Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
A drug is defined as any substance taken into the body that modifies or affects chemical reactions. Alcohol and tobacco are common examples of legal drugs that are frequently misused.
Alcohol (Ethanol, ) is a depressant. It slows down the central nervous system, resulting in increased reaction times and impaired coordination.
Excessive alcohol consumption can lead to liver cirrhosis, a condition where healthy liver tissue is replaced by scar tissue, and Fetal Alcohol Syndrome if consumed during pregnancy.
Tobacco smoke contains four primary harmful components: Nicotine, Tar, Carbon Monoxide (), and Particulates (smoke particles).
Nicotine is an addictive stimulant that increases heart rate and narrows arterioles, contributing to hypertension (high blood pressure).
Tar is a carcinogen that settles in the lungs, increasing the risk of lung, mouth, and throat cancers. It also paralyzes the cilia in the airways.
Carbon Monoxide () is a toxic gas that binds irreversibly to hemoglobin to form carboxyhemoglobin (), reducing the blood's capacity to transport oxygen ().
Chronic Obstructive Pulmonary Disease (COPD) comprises Chronic Bronchitis (inflammation and excess mucus) and Emphysema (destruction of alveolar walls, reducing the surface area for gas exchange).
📐Formulae
💡Examples
Problem 1:
Calculate the effect of Carbon Monoxide () on the oxygen-carrying capacity of blood if of hemoglobin () is converted to carboxyhemoglobin ().
Solution:
If of is bound to , then only of the hemoglobin is available to form oxyhemoglobin ().
Explanation:
Because has a much higher affinity for than , even small amounts of smoke can significantly reduce the volume of delivered to tissues for respiration.
Problem 2:
Explain why smokers are more susceptible to respiratory infections.
Solution:
Tar in tobacco smoke paralyzes the cilia that line the trachea and bronchi. Goblet cells are stimulated to produce more mucus. Without moving cilia, the mucus (trapping bacteria) remains in the lungs.
Explanation:
The accumulation of infected mucus leads to chronic inflammation and provides a breeding ground for pathogens, resulting in bronchitis.
Problem 3:
A driver consumes alcohol and his reaction time increases from to . Explain the biological reason behind this.
Solution:
Alcohol () is a depressant that increases the time taken for impulses to travel across synapses in the brain.
Explanation:
By slowing down neurotransmission, the 'thinking time' and 'braking time' are effectively doubled, making the driver significantly less responsive to hazards.