the bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body
the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands
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
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
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 cleft.
chemical messengers that traverse 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.
"morphine within"--natural, opiatelike neurotransmitters linked to pain control and to pleasure.
the body's speedy, electrochemical communication system, consisting of all the nerve cells of the peripheral and central nervous systems
peripheral nervous system
the sensory and motor neurons that connect the central nervous system to the rest of the body
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
neurons that carry incoming information from the sense receptors to the central nervous system.
Central nervous system neurons that internally communicate and intervene between the sensory inputs and motor outputs
neurons that carry outgoing information from the central nervous system to the muscles and glands
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 in stressful situations
parasympathetic nervous system
the division of the autonomic nervous system that calms the body, conserving its energy
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
a nerve network in the brainstem that plays an important role in controlling arousal
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
tissue destruction. A brain lesion is a naturally or experimentally caused destruction of brain tissue
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.
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.
the "little brain" attached to the rear of the brainstem; it helps coordinate voluntary movement and balance
MRI (magnetic resonance imaging)
a technique that uses magnetic fileds and radio waves to produce computer generated images that distinguish among different types of soft tissue; allows us to see structures within the brain
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.
two almond-shaped neural clusters that are components of the limbic system and are linked to emotion
a neural structure lying below (hypo) 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.
the intricate fabric of interconnected neural cells that covers the cerebral hemispheres; the body's ultimate control and information-processing center
the portion of the cerebral cortex lying just behind the forehead; involved in speaking and muscle movements and in making plans and judgements
The portion of the cerebral cortex lying at the top of the head and toward the rear; includes the sensory cortex
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
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
the area at the front of the parietal lobes that registers and processes body sensations
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
impairment of language, usually caused by left hemisphere damage either to Broca's area (impairing speaking) or to wernicke's area (impairing understanding)
controls language expression-an aread of the frontal, usually in the left hemisphere, that directs the muscle movements involved in speech
controls language reception-a brain area involved in language comprehension and expression;usually in the left temporal lobe
the property of being physically malleable, 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
the large band of neural fibers connecting the two brain hemispheres and carrying messages between them.
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.
the body's "slow" chemical communication system; a set of glands that secrete hormones into the bloodstream
chemical messengers, mostly those manufactured by the endocrine glands, that are produced in one tissue and affect another
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.