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 the United States (under federal law): alcohol, cannabis, tobacco, cocaine, caffeine.

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.

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

The diagrams represent the effect of the three main groups of drugs on nervous system activity: the dashed gray line shows normal activity and the colored 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 explain why this classification does not take into account whether the drug is legal or illegal.

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.

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

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

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.

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 behavior and three effects of tobacco on the respiratory system.

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". Analyze that argument: explain what effects cannabis has on memory, attention, and motivation during adolescence and other developmental stages, and reason why "natural" does not mean harmless.

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 role advertising, movies, 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 teenagers 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.

Following the implementation of a law that increased tobacco taxes by 25% and banned its consumption on outdoor patios and at entrances to schools, 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 room 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 patios and the direct decrease in asthma attacks in the non-smoking child population.

The human liver metabolizes 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.

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.