Nervous System and Neuronal Communication

Flashcards covering the basic parts of a neuron, how neurons communicate, and how drugs act as agonists or antagonists within neurotransmitter systems, based on lecture notes.

Nervous system

Composed of two basic cell types: glial cells and neurons, studied by psychologists to understand the human mind's biological basis.

Glial cells (glia)

Supportive cells in the nervous system that provide scaffolding, insulation, nutrient transport, waste removal, and mediate immune responses to neurons.

Neurons

Interconnected information processors that are the central building blocks of the nervous system, essential for all its tasks.

Semipermeable membrane (of a neuron)

A neuron's outer surface that allows smaller, uncharged molecules to pass through while stopping larger or highly charged molecules.

Soma (cell body)

The part of the neuron where the nucleus is located.

Dendrites

Branching extensions from the soma that serve as input sites where signals are received from other neurons.

Axon

A major extension from the soma that transmits electrical signals and ends at multiple terminal buttons.

Terminal buttons

Ends of the axon that contain synaptic vesicles.

Synaptic vesicles

Small sacs housed within terminal buttons that contain neurotransmitters.

Neurotransmitters

Chemical messengers of the nervous system released from synaptic vesicles into the synaptic cleft.

Myelin sheath

A fatty substance formed by glial cells that coats the axon, acting as an insulator to increase the speed of signal transmission.

Nodes of Ranvier

Small gaps that occur down the length of the axon, in between sections of the myelin sheath.

Multiple Sclerosis (MS)

An autoimmune disorder involving a large-scale loss of the myelin sheath on axons throughout the nervous system, leading to interference in electrical signals.

Synaptic cleft

A very small space between two neurons where communication between them occurs via neurotransmitter release.

Receptors

Proteins on the cell surface of a neuron where neurotransmitters attach, varying in shape to match specific neurotransmitters akin to a 'lock-and-key' relationship.

Lock-and-key relationship (neurotransmitter-receptor)

Describes how specific neurotransmitters fit specific receptors, similar to how a key fits a lock, enabling neuronal communication.

Membrane potential

The difference in electrical charge across the neuronal membrane, which provides energy for the electrical signal.

Ions

Charged molecules dissolved in the intra- and extracellular fluids that cause the electrical charge, crucial for neuronal signaling.

Resting potential

The state of readiness of the neuron membrane's potential between signals, where ions are lined up and ready to move across the membrane.

Sodium-potassium pump

A mechanism that actively transports three sodium ions out of the cell for every two potassium ions in, creating a net negative charge inside the cell at resting potential.

Threshold of excitation

A certain level of internal charge that, if reached, causes the neuron to become active and initiates an action potential.

Action potential

The electrical signal that typically moves from the cell body down the axon to the axon terminals, initiated when the threshold of excitation is met.

All-or-none phenomenon (action potential)

The principle that an incoming signal is either sufficient or insufficient to reach the threshold of excitation; there is no in-between, and once started, an action potential cannot be stopped.

Reuptake

A process where unused neurotransmitters in the synaptic cleft are pumped back into the neuron that released them, helping to clear the synapse.

Electrochemical event (neuronal communication)

Refers to neuronal communication, where the action potential moving down the axon is an electrical event, and neurotransmitter movement across the synaptic space is a chemical event.

Electrical synapse

Specialized connections between neurons where they physically connect via gap junctions, allowing direct current flow and much faster communication than chemical synapses.

Psychotropic medications

Drugs that treat psychiatric symptoms by restoring neurotransmitter balance within the nervous system.

Agonists

Chemicals that mimic a neurotransmitter at the receptor site, binding to receptors and activating them to produce a response similar to the natural neurotransmitter.

Antagonist

A chemical that blocks or impedes the normal activity of a neurotransmitter at the receptor by binding to it without activating it, preventing the neurotransmitter's effects.

Reuptake inhibitors

Drugs that prevent unused neurotransmitters from being transported back into the neuron that released them, allowing them to remain active in the synaptic cleft for longer durations.

Selective serotonin reuptake inhibitors (SSRIs)

A type of antidepressant medication that treats depression by preventing the reuptake of serotonin, thereby strengthening its effect in the synaptic cleft.