Exercises: 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 Mexico: alcohol, cannabis, tobacco, cocaine, caffeine.

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

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

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.

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 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.

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.

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.

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.