Neurons - neurotransmitters - Drugs

Neurotransmitters

chemical messengers that cross the synaptic gaps between neurons

Neurons

a nerve cell; the basic building block of the nervous system

Dendrites

Branchlike parts of a neuron that are specialized to receive information.

Soma

cell body of a neuron

Axon terminal

The endpoint of a neuron where neurotransmitters are stored

Axon hillock

The conical region of a neuron's axon where it joins the cell body; typically the region where nerve signals is generated.

Axon body

neuron structure that transmits nerve impulses from the cell body to other neurons and muscles

synaptic cleft

The narrow gap that separates the presynaptic neuron from the postsynaptic cell.

Resting membrane potential

An electrical potential established across the plasma membrane of all cells by the Na+/K+ ATPase and the K+ leak channels. IN most cells, the resting membrane potential is approximately -70 mV with respect to the outside of the cell.

Action potential

a neural impulse; a brief electrical charge that travels down an axon

Graded potential

a membrane potential that varies in magnitude in proportion to the intensity of the stimulus

Ion channel

A transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient.

Membrane depolarization

A change in a membrane potential which decreases or reverses the voltage difference across the membrane

spatial summation

The sum of multiple synapses firing at different locations at one time to create a net effect.

temporal summation

Summation by a postsynaptic cell of input (EPSPs or IPSPs) from a single source over time.

Initial segment

first part of the axon as it emerges from the axon hillock, where the electrical signals known as action potentials are generated

Tetradotoxin (TTX)

marine bacteria in Japanese puffer fish - binds to outside of Na channels and blocks sodium entry - impairs impulse conduction

Pareidolia

tendency to perceive meaningful images in meaningless visual stimuli

excitory neurotransmitters

depolarize the membrane, making an action potential more likely

inhibitory neurotransmitters

chemicals released from the terminal buttons of a neuron that inhibit the next neuron from firing

synapse

A junction where information is transmitted from one neuron to the next.

Vesicles

small membrane sacs that specialize in moving products into, out of, and within a cell

Synthesis of neurotransmitters

Process of creating neurotransmitters in neurons.

Reuptake

a neurotransmitter's reabsorption by the sending neuron

Binding of neurotransmitter

Triggers the opening of ligand-gated ion channels at a synapse.

Storage of neurotransmitter

loaded into synaptic vesicles

vesicles contain thousands of molecules

agonist drug action

stimulate something to occur

Antagonist drug action

block of suppress against drugs - medicated responses

Acetylcholine

A neurotransmitter that enables learning and memory and also triggers muscle contraction

Dopamine

A neurotransmitter associated with movement, attention and learning and the brain's pleasure and reward system.

Parkinson's disease

Loss of dopamine-producing neurons in the substantia nigra.

Schizophrenia

a group of severe disorders characterized by disorganized and delusional thinking, disturbed perceptions, and inappropriate emotions and actions

Deep brain stimulation for Parkinson's

electrical stimulation applied through surgically implanted electrodes

Agonists vs. Antagonists

Agonists = causes stimulation of receptors

- nicotine, black widow spider venom

Antagonists = binds to receptors and block other meds

scopolamine (motion sickness pills), botulinum toxin (paralysis)

Sensory neurons

neurons that carry incoming information from the sensory receptors to the brain and spinal cord

Motor Neurons

neurons that carry outgoing information from the brain and spinal cord to the muscles and glands

Inter Neurons

neurons within the brain and spinal cord that communicate internally and intervene between the sensory inputs and motor outputs

Spinal cord

Nerves that run up and down the length of the back and transmit most messages between the body and brain, the vertebrae, protect the neurons

somatic nervous system

Contains Sensory neurons transmit messages from the eyes,ears etc, and motor neurons (group together to form sensory nerves and motor nerves)

Automatic Nervous system

the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses; its parasympathetic division calms.

sympathetic nervous system

a set of nerves that prepares the body for action in challenging or threatening situations

parasympathetic nervous system

a set of nerves that helps the body return to a normal resting state

intercranial self stimulation

Rats pressed a lever and their brain was stimulated. If the area being stimulated was a reward region, they would continue to press the lever. Allowed researchers to map out reward centres in the rat brain.

reward system

factors that link a particular stimulus with a form of satisfaction or pleasure.

nucleus accumbens

structure located in the brainstem and part of the dopaminergic reward pathway; releases dopamine in response to many drugs contributing to addictive behavior

ventral tegmental area (VTA)

where dopamine is produced; associated with mood, reward, and addiction

the reflex

a simple, automatic response to a sensory stimulus

Monasynaptic stretch reflex

simple reflex, where a sensory neuron directly synapses with a motor neuron - causing a rapid muscle contraction to resist a sudden stretch.

Polysynaptic reflex

A reflex invovling one or several interneurons.

Synaptic excitation

signals sent across synapses increase activity of the receiving neuron, increased likelihood of it firing an action potential.

Synaptic inhibition

when a synapse reduces the likelihood of a target neuron firing an action potential.

Vestibulo - occular reflex

stabilizes vision and allows humans to maintain good vision while the head is moving during running and walking - counter rotates the eyes in the opposite direction.