PSYCH100 WEEK 5: NEURINS

A vocabulary set covering neuron structure, signaling, glial roles, synapses, membrane potentials, endocrine system, and psychopharmacology.

Neuron

The basic signaling cell of the nervous system; about 100 billion in the brain; composed of dendrites, soma, and axon.

Dendrites

Extensions from the soma that receive input from other neurons and serve as the main input region.

Soma (cell body)

Contains the nucleus; directs protein synthesis and houses genetic information.

Axon

Carries action potentials away from the soma to other neurons; often insulated by myelin.

Myelin sheath

Insulating layer around some axons that speeds signal transmission.

Synapse

Gap between neurons where neurotransmitters cross to affect the next neuron.

Presynaptic terminal button

End of the axon that releases neurotransmitters into the synapse.

Synaptic vesicles

Vesicles in the presynaptic terminal that store neurotransmitters.

Postsynaptic neuron

The neuron that receives neurotransmitters via receptors on its membrane.

Dendrites (structure)

Extensions from the cell body that receive input from other neurons.

Unipolar neuron

Neuron with a single process (axon) extending from the cell body.

Bipolar neuron

Neuron with two processes (typically one axon and one dendrite) from the cell body.

Multipolar neuron

Most common type with many dendrites and one axon.

Glia

Support cells in the nervous system; include oligodendrocytes, microglia, and astrocytes.

Oligodendrocyte

Glial cell that forms the myelin sheath around CNS axons.

Microglia

Glial cells that digest debris of dead neurons.

Astrocyte

Glial cells that deliver nutrients, regulate ions, and maintain extracellular fluid.

Resting membrane potential

Steady-state voltage across the neuron's membrane at rest; about -70 mV; maintained by diffusion and electrostatic forces.

Ion channels

Proteins spanning the membrane that allow specific ions to pass.

Diffusion

Movement of particles from high to low concentration, contributing to ion distribution.

Electrostatic pressure

Electrical force that moves ions based on charge differences.

Equilibrium potential

Ion-specific voltage where diffusion and electrostatic forces balance; no net ion flow.

Sodium-potassium pump

Active transporter that maintains ion gradients by moving Na+ out and K+ in.

Depolarization

Inside of the neuron becomes less negative, often due to Na+ influx, moving toward threshold.

Hyperpolarization

Inside becomes more negative than resting potential, making firing less likely.

Threshold of excitation

Membrane potential (~-50 mV) that must be reached to trigger an action potential.

Action potential

All-or-none electrical impulse that travels along the axon once threshold is reached.

Excitatory postsynaptic potential (EPSP)

Depolarizing postsynaptic potential that brings the membrane closer to threshold.

Inhibitory postsynaptic potential (IPSP)

Hyperpolarizing postsynaptic potential that moves membrane away from threshold.

Summation

Integration of multiple EPSPs and IPSPs to determine whether an action potential will occur.

Neurotransmitter

Chemical released by the presynaptic neuron into the synapse; binds receptors on the postsynaptic neuron.

Receptors

Proteins on the postsynaptic membrane that bind neurotransmitters and open ion channels.

Presynaptic neuron

Neuron that sends signals and releases neurotransmitters into the synapse.

Postsynaptic neuron

Neuron that receives neurotransmitters via receptors in its membrane.

Endocrine system

System of glands that release hormones into the bloodstream to regulate body functions.

Pituitary gland

Master gland; releases hormones and is controlled by the hypothalamus.

Hypothalamus

Brain region that regulates the endocrine system via the pituitary.

Thyroid gland

Endocrine gland that regulates metabolism through thyroid hormones.

Pineal gland

Gland in the brain that secretes melatonin; helps regulate sleep-wake cycles.

Adrenal gland

Gland that secretes adrenaline and cortisol in response to stress.

Gonads

Ovaries and testes; produce sex hormones that influence reproduction and secondary sex characteristics.

Estrogen

Sex hormone regulating female reproductive system and sexual motivation; example estradiol.

Androgens

Male sex hormones (e.g., testosterone) affecting development and behavior.

Anabolic steroids

Synthetic steroids mimicking testosterone; can increase muscle mass but have health risks and ethical concerns.

Agonist

Drug that increases activity at the synapse by mimicking or enhancing neurotransmitter effects.

Antagonist

Drug that decreases activity at the synapse by blocking receptors or reducing neurotransmitter release.

Psychopharmacology

Study of how psychoactive drugs affect brain function and behavior by altering neurotransmission.

All-or-none

Principle that an action potential is either fully present or not at all; no partial amplitude.