Nerve Cells

Neurons

cell that carries messages throughout the nervous system

Brain

The part of the central nervous system that is located in the skull and controls most functions in the body

Ganglia

groups of nerve cells

Central Nervous System

the portion of the vertebrate nervous system consisting of the brain and spinal cord

Peripheral Nervous System

the sensory and motor neurons that connect the central nervous system to the rest of the body

Sensory Neurons

neurons that carry incoming information from the sense receptors to the central nervous system

Interneurons

central nervous system neurons that internally communicate and intervene between the sensory inputs and motor outputs

Motor Neurons

neurons that carry outgoing information from the central nervous system to the muscles and glands

Dendrites

branching extensions of neuron that receives messages from neighboring neurons

Axon

the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands

Synapse

the junction between two neurons (axon-to-dendrite) or between a neuron and a muscle

Neurotransmitters

Chemicals that transmit information from one neuron to another.

Glial Cells

cells in the nervous system that support, nourish, and protect neurons

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 potential difference between the two sides of the membrane of a nerve cell when the cell is not conducting an impulse

Ion Channels

a transmembrane protein channel that allows a specific ion to flow across the membrane down its concentration gradient

Equilibrium Potential (Eion)

the membrane potential at which chemical and electrical forces are balanced for a single ion.

Gated Ion Channels

a pore that allows ions to pass through, but has a mechanism that allows to it be open and closed

Hyperpolarization

The movement of the membrane potential of a cell away from rest potential in a more negative direction.

Depolarization

the process during the action potential when sodium is rushing into the cell causing the interior to become more positive

Graded Potential

A local change in membrane potential that varies directly with the strength of the stimulus, declines with distance.

Action Potential

a neural impulse; a brief electrical charge that travels down an axon

Voltage Gated

Term used to describe ion channels whose opening and closing is sensitive to membrane potential

Threshold

Action potential occurs whenever a depolarization increases the membrane voltage to a particular value

Refractory Period

(neurology) the time after a neuron fires or a muscle fiber contracts during which a stimulus will not evoke a response

Mylein Sheath

fatty membrane covering the neurons axon; good conductor of electricity saves ATP

Oligodendrocytes

produces myelin sheath in Central Nervous System

Schwann Cells

produce myelin in Peripheral Nervous System; (so type of glial cell)

Nodes of Ranvier

Gaps in the myelin sheath of the axons of peripheral neruons. Action potentials can 'hump' from node to node, thus increasing the speed of conduction (saltatory conduction).

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 protein pore in cellular membranes that opens or closes in response to a signaling chemical (its ligand), allowing or blocking the flow of specific ions.

Excitatory postsynaptic potential

a postsynaptic potential that depolarizes the neuronal membrane, making the cell more likely to fire an action potential

Inhibitory postsynaptic potential

a postsynaptic potential that hyperpolarizes the neuronal membrane, making a cell less likely to fire an action potential

Temporal Summation

A phenomenon of neural integration in which the membrane potential of the postsynaptic cell in a chemical synapse is determined by the combined effect of EPSPs or IPSPs produced in rapid succession.

Spatial Summation

The sum of multiple synapses firing at different locations at one time to create a net effect.

Glutamate

a major excitatory neurotransmitter; involved in memory

Gamma-aminobutyric acid

GABA. Inhibitory. Modulates other neurotransmitter systems. Drugs that increase GABA are used to treat anxiety and induce sleep.

Biogenic Amines

Neurotransmitters derived from amino acids

Norepinephrine

helps control alertness and arousal

Dopamine

a monoamine neurotransmitter found in the brain and essential for the normal functioning of the central nervous system--paying attention

Serotonin

a neurotransmitter that affects hunger,sleep,arousal,and mood. appears in lower than normal levels in depressed persons

Neuropeptides

relatively short chains of amino acids, serve as neurotransmitters.

Endorphins

natural, opiatelike neurotransmitters linked to pain control and to pleasure