Chapter 48: Neurons, Synapses, and Signaling Flashcards
Stages of information processing
- Sensory input
- Integration
- Motor output
Integration happens where?
Central nervous system
Motor output happens where?
Peripheral nervous system
Neurons
the nerve cells that transfer information within the body
Most of a neuron’s organelles, including its
nucleus, are located in the….
cell body
brain
Organ of the central nervous system where
information is processed and integrated.
ganglia
A cluster (functional group) of nerve cell bodies
dendrite
One of usually numerous, short, highly branched extensions of a neuron that receive signals from other neurons.
axon
A typically long extension, or process, of a neuron that carries nerve impulses away from the cell body toward target cells
synapse
The junction where a neuron communicates with another cell across a narrow gap via a neurotransmitter or an electrical coupling.
neurotransmitter
A molecule that is released from the synaptic terminal of a neuron at a chemical synapse, diffuses across the synaptic cleft, and binds to the postsynaptic cell, triggering a response
glia (glial cells)
Cells of the nervous system that support, regulate, and augment the functions of neurons
Sensory neuron
A nerve cell that receives information from the internal or external environment and transmits signals to the central nervous system
Interneurons
An association neuron; a nerve cell within the central nervous system that forms synapses with sensory and/or motor neurons and integrates sensory input and motor output
Motor neuron
A nerve cell that transmits signals from the brain or spinal cord to muscles or glands.
central nervous system (CNS)
The portion of the nervous system where signal integration occurs; in vertebrate animals, the brain and spinal cord.
peripheral nervous system (PNS)
The sensory and motor neurons that connect to the
central nervous system.
membrane potential
The difference in electrical charge (voltage) across a cell’s plasma membrane due to the differential distribution of ions. Membrane potential affects the activity of excitable cells and the transmembrane
movement of all charged substances
resting potential
The membrane potential characteristic of a nonconducting excitable cell, with the inside of the cell more negative than the outside.
sodium-potassium pump
A transport protein in the plasma membrane of animal cells that actively transports sodium out of the cell and potassium into the cell.
ion channels
A transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient.
Myelination speeds up _______
action potential
Why are action potentials usually conducted in one direction?
Brief refractory period prevents reopening of voltage gated sodium channels
equilibrium potential
The magnitude of a cell’s membrane voltage at equilibrium; calculated using the Nernst equation.
voltage-gated ion channel
A specialized ion channel that opens or closes in response to changes in membrane potential
hyperpolarization
A change in a cell’s membrane potential such that the inside of the membrane becomes more negative relative to the outside. Hyperpolarization reduces the
chance that a neuron will transmit a nerve impulse.
depolarization
A change in a cell’s membrane potential such that the inside of the membrane is made less negative relative to the outside. For example, a neuron membrane is depolarized if a stimulus decreases its voltage from the resting potential of - 70mV in the direction of zero voltage.
action potential
An electrical signal thatpropagates (travels) along the membrane of a neuron or other excitable cell as a nongraded (all-or-none) depolarization.
threshold
The potential that an excitable cell membrane must reach for an action potential to be initiated.
refractory period
The short time immediately after an action potential in which the neuron cannot respond to another stimulus, owing to the inactivation of voltage-gated sodium channels.
myelin sheath
Wrapped around the axon of a neuron, an insulating coat of cell membranes from Schwann cells or oligodendrocytes. It is interrupted by nodes of Ranvier, where action potentials are generated.
oligodendrocytes
A type of glial cell that forms insulating myelin sheaths around the axons of neurons in the central nervous system.
Schwann cells
A type of glial cell that forms insulating myelin sheaths around the axons of neurons in the peripheral nervous system.
nodes of Ranvier
Gap in the myelin sheath of certain axons where an action potential may be generated. In saltatory conduction, an action potential is regenerated
at each node, appearing to “jump” along the
axon from node to node.
saltatory conduction
Rapid transmission of a nerve impulse along an
axon, resulting from the action potential jumping from one node of Ranvier to another, skipping the myelin-sheathed regions of membrane.
ligand-gated ion channel
A transmembrane protein containing a pore that
opens or closes as it changes shape in response
to a signaling molecule (ligand), allowing or
blocking the flow of specific ions; also called
an ionotropic receptor.
excitatory postsynaptic potential (EPSP)
An electrical change (depolarization) in the membrane of a postsynaptic cell caused by the binding of an excitatory neurotransmitter from a presynaptic cell to a postsynaptic receptor; makes it more likely for a postsynaptic cell to generate an action potential.
inhibitory postsynaptic potential (IPSP)
An electrical change (usually hyperpolarization) in the membrane of a postsynaptic neuron caused by the binding of an inhibitory neurotransmitter from a presynaptic cell to a postsynaptic receptor; makes
it more difficult for a postsynaptic neuron to
generate an action potential.
summation
A phenomenon of neural integration in which the membrane potential of the postsynaptic cell is determined by the combined effect of EPSPs or IPSPs produced in rapid succession at one synapse or simultaneously at different synapses.
acetylcholine
One of the most common neurotransmitters; functions by binding to receptors and altering the permeability of the postsynaptic membrane to specific ions, either depolarizing or hyperpolarizing the membrane.
neuropeptides
A relatively short chain of amino acids that serves as a neurotransmitter (ex: endorphins)
endorphins
Any of several hormones produced in the brain and anterior pituitary that inhibit pain perception
A shortage of acetylcholine is associated with….
Alzheimer’s disease
biogenic amines (examples)
dopamine, norepinephrine, serotonin
Dopamine
associated with reward, reinforcement, how we feel pleasure; cocaine will stimulate this
Norepinephrine
increases heart rate and blood pumping from the heart
Serotonin
stabilizes our mood, feelings of well-being, and happiness; levels affected by LSD
5 classes of neurotransmitters
- acetylcholine
- amino acids
- biogenic amines
- neuropeptides
- gases
GABA
Amino acid that operates at most inhibitory synapses of the brain
