Unit 2A: Biology

axon

Transfers messages from the soma.

glial cells

Support and nourish neurons.

threshold

Minimum amount of stimulation needed for the soma to create a neural impulse.

Refractory Period

Rest period after an impulse.

neurotransmitter

Chemicals that transmit signals across a synapse.

Excitatory

Promotes the generation of an action potential.

Inhibitory

Prevents generation of an action potential on the receiving neuron.

agonist

Chemicals that mimic the effects of a neurotransmitter (Ex: Heroin mimics endorphins).

antagonist

Blocks the transmission of reception of a neural transmitter (black widow bites).

acetylcholine

Excitatory signal for muscle movement and memory (deficit leads to paralysis and Alzheimer's).

endorphins

Inhibitory signal that blocks pain; deficit relates to withdrawal symptoms.

serotonin

Inhibitory signal for sleep, mood, and appetite (deficit leads to depression).

norepinephrine

Excitatory signal for increasing heart rate, breathing, blood pressure; related to flight or flight.

dopamine

Excitatory signal for addiction, involuntary muscle stability, attention; excess leads to ADHD, schizophrenia, Tourette's; deficit leads to Parkinson's.

glutamate

Excitatory signal for thinking and learning and the internal clock; excess leads to migraines and seizures.

GABA

Inhibitory signal for calming and relaxation; deficit leads to anxiety disorders.

Substance P

Opposite of endorphins; causes pain.

Psychoactive Drug

Drugs that change consciousness.

Depressants

Slow down neural activity through GABA and/or endorphins.

Stimulants

Speeds up neural activity through dopamine or norepinephrine.

Hallucinogens

Distorts perception through serotonin.

Opiates

Painkilling drugs derived from opium or are synthetically produced.

Central Nervous system

The part of the nervous system consisting of the brain and spinal cord.

peripheral nervous system

The part of the nervous system outside the brain and spinal cord.

somatic nervous system

Controls voluntary movements.

autonomic nervous system

Controls internal organs.

sympathetic nervous system

Under autonomic, responsible for fight or flight.

Parasympathetic nervous system

Under autonomic, responsible for rest and digest.

lesion

Damaged tissue of the brain used to study portions of the brain.

endocrine system

The slow chemical communication system, responsible for puberty and growth.

hormones

Not neurotransmitters, responsible for growth and puberty, released in the endocrine system.