all-or-none response
a neuron's reaction of either firing (with a full-strength response) or not firing
hippocampus
a neural center located in the limbic system; helps process explicit (conscious) memories of facts and events for storage
memory consolidation
the neural storage of a long term memory
reuptake
a neurotransmitter's reabsorption by the sending neuron
neuron
a nerve cell; the basic building block of the nervous system
dendrite
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, muscles, or glands
myelin sheath
fatty tissue layer segmentally encasing the axons of some neurons; enables vastly greater transmissions speed as neural impulses hop from one node to the next
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
synapse
the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neurons. The tiny gap is called the synaptic gap or synaptic cleft
neurotransmitters
chemical messengers that cross the synaptic gap between neurons. When released by the sending neuron, they travel across synapse and bind to recepter sites on the receiving neuron, influencing whether that neuron will generate a neural impulse
acetylcholine
a neurotransmitter that, among its functions, triggers muscle contraction
endorphins
"morphine within". natural, opiate-like neurotransmitters linked to pain control and pleasure
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
brain and spinal cord
peripheral nervous system
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 (CNS) with muscles, glands, and sense organs
sensory neurons
afferent neurons; neurons that carry important incoming information from the body's tissues and sensory receptors to the brain and spinal cord
motor neurons
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 process information between the sensory inputs and motor outputs
somatic nervous system
the division of the peripheral nervous system that controls the body's electrical skeletal muscles, aka the skeletal nervous system
automatic 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 automatic nervous system that arouses the body, mobilizing its energy in stressful situations
parasympathetic nervous system
the division of the automatic nervous system that calms the body, conserving its energy
neural networks
interconnected neural cells. With experience, ___ can learn, as feedback strengthens or inhibits connections that produce certain results
endocrine system
the body's "slow" chemical communication system; a set of glands that secrete hormones into the bloodstream
hormones
chemical messengers, mostly those manufactured by the endocrine glands, that are produced in one tissue and affect another
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, it regulates growth and controls other endocrine glands
brainstem
the oldest part and central core of the brain, beginning where the spinal cord swells as it enters the skull; it is responsible for automatic survival functions
medulla
the base of the brainstem; controls heartbeat and breathing
reticular formation
a nerve network that travels through the brainstem into the thalamus and plays an important role in controlling arousal
thalamus
the brain's sensory control center (switchboard), 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
cerebellum
the "little brain" at the rear of the brainstem; functions include processing sensory input and coordinating movement output and balance
limbic system
a donut-shaped neural system (including amygdala, hypothalamus, and hippocampus) located below the cerebral hemispheres: associated with emotions and drives
amygdala
two lima bean-sized neural clusters that are components of the limbic system and are 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
gilal cells
cells in the nervous system that support, nourish, and protect neurons
frontal lobes
the 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
sensory cortex
the area at the front of the parietal lobes that registers and processes body 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
Broca's area
helps control language expression—an area of the frontal lobe, usually in the left hemisphere, that directs the muscle movements involved in speech
Wernicke's area
the region of the brain involved in language comprehension and expression, usually in the left temporal lobe
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