D.5 Stimulants

D.5.1 List the physiological effects of stimulants.
Stimulants:
- increase activity in the brain & mental alertness; prevents drowsiness, allowing greater concentration
- affects CNS, functions oppositely to depressants

Physiological effects:
- help facilitate breathing (relaxes air passage ways) & treats respiratory infections (e.g. severe bronchitis)
- may reduce appetite
- may cause palpitation/tremors
- in excess: extreme reslessness, sleeplessness, fits, delusions & hallucincations

D.5.2 Compare amphetamines and epinephrine (adrenaline).
Amphetamines
- stimulants that mimic adrenaline
- acts to enhance effects of adrenaline and noradrenaline
- similar structure to adrenaline and noradrenaline
- also called sympathomimetic drugs - stimulates sympathetic nervous system
- increases mental alertness & physical energy
- side effects: dilation of pupils, decrease appetite, possible blurred vision & dizziness
- regular use: rapid development of tolerance & dependence; long-term effects: severe depression & reduced infection resistance.

Adrenaline (epinephrine) enables body to cope with pain, fear, cold and shock - it is a part of the 'flight or fight' response, which stimulates pathways that increase:
- heart rate and blood pressure
- blood flow to the brain and muscles
- air flow to the lungs
- mental awareness

Noradrenaline (norepinephrine)
- a neurotransmitter
- similar structure & physiological effects to adrenaline
- responsible for communication in the sympathetic nervous system, and to stimulate pathways.

They are derivatives of the phenylethylamine structure:

Designer drugs
(e.g. speed, crystal meth, ecstasy)
- modified amphetamine structure (inclues methamphetamine)
- powerful & dangerously addictive stimulant
- long-term use: serious brain damage/ small doses for some is also fatal



D.5.3 Discuss the short- and long-term effects of nicotine consumption.
Nicotine

- found in tobacco plants; low concentration in tomato, potato, eggplant & green pepper plants
- stimulant & highly addictive
- lipid soluble, able to cross blood-brain barrier (rapid effects on brain activity) - increases levels of adrenaline & alters concentration of certain neurotransmitters in the brain.
- effects change with increased consumption
- habit forming (dependence/ addiction)
- addiction: suffers withdrawal symptoms of consumption (e.g. nausea, weight gain, drowsiness, inability to concentration, depression & craving)
- most widespread & abused stimulant; often linked to social factors e.g. peer pressure

Nicotine in tobacco - includes tar & carbon monoxide
- long term smoking: correlated with increased risk of chronic lung disease, adverse pregnancy effects, lung, mouth, throat cancer
- high costs of obtaining tobacco
- stains skin & nails
- lingering smell on clothes


D.5.4 Describe the effects of caffeine and compare its structure with that of nicotine.
Caffeine
- in coffee, tea, chocolate & colas
- acts to reduce physical fatigue & restore mental alertness (people work longer hours & cope with body clock changes)
- acts as a respiratory stimulant
- increase rate of energy release within cells
- enhances & prolongs adrenaline effects

Consumption in small amounts
- mental energy, alertness & concentration ability enhancement
- acts as a diuretic, increases urine volume; can cause dehydration.

Consumption in large amounts
- causes anxiety, irritability & insomnia
- causes dependence, withdrawal
- side-effects: headaches, nausea

**helps body absorb some analgesics