Table of Contents

• Prequiz...
• Just Plain Movement
• 1: Measuring Movement
• 2: Directed vs. Undirected Movement
• 3: Measuring Movement Using Flux
• Introducing Gradients
• 4: What is a gradient?
• 5: Watching diffusion happen (applet)
• 6: Visualizing the Gradient
• Fick's Laws, Part I
• 7: Fick's First Law
• 8: The gradient in Fick's First Law
• 9: A familiar equation for Fick's first law
• 10: The diffusion coefficient is the slope
• 11: What are the units for D?
• 12: How does flux depend on distance?
• 13: A fragrant example
• 14: General Transport Equations and Fick's First Law
• Fick's Laws, Part II
• 15: Fick's Second Law ...
• 16: ... is about "time to diffuse"
• 17: A Very Useful Formula
• 18: Time-to-diffuse "explodes"
• 19: General Functions and Diffusion
• Biological Applications
• 20: Biological Applications
• 21: Why do rhinos have lungs and amoebas don't?
• 22: Diffusion is efficient in small organisms, but not big ones
• 23: Diffusion within lungs
• 24: How many macrophages does it take to kill a virus?
• 25: You need a lot of macrophages - or one smart one!
• Review
• 26: Final Review

Biological Applications

So how does this really apply to biology??? Does it apply to biology at all??

We offer two examples of how the equations and mathematical approaches can help us understand biological concepts. First, we talk about why rhinos (and other vertebrates) have lungs, then we show how we can use math to determine how quickly we can fight off a cold.