1. General Physiology Dr. Tony Serino
Cell Membrane
General Physiology Dr. Tony Serino

2. The Cell: Components
Cell Membrane
Cytoplasm
Organelles

3. Membrane Components
Hydrophobic area

4. Membrane Protein Functions

5. Movement through the membrane

6. Diffusion
-is the movement of substances from areas of high concentration to areas of lower concentration until an equilibrium is reached.
The movement of these substances is provided by the heat of the system (thermokinetic energy). Increasing the heat, increases the rate of diffusion; decreasing the heat has the opposite effect.
(Diffusion ceases at absolute zero (0oK or –273 oC)

7. Diffusion
Only particles that are not charged and relatively small can pass through the membrane by diffusing.
Water*, Oxygen, Carbon dioxide, and lipids can move freely.

8. Facilitated Diffusion

9. Active Transport

10. (solvent diffusion)

11. Osmosis Less solute Equal solute More solute swells same shrinks
Hypotonic
Isotonic
Hypertonic
Crenates

13. Exocytosis
Endocytosis

14. Membrane Potentials
Produced by the unequal distribution of ions across a selectively permeable membrane
The inside of the cell is called negative by convention
The intensity of the ion difference is expressed as voltage (measured in millivolts (mV))

15. Measuring Membrane Potentials

16. Resting Membrane Potential
Parameters necessary to create a resting membrane potential:
A semi-permeable membrane
Distribution of ions across membrane
Presence of large non-diffusible anions in interior
Na-K pump (3 Na+ out for every 2 K+ in)