Signal_Transduction.csv

oligodendrocytes; Schwann cells; astrocytes; microglial cells

production of myelin in the CNS

production of myelin in the PNS

nutritive and supportive connections between neurons and capillaries in the CNS

phagocytosis of damaged cells; the macrophages of the CNS

oligodendrocytes in CNS and Schwann cells in PNS; oligodendrocytes myelinate many cells while Schwann cells myelinate only one cell

one of two components of the CNS; consists mainly of myelinated cells; appears white because myelin is made up mainly of lipids

separates circulating blood from cerebrospinal fluid; composed mainly of tight junctions in capillary endothelial cells; filters blood plasma; permits entry of ions but not proteins into CSF

prevention of entry of pathogens into CNS; maintenance of homeostasis in CSF

specialized tissue that secretes cerebrospinal fluid into the ventricles; found in multiple locations in the ventricles of the brain; filters blood and actively transports ions to produce CSF

small protrusions of arachnoid mater in the brain that uptake circulating cerebrospinal fluid and allow it to re-enter the bloodstream

"the process of axonal degeneration following nerve damage to the axon & separation of the axonal process from the cell body; occurs in both the CNS and the PNS; ""clean-up"" assisted by microglia"

lysis of neuronal chromatin; occurs in response to cellular damage; involves swelling of the cell and dispersal of the rER

input; summation; conduction; output

the most electrically sensitive part of the axon; has the lowest threshold for an action potential; initiation site for action potential; involved in summation

the difference in voltage between the interior and exterior of a quiescent cell; primarily determined by potassium in neurons

used to calculate the membrane potential based on the internal and external concentrations of a single ion; assumes that only that ion is permeable

sodium low inside & high outside; potassium high inside & low outside; chlorine low inside & high outside; calcium very low inside & low outside

used to calculate the membrane potential based on the internal and external concentrations of several monovalent ions

sodium influx provokes depolarization of membrane; depolarization provokes opening of neighboring sodium channels; opening of sodium channels leads to further sodium influx; channels are temporarily inactivated after opening to prevent reversal of direction

used by electrophysiologists to measure ion flow while holding membrane potential steady; used by Hodgkin and Huxley to elucidate ionic causes of action potentials

the electric potential at which a cell membrane is held in experiments involving voltage clamps

represented by lambda; describes the distance that passive voltage will spread along an axon or dendrite; depends on the resistance across and inside the membrane; depends on the number of open ion channels and the diameter of the cell process

describes the speed at which a cell membrane potential changes; represented by tau

ATP-driven enzyme that pumps 3 sodium ions out of the cell for every 2 potassium ions it pumps into the cell

removal of external K+ decreases rate of Na+ transfer; blockage of ATP synthesis decreases rate of Na+ transfer

sodium binding on inner cell membrane; phosphorylation of membrane receptor; conformational change of membrane receptor; sodium release; potassium binding; dephosphorylation of receptor; potassium release

a junction for communication between two cells

between two neurons; between a pre-synaptic neuron and a post-synaptic non-neuronal target; between a pre-synaptic sensory cell and a post-synaptic neuron

electrical and chemical

electrical synapses are much smaller; electrical synapses have cytoplasmic continuity while chemical synapses do not; electrical synapses have no synaptic delay while chemical synapses have variable-length synaptic delays; electrical synapses are theoretically bidirectional while chemical synapses are unidirectional

occurs at electrical synapses; made up of connexon units that form channels; allow passage of small molecules such as cyclic AMP

visible as thick black lines on EM of a synapse; composed of exocytotic machinery on the presynaptic side and neurotransmitter-binding receptors on the postsynaptic side

the region of the presynaptic plasma membrane at which synaptic vesicles dock

found in neuromuscular junctions; postsynaptic membrane displays folding

depolarization of nerve terminal; opening of voltage-gated calcium channels; calcium influx; exocytosis of ACh; activation of nAChRs; opening of sodium and potassium channels; depolarization of post-synaptic cell membrane; conformational change of calcium channels on sarcoplasmic reticulum; calcium release; muscle contraction

small molecues; peptides and polypeptides

amines - dopamine and norepinephrine; amino acids - glutamate and GABA and glycine; nucleosides and nucleotides; lipids

hypothalamic peptides - oxytocin and vasopressin; gut peptides - somatostatin and vip; endorphins

small molecules are synthesized locally while peptides are synthesized at the cell body and transported; small molecules are packaged in small clear vesicles while peptides are packaged in large dense core vesicles; small molecule vesicles are recycled while peptide vesicles are not; small molecules require low Ca2+ concentration for release while peptides require high Ca2+ concentration for release

a small molecule neurotransmitter syntheized in the cytosol from acetate and choline; occurs in neuromuscular junctions

"""kiss and run"" or complete fusion/conventional vesicle exocytosis"

a process by which vesicles release neurotransmitter into the synaptic cleft; involves incomplete fusion with the cell membrane and formation of a fusion pore; involves vesicle recycling; occurs when large amounts of neurotransmitter are being released

a process by which vesicles release neurotransmitter into the synaptic cleft; involves complete fusion with the cell membrane; involves recovery of the vesicle membrane via clathrin-mediated endocytosis

describes the mechanism by which vesicle fusion occurs; involves recognition of vesicle SNARES by target SNARES on the cell membrane

target SNARES; protein complexes on the cell membrane that interact with v-SNARES to promote vesicle docking

vesicle SNARES; protein complexes on the vesicle that interact with t-SNARES to promote vesicle docking

the coiled-coil protein domains of v-SNARES and t-SNARES interact to pull the vesicle into a docked position on the membrane for exocytosis

a protein involved in exocytosis; two C2 domains bind calcium; acts as a calcium sensor

a toxin that blocks inhibitory neuronal transmission via proteolysis of the SNARE family VAMP-2; causes rigidity and spasms

a toxin that blocks excitatory neuronal transmission via proteolysis of the SNARE family VAMP-1 at the NMJ; causes flaccid paralysis

small graded electric responses provoked at the postsynaptic membrane; can be excitatory or inhibitory

quantity of neurotransmitter released; quantity of neurotransmitter that reaches receptors; number of receptors activated

spontaneous EPSPs that result in the absence of presynaptic stimulation; result from the release of one vesicle's contents

EPSP amplitude is quantal because it depends on the number of presynaptic vesicles released

excitatory post-synaptic potentials increase the probability that an action potential will occur post-synaptically; usually involve depolarization

inhibitory post-synaptic potentials decrease the probability that an action potential will occur post-synaptically; usually involve hyperpolarization

are linked directly to post-synaptic ion channels; mediate fast synaptic transmission; decay is due to diffusion or hydrolysis of neurotransmitter

movement of ions through post-synaptic channels depends on intermediary molecules; mediate slow synaptic transmission; decay depends on lifetime of second messengers

nAChRs; GABAARs; NMDA-Rs

G-protein couple receptors such as beta-adrenergic receptors

a family of G-protein coupled receptors; stimulate heart contraction; stimulation leads to a cascade that eventually results in phosphorylation of an ion channel; compete with mAChRs (inhibitory)

NTs can be inactivated by diffusion or reuptake or enzymatic degradation

presynaptic events; neurotransmitter diffusion across cleft; binding of NT to post-synaptic receptors; activation of ionotropic or metabotropic receptors; postsynaptic potentials; transmitter inactivation

an autoimmune disease that affects nAChRs; antibodies decrease nAChRs at the NMJ by causing them to cluster and be internalized and degraded; causes muscle fatigue

anti-immune drugs; acetylcholinesterase inhibitors

electromyogram; records summation of action potentials in muscle fibers

a toxin that blocks nicotinic acetylcholine receptors

quantity of neurotransmitter per vesicle; number of vesicles available; number of vesicles released; number of post-synaptic receptors; sensitivity of receptors to transmitter; transmitter inactivation