Chapter 3 Terms Flashcards
absolute refractory period
the period after the action potential when another action potential cannot occur
ATP
the molecules that stores cellular energy in high energy bonds between phosphate groups
all or none law
the principle governing action potentials where whenever the membrane threshold is reached action potentials with the same amplitude will always occur
amino acid
a molecule in which proteins are synthesized
anabolic reactions
reactions in which molecules are joined together
anion
a negative ion
anterograde transport
transport of materials away from the neuron’s soma
astrocyte
a glial cell that cleans up cellular debris and controls external environment for neurons
axon
the long projection from the soma where action potentials are generated and propagated
axon terminal
a thickened region at the end of an axon (pre synaptic terminal)
axon hillock
the point at which an axon joins its cell body and the first part of the cell that is capable of generating an action potential
axon collaterals
axon branches that leave the main axon well before it reaches its terminal branches
axonal transport
the transport of vesicles along microtubules
bipolar neuron
a neuron with two projections from the soma
catabolic reactions
reactions in which molecules are split apart
cation
a positive ion
chemically gated channel
an ion channel that opens when a molecule reaches its binding site
chromosome
a long coiled strand of DNA
codon
a series of 3 base pairs that codes for specific amino acid during protein synthesis
concentration gradient
where ions are in a higher concentration in one area than in another, causing a net movement of ions to the low concentration area
conductance
the ease with which an ion can pass through the membrane
cytoplasm
the internal contents of the cell
cytoskeleton
the internal cellular skeleton comprised of microtubules
cytosol
the liquid found inside the cell
decremental conduction
the gradual reduction of the intensity of a sub-threshold electrical event as it spreads under the myelin sheath or along a dendrite
dendrite
a short, threadlike extension from the neuron soma that conducts electrical events as it spreads under the myelin sheath or along a dendrite
dendritic spine
a specialized region on a dendrite that contains receptor molecules for the neurotransmitter liberated into the synapse
depolarization
an event in which the membrane potential becomes more positive
diffusion
ions moving from high concentration to low concentration
electrostatic gradient
a condition where charged particles are attracted to a region of the opposite charge
endoplasmic reticulum
a membrane-bound network of tubes and channels found inside the cell
enzymes
proteins that facilitate chemical reactions but are not changed themselves
ECF
the CSF that surrounds all neurons
gene
a length of DNA that codes for a specific protein or other functional product in the cell
glial cell
cells that support neurons and help to regulate their external environemnt
golgi body
a series of flattened tubes or chambers that process cellular vesicles
hyper polarization
an event in which the membrane potential becomes more negative
ions
charged particles that generate bioelectrical signals
leak channel
a gated potassium channel that provides control over potassium concentration inside the neuron
membrane transporters
molecules that carry other molecules, such as neurotransmitters, across the cell membrane
membrane threshold
the value of the membrane potential at which an action potential will occur
mRNA
the molecule that carries the DNA code for a protein to the ribosome
metabolism
the chemical process that occur in the cell
microglia
immune cells found in the brain and the spinal cord
micro trabecular lattice
part of the cytoskeleton of the neuron
microtubules
microscopic tubes that extend throughout the neuron
mitochondrion
a cellular organelle that provides energy for the neuron
multipolar neuron
a neuron with several projects from the soma
myelin sheath
a fatty insulating layer that wraps around an axon
neural compartment
the physical space surrounding a neuron
neurofilament
long, thin components of the cytoskelaton
nitrogen base
the molecules that form the runs in the DNA double helix molecule
node of ranvier
a bare region on a myelinated axon
nucleotides
the side molecule in the DNA double helix
nucleus
the cellular organelle that contains DNA also a brain region where synapses occur and information processing takes place
oligodendrocyte
a glial cell in the CNS that forms insulin sheaths around several axons
passive spread
the movement of a sub-threshold potential along an axon or dendrite
phospholipid
the basic molecule that makes up the neuronal membrane
phospholipid bilayer
the structure of the cell membrane and several membrane-bound cellular organelles
phosphorylation
a process in which a phosphate group is transferred to a target molecule, activating that molecule
potassium leak channels
potassium channels that remain open for a long time contributing to the resting potential
potential
a tendency for ions to move in a solution
protein kinases
an enzyme that is activated through phosphorylation
rate law
the finding that frequency of firing in a neuron increases as the intensity of the stimulus increases
receptor
a protein molecule with a binding site and an ion channel
relative refractory period
the period after the absolute refractory period when it takes stronger stimulus to produce another action potential
resistance
the tendency of the axon to prevent passive spread along its length
resting potential
the polarized state of the neuron when it is at rest
retrograde transport
transport of material back to the neuron’s soma
ribosome
the cellular organelle where protein synthesis occurs
saltatory conduction
conduction along a myelinated axon in which an action potential appears to jump from node to node
Schwann cell
a glial cell in the PNS that forms an insulin sheath around a single axon
soma
in a neuron the thickened region containing the nucleus
bioelectric signals
electrical currents generated by the movement of ions across a membrane
sodium/potassium pump
a membrane transporter that contributes to the resting potential by carrying three sodium ions out of cell and two potassium into the cell
TEA
blocks potassium channels
TTX
obtained from puffer fish, selectively blocks sodium channel
transfer RNA (tRNA)
the molecule at the ribosome that binds with mRNA during protein synthesis
unipolar neuron
a neuron, typically a sensory neuron, with only a single projection from the soma
vesicle
a spherical membrane-bound package that contains cellular chemicals, such as neurotransmitters
voltage-gated channels
an ion channel that opens when ions flow by it
