Which law states that the amount of a substance crossing a given area is directly proportional to the area available for diffusion, concentration gradient and diffusion coefficient?
Fick's Law of Diffusion is definitely the key here. It states that the rate of diffusion is proportional to the surface area and the concentration gradient, and inversely proportional to the membrane thickness. The question mentions the area, concentration gradient, and diffusion coefficient, which are all components of Fick's Law.
Now, the correct answer is Fick's Law. The formula is J = -D*(dC/dx)*A, where J is the diffusion flux, D is the diffusion coefficient, dC/dx is the concentration gradient, and A is the area. So the factors mentioned in the question (area, concentration gradient, diffusion coefficient) are all part of this law.
For the incorrect options, they might be other laws like Henry's Law, which deals with solubility of gases, Graham's Law about effusion rates, or maybe Ohm's Law for fluid dynamics. Each of these is unrelated to the factors mentioned in the question.
Clinical pearl: Remember that Fick's Law is crucial in understanding gas exchange in the lungs and across capillaries. The student should note that increasing surface area (like in the alveoli) or the concentration gradient enhances diffusion, which is why conditions like emphysema reduce surface area and impair gas exchange.
Putting it all together, the correct answer is Fick's Law. Need to make sure each section is concise and covers the necessary points without exceeding the character limit.
**Core Concept**
The question tests understanding of **Fick's Law of Diffusion**, which quantifies passive diffusion across membranes. It relates the diffusion rate to surface area, concentration gradient, and diffusion coefficient.
**Why the Correct Answer is Right**
**Fick's Law** states that the rate of diffusion (J) is proportional to the surface area (A), concentration gradient (ΔC/Δx), and diffusion coefficient (D), while inversely related to membrane thickness. The formula is **J = -D × (ΔC/Δx) × A**. The law explains physiological processes like gas exchange in alveoli, where large surface area and thin membranes maximize diffusion.
**Why Each Wrong Option is Incorrect**
**Option A:** *Henry’s Law* relates gas solubility to partial pressure, not diffusion. **Option B:** *Graham’s Law* describes effusion rates based on molecular weight, not membrane diffusion. **Option C:** *Ohm’s Law* applies to fluid flow through vessels, not passive diffusion.
**Clinical Pearl / High-Yield Fact**
Fick’s Law underpins clinical scenarios like **pulmonary gas exchange** and **renal filtration**. Remember: **increased surface area** (e.g., alveolar capillaries) and **steep concentration gradients** enhance diffusion efficiency.
**Correct Answer: D. Fick’s Law**