites of postsynaptic cells or cell bodies, but cannot transmit information directly to axons.
What is myelin?
Fatty substance that wraps around some axons and helps determine the speed at which action potentials travel along axons. Myelin wraps around the axon create areas where the signal can jump over instead of passing through the axon, which accelerates transmission.
What effect do demyelinating diseases have on the body?
Demyelinating diseases can slow or entirely disrupt the transmission of information.
What are three examples of demyelinating diseases?
Multiple sclerosis, Charcot-Marie-Tooth, Guillain-Barre
What causes multiple sclerosis?
Failure of oligodendrocytes in the CNS to produce myelin.
What causes Charcot-Marie-Tooth (a chronic, hereditary condition) and Guillain-Barre (an acute condition)?
Failure of Schwann cells in the PNS to produce myelin.
What are the three types of glial cells?
- Oligodendrocytes (CNS) and Schwann Cells (PNS)
- Astrocytes
- Microglia
What are oligodendrocytes?
Glial cells in the CNS that produce myelin.
What are Schwann cells?
Glial cells in the PNS that produce myelin.
What cells are considered the “sanitation workers of the brain”?
Astrocytes, a type of glial cell
What are astrocytes?
Glial cells that keep synaptic environments clean and help neurons develop and go where they need to go.
What are microglia?
Glial cells that serve as medics. They are immune cells that come from the blood and repair problems, but that can cause problems if overactive.
Oligodendrocytes/Schwann cells comprise what percentage of all glial cells?
75%
Astrocytes comprise what percentage of all glial cells?
20%
Microglia comprise what percentage of all glial cells?
5%
What causes neurons to fire?
Changes in the electrical charge (ions) of cells.
Ions are molecules where the number of protons and electrons are unequal. It is the influx and efflux of positively- and negatively-charged ions that changes the electrical state or neurons and activates action potentials via the processes of depolarization and repolarization.
Positively-charged ions contain more ______ than ______.
Protons; electrons.
Negatively-charged ions contain more ______ than ______.
Electrons; protons.