|
Neuroscience |
Acetylcholine
A neurotransmitter that, among its functions, triggers muscle contraction.
Action potential
A neural impulse; a brief electrical charge that travels down an axon. The action potential is generated by the movement of positively charged atoms in and out of channels in the axon’s membranes.
Adrenal glands
A pair of endocrine glands just above the kidneys. The adrenals secrete the hormones epinephrine and norepinephrine, which help to arouse the body in times of stress.
Agonists
They excite by mimicking a particular neurotransmitter or blocking its reuptake.
All –or-none response
A neuron either fires or it doesn’t.
Antagonists
They inhibit by blocking neurotransmitters or by diminishing their release.
Autonomic nervous system
The part of the peripheral nervous system that controls the glands and the muscles of the internal organs.
Axon
The extension of a neuron, ending in branching terminal fibers, through which messages are sent to other neurons or to muscles or glands.
Biological psychology
A branch of psychology concerned with the links between biology and behavior.
Blood-brain barrier
This enables the brain to fence out unwanted chemicals circulating in the blood.
Central nervous system
The brain and spinal cord.
Dendrite
The bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body.
Endocrine system
The body’s “slow” chemical communication system; a set of glands that secrete hormones into the bloodstream.
Endorphins
“Morphine within”- natural, opiate like neurotransmitters linked to pain control and to pleasure.
Hormones
Chemical messengers that are produced in one tissue and affect another.
Interneurons
Central nervous system neurons that internally communicate and intervene between the sensory inputs and motor outputs.
Ions
Electrically charged atoms.
Motor neurons
The neurons that carry outgoing information from the central nervous system to the muscles and glands.
Myelin sheath
A layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next.
Nerves
Neural “cables” containing many axons. These bundled axons, which are part of the peripheral nervous system, connect the central nervous system with the muscles, glands, and sense organs.
Nervous system
The body’s speedy, electrochemical communication system, consisting of all the nerve cells of the peripheral and central nervous systems.
Neural networks
Interconnected neural cells. With experience, networks can learn, as feedback strengthens or inhibits connections that produce certain results.
Neuron
A nerve cell; the basic building block of the nervous system.
Neurotransmitters
Chemical messengers that traverse the synaptic gaps between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether it will generate a neural impulse.
Parasympathetic nervous system
The division of the autonomic nervous system that calms the body, conserving its energy.
Peripheral nervous system
The sensory and motor neurons that connect the central nervous system to the rest of the body.
Pituitary gland
The endocrine system’s most influential gland. Under the influence of the hypothalamus, the pituitary regulates growth and controls other endocrine glands.
Reflex
A simple, automatic, inborn response to a sensory stimulus.
Refractory period
Resting pause during which the neuron pumps the positively charged sodium atoms back outside.
Resting potential
Positive-outside/negative-inside polarization.
Sensory neurons
Neurons that carry incoming information from the sense receptors to the central nervous system.
Somatic nervous system
The division of the peripheral nervous system that controls the body’s skeletal muscles.
Sympathetic nervous system
The division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations.
Synapse
The junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or cleft.
Threshold
The level of stimulation required to trigger a neural impulse.