The mass of nerve tissue encased in the skull that controls virtually everything we are and everything we do.
What is soma?
The cell body of a neuron that contains the nucleus of the cell and carries out the cell's metabolic functions.
What is axon?
The tubelike part of a neuron that carries messages away from the cell body toward other neurons.
What are terminal buttons?
Swellings at the tips of axons from which neurotransmitters are dispatched to the synapse.
What are neurotransmitters?
Chemical messengers that transport nerve impulses from one nerve cell to the another.
What is the synapse?
The small fluid-filled gap between neurons through which neurotransmitters carry neural impulses.
What are dendrites?
Rootlike structures at the end of axons that receive neural impulses from neighboring neurons.
What are sensory neurons?
Neurons that transmit information from sensory organs, muscles, and inner organs to the spinal cord and brain.
What are motor neurons?
Neurons that convey nerve impulses from the central nervous system to muscles and glands.
What are glands?
Body organs or structures that produce secretions called hormones.
What are hormones?
Secretions from endocrine glands that help regulate bodily processes.
What are interneurons?
Nerve cells within the central nervous system that process information.
What is a nerve?
A bundle of axons from different neurons that transmit nerve impulses.
What are glial cells?
Small but numerous cells in the nervous system that support neurons and that form the myelin sheath found on many axons.
What is a myelin sheath?
A layer of protective insulation that covers the axons of certain neurons and helps speed the transmission of nerve impulses.
What are nodes of Ranvier?
Gaps in the myelin sheath that create noninsulated areas along the axon.
What are ions?
Electrically charged chemical particles.
What is resting potential?
The electrical potential across the cell membrane of a neuron in its resting state.
What is depolarization?
A positive shift in the electrical charge in the neuron's resting potential making it less negatively charged.
What is action potential?
An abrupt change from a negative to a positive charge of a nerve cell, also called a neural impulse.
What is the all-or-none principle?
The principle by which neurons will fire only when a change in the level of excitation occurs that is sufficient to produce an action potential.
What is refractory period?
A temporary state in which a neuron is unable to fire in response to continued stimulation.
What is a receptor site?
A site on the receiving neuron in which neurotransmitters dock.
What is reuptake?
The process by which neurotransmitters are reabsorbed by the transmitting neuron.
What are enzymes?
Organic substances that produce certain chemical changes in other organic substances through a catalytic action.
What are neuromodulators?
Chemicals released in the nervous system that influence the sensitivity of the receiving neuron to neurotransmitters.
What are antagonists?
Drugs that block the actions of neurotransmitters by occupying the receptor sites in which the neurotransmitters dock.
What is Parkinson's disease?
A progressive brain disease involving destruction of dopamine-producing brain cells and characterized by muscle tremors, shakiness, rigidity, and difficulty in walking and controlling fine body movements.
What is schizophrenia?
A severe and chronic psychological disorder characterized by disturbances in thinking, perception, emotions, and behavior.
What are hallucinations?
Perceptions experienced in the absence of corresponding external stimuli.
What are delusions?
Fixed but patently false beliefs, such as believing that one is being hounded by demons.
What are agonists?
Drugs that either increase the availability or effectiveness of neurotransmitters or mimic their actions.
What are stimulants?
A drug that activates the central nervous system, such as amphetamines, or cocaine.
What are amphetamines?
A class of synthetically derived stimulant drugs such as methamphetamines or "speed".
What are antidepressants?
Drugs that combat depression by affecting the levels or activity of neurotransmitters.
What are endorphins?
Natural chemicals released in the brain that have pain-killing and pleasure-inducing effects.
What is the nervous system?
The network of nerve cells and support cells for communicating and processing information within and outside the body.
What is the central nervous system?
The part of the nervous system that consists of the brain and the spinal cord.
What is the spinal cord?
The column of nerves that transmits information between the brain and the peripheral nervous system.
What is the spine?
The protective bony column that houses the spinal cord.
What is a reflex?
An automatic unlearned response to particular stimuli.
What is a spinal reflex?
A reflex controlled at the level of the spinal cord that may involve as few as two neurons.
What is the peripheral nervous system?
The part of the nervous system that connects the spinal cord and the brain with the sensory organs, muscles, and glands.
What is the somatic nervous system?
The part of the peripheral nervous system that transmits information between the central nervous system and the sensory organs and muscles; also controls voluntary movements.
What is the autonomic nervous system?
The part of the peripheral nervous system that automatically regulates involuntary bodily processes, such as heart rate, breathing, and digestion.
What is the sympathetic nervous system?
The branch of the autonomic nervous system that accelerates bodily processes and releases stores of energy needed to meet increased physical demands.
What is the parasympathetic nervous system?
The branch of the autonomic nervous system that regulates bodily processes, such as digestion, that replenish stores of energy.
What is an EEG?
A device that records electrical activity in the brain.
What is a CT (computerized tomography) scan?
A computer enhanced imaging technique in which an X-Ray beam is passed through the body at different angles to generate a 3D image of bodily structures. (Also called a CAT scan, short for computerized axial tomography)
What is a PET (positron emission tomography)scan?
An imaging technique in which a radioactive sugar tracer is injected into the bloodstream and used to measure levels of activity of various parts of the brain.
What is an MRI? (magnetic resonance imaging)
A technique that uses a magnetic field to create a computerized image of internal bodily structures.
What is lesioning?
In studies of brain functioning, the intentional destruction of brain tissue in order to observe the effects on behavior.
What is electrical recording?
As a method of investigating brain functioning, a process of recording the electrical charges that occur in a specific neuron or groups of neurons in the brain in relation to particular activities or behaviors.
What is electrical stimulation?
As a method of investigating brain functioning, a process of electrically stimulating particular parts of the brain to observe the effects on behavior.
What is lateralization?
The specialization of the right and left cerebral hemispheres for the particular functions.
What is Broca's area?
An area of the left frontal lobe involved in speech.
What is Wernicke's area?
An area of the left temporal lobe involved in processing written and spoken language.
What is aphasia?
Loss or impairment of the ability to understand or express language.
What is epilepsy?
A neurological disorder characterized by seizures that involve sudden, violent discharges of electrical activity in the brain.
What are split-brain patients?
Persons whose corpus callosum has been surgically severed.
What is the prefrontal cortex?
The area of the frontal lobe that lies in front of the motor cortex and that is involved in higher mental functions, including thinking, planning, impulse control, and weighing the consequences of behavior.
What is plasticity?
The ability of the brain to adapt itself after trauma or surgical alteration.