Neuron
a nerve cell; the basic building block of the nervous system
Dendrite
the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body
Axon
the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or 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
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 membrane
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 neuron
Neurotransmitters
chemical messengers that traverse the synaptic gaps between neurons
Acetylcholine
a neurotransmitter that enables learning and memory and also triggers muscle contraction
Endorphins
morphine within"--natural, opiatelike neurotransmitters linked to pain control and to pleasure.
Reuptake
a neurotransmitter's reabsorption by the sending neuron
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 just above the kidneys. the adrenals secrete the hormones epinephrine (adrenaline) and norepinephrine (noradrenaline), which help to 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
Nervous System
the body's speedy, electrochemical communication system, 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 CNS to the rest of the body
Nerves
neural "cables" containing many axons. These bundled axons, which are part of the peripheral nervous system, connect the central nervous system with muscles, glands, and sense organs
Sensory Neurons
neurons that carry incoming information from the sense receptors to the central nervous system
Interneurons
Central nervous system neurons that internally communicate and intervene between the sensory inputs and motor outputs
Motor Neurons
neurons that carry outgoing information from the central nervous system to the muscles and glands
Skeletal (somatic) Nervous System
the division of the peripheral nervous system that controls the body's skeletal muscles.
Autonomic Nervous System
The part of the peripheral nervous system that controls the glands and the muscles of the internal organs
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, inborn response to a sensory stimulus, such as the knee-jerk response
Neural Networks
interconnected neural cells. With experience, networks can learn, as feedback strengthens or inhibits connections that produce certain results.
Lesion
tissue destruction
CAT Scan
a series of exray photographs taken from different angles and combined by computer into a composite representation of a slice through the body
PET Scan
a visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task.
MRI
a technique that uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of soft tissue; allows us to see structures within the brain
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 that controls heartbeat and breathing
Reticular Formation
a nerve network in the brainstem that plays an important role in controlling arousal
Thalamus
the brain's sensory 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" attached to the rear of the brainstem; it helps coordinate voluntary movement and balance
Limbic System
A doughnut-shaped system of neural structures at the border of the brainstem and cerebral hemispheres; associated with emotions such as fear and aggression and drives such as those for food and sex. Includes the hippocampus, amygdala, and hypothalamus.
Amygdala
two almond-shaped neural clusters that are components of the limbic system and are linked to emotion
Hypothalamus
a neural structure lying below the thalamus; directs eating, drinking, body temperature; helps govern the endocrine system via the pituitary gland, and is linked to emotion
EEG
An amplified recording of the waves of electrical activity that sweep across the brain's surface. These waves are measured by electrodes placed on the scalp.
Cerebral Cortex
the intricate fabric of interconnected neural cells that covers the cerebral hemispheres; the body's ultimate control and information-processing center
Frontal Lobes
the portion of the cerebral cortex lying just behind the forehead; involved in speaking and muscle movements and in making plans and judgements
Parietal Lobes
the 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
the portion of the cerebral cortex lying at the back of the head; includes the visual areas, which receive visual information from the opposite visual field
Temporal Lobes
the portion of the cerebral cortex lying roughly above the ears; includes the auditory areas, each of which receives auditory 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 touch and movement sensations
Glial Cells
cells in the nervous system that support, nourish, and protect neurons
Neurogenesis
the formation of new neurons.
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
Aphasia
impairment of language, usually caused by left hemisphere damage either to Broca's area (impairing speaking) or to wernicke's area (impairing understanding)
Broca's Area
controls language expression-an aread of the frontal, usually in the left hemisphere, that directs the muscle movements involved in speech
Wernicke's Area
controls language reception-a brain area 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 in which the two hemispheres of the brain are isolated by cutting the connecting fibers (mainly those of the corpus callosum) between them
Plasticity
the brain's capacity for modification, as evident in brain reorganization following damage (especially in children) and in experiments on the effects of experience on brain development