L4: Neurochemistry & Drug Addiction

Question 1

Is the inside of a cell negatively or positively charged in its resting state? What is the potential?

Answer 1

Resting state = negatively charged

Potential is around 70nV

Question 2

What is depolarisation?

Answer 2

When a stimulus opens activation gates, Na+ channels rush to the negative interior of the cell and becomes positive. Action potential is triggered.

Question 3

What is Hyperpolarisation?

Answer 3

When a change in the cell membrane potential makes it more negative. It inhibits action potentials.

Question 4

What are these neurotransmitters associated with?

a) serotonin
b) dopamine
c) Anandoamide

Answer 4

a) mood/temperature regulation. Sleep cycles
b) motor function and reward system
c) pain reduction and increasing apetite

Question 5

What are these neurotransmitters associated with?

a) Acetylcholine
b) Norepinephrine
c) GABA
d) Glutamate

Answer 5

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

Question 6

What are the 3 ways drugs can affect communication between cells and the chemical synapse?

Answer 6

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

Question 7

Where does nicotine bind to its receptors?

Answer 7

In the VTA which is in the Basil Ganglia. nACC received dopamine from VTA.

Question 8

What impact does alcohol have on the brain?

Answer 8

Depresses neural firing in the brain

Question 9

What does cannabis target in the brain?

Answer 9

Receptors for endocannabinoids

Question 10

What does cocaine block?

Answer 10

The reuptake transporter protein (dopamine)

Question 11

What do opiates prevent being released?

Answer 11

GABA, which then inhibits the release of dopamine

Question 12

What does Effect Selectivity and Cross Tolerance mean in relation to drug tolerance?

Answer 12

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

Question 13

What is Functional Tolerance and Metabolic Tolerance?

Answer 13

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

Question 14

What is drug withdrawal?

Answer 14

When the nervous system adapts to the drug and then requires it for normal functioning.

Question 15

How has contingent tolerance been shown in rats?

Answer 15

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

Question 16

How has the alcohol hyperthermic effect been demonstrated?

Answer 16

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)

Question 17

What are some limitations of physical dependence theories of addiction?

Answer 17

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

Question 18

How is dopamine involved with drug reward?

Answer 18

Self-stimulation targets sites in meso-cortical-limbic pathway and increases dopamine activity in this pathway

Question 19

How does the incentive-sensitisation theory of drug addiction explain drug addicts enjoying drugs less?

Answer 19

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.