Studied by 14 people
neuron
a nerve cell; the basic building block of the nervous system.
dendrites
a neuron’s bushy, branching extensions that receive messages and conduct impulses toward the cell body.
axon
the neuron extension that passes messages through its branches to other neurons or to muscles or glands.
myelin sheath
a fatty tissue layer segmentally encasing the axons of some neurons; enables vastly greater transmission speed as neural impulses hop from one sausage-like node to the next.
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 synaptic clef.
action potential
a neural impulse; a brief electrical charge that travels down an axon.
refractory period
a period of inactivity after a neuron has fired.
threshold
the level of stimulation required to trigger a neural impulse.
all-or-none response
a neuron’s reaction of either firing (with a full-strength response) or not firing.
reuptake
a neurotransmitter’s reabsorption by the sending neuron.
agonist
a molecule that, by binding to a receptor site, stimulates a response.
antagonist
a molecule that, by binding to a receptor site, inhibits or blocks a response.
neurotransmitters
chemical messengers that cross 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 that neuron will generate a neural impulse.
biological psychology
the scientific study of the links between biological (genetic, neural, hormonal) and psychological processes. (Some biological psychologists call themselves behavioral neuroscientists, neuropsychologists, behavior geneticists, physiological psychologists, or biopsychologists.)
endorphins
“morphine within”–natural, opiate-like inhibitory neurotransmitters linked to pain control and to pleasure.
acetylcholine (ACh)
an excitatory neurotransmitter that enables muscle action, learning, and memory.
dopamine
an inhibitory neurotransmitter that influences movement, learning, attention, and emotion; gives a sense of pleasure.
serotonin
an inhibitory neurotransmitter that affects mood, hunger, sleep, and arousal.
norepinephrine
an excitatory neurotransmitter that helps control alertness and arousal.
GABA (gamma-aminobutyric acid)
a major inhibitory neurotransmitter; regulates sleep/arousal, and produces a calming effect.
glutamate
a major excitatory neurotransmitter; involved in memory.
soma
the part of a neuron that contains its nucleus and other standard cellular structures.
nodes of Ranvier
gaps in the myelin sheath coating on the neural axon.
resting potential
the value a neuron’s membrane potential keeps as long as it is not receiving stimulation or undergoing an action potential.
depolarization
the process that carries the neural impulse through the axon; sodium flows into the cell bringing a neutral charge.
inhibitory neurotransmitters
block or prevent the chemical message from being passed along any farther.
excitatory neurotransmitters
“excite” the neuron and cause it to “fire off the message,” meaning, the message continues to be passed along to the next cell.
nervous system
the body’s speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems.
central nervous system (CNS)
the brain and spinal cord.
peripheral nervous system (PNS)
the sensory and motor neurons that connect the central nervous system to the rest of the body.
nerves
bundled axons that form neural “cables’ connecting the central nervous system with muscles, glands, and sense organs.
sensory (afferent) neurons
neurons that carry incoming information from the sensory receptors to the brain and spinal cord.
motor (efferent) neurons
neurons that carry outgoing information from the brain and spinal cord to the muscles and glands.
interneurons
neurons within the brain and spinal cord that communicate internally and intervene between sensory inputs and motor outputs.
somatic nervous system
the division of the peripheral nervous system that controls the body’s skeletal muscles. Also called the skeletal nervous system.
autonomic nervous system (ANS)
the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms.
sympathetic nervous system
the division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations.
parasympathetic nervous system
the division of the autonomic nervous system that calms the body, conserving its energy.
reflex
a simple, automatic response to a sensory stimulus, such as a knee-jerk response.
endocrine system
the body’s “slow” chemical communications system; a set of glands that secrete hormones into the bloodstream.
hormones
chemical messages that are manufactured by the endocrine glands travel through the bloodstream and affect other tissues.
adrenal glands
a pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress.
pituitary gland
the endocrine system’s most influential gland. Under the influence of hypothalamus, the pituitary regulates growth and controls other endocrine glands.
lesion
tissue destruction. A brain _ is a naturally or experimentally caused destruction of brain tissue.
EEG (electroencephalogram)
an amplified recording of electrical activity sweeping across the brain’s surface. These waves are measured by electrodes placed on the scalp.
CT (computed tomography) scan
a series of X-ray photographs taken from different angles and combined into a composite representation of a slice of the brain’s structure.
PET (positron emission tomography) scan
a visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task.
MRI (magnetic resonance imaging)
a technique that uses magnetic fields and radio waves to produce computer-generated images of soft tissue. Shows brain anatomy.
fMRI (functional MRI)
a technique for revealing bloodflow, and therefore, brain activity by comparing successive MRI scans. Shows brain function as well as structure.
brainstem
the oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull; responsible for automatic survival functions.
medulla
the base of the brainstem; controls heartbeat and breathing.
thalamus
the brain’s sensory control center, located on top of the brainstem; it directs messages to the sensory receiving areas in the cortex and transmits replies to the cerebellum and the medulla.
reticular formation
a nerve network that travels through the brainstem and thalamus and plays an important role in controlling arousal.
cerebellum
the “little brain” at the rear of the brainstem; functions include processing sensory input, coordinating movement output and balance, and enabling nonverbal learning and memory.
limbic system
neural system (including the hippocampus, amygdala, and hypothalamus) located below the cerebral hemispheres; associated with emotions and drives.
amygdala
two lima-bean-sized neural clusters in the limbic system; linked to emotion.
hypothalamus
a neural structure lying below the thalamus; it directs several maintenance activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion and reward.
cerebral cortex
the intricate fabric of interconnected neural cells covering the cerebral hemispheres; the body’s ultimate control and information-processing center.
glial cells
cells in the nervous system that support, nourish, and protect neurons; they may also play a role in learning and thinking.
frontal lobes
portion of the cerebral cortex lying just behind the forehead; involved in speaking and muscle movements and in making plans and judgments.
parietal lobes
portion of the cerebral cortex lying at the top of the head and toward the rear; receives sensory input for touch and body position.
occipital lobes
portion of the cerebral cortex lying at the back of the head; includes areas that receive information from the visual fields.
temporal lobes
portion of the cerebral cortex lying roughly above the ears; includes the auditory areas, each receiving information primarily from the opposite ear.
motor cortex
an area at the rear of the frontal lobes that controls voluntary movements.
somatosensory cortex
area at the front of the parietal lobes that registers and processes body touch and movement sensations.
association areas
areas of the cerebral cortex that are not involved in primary motor or sensory functions; rather, they are involved in higher mental functions such as learning, remembering, thinking, and speaking.
plasticity
the brain’s ability to change, especially during childhood, by reorganizing after damage or by building new pathways based on experience.
neurogenesis
the formation of new neurons
Broca’s area
association area on the left side of the frontal lobe that is linked to speech production.
Wernicke’s Area
association area on the left side of the temporal lobe that is linked to speech comprehension.
corpus callosum
the large band of neural fibers connecting the two brain hemispheres and carrying messages between them.
split brain
a condition resulting from surgery that isolates the brain’s two hemispheres by cutting the fibers (mainly those of the corpus callosum) connecting them.
consciousness
our awareness of ourselves and our environment.
cognitive neuroscience
the interdisciplinary study of the brain activity linked with cognition (including perception, thinking, memory, and language).
dual processing
the principle that information is often simultaneously processed on separate conscious and unconscious tracks.
circadian rhythm
the biological clock; regular bodily rhythms (for example, of temperature and wakefulness) that occur on a 24-hour cycle.
REM sleep
rapid eye movement sleep; a recurring sleep stage during which vivid dreams commonly occur. Aso known as paradoxical sleep, because the muscles are relaxed (except for minor twitches) but other body systems are active.
alpha waves
the relatively slow brain waves of a relaxed, awake state.
sleep
periodic, natural loss of consciousness—as distinct from unconsciousness resulting from a coma, general anesthesia, or hibernation.
hallucinations
false sensory experiences, such as seeing something in the absence of an external visual stimulus.
delta waves
the large, slow brain waves associated with deep sleep.
NREM sleep
non–rapid eye movement sleep; encompasses all sleep stages except for REM sleep.
suprachiasmatic nucleus (SCN)
a pair of cell clusters in the hypothalamus that controls circadian rhythm. In response to light, causes the pineal gland to adjust melatonin production, thus modifying our feelings of sleepiness.
insomnia
recurring problems in falling or staying asleep.
narcolepsy
a sleep disorder characterized by uncontrollable sleep attacks. The sufferer may lapse directly into REM sleep, often at inopportune times.
sleep apnea
a sleep disorder characterized by temporary cessations of breathing during sleep and repeated momentary awakenings.
night terrors
a sleep disorder characterised by high arousal and an appearance of being terrified; unlike nightmares, night terrors occur during NREM-3 sleep, within two to three hours of sleep, and are rarely remembered.
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