the nervous system
The body's electrochemical communication circuitry.
plasticity
The brain's special capacity for change.
afferent nerves
Also called sensory nerves. Carry information about the external environment to the brain and spinal cord. "Arrive at the brain".
efferent nerves
Also called motor nerves. Carry information out of the brain and spinal cord to other areas of the body. "Exit the brain".
central nervous system
The brain and spinal cord
peripheral nervous system
Network of nerves that connects the brain and spinal cord to other parts of the body.
somatic nervous system
Sensory nerves: convey information from the skin and muscles to the CNS about conditions about pain and temperature. Motors nerves: tell muscles what to do.
autonomic nervous system
Takes messages to and from the body's internal organs; monitors processes such as breathing, heart rate and digestion.
sympathetic nervous system
Part of the autonomic nervous system; mobilizes the body for action, involved in the experience of stress.
parasympathetic nervous system
Part of the autonomic nervous system that calms the body.
stress
Response of individuals to environmental stressors.
stressors
Circumstances and events that threaten individuals and tax their coping abilities; cause psychological changes to ready the body to handle the assault of stress.
neurons
Nerve cells that handle the information-processing function.
glial cells
Provide support, nutritional benefits and other functions to keep neurons running smoothly.
cell body
Contains the nucleus; directs the manufacture of substances that the neuron needs for growth and maintenance.
dendrite
Treelike fibers projecting from a neuron; receive information and orient it toward the cell body.
axon
Carries information away from the cell body toward other cells.
myelin sheath
Layer of fat cells that encase and insulate most axons
resting potential
Stable, negative charge of a resting neuron.
action potential
Brief wave of positive electrical charge that sweeps down the axon.
all-or-nothing principle
Once an electrical impulse reaches a certain level of intensity, it fires and moves all the way down the axon without losing any intensity.
synapses
Tiny spaces between neurons; also referred to as synaptic gaps.
neurotransmitters
Chemical substances stored within the terminal button; involved in transmitting information across a synaptic gap to the next neuron.
acetylcholine (ACh)
Stimulates the firing of neurons; involved in the action of muscles, learning and memory. Black widow spider venom causes ACh to gush out of the synapses between spinal cord and skeletal muscles, producing violent spasms.
GABA (gamma animobutyric acid)
Neurotransmitter for 1/3 of the brain's synapses. Controls the precision of the signal being carried from one neuron to the next. Low levels are linked to anxiety.
Norepinephrine
Inhibits firing of neurons in the central nervous system, but excites the heart muscle, intestines and urogenital tract. Too little = depression; too much = manic states.
Dopamine
Controls voluntary movement and affects mood, sleep, attention, learning and ability to recognize rewards in the environment. Associated with personality trait of extraversion
Serotonin
Regulates sleep, mood, attention and learning. Lower levels = depression.
Endorphins
Natural opiates; stimulate the firing of neurons. Shield body from pain and elevate feelings of pleasure.
Oxytocin
Hormone and transmitter; plays an important role in love and social bonding. Associated with "Love at first sight" with newborns.
antagonist
A drug that blocks neurotransmitter's effects.
agonist
A drug that mimics or increases a neurotransmitter's effects.