Neuron and Nervous System

brain

Biological Psychology

the scientific study of the links between biological and psychological processes

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 node to the next

Action Potential

a neural impulse; a brief electrical charge that travels down an axon

Ions

positively and negatively charged atoms

Refractory Period

a period of inactivity after a neuron has fired

Inhibitory

Keeps next cell from firing

excitatory

Causes next cell to fire

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.

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 cross the synaptic gaps between neurons. When released by sending the 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.

Agonists

a molecule that, by binding to a receptor site, stimulates a response

Antagonists

a molecule that, by binding to a receptor site, inhibits or blocks a response

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

the brain and the spinal cord

Peripheral Nervous System

the sensory and motor neurons that connect the central nervous system to the rest of the body

Nerves

neurons that carry outgoing information from the brain and spinal cord to the muscles and glands

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 the sensory inputs and motor outputs

Somatic Nervous System

the division of the peripheral nervous system that controls the body's skeletal muscles

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

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

Electroencephalogram (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.

computed tomography (CT)

a series of x-ray photographs taken from different angles and combined by computer into a composite representation of a slice through the body

Positron Emission Tomography (PET)

a visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task

Magnetic Response Imaging (MRI)

a technique that uses magnetic fields and radio waves to produce computer-generated images of soft tissue. Shows brain anatomy.

Function Magnetic Response Imaging (fMRI)

a technique for revealing blood-flow and, therefore, brain activity by comparing successive MRI scans. fMRI scans show brain function as well as its 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 and plays an important role in controlling arousal

Limbic System

neural system 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

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

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

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