Psychology Unit 2 Flashcards
neuron
a nerve cell; the basic building block of the nervous system.
cell body
the part of a neuron that contains the nucleus; the cell’s life-support center.
dendrites
a neuron’s often bushy, branching extensions that receive and integrate messages, conducting 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 node to the next.
glial cells (glia)
cells in the nervous system that support, nourish, and protect neurons; they may also play a role in learning, thinking, and memory.
action potential
a neural impulse; a brief electrical charge that travels down an axon.
threshold
the level of stimulation required to trigger a neural impulse.
refractory period
in neural processing, a brief resting pause that occurs after a neuron has fired; subsequent action potentials cannot occur until the axon returns to its resting state.
all-or-none response
a neuron’s reaction of either firing (with a full-strength response) or not firing.
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 cleft.
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.
reuptake
a neurotransmitter’s reabsorption by the sending neuron.
endorphins
“morphine within”—natural, opiate-like neurotransmitters linked to pain control and to pleasure.
agonist
a molecule that increases a neurotransmitter’s action.
antagonist
a molecule that inhibits or blocks a neurotransmitter’s action.
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 (CNS) 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 body’s tissues and 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; they communicate internally and process information between the 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
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.
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 the knee-jerk response.
endocrine system
the body’s “slow” chemical communication system; a set of glands that secrete hormones into the bloodstream.
hormones
chemical messengers 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 the hypothalamus, the pituitary regulates growth and controls other endocrine glands.
lesion
tissue destruction. A brain lesion is a naturally or experimentally caused destruction of brain tissue.
EEG
(electroencephalogram) an amplified recording of the waves of electrical activity sweeping across the brain’s surface. These waves are measured by electrodes placed on the scalp.
MEG
(magentoencephalography) a brain imaging technique that measures magnetic fields from the brain’s natural electrical activity.
CT (computed tomography) scan
a series of x-ray photographs taken from different angles and combined by computer into a composite representation of a slice of the brain’s structure. (Also called CAT scan.)
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
(magentic resonance imaging) a technique that uses magnetic fields and radio waves to produce computer-generated images of soft tissue. MRI scans show brain anatomy.
fMRI (functional MRI)
a technique for revealing bloodflow and, therefore, brain activity by comparing successive MRI scans. fMRI scans show 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; the brainstem is 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 medulla.
reticular formation
a nerve network that travels through the brainstem into the thalamus and plays an important role in controlling arousal.
cerebellum
the “little brain” at the rear of the brainstem; functions include processing sensory input and coordinating movement output and balance, and enabling nonverbal learning and memory.
limbic system
neural system (including the amygdala, hypothalamus, and hippocampus) 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 (hypo) the thalamus; activities (eating, drinking, body temperature), helps govern the endocrine system via the pituitary gland, and is linked to emotion and reward.
