Cell membranes

Why this matters

Every dental cell must control ions, water, nutrients and signals. Membrane transport powers salivary fluid secretion, supports nerve impulses and explains why local anaesthetics can stop pain conduction.

The big picture

1 The hydrophobic bilayer blocks most ions and polar solutes. 2 Proteins provide selective routes for signals and substances. 3 Concentration, voltage and ATP determine transport direction. 4 Controlled movement preserves composition, volume and function.

You will be able to

1. 1.Explain why phospholipids form a bilayer.
2. 2.Relate proteins and cholesterol to membrane function.
3. 3.Distinguish diffusion, osmosis and tonicity.
4. 4.Compare channels, carriers and ATP-driven pumps.
5. 5.Predict transport direction from a gradient.
6. 6.Apply membrane transport to salivary secretion.

The 12 cards in this lesson

1. 01The plasma membrane creates a selective boundary
2. 02Amphipathic phospholipids assemble into a bilayer
3. 03Read the membrane from outside to inside
4. 04Membrane proteins turn the bilayer into a working interface
5. 05Cholesterol and lipid tails tune membrane fluidity
6. 06Diffusion follows a gradient without cellular energy
7. 07Osmosis is the net movement of water
8. 08Tonicity predicts the sustained effect on cell volume
9. 09Ion channels are fast, selective aqueous pores
10. 10Carriers bind solute and alternate access
11. 11Pumps and coupled carriers move selected solutes uphill
12. 12Membrane transport builds primary saliva

You have got it when

You are ready to continue when you can classify a transport process, state its energy source and predict the direction of solute or water movement.