Glossary 1 Flashcards
Acetylcholine
A critical neurotransmitter that controls functions such as memory, attention, sleep, heart rate, and muscular activity.
Action Potential
An electrical charge that travels along the axon to the neuron’s terminal, where it triggers the release of a neurotransmitter. This occurs when a neuron is activated and temporarily reverses the electrical state of its interior membrane from negative to positive.
Addiction
Loss of control over drug intake or compulsive seeking and taking of drugs, despite adverse consequences.
Adenosine
A neurochemical that inhibits wakefulness, serving the purpose of slowing down cellular activity and diminishing arous¬al. Adenosine levels decrease during sleep.
Adrenal Gland
An endocrine organ that secretes hormones. The outer layer (adrenal cortex) secretes the stress hormone cortisol. The inner portion (adrenal medulla) secretes epinephrine and norepinephrine in concert with the activation of the sympathetic nervous system in the “fight or flight” response.
Alzheimer’s Disease (AD)
A major cause of dementia in the elderly, this neurodegener¬ative disorder is characterized by the death of neurons in the hippocampus, cerebral cortex, and other brain regions. The earliest symp¬toms of the disease include forgetfulness; dis¬orientation as to time or place; and difficulty with concentration, calculation, language, and judgment. In the final stages, individuals are incapable of self-care and may be bedridden.
Amnesia
A memory impairment usually caused by brain damage or disease, or by drugs such as some anesthetics. People with amnesia may be unable to recall events from the past, form new memories, or both.
Amygdala
A structure in the forebrain that is an important component of the limbic system and plays a central role in emotional learning, particularly within the context of fear.
Amyotrophic Lateral Sclerosis (ALS)
Commonly known as Lou Gehrig’s disease, ALS causes motor neurons in the brain and spinal cord to disintegrate, resulting in loss of control of voluntary muscle movements such as walking.
Analgesic
A drug that relieves pain without causing a loss of consciousness.
Anxiety
A state of heightened arousal charac¬terized by intense worry.
Aphasia
Disturbance in language compre¬hension or production, often as a result of a stroke.
Apoptosis
Programmed cell death induced by specialized biochemical pathways, often serving a specific purpose in the development of an animal.
Arousal
A physiological state involving changes in the body and brain that motivate behavior and enable response to stimuli.
Astrocyte
A star-shaped glial cell in the cen¬tral nervous system that nourishes neurons; regulates the formation, maintenance, and pruning of synapses; and contributes to the blood-brain barrier.
Attention
A state of arousal in which the brain’s sensory processing is directed at a limited number of stimuli. Voluntary (en¬dogenous) attention is a conscious decision to focus on a particular stimulus. Involuntary (exogenous) attention is an unplanned focus on a change in the environment, such as a loud noise or sudden movement.
Auditory Nerve
A branch of the vestib¬ulocochlear nerve that transmits auditory information from the cochlea of the ear to the brain.
Autism Spectrum Disorder (ASD)
A set of conditions characterized, in part, by impaired social communication and inter¬action, and narrow, obsessive interests or repetitive behaviors.
Autonomic Nervous System
A part of the peripheral nervous system responsible for regulating the activity of internal organs. It includes the sympathetic and parasympa¬thetic nervous systems.
Axon
The fiber-like extension of a neuron by which it sends information to target cells.