Neurons and Neurotransmitters

Comprehensive vocabulary flashcards covering the structure and function of neurons, synaptic transmission, neurotransmitters, and reflex arc components from Chapter 3.

Neuron

A fundamental nerve cell composed of three primary components: a cell body, dendrites, and an axon.

Cell Body (Soma)

A relatively large, egg-shaped structure that provides fuel, manufactures chemicals, and maintains the entire neuron in working order.

Dendrites

Branchlike extensions arising from the cell body that receive signals from other neurons, muscles, or sense organs and pass these signals to the cell body.

Axon

A single threadlike structure extending from the cell body that carries signals away toward neighbouring neurons, organs, or muscles.

Myelin

A fatty substance that coats, wraps around, and insulates the axon.

Multiple Sclerosis

A disease that attacks the myelin sheaths insulating the central nervous system, disrupting messages between the brain and other parts of the body and often causing problems in motor coordination.

Terminal Bulbs

Tiny bubble-like structures located at the extreme ends of axon branches that act as miniature containers storing neurotransmitters.

Synaptic Gap

The physical space between the axon of one neuron and the dendrites of another across which electrical signals jump via chemical neurotransmitters.

Transmitters

Chemical messengers that transmit information between nerves and organs.

Excitatory Transmitter

A chemical transmitter that increases the action of an organ.

Inhibitory Transmitter

A chemical transmitter that decreases the action of an organ.

Neurotransmitters

Chemicals manufactured by neurons that allow them to communicate with each other to carry out and coordinate mental and physical tasks.

Depressant

A drug classification, exemplified by alcohol, that depresses neural activity within the central nervous system.

Stimulant

A drug classification, exemplified by caffeine, that stimulates central nervous system function.

Endorphins

A class of neurotransmitters that serve as the body's natural painkillers—functioning as naturally occurring morphine released during trauma to decrease pain.

Reflex

An unlearned, involuntary response to a stimulus that protects the body from injury and operates rapidly via pre-programmed genetic networks involving few neural connections.

Sensors

Receptors located in the skin sensitive to external conditions such as heat and cold that activate neurons to initiate a withdrawal response.

Afferent Neuron

A sensory neuron possessing dendrites up to $3\,\text{ft}$ long that carries information in the form of electrical signals to the spinal cord.

Interneuron

A specialized neuron inside the spinal cord that transfers information and forms connections between sensory and motor neurons.

Efferent Neuron (Motor Neuron)

A neuron whose axon can extend up to $3\,\text{ft}$ in length, carrying signals away from the spinal cord to muscles and organs throughout the body.

Phantom Limb

A phenomenon where an individual continues to feel sensations and movements from an amputated or missing extremity due to severed sensory neurons continuing to fire.