1.3 The Neuron and Neural Firing

the cell’s life support center

cell body

receive messages from other cells

dendrites

passes messages away from the cell body to other neurons, muscles, or glands

axon

action potential, electrical signal travelling down the axon

neutral impulse

forms junctions with other cells

terminal branches of axon

covers the axon of some neurons and helps speed neural impulses

myelin sheath

transmits information

neurons

• structure - the glue

• insulation

• communication

  • waste transport

glial cells

What are the two common types of neural cells in the brain

neurons, glial cells

• minimum intensity needed to fire a stimulus

• not enough message →no communication passed on

threshold

• neural impulse

• electrical charge travelling down axon: message transmitted across axon

action potential

the movement of a cell’s membrane potential to a more positive value

depolarization

the neuron is unable to fire while it resets

refractory period

• The neuron’s electrical charge is always the same (goes or doesn’t)

• bigger or smaller stimulus → faster or slower firing, not bigger or smaller

all or none principle

neuron more likely to fire

excitatory

neuron less likely to fire

inhibitory

skeletal and heart muscles, alertness, interneuron communication

acetylcholine

fight or flight; attention and memory

norepinephrine

movement, learning

dopamine

moods and emotional states; regulation of sleep-wake cycle

serotonin

modulates the experience of pain or pleasure

endorphins

modulation of pain

substance p

learning and memory; sensory and motor functions

glutamate

most abundant inhibitory neurotransmitter; regulates daily sleep-wake cycles

gaba

• Internal

• Nervous system

• Quick-acting

neurotransmitter

• Internal

• Endocrine system (bloodstream)

• Long-lasting

hormones

fight or flight

adrenaline

hunger (suppressant)

leptin

sleep

melatonin

hunger (stimulation)

ghrelin

labor, lactation, love

oxytocin

drug that enhances the effects of a neurotransmitter by mimicking/facilitating

agonist

prevents the effects of a neurotransmitter

antagonist

enhances the effects of a neurotransmitter by preventing the process of reuptake

reuptake inhibitor

increased neural activity

stimulants

decreased neural activity

depressants

distortions in perception/cognition

hallucinogens

pain relievers

opioids