Stretching an amphiphilic bilayer

Now, think about the structure of an amphiphilic bilayer and imagine that the molecules are held together in some way, say by little springs. We can see that an attempt to stretch the membrane will stretch all the little springs.

Note: We must be very cautious when considering extremely simple models like the spring model above. In reality the forces between the molecules are much more complicated. However, this gives the correct idea about how such a membrane could be stretched by a small amount.