Drugs and health

Explain what a drug is from the point of view of its effect on the body, and classify these substances as legal or illegal drugs in Ireland: alcohol, cannabis, tobacco, cocaine, caffeine.

Explain the difference between use, abuse and dependence on a drug, illustrating each term with an example related to alcohol.

Medicines are also substances that act on the body. Explain the difference between taking them following medical advice and self-medicating, and give an example of a risk of self-medication.

The diagrams represent the effect of the three main groups of drugs on nervous system activity: the dashed grey line shows normal activity and the coloured line shows activity after consumption. Name the group (depressants, stimulants or hallucinogens) that corresponds to each diagram (A, B and C), explain what each one consists of, give an example of each group, and reason why this classification does not take into account whether the drug is legal or illegal.

Mixing alcohol with energy drinks is especially deceptive. Explain what each substance does to the nervous system and what danger there is in not noticing the effects of alcohol even though they are acting.

Explain what it means for a drug to cause dependency, and distinguish, using an example, between physical dependency and psychological dependency.

Explain what tolerance and withdrawal symptoms are, and how these two phenomena contribute to an addicted person consuming increasingly more of a drug and finding it so difficult to quit.

In the brain reward circuit, neurotransmitters like dopamine generate pleasurable feelings. A psychoactive drug blocks the reuptake of dopamine, causing its concentration in the synapse to multiply artificially.

1. a) Predict how the postsynaptic neuron membrane will respond (by decreasing or increasing the number of dopamine receptors) after weeks of continuous consumption to defend itself from this excessive stimulation. Justify why this cellular mechanism explains the phenomenon of tolerance.
2. b) Based on your previous answer, deduce why, when the person abruptly stops consumption, they experience intense physical and psychological discomfort (withdrawal syndrome) during normal daily activities.

Describe three effects of tobacco on the respiratory and circulatory systems, and explain why quitting smoking improves health even after many years of smoking.

Name three immediate effects of alcohol consumption on behaviour and three effects of tobacco on the respiratory system.

Explain what nicotine is and why it makes smoking lead to dependence so easily.

State whether these statements are true or false and justify your answer: a) alcohol is a depressant drug of the nervous system; b) tobacco smoke only harms the person who smokes; c) quitting smoking provides health benefits at any age.

Alcohol is legal for adults and plays a large role in social life. Explain why, despite this, it is particularly dangerous for adolescents, taking into account that their brain is still developing, and state two specific consequences of its consumption at this age.

A $45\ \text{kg}$ teenage girl and a $75\ \text{kg}$ adult drink the same amount of alcohol, but she gets drunk sooner. Explain, taking into account body mass and the maturation of her liver and brain, why alcohol affects adolescents more.

Explain what passive smoking is, which people are especially vulnerable to it, and what measures reduce it at home and in the car.

A friend claims that cannabis "is natural and harmless". Analyse that argument: explain what effects cannabis has on memory, attention and motivation at developmental ages, and reason why "natural" does not mean harmless.

Explain what role advertising, films and the group of friends play in starting tobacco and alcohol use, and describe two strategies for saying no without losing your friends.

An advertising brochure states: "Our vapes only contain water vapor with harmless fruit flavorings; they are the 100% safe substitute for quitting smoking." Critically analyze this statement based on scientific evidence:

1. a) Refute the claim that it is "water vapor": explain what that aerosol actually is and what toxic or addictive substances have been detected in it, detailing how they affect the epithelium of the respiratory tract.
2. b) Epidemiological studies indicate that adolescents who vape are up to four times more likely to smoke traditional tobacco two years later than non-vapers. Propose a biological and behavioral hypothesis explaining why vaping acts as a "gateway" to smoking.

At 90 km/h, a car travels 25 m every second. Under sober conditions, the average reaction time of a driver to an unexpected event is 0.8 s. After consuming two beers (blood alcohol content of 0.4 g/l), their reaction time increases to 1.3 s.

1. a) Calculate the distance traveled during the reaction phase in both cases before the driver actually steps on the brake pedal. Interpret the practical consequences of this metric difference when faced with an obstacle at 30 m.
2. b) Alcohol is a central nervous system depressant. Justify the apparent contradiction whereby the driver claims to feel "more awake, confident, and with better reflexes" after drinking, relating it to the disinhibition of the prefrontal cortex.

Following the implementation of a law that increased tobacco taxes by 25% and banned its consumption on outdoor terraces and at entrances to educational facilities, the following data were recorded after two years:

• A 32% reduction in smoking initiation among young people aged 12 to 17.

• An 18% decrease in pediatric emergency visits for acute asthma attacks.

• An 8% reduction in overall consumption among chronically smoking adults.

1. a) Interpret why the recorded percentage reduction was four times greater among young people (smoking initiation) than among dependent adults (overall consumption), drawing on socioeconomic factors and the plasticity of the adolescent brain compared to established addiction.
2. b) Justify the physiological cause-and-effect relationship between the ban on smoking on outdoor terraces and the direct decrease in asthma attacks in the non-smoking child population.

The human liver metabolises alcohol using the enzyme alcohol dehydrogenase at a constant maximum rate of about 0.15 g/l per hour, becoming easily saturated.

1. a) Compare what happens in the brain if a person drinks 60 g of alcohol spread over 8 hours versus if they ingest it in 90 minutes ("binge drinking"). Explain why, in the second case, the blood concentration can reach levels that severely depress the functions of the brainstem (breathing and heart rate) and induce an alcohol-induced coma.
2. b) If a friend loses consciousness at a party due to alcohol poisoning, critically evaluate these three common proposals: "lay him on his back to sleep", "make him drink hot coffee", and "put him under a cold shower". Justify the life-threatening danger of each and describe the correct recovery anatomical position and the action protocol.

An elite athlete uses injections of recombinant erythropoietin (EPO), a hormone that stimulates the maturation and proliferation of erythrocytes in the bone marrow, raising their haematocrit (volume of red blood cells in blood) from 42 % to 57 %.

1. a) Explain the physiological basis by which this doping artificially increases their performance in an endurance event, relating erythrocytes, haemoglobin, O₂ transport, and mitochondrial cellular respiration in muscle fibres.
2. b) Predict the effect of this massive increase in cells on blood viscosity and blood pressure. Justify why the risk of suffering a thrombosis or cardiac arrest skyrockets especially at night, when the athlete is at rest and their heart rate drops.

The consumption of certain synthetic stimulant drugs (such as ecstasy or MDMA) alters the thermoregulatory centres of the hypothalamus, while increasing muscular activity and causing peripheral vasoconstriction.

1. a) If a person takes this substance and dances non-stop in a crowded, humid nightclub at 28 °C, explain why their homeostatic cooling mechanisms (sweating and thermal dissipation through skin vasodilation) fail and how this leads to heatstroke above 41 °C with multiple organ failure.
2. b) To try to help the affected person, their friends force them to drink four litres of pure mineral water in 15 minutes. Justify physiologically why this action does not resolve hyperthermia and can trigger lethal cerebral oedema due to hyponatraemia (critical dilution of blood plasma salts).

In a conversation, someone claims: "My uncle smoked two packs a day since he was 14 and died at 91, sharp as a tack and of old age; therefore, tobacco cannot be as harmful as health campaigns say, it is just a matter of individual constitution".

1. a) Identify the scientific reasoning flaw (survivorship bias and the use of anecdotal evidence) in this statement, and justify why an exceptional individual case cannot invalidate a general biomedical law or conclusion.
2. b) A cohort study followed 30 000 people over 40 years: 50 % of regular smokers died prematurely due to conditions directly linked to smoke. Use these data to refute the long-lived uncle argument and explain the damaging mechanisms of tar and carbon monoxide (CO) on the respiratory and circulatory systems.