L4: Neurochemistry & Drug Addiction Flashcards
Is the inside of a cell negatively or positively charged in its resting state? What is the potential?
Resting state = negatively charged
Potential is around 70nV
What is depolarisation?
When a stimulus opens activation gates, Na+ channels rush to the negative interior of the cell and becomes positive. Action potential is triggered.
What is Hyperpolarisation?
When a change in the cell membrane potential makes it more negative. It inhibits action potentials.
What are these neurotransmitters associated with?
a) serotonin
b) dopamine
c) Anandoamide
a) mood/temperature regulation. Sleep cycles
b) motor function and reward system
c) pain reduction and increasing apetite
What are these neurotransmitters associated with?
a) Acetylcholine
b) Norepinephrine
c) GABA
d) Glutamate
a) Muscle contraction (PNS), cortical arousal (CNS)
b) brain arousal, mood, hunger, sleep
c) Inhibitory neurotransmitter
d) Excitatory neurotransmitter, relay of sensory information and learning
What are the 3 ways drugs can affect communication between cells and the chemical synapse?
1) By blocking the deactivation of neurotransmitter molecules by blocking degradation or reuptake
2) Blocking synthesis of neurotransmitters molecules, leak from vesicles
3) Activating autoreceptors, inhibits neurotransmitter release
Where does nicotine bind to its receptors?
In the VTA which is in the Basil Ganglia. nACC received dopamine from VTA.
What impact does alcohol have on the brain?
Depresses neural firing in the brain
What does cannabis target in the brain?
Receptors for endocannabinoids
What does cocaine block?
The reuptake transporter protein (dopamine)
What do opiates prevent being released?
GABA, which then inhibits the release of dopamine
What does Effect Selectivity and Cross Tolerance mean in relation to drug tolerance?
Effect Selectivity: Forming a tolerance to some effects of the drug but not all
Cross Tolerance: Tolerance may extend to other drugs that work by similar means
What is Functional Tolerance and Metabolic Tolerance?
Functional Tolerance: Site of action becomes less responsive to the drug as the number of receptors reduce.
Metabolic Tolerance: Less of the drug gets to the site of action
What is drug withdrawal?
When the nervous system adapts to the drug and then requires it for normal functioning.
How has contingent tolerance been shown in rats?
Rats were split into 2 groups. 1st group were given alcohol with anti-convulsion before Amygdala stimulation. 2nd group have alcohol after stimulation.
The first group who experienced the effects of alcohol build a tolerance
How has the alcohol hyperthermic effect been demonstrated?
2 groups:
1st group - received alcohol and saline in different rooms (showed some initial effect)
2nd group - received in the same room (built a tolerance)
What are some limitations of physical dependence theories of addiction?
1 - Cant explain why addicts relapse after long detox
2 - Cant explain why people begin using drugs
3 - Cant explain when addictions develop when a drug doesnt produce severe withdrawal symptoms
How is dopamine involved with drug reward?
Self-stimulation targets sites in meso-cortical-limbic pathway and increases dopamine activity in this pathway
How does the incentive-sensitisation theory of drug addiction explain drug addicts enjoying drugs less?
Positive-incentive value increases due to memory of early pleasure with drug experience.
Hedonic value decreases due to forming a tolerance.
Results in addicts craving drugs more but enjoying them less.
