1.3 - The Neuron & Neural Firing

Neural transmission

the process by which neurons communicate with each other through electrical and chemical signals

Threshold

Level of stimulation required to trigger an action potential in a neuron

• it is the minimum amount of stimulation necessary to produce a response

Action Potential

brief electrical impulse that travels along the axon of a neuron

• occurs when the neuron receives a stimulus that causes the inside of the cell to become more positively charged than the outside.

All-or-nothing Principle

States that once an neuron reaches its threshold of excitation, it will fire an action potential at full strength

Depolarization

Phase of action potential where the inside of the neuron becomes less negative compared to the outside due to the influx of positively charged ions, such as sodium ions, through ion channels in the cell membrane.

Refractory Period

Brief period following an action potential during which a neuron is unable to generate another action potential

• occurs because the neuron’s sodium channels are temporarily inactivated and the cell membrane returns to its resting state.

Resting Potential

the stable, negative electrical charge that exist across the cell membrane of a neuron when it is not actively transmitting signals

• it is maintained by unequal distribution of ions, with more sodium ions outside the cell and more potassium ions inside.

Reuptake

process in which neurotransmitters that have been released into the synapse are reabsorbed by the presynaptic neuron from which they were originally released.

Multiple Sclerosis

Chronic autoimmune disease that affects the CNS.

• Occurs when the immune system mistakenly attacks the protective myelin sheath, a fatty substance that surrounds and insulates nerve fibers, causing inflammation and damage.

Myasthenia Gravis

Chronic autoimmune disorder that affects the neuromuscular junction, where nerve impulses are transmitted to muscles

• occurs when the immune system produces antibodies that block or destroy the receptors for acetylcholine, a neurotransmitter that stimulates muscle contraction.

Neurotransmitters

Chemical messengers that transmit signals between neurons, allowing for communication within the nervous system.

Excitatory Neurotransmitters

Chemicals released by neurons that increase(speed up) the likelihood of an action potential occurring in the postsynaptic neuron

• binds to receptor sites on the postsynaptic membrane, causing depolarization and making the neuron more likely to fire an action potential.

Inhibitory Neurotransmitters

Chemicals released by neurons that decreases(stop) the likelihood of an action potential occurring in the postsynaptic neuron

Glutamate

Excitatory

• learning & memory

GABA

Excitatory

• relaxing

Dopamine

reward & pleasure

Serotonin

mode

Endorphins

body’s natural pain relievers

Substance P

pain

Acetylcholine (ACh)

muscle memory & learning

Hormones

chemical messengers produced by glands in the endocrine system that travel through the blood stream to target cells or organs, where they regulate various physiological processes and behaviors

Ghrelin

hormone

• hunger

Leptin

hormone

• lets you know you’re full

Melatonin

hormone

• sleep-wake cycle

Oxytocin

hormone & neurotransmitter

• Love / bonding connector

Adrenaline

hormone & neurotransmitter

• stress response: “flight or fight”

Norepinephrine

hormone & neurotransmitter

• alertness: “flight or fight”