Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
A drug is any substance taken into the body that modifies or affects chemical reactions in the body.
Alcohol () is a depressant that slows down the Central Nervous System (CNS) by increasing the time taken for nerve impulses to travel across synapses.
The liver is the primary site for the metabolism of ethanol. Chronic alcohol abuse leads to liver cirrhosis, where healthy hepatocytes are replaced by fibrous scar tissue.
Tobacco smoke contains Nicotine, an addictive stimulant that causes the release of adrenaline and narrows arterioles, leading to increased blood pressure.
Carbon Monoxide () in tobacco smoke binds irreversibly with hemoglobin () to form carboxyhemoglobin (), which significantly reduces the oxygen () carrying capacity of the blood.
Tar is a carcinogen found in tobacco smoke that triggers mutations in the DNA of bronchial epithelial cells, leading to uncontrolled cell division and lung cancer.
Chronic Obstructive Pulmonary Disease (COPD) includes chronic bronchitis (inflammation and excess mucus) and emphysema (destruction of alveolar walls, reducing the surface area for gas exchange).
📐Formulae
💡Examples
Problem 1:
Explain why a smoker might experience breathlessness during physical exercise, referring to the effects of Carbon Monoxide ().
Solution:
During exercise, the demand for oxygen () for aerobic respiration increases. In a smoker, competes with for binding sites on hemoglobin, forming stable carboxyhemoglobin ().
Explanation:
Because does not easily dissociate, the concentration of oxyhemoglobin () is lower. This reduces the total volume of delivered to muscle tissues, forcing the body to increase heart and breathing rates to compensate, resulting in breathlessness.
Problem 2:
Calculate the impact of emphysema on the rate of gas exchange if the total surface area () of the alveoli is reduced by .
Solution:
According to Fick's Law, the rate of diffusion is directly proportional to the surface area (). If , the rate of diffusion will also decrease to of its original value.
Explanation:
Emphysema causes the walls of the alveoli to burst and fuse, creating larger but fewer sacs. This decrease in the surface area-to-volume ratio () limits the efficiency of uptake into the blood.