Neurons + rec. drugs

Question 1

A neuron is…

Answer 1

A nerve cell in the nervous system, transmitting signals electrically and chemically

Question 2

Name the three types of neurons

Answer 2

Sensory, motor and relay.

Question 3

Describe sensory neurons (function, adaptations).

Answer 3

Messages from sensory receptors along nerves in peripheral nervous system (PNS) to CNS. Long dendrites and short axons. (recieve more, shorter distance)

Question 4

Describe a motor neuron (function, adaptations).

Answer 4

Messages from CNS, along PNS, to effectors in body (muscles, glands). Short dendrites, long axons. (recieve less, longer distance)

Question 5

Describe relay neurons (function, adaptations).

Answer 5

Connect sensory and motor neurons as well as other relay neurons. Short dendrites, short axons and only in CNS.

Question 6

Describe how neurons transmit signals. (depolarisation/ap)

Answer 6

When neuron resting, inside -ve charged relative to outside. When sufficiently activated by stimulus, inside briefly +ve (rapid -ve to +ve is depolarisation) and creates electrical impulse (AP) that travels down axon to terminal buttons.
Threshold for depolarisation (AP) is always same regardless of stimulus size. (All or nothing)

Question 7

What is synaptic transmission?

Answer 7

Chemical process using biochemical substances (neurotransmitters).

Question 8

Describe synaptic transmission.

Answer 8

When AP is triggered and reaches presynaptic terminal button, it triggers release of neurotransmitter from synaptic vesicles (tiny sacs). Neurotransmitters (e.g. GABA, dopamine) diffuse across synaptic cleft into respective receptor sites (lock and key theory) in postsynaptic neuron. Chemical signal converted back to electrical signal which may fire another AP.

Question 9

Describe reuptake.

Answer 9

Neurotransmitter molecules that remain in the synapse can be reabsorbed back into the presynaptic neuron, usually being broken down first. Neurotransmitters can be therefore reused.

Question 10

What is the effect of inhibitory neurotransmitters (e.g. serotonin) on neighbouring neurons?

Answer 10

Inhibition in postsynaptic neuron -> makes neuron more -ve therefore less likely to fire AP.

Question 11

What is the effect of excitatory neurotransmitters (e.g. dopamine) on neighbouring neurons?

Answer 11

Excites postsynaptic neuron by increasing +ve charge therefore more likely to fire AP.

Question 12

What does firing depend on?

Answer 12

Summation of signals over time (temporal summation) or ‘space’ (spatial summation) - net effect.

Question 13

Recreational drugs include…

Answer 13

Stimulants, sedatives, hallucinogens and opioids.

Question 14

Describe effects of amphetamines (cocaine).

(type, effects and neurotransmitters inv.)

Answer 14

Stimulant effect on CNS esp. main reward sys. (meso(cortic)limbic pathways). Altering synaptic transmission of noradrenaline, serotonin, acetylcholine and dopamine. Euphoric high.

Question 15

How does amphetamines (cocaine) work?

Answer 15

Blocks dopamine reuptake by binding with presynaptic terminal buttons, increasing overall levels of dopamine in the synapse, causing the ‘euphoric high’.

Question 16

Describe long-term effects of recreational drugs .

(tolerance)

Answer 16

Prolonged use of rec. drugs downregulates receptor sites. Fewer are active meaning dopamine production declines. This is ‘withdrawal’, craving for the drug. Higher doses are required to reach the same effect, aka tolerance.

Question 17

Describe effects of heroin (diacetylmorphine).

(type, effects and neurotransmitters inv.)

Answer 17

Relaxant (agonist mimicing natural opoids), depressant on CNS decreasing activity (hence analgesics/pain relief). Processed in brain into morphine, using CNS’s natural opoid system– binding and enhancing natural responses.
Affects hippocampus (memory).

google thinks im doing things :sparkles:

Question 18

Describe effects of alcohol.

(type, effects and neurotransmitters inv.)

Answer 18

Depressant, increases dopamine, GABA and serotonin. GABA is inhibitory on neurotransmitters e.g. norepinephrine but can have a double negative effect on dopamine, increasing overall levels. Less stress but tolerance + less neurotransmission in hippocampus, less memory.

Question 19

How can drug addiction be treated?

Answer 19

Drug Reduction Therapy (DRT) where the real substance is substituted with a less addictive version (e.g. methadone for heroin) and incrementally decreased till dopamine production in the brain is normal again.