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autonomic nervous system: part of the peripheral nervous system that controls internal organ functions (e.g. blood pressure, respiration, intestinal function, perspiration, body temperature); actions are primarily involuntary
axon: a nerve fiber that sends messages via electrochemical impulses from the body of the neuron to the dendrites of other neurons or directly to body tissues (e.g. muscles)
axon terminal: the end of an axon, where electrochemical signals pass through a synapse to neighboring cells with the help of neurotransmitters and other chemicals
cell body: the central part of the neuron; contains the nucleus of the neuron; the axon and dendrites connect to this part of the cell on opposing ends
central nervous system: made up of the brain and spinal cord; part of the broader nervous system along with the peripheral nervous system
chromosome: a structure that carries an organism’s genetic information
dendrite: short nerve fibers that extend from a neuron; receives messages from the axons of other neurons and relays them to the cell’s nucleus
DNA (deoxyribonucleic acid): the material that makes up the 46 chromosomes in each cell’s nucleus; contains codes for the body’s approximately 30,000 genes
endorphins: hormones produced primarily by the brain’s hypothalamus and pituitary gland in response to pain or stress to lessen the sensation of pain
epigenetics: a subcategory of genetics that focuses on how environmental factors can influence where, when, and how a gene is expressed
gene: a distinct section of DNA code that instructs the cell to make a particular molecule; the most basic unit of inheritance
genome: the entire genetic map for an organism; in humans, this includes approximately 30,000 genes, over half of which are related to brain functions
glia: the supporting cells of the central nervous system; contribute to sending nerve impulses and play a critical role in protecting and nourishing neurons
gray matter: the parts of the brain and spinal cord made up primarily of groups of neuron cell bodies
hormone: a chemical released by the body’s endocrine glands and some tissues; acts on receptors in other parts of the body to influence body functions or behavior
limbic system: a group of anatomically and functionally connected brain structures that play complex roles in emotion, instinct, and behavior
nerve impulse: the way a neuron communicates with other cells by transmitting an electrochemical signal down the axon
nervous system: the body system that processes and transmits signals from the brain to the rest of the body to initiate movement and behavior; it consists of the central nervous system and the peripheral nervous system
neural circuit: a group of neurons connected by synapses to carry out a specific function when activated; neural circuits connect to each other to form larger-scale brain networks
neuron: also referred to as a “nerve cell”; responsible for the transmission of nerve impulses; unlike other cells in the body, a neuron consists of a central cell body as well as axons and dendrites
neurotransmitter: a chemical that is released into the synaptic cleft when a nerve impulse reaches the end of the axon; transmits information between neurons
peripheral nervous system: the nervous system outside of the brain and spinal cord; made up of nerves extending throughout the body that relay information between the brain and the rest of the body
somatic nervous system: part of the peripheral nervous system; controls muscle movement and sends sensory information to the central nervous system
synapse: the end of an axon, where it approaches a neuron or its dendrite; the point where communication between nerves occurs
synaptic cleft: the space between neurons where neurotransmitters are released after a nerve impulse travels down the axon
white matter: brain or spinal cord tissue made up of myelin-covered axons extending from nerve cell bodies that make up the gray matter of the central nervous system
Dana Foundation. (2021). Key brain terms. https://dana.org/explore-neuroscience/brain-basics/key-brain-terms-glossary/
Eunice Kennedy Shriver National Institute of Child Health and Human Development. (2018, October 1). Parts of the nervous system. https://www.nichd.nih.gov/health/topics/neuro/conditioninfo/parts
Purves, D., Augustine, G.J., Fitzpatrick, D., et al. (2001). Neural circuits. Neuroscience, 2nd edition. https://www.ncbi.nlm.nih.gov/books/NBK11154/
Queensland Brain Institute. (2019, January 24). The limbic system. https://qbi.uq.edu.au/brain/brain-anatomy/limbic-system
UC San Diego Health Neurological Institute. (2021). About peripheral nerves. https://health.ucsd.edu/specialties/neuro/specialty-programs/peripheral-nerve-disorders/pages/about-peripheral-nerves.aspx