neurons and addiction

what is action potential?

raid electrical signal that travels along a neutron

what ions are involved in action potential?

sodium (Na)

potassium (K)

what are the stages of action potential?

1-resting potential-inside negative

2-depolarisation-Na enters-cell becomes negative

3-repolarisation- K exits- cell becomes negative again

4-hyperpolarisation- overshoot-more negative than resting

5-returning to resting state

what happens presynaptically In synaptic transmission?

action potential arrives

neurotransmitters released into synapse

what happens postsynaptically in synaptic transmission

neurotransmitters bind to receptors

changes neuron activity

What is EPSP?

excitatory- increases chance of firing

what is IPSP?

inhibitory- decreases chance of firing

Neurotransmitters functions-

dopamine-reward, motivation, addiction

serotonin- mood, sleep, emotion

GABA-main inhibitory neurotransmitter

glutamate-main excitatory neurotransmitter

acetylcholine- muscle movement, memory

glial cells functions-

astrocytes-supports neurons, maintains environment

oligodendrocytes-produces myelin-insulation

microglia-immune defence in brain

what is the blood-brain barrier?

protective barrier between blood and brain

how does it work?

tight junctions block harmful substances

only certain molecules pass-eg oxygen and glucose

why is it important?

protects brain from toxins and pathogens

neural pathway of addiction-reward pathway-

main pathway-dopamine system

key structure- neural pathway of addiction

ventral tegmental area

nucleus accumbens

pre-frontal cortex

what happens in addiction?

dopamine releases increase

reinforces behaviour

leads to craving and dependence

stages of addiction

1-binge/intoxication-reward system activated

2-withdrawl/negative effect-stress system activated

preoccupation- loss of control, relapse risk

key brain systems in addiction

reward system-dopamine-pleasure

stress system-amygdala-withdrawl

control system-prefrontal cortex-decision making