Definitions Flashcards
Neurogenesis
Production of new neurons through the division of neural stem cells; occurs in the hippocampus and olfactory bulb and appears to play a role in learning.
Neuro Plasticity
In the nervous system, this refers to change, flexibility, or adaptation, usually in response to an experience or learning.
Dualism
The belief that the body is physical but the mind (or soul) is not.
Monism
The belief that the world consists only of matter and energy and that the mind is a phenomenon produced by the workings of the nervous system.
Doctrine of specific nerve energies
Müller’s conclusion that, because all nerve fibers carry the same type of message, sensory information must be specified by the particular nerve fibers that are active.
Broca’s Area
This region of the brain is named for French surgeon Paul Broca, who discovered that damage to a part of the left side of the brain disrupted a person’s ability to speak.
Epigenetics
Changes to gene expression induced by environmental factors.
Neoteny
A slowing of the process of maturation, allowing more time for growth; an important factor in the development of large brains.
Neuroethics
An interdisciplinary field devoted to understanding implications of and developing best practices in ethics for neuroscience research.
Central Nervous System (CNS)
The brain and spinal cord.
Myasthenia gravis
Grave muscle weakness
Peripheral nervous system (PNS)
The part of the nervous system outside the brain and spinal cord, including the nerves attached to the brain and spinal cord.
Nerves
Bundles of individual neurons contained within a protective membrane; that relay sensory to the CNS from the body and relay motor information from the CNS to the rest of the body.
Interneuron
A neuron located entirely within the central nervous system.
Synapse
A junction between the terminal button of an axon and the membrane of another neuron.
Axoplasmic transport
An active process by which substances are propelled along microtubules that run the length of the axon.
Anterograde
traveling In a direction along an axon from the cell body toward the terminal buttons.
Retrograde
Traveling In a direction along an axon from the terminal buttons toward the cell body
Myelin sheath
sheath that surrounds axons and insulates them, preventing messages from spreading between adjacent axons.
Neurotransmitter
A chemical that is released by a terminal button; has an excitatory or inhibitory effect on another neuron.
Membrane
A structure consisting principally of lipid molecules that defines the outer boundaries of a cell and also constitutes many of the cell organelles.
Cytoskeleton
Formed of microtubules and other protein fibers, linked to each other and forming a cohesive mass that gives a cell its shape.
Microtubule
A long strand of bundles of protein filaments arranged around a hollow core; part of the cytoskeleton and involved in transporting substances from place to place within the cell.
Cytoplasm
The viscous, semiliquid substance contained in the interior of a cell.
Nucleus
A structure in the central region of a cell, containing the chromosomes.
Chromosome
A strand of DNA, with associated proteins, found in the nucleus; carries genetic information.
Deoxyribonucleic acid (DNA)
A long, complex macromolecule consisting of two interconnected helical strands; along with associated proteins, strands of DNA constitute the chromosomes.
Gene
The functional unit of the chromosome, which directs synthesis of one or more proteins.
Enzyme
A molecule that controls a chemical reaction, combining two substances or breaking a substance into two parts.
Mitochondria
Organelles that are responsible for extracting energy from nutrients.
Adenosine triphosphate (ATP)
A molecule of prime importance to cellular energy metabolism; its breakdown liberates energy.
Glia
The supporting cells of the central nervous system.
Astrocyte
A glial cell that provides support for neurons of the central nervous system, provides nutrients and other substances, and regulates the chemical composition of the extracellular fluid.
Phagocytosis
The process by which cells engulf and digest other cells or debris caused by cellular degeneration.
Oligodendrocyte
A type of glial cell in the central nervous system that forms myelin sheaths.
Node of Ranvier
A naked portion of a myelinated axon between adjacent oligodendroglia or Schwann cells.
Microglia
The smallest of glial cells; they act as phagocytes and protect the brain from invading microorganisms.
Schwann cell
A cell in the peripheral nervous system that is wrapped around a myelinated axon, providing one segment of its myelin sheath.
Blood–brain barrier
A semipermeable barrier between the blood and the brain produced by the cells in the walls of the brain’s capillaries.
Area postrema
A region of the medulla where the blood–brain barrier is weak; poisons can be detected there and can initiate vomiting.
Membrane potential
The electrical charge across a cell membrane; the difference in electrical potential inside and outside the cell.
Resting potential
The membrane potential of a neuron when it is not being altered by excitatory or inhibitory postsynaptic potentials; approximately ∙70 mV in many neurons.
Hyperpolarization
An increase in the membrane potential of a cell, relative to the normal resting potential.
Depolarization
Reduction (toward zero) of the membrane potential of a cell from its normal resting potential.
Threshold of excitation
The value of the membrane potential that must be reached to produce an action potential.
Action potential
The brief electrical impulse that provides the basis for conduction of information along an axon.
Diffusion
Movement of molecules from regions of high concentration to regions of low concentration.
Ion
A charged molecule. Cations are positively charged, and anions are negatively charged.
Electrostatic pressure
The attractive force between atomic particles charged with opposite signs or the repulsive force between atomic particles charged with the same sign.
Intracellular fluid
The fluid contained within cells.
Extracellular fluid
Body fluids located outside of cells.
Sodium–potassium transporter
A protein found in the membrane of all cells that extrudes sodium ions from and transports potassium ions into the cell.
Ion channel
A specialized protein molecule that permits specific ions to enter or leave cells.
Voltage-dependent ion channel
An ion channel that opens or closes according to the value of the membrane potential.
All-or-none law
The principle that once an action potential is triggered in an axon, it is propagated, without decrement, to the end of the fiber.
Rate law
The principle that variations in the intensity of a stimulus or other information being transmitted in an axon are represented by variations in the rate at which that axon fires.
Saltatory conduction
Conduction of action potentials by myelinated axons. The action potential appears to jump from one node of Ranvier to the next.
Postsynaptic potential
Alterations in the membrane potential of a postsynaptic neuron, produced by liberation of neurotransmitter at the synapse.
Binding site
The location on a receptor protein to which a ligand binds.
Ligand
A chemical that binds with the binding site of a receptor.
Dendritic spine
A small bud on the surface of a dendrite, with which a terminal button of another neuron forms a synapse.
Presynaptic membrane
The membrane of a terminal button that lies adjacent to the postsynaptic membrane and through which the neurotransmitter is released
Postsynaptic membrane
The cellmembrane opposite the terminal button in
a synapse; the membrane of the cell that
receives the message.
Synaptic vesicle
A small, hollow, beadlike structure found in terminal buttons; contains molecules of a neurotransmitter.
Postsynaptic receptor
A receptor molecule in the postsynaptic membrane of a synapse that contains a binding site for a neurotransmitter.
Neurotransmitter-dependent ion
channel
An ion channel that opens when a molecule of a neurotransmitter binds with a postsynaptic receptor.
Ionotropic receptor
A receptor that contains a binding site for a neurotransmitter and an ion channel that opens when a molecule of the neurotransmitter attaches to the binding site.
Metabotropic receptor
A receptor that contains a binding site for a neurotransmitter; activates an enzyme that begins a series of events that opens an ion channel elsewhere in the membrane of the cell when a molecule of the neurotransmitter attaches to the binding site.
G protein
A protein coupled to a metabotropic receptor; conveys messages to other molecules when a ligand binds with and activates the receptor.
Second messenger
A chemical produced when a G protein activates an enzyme; carries a signal that results in the opening of the ion channel or causes other events to occur in the cell.
Excitatory
postsynaptic potential
(EPSP)
An excitatory depolarization of the postsynaptic membrane of a synapse caused by the liberation of a neurotransmitter by the terminal button.
Inhibitory postsynaptic potential
(IPSP)
An inhibitory hyperpolarization of the postsynaptic membrane of a synapse caused by the liberation of a neurotransmitter by the terminal button.
Reuptake
The reentry of a neurotransmitter released from a terminal button back through its membrane. This process terminates the postsynaptic potential.
Enzymatic deactivation
The destruction of a neurotransmitter by an enzyme after its release—for example, the destruction of acetylcholine by acetylcholinesterase.
Acetylcholinesterase (AChE)
The enzyme that destroys acetylcholine soon after it is released from the terminal buttons. This action terminates the postsynaptic potential.
Acetylcholine (ACh)
A neurotransmitter found in the brain, spinal cord, and parts of the peripheral nervous system; responsible for muscular contraction.
Neural integration
The process by which inhibitory and excitatory postsynaptic potentials summate and control the rate of firing of a neuron.
Autoreceptor
A receptor molecule located on a neuron that responds to the neurotransmitter released by that neuron.
Presynaptic inhibition
The action of a presynaptic terminal button in an axoaxonic synapse; reduces the amount of neurotransmitter released by the postsynaptic terminal button.
Presynaptic facilitation
The action of a presynaptic terminal button in an axoaxonic synapse; increases the amount of neurotransmitter released by the postsynaptic terminal button.
Neuromodulator
A naturally secreted substance that acts like a neurotransmitter except that it is not restricted to the synaptic cleft but diffuses through the extracellular fluid.
Peptide
A chain of amino acids joined together by peptide bonds. Most neuromodulators, and some hormones, consist of peptide molecules.
Hormone
A chemical substance that is released by an endocrine gland that has effects on target cells in other organs.
Endocrine gland
A gland that releases chemical messengers into the extracellular fluid around capillaries and hence into the bloodstream.
Target cell
The type of cell that is directly affected by a hormone or other chemical signal.
Organic Anions (A-)
negative charge (anion) and only found inside of the neuron. cannot pass through the cell membrane (they are stuck there) this contributes to the negative charge.
Potassium ions (K+)
positive charge (cation) and found mostly inside the neuron. Diffusion pushes it out of the neuron, but electrostatic pressure pushes it in (outside of the neuron is positive and like charges repel)
Chloride ions (CI -)
negative charge (anion) and found mostly outside the neuron. Diffusion pushes it into the neuron. But electrostatic pressure pushes it out (inside is negative and like charges repel)
Sodium ions (Na+)
positive charge (cation) and found mostly outside the neuron. Diffusion pushes it into the neuron as does electrostatic pressure (inside of the neuron is positive opposite charges attract)
The sodium potassium pump
the cell membrane isn’t very permeable to sodium, the pump pushes sodium out of the cell. for every 3 sodium ions that get pumped out 2 potassium ions go back in.
Axodendritic synapse
attaches to the dendritic membrane of the receiving cell (smooth dendrite or dendritic spine)
Axosomatic synapse
attaches to the somatic membrane of the receiving cell
Axoaxonic synapse
attaches to the terminal button of the receiving cell
Sodium (Na+) ion channels
opening = excitatory postsynaptic potentials
Potassium (K+) ion channels
opening = inhibitory postsynaptic potentials
Chloride (Cl-) ion channels
opening = either nothing or inhibitory postsynaptic potentials
Calcium (Ca2+) ion channels
opening = excitatory postsynaptic potentials, and more
Opening calcium ion channels activates special enzymes which cause biochemical and structural changes in the postsynaptic neuron.
Cerebrospinal fluid (CSF)
A clear fluid, similar to blood plasma, that fills the ventricular system of the brain and the subarachnoid space surrounding the brain and spinal cord.
Neuraxis
An imaginary line drawn through the center of the length of the central nervous system, from the bottom of the spinal cord to the front of the forebrain.
Rostral or anterior
“Toward the beak”; with respect to the central nervous system, in a direction along the neuraxis toward the front of the face.
Caudal or Posterior
“Toward the tail”; with respect to the central nervous system, in a direction along the neuraxis away from the front of the face.
Dorsal
“Toward the back”; with respect to the central nervous system, in a direction perpendicular to the neuraxis toward the top of the head or the back.
Ventral
“Toward the belly”; with respecto the central nervous system, in a direction perpendicular to the neuraxis toward the bottom of the skull or the front surface of the body.
Lateral
Toward the side of the body, away from the middle.
Medial
Toward the middle of the body, away from the side.
Ipsilateral
Located on the same side of the body.
Contralateral
Located on the opposite side of the body.
Cerebral cortex
The outermost layer of gray matter of the cerebral hemispheres.