Chapter 48 Vocabulary: Neurons, Synapses, and Signaling Flashcards

myelin sheath
Terms Definitions
Neurons
Nerve cells that transfer information within the body
Sensory Neurons
Transmit information from eyes and other sensors that detect external stimuli
Interneurons
Make only local connections
Motor Neurons
Transmit signals to muscle cells, causing them to contract
Central Nervous System (CNS)
Includes the brain and a longitudinal nerve cord
Peripheral Nervous System (PNS)
Carries information into and out of the CNS
Cell Body
Contains most of a neuron's organelles and its nucleus
Dendrites
highly branched extensions that receive signals from other neurons
Axon
A long extension that transmits signals to other cells
Axon Hillock
Cone shaped region of an axon where it joins the cell body
Synapse
The end of an axon that transmits information
Synaptic Terminal
The part of each axon branch that forms a special connection
Neurotransmitters
Pass information from the transmitting neuron to the receiving cell
Presynaptic Cell
the transmitting neuron in a synapse
Postsynaptic Cell
The neuron, muscle, or gland cell that receives the signal
Membrane Potential
A voltage across a cell's plasma membrane
Resting Potential
The membrane potential of a neuron that is not sending signals
Ion Channels
Pores formed by clusters of specialized proteins that span the membrane
Equilibrium Potential
The magnitude of the membrane voltage at equilibrium for a particular ion
Gated Ion Channels
Protein channels that open or close in response to stimuli
Hyperpolarization
The increase in the magnitude of the membrane potential
Depolarization
Reduction in the magnitude of the membrane potential- involves gated sodium channels
Voltage-Gated Ion Channels
Channels that open or close in response to a change in the membrane potential
Action Potential
A massive change in membrane voltage
Threshold
The particular value to which a depolarization increases, causing an action potential
Refractory Period
The "downtime" following an action potential
Myelin Sheath
A layer of electrical insulation that surrounds the axon
Oligodendrocytes
Type of glia in the CNS
Schwann Cells
Type of glia in the PNS
Nodes of Ranvier
Gaps in the Myelin sheath to which voltage-gated sodium channels are confined
Saltatory Conduction
The inward current produced during the rising phase of an action potential that travels from one node to the next
Synaptic Vesicles
Membrane-bounded compartments in which synthesized neurotransmitters are kept
Synaptic Cleft
The narrow gap that separates the presynaptic neuron from the postsynaptic cell
Excitatory Postsynaptic Potentials (EPSPs)
Depolarizations that bring the membrane potential back toward threshold
Inhibitory Postsynaptic Potentials (IPSPs)
Hyperpolarizations that move the membrane potential away from threshold
Temporal Summation
Two or more presynaptic impulses arrive in rapid succession and impulses summate (two different times add up)
Spatial Summation
Integration by a postsynaptic neuron of inputs (EPSPs and IPSPs) from multiple sources.
Acetylcholine
Common vertebrate neurotransmitter that creates an EPSP (excitatory everywhere but the heart)
Biogenic Amines
Neurotransmitters derived from amino acids
Serotonin
A biogenic amine synthesized from tryptophan
Dopamine
A catecholamine that acts only as a neurotransmitter
Epinephrine and Norepinephrine
Both neurotransmitters and hormones
Gamma-Aminobutyric Acid (GABA)
An inhibitory neurotransmitter in the brain
Glutamate
Excitatory- most common neurotransmitter in the brain
Neuropeptides
Relatively short chains of amino acids that act as neurotransmitters that act via signal transduction pathways
Substance P
An excitatory neurotransmitter that mediates perception of pain
Endorphins
Natural analgesics that decrease pain perception
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