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How The Brain Works


Human Brain 101 How The Brain Communicates What is Serotonin? What is GABA? What is Acetylcholine? What is Glutamate? What are Endorphins? What is Dopamine? What is Adrenaline? What is Noradrenaline?


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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.

Eunice Kennedy Shriver National Institute of Child Health and Human Development. (2018, October 1). Parts of the nervous system.

Purves, D., Augustine, G.J., Fitzpatrick, D., et al. (2001). Neural circuits. Neuroscience, 2nd edition.

Queensland Brain Institute. (2019, January 24). The limbic system.

UC San Diego Health Neurological Institute. (2021). About peripheral nerves.