Anatomy and Physiology: Cell Transport Lecture

Introduction

• Instructor: Kevin Tokeoff
• Focus: Key concepts from Exercise 3 related to cell transport

Key Concepts

Kinetic Energy

• Definition: Energy due to the movement of particles
• Particles in cells are always in motion, contributing to kinetic energy
• Faster-moving particles have more kinetic energy

Selectively Permeable Membranes

• Definition: Membranes that allow some molecules to pass while blocking others
• Importance in cellular transport

Concentration Gradient

• Definition: Difference in concentration of molecules on either side of a membrane
• Example: Higher concentration of blue circles on one side compared to the other

Diffusion

• Definition: Movement of solute particles from high concentration to low concentration
• Types:
  • Simple Diffusion: No energy required, solutes move down the gradient
  • Facilitated Diffusion: Requires a protein to assist in transport
• Characteristics:
  • Passive process
  • Energetically favorable

Diffusion and Membranes

• Selectively permeable membranes allow certain solutes to cross
• Diagram explanation: Yellow and red molecules can cross; green cannot

Osmosis

• Definition: Movement of water across a membrane toward higher solute concentration
• Water movement direction: Toward side with higher solute concentration
• Diagram explanation: Water moves left in the presence of high solute concentration

Solutions and Cell Environment

• Hypotonic Solution: Low external salt concentration; water moves into the cell, causing it to burst
• Hypertonic Solution: High external salt concentration; water moves out, causing cell to shrink
• Isotonic Solution: Equal salt concentration inside and outside; no net change in cell size

Clinical Application

• Importance of isotonic solutions in IV administration to prevent cell damage

Diffusion Rate Factors

• Molecular Weight: Inversely related to diffusion rate; lighter molecules diffuse faster
• Surface Area to Volume Ratio: Greater ratio increases diffusion speed
• Temperature: Higher temperatures increase diffusion rate
• Concentration Gradient: Greater gradient increases diffusion rate

Practice and Application

• Understand and identify the types of solutions from lab models (e.g., egg experiments)
• Know definitions and mechanisms of diffusion and osmosis

Conclusion

• Review concepts for upcoming quiz
• Additional video on Brownian Motion available
• Quiz on Tuesday