Neuron Structure, Neural Communication, and the Endocrine System

Vocabulary flashcards covering the structure and support cells of neurons, electrical and chemical signaling, specific neurotransmitters, sensory and motor pathways, the endocrine system, and related neurological disorders.

Neurons

Specialized nerve cells that receive, process, and transmit information throughout the nervous system.

Cell Body (Soma)

The core part of a neuron containing the nucleus; it maintains the cell's life and integrates incoming signals.

Dendrites

Branch-like extensions of a neuron that receive chemical signals from other neurons and carry them to the cell body.

Axon

A long, slender fiber that carries electrical impulses (action potentials) away from the cell body toward other cells.

Myelin

A protective, fatty layer wrapped around axons that insulates them and greatly increases the speed of electrical signals.

Synapse

The microscopic gap or junction where information is transmitted from the axon terminal of one neuron to the dendrite of another.

Glial Cells

Support cells in the nervous system that protect, nourish, insulate, and clean up after neurons.

Resting Potential

The stable, negative electrical charge of a neuron when it is inactive (typically around $-70\,\text{mV}$).

Threshold

The minimum level of electrical stimulation required to trigger a neural impulse.

Depolarization

A change in a neuron's electrical charge from negative to positive, which happens when sodium ions rush into the cell.

Action Potential

A brief electrical impulse or wave of depolarization that travels down the axon of a neuron.

All-or-Nothing Principle

The rule that a neuron either fires completely once it hits the threshold, or it does not fire at all; there are no weak or strong action potentials.

Refractory Period

A brief resting pause after a neuron fires during which it cannot generate another action potential.

Neurotransmitter

Chemical messengers released by neurons that cross the synaptic gap to bind to and influence receiving cells.

Excitatory Neurotransmitters

Chemical messengers that stimulate the receiving neuron, making it more likely to fire an action potential.

Inhibitory Neurotransmitters

Chemical messengers that calm the receiving neuron, making it less likely to fire an action potential.

Reuptake

The process by which a sending neuron reabsorbs excess neurotransmitters from the synapse after signaling is complete.

Acetylcholine (ACh)

A neurotransmitter vital for muscle movement, attention, arousal, and memory.

Dopamine

A neurotransmitter tied to reward, motivation, pleasure, and voluntary motor movement.

Serotonin

A neurotransmitter that regulates mood, hunger, sleep, and emotional states.

Norepinephrine

A neurotransmitter involved in alertness, focus, and the body's fight-or-flight stress response.

GABA

The primary inhibitory neurotransmitter in the brain; it reduces anxiety and calms central nervous system activity.

Glamate

The primary excitatory neurotransmitter in the brain; it is crucial for learning and memory.

Substance P

A neurotransmitter heavily involved in transmitting pain signals to the brain.

Endorphins

Natural chemicals released by the body to reduce pain and boost feelings of pleasure or euphoria.

Sensory Neurons (Afferent)

Neurons that carry incoming sensory information from the body's tissues and receptors inward to the brain and spinal cord.

Motor Neurons (Efferent)

Neurons that carry outgoing instructions from the brain and spinal cord outward to the body's muscles and glands.

Interneurons

Neurons within the brain and spinal cord that communicate internally and process information between sensory inputs and motor outputs.

Reflex Arc

A simple, automatic neural pathway that controls an immediate, involuntary action (like pulling away from a hot stove) without waiting for the brain's input.

Endocrine System

The body's "slow" chemical communication network, made up of glands that secrete hormones directly into the bloodstream.

Hormones

Chemical messengers produced by endocrine glands that travel through the blood to affect target organs and tissues.

Adrenaline (Epinephrine)

A hormone triggered by fear or stress that increases heart rate, blood pressure, and energy to prepare the body for action.

Leptin

A hormone produced by fat cells that signals the brain that you are full, helping to suppress appetite.

Ghrelin

A hormone produced by the stomach that signals the brain that you are hungry, helping to stimulate appetite.

Melatonin

A hormone produced by the pineal gland that regulates sleep-wake cycles and promotes sleepiness.

Oxytocin

A hormone involved in social bonding, trust, empathy, childbirth, and breastfeeding.

Multiple Sclerosis (MS)

A chronic disease where the immune system mistakenly attacks the myelin sheath surrounding axons, disrupting neural communication.

Myasthenia Gravis

An autoimmune disorder where the immune system destroys acetylcholine receptors at the junction between nerves and muscles, causing muscle weakness.