1. Unit Two: Membrane Physiology, Nerve, and Muscle
Chapter 4: Transport of Substances Through Cell Membranes
Guyton and Hall, Textbook of Medical Physiology, 12th edition

2. Fig. 4.1 Chemical Compositions of
extracelluar and intracellular fluids

3. Through the cell membrane
Diffusion
Diffusion
Through the cell membrane

4. Diffusion of lipid soluble substances
Diffusion (cont.)
Diffusion of lipid soluble substances
Diffusion of water and other lipid-insoluble substances
Diffusion through protein pores and channels
Selective permeability of protein channels
Fig Structure of a potassium channel

5. Gating of protein channels (voltage and chemical)
Diffusion (cont.)
Gating of protein channels (voltage and chemical)
Open state vs. closed state
Fig Transport of sodium and
potassium through protein channels

6. Facilitated Diffusion
Diffusion (cont.)
Facilitated Diffusion
Fig Effect of concentration
on the rate of diffusion by
simple diffusion and facilitated
diffusion

7. Fig. 4.8 Postulated mechanism for facilitated diffusion

8. Factors Affecting the Net Rate of Diffusion
Net diffusion rate is proportional to the concentration
difference across a membrane.
Effect of membrane electrical potential on diffusion
of ions---the Nernst equation
Effects of pressure differences across the membrane

9. Fig. 4.9 Effect of concentration difference
electrical potential difference affecting
negative ions, (B) pressure difference, (C) to
cause diffusion of molecules and ions
through a cell membrane.

10. Osmosis: “Net” Diffusion of Water
Fig Osmosis at a cell membrane when a sodium chloride solution is placed on one
side of the membrane and water is placed on the other side.

11. Importance of the number of osmotic particles (molar concentration)
Osmosis (cont.)
Osmotic Pressure
Importance of the number of osmotic particles
(molar concentration)
Osmolality: 1 gram molecular weight of
osmotically active solute
c. Relation of osmolality to osmotic pressure

12. Osmosis (cont.)
Fig Osmotic pressure caused by osmosis at a semipermeable membrane

13. Active Transport
Primary Active Transport
Na+-K+ pump

14. Active Transport (cont.)
b. Na+-K+ pump is important in controlling cell volume
c. Electrogenic nature of the Na+-K+ pump
Primary active transport of calcium
Primary active transport of hydrogen ions
Energetics of primary active transport

15. Secondary Active Transport
Co-transport of glucose and amino acids along with
sodium ions

16. Secondary active transport (cont.)
Sodium Counter-transport of Calcium and
Hydrogen Ions

17. Fig. 4.15 Basic mechanism of active transport across a layer of cells.