Psych 001 - Chapter 3 Pt I Nervous System

Vocabulary terms covering the basic functions, cells, electrical processes, and chemicals of the human nervous system as described in Chapter 3 Part I.

Nervous System

A network of billions of cells in the brain and throughout the body, responsible for all aspects of what we feel, think, and do.

Neurons

The discrete cells that make up the nervous system, with a total estimated population of nearly 100 billion in humans.

Axon

The long, narrow outgrowth of a neuron that enables it to transmit information to other neurons.

Cell body

The part of the neuron where information from thousands of other neurons is collected and integrated.

Dendrites

Branchlike extensions of the neuron with receptors that detect chemicals from other neurons.

Glia

Cells that support neurons by providing insulation, removing waste, and generating myelin; they are $1/10\text{th}$ the size of neurons but 10 times as numerous.

Myelin

A coating on axons generated by glial cells that speeds up the transmission of information.

Stem cells

Undifferentiated cells capable of developing into other cell types; they may be stimulated after certain types of brain damage.

Sensory neurons (Afferent)

Neurons that carry information from sense organs to the central nervous system.

Inter-Neurons

Neurons in the central nervous system that process and interpret information, then send commands to muscles, glands, and organs.

Motor neurons (Efferent)

Neurons that carry information from the central nervous system to the muscles.

Action Potential

An electrochemical impulse that travels along the length of an axon with constant strength regardless of distance.

Excitatory messages

Signals that increase the probability that the next cell will ‐fire‐ or continue to carry a message.

Inhibitory messages

Signals that decrease the likelihood that the next cell will ‐fire‐.

All-or-none law

The principle that an action potential is an all-or-nothing process without any ‐sort of‐ state; it is either happening or not.

Resting Potential

The electrical polarization across the membrane of an unstimulated axon, with an inside charge of $-70\text{ millivolts}$ relative to the outside.

Sodium-potassium pump

A mechanism that maintains resting potential by pumping $3\text{ Na}^+$ out and $2\text{ K}^+$ in.

Electrostatic gradient

A mechanism where positive ions are attracted to negative areas, such as when $\text{K}^+$ or $\text{Na}^+$ is pulled into a negative axon.

Concentration gradient

A mechanism where ions flow from areas of high concentration to areas of low concentration.

Synapse

A specialized junction between two neurons where chemical messages cross from one to the other.

Terminal bouton

A bulge at the end of an axon that releases neurotransmitter molecules when an action potential reaches it.

Neurotransmitter

A chemical stored in synaptic vesicles that is released to activate special receptors on other neurons.

Reuptake

The process by which a neurotransmitter is reabsorbed by the axon that released it.

Parkinson’s Disease

A condition linked to the decay of axons that release dopamine, resulting in tremors, rigidity, and trouble executing voluntary movements.

L-dopa

A drug used to manage Parkinson’s Disease that is synthesized into dopamine by neurons.

Substantia nigra

The brain region associated with the decay of dopamine-releasing axons in Parkinson’s Disease.

Agonists

Drugs that enhance the actions of neurotransmitters.

Antagonists

Drugs that inhibit the actions of neurotransmitters.

MAOIs

Drugs that work on the enzymes that break down neurotransmitters.

SSRIs

Drugs that work by affecting the reuptake of neurotransmitters.

Acetylcholine

A neurotransmitter responsible for motor control over muscles, attention, memory, learning, and sleeping.

Epinephrine

A neurotransmitter responsible for energy, formerly known as adrenaline.

Norepinephrine

A neurotransmitter responsible for arousal and alertness.

Glutamate

A neurotransmitter that enhances action potentials and is involved in learning and memory.

Endorphins

Neurotransmitters involved in pain reduction and reward.