Anatomy and Physiology 1 Laboratory - Exercise 3: Cell Transport

Instructor: Kevin Tokoff

Key Concepts

• Focus: Exercise 3, Cell Transport
• Topics: Diffusion and Osmosis

Important Terms

• Kinetic Energy

  • Molecules in cells are always in motion, possessing kinetic energy.
  • Faster particles have greater kinetic energy.
  • Kinetic energy aids particles in traversing cell membranes.

• Selectively Permeable Membranes

  • Cell membranes allow some molecules to pass through while blocking others.

• Concentration Gradient

  • Difference in concentration of molecules on either side of a membrane.

Diffusion

• Definition: Movement of solutes from high concentration to low concentration.
• Types of Diffusion
  • Regular diffusion
  • Facilitated diffusion (requires a protein)
• Characteristics
  • Passive process: occurs spontaneously without energy.
  • Only passive processes are considered in this lab course.

Selectively Permeable Membranes

• Function: Determine which molecules can cross the membrane.
• Lipid-soluble molecules: Can diffuse across membranes.
• Protein-dependent molecules: Require proteins to cross.

Osmosis

• Focus: Movement of water instead of solutes.
• Water Movement
  • Water moves towards higher solute concentration.

Solution Types

• Hypotonic Solution

  • Low salt concentration outside the cell.
  • Water moves into the cell, potentially causing cells to burst.

• Hypertonic Solution

  • High salt concentration outside the cell.
  • Water moves out of the cell, causing cells to shrivel (cremation).

• Isotonic Solution

  • Equal salt concentration inside and outside the cell.
  • No net change in cell size.
  • Important for clinical applications, e.g., IV administration.

Rate of Diffusion

• Factors Influencing Diffusion Rate
  • Molecular Weight: Lower weight, higher diffusion rate (inverse relationship).
  • Surface Area to Volume Ratio: Higher ratio, higher diffusion rate.
  • Temperature: Higher temperature, higher diffusion rate.
  • Concentration Gradient: Higher gradient, higher diffusion rate.
• Concept Application
  • Larger differences in concentration gradient result in faster diffusion rates.

Other Notes

• Ensure understanding of osmosis and solution types for lab quiz.
• Watch supplementary video on Brownian motion for additional understanding.

Reminder

• Study these concepts for the upcoming quiz on Tuesday.