Chapter (1.3A) Vocab

Acetylcholine

Acetylcholine is responsible for muscle movement and memory; it carries the signal at every junction between nerve and muscle, and the loss of neurons that produce it is linked to Alzheimer’s disease

Action Potential (Depolarization)

A neutral impulse; a brief electrical charge that travels down an axon.

Adrenaline

Agonist

A molecule that increases a neurotransmitter’s action.

All-or-None Response

A neuron’s reaction of either firing (with a full-strength response) or not firing.

Antagonist

A molecule that inhibits or blocks a neurotransmitter’s actions.

Axon

The segmented neuron extension that passes messages through its branches to other neurons or to muscles or glands.

Axon Hillocks

The starting trigger zone where a nerve signal begins.

Axon Terminal

The ending branch where the signal is passed on to the next cell.

Cell Body

The part of a neuron that contains the nucleus the cell’s life-support center.

Dendrites

A neuron’s often bushy, branching extensions that receive and integrate messages conducting impulses toward the cell body.

Dopamine

Dopamine’s role in behavior and cognition is movement, learning, and pleasure. However too much dopamine can lead to schizophrenia while too little can lead to parkinsons.

Endocrine System

The body’s “slow” chemical communication system through secreting hormones into the bloodstream.

Endorphins

“Natural painkillers or morphine” an opioid-like neurotransmitter linked to pain control and pleasure.

Excitatory Messages

Increases the chance of a neuron firing.

GABA

GABA is a major inhibitory neurotransmitter, reduces anxiety; it calms neural activity, and alcohol and anti-anxiety medications work partly by enhancing GABA.

Ghrelin

Triggers hunger; released by an empty stomach, it signals the brain that it is time to eat.

Glial Cells (Glia)

Cells in the nervous systems that support, nourish, and protect neurons they may also play a role in learning and thinking memory.

Glutamate

Glutamate a major excitatory neurotransmitter, linked to learning; it strengthens connections between neurons as memories form, but too much can overexcite the brain (linked to migraines and seizures).

Hormones

Chemical messengers that are manufactured by the endocrine glands that travel through the blood stream and affect other tissue.

Inhibitory Messages

Inhibits the chance of a neuron firing.

Leptin

Regulates hunger and metabolism; released by fat cells, it tells the brain the body has enough energy stored, reducing appetite

Melatonin

Regulates sleep-wake cycles; released by the pineal gland as it gets dark, it signals the body to prepare for sleep.

Multiple Sclerosis (MS)

Damage to the myelin sheath slows or blocks signals traveling down the axon, impairing movement and sensation.

Myasthenia Gravis

The immune system makes antibodies that block or destroy acetylcholine receptors where nerves meet muscles, so the signal to contract arrives weakly.

Myelin Sheath

A fatty tissue layer segementally encasing the axons of some neurons it enables vastly transmission speed as neutral impulses hop from one node to the next.

Neuron

A nerve cell the basic building block of the nervous system.

Neurotransmitters

Chemical messengers that cross the synaptic gap between neurons.

Neural Transmission

Follows a structured process that underlies all thoughts and behaviors.

Nodes of Ranvier

Tiny, exposed gaps in the insulating fatty layer (myelin sheath) that covers nerve fibers

Norepinephrine

Norepinephrine is responsible for alertness and arousal; it sharpens attention and helps prepare the brain and body for action during stress.

Oxytocin

Promotes bonding and trust; released during childbirth, breastfeeding, and physical closeness, it strengthens social attachments

Reflex Arc

A simple, automatic response to a stimulus. (ex. A doctor hitting below your knee and you kicking)

Refractory Period

In neural processing a brief resting pause that occurs after a neuron has fired.

Reuptake

A neurotransmitter’s reabsorption by the sending neuron.

Serotonin

Serotonin is responsible for mood and appetite (It also helps with sleep regulation).

Substance P

Substance P is responsible for transmitting pain signals to the spinal cord and brain; endorphins can reduce pain by blocking its release.

Synapse

The junction between the axons tip of the sending neuron and the dendrite or cell body of the receiving neuron.

Threshold

The level of stimulation required to trigger a neutral impulse.