Heating - when heated phospholipid bilayer has an increased kinetic energy causing it to move more increasing fluidity and eventually breaking it down. The loss of this structure increases permeability making it easier for particles to cross.
Carrier and channel proteins will be denatured at higher temperatures meaning membrane permeability will be affected.
Organic solvents less polar than water will dissolve membranes, disrupt cells. Pure or very strong alcohol solutions are toxic as they destroy cells in the body. Less concentrated alcohols won't dissolve the membranes but can still do damage.Non-polar alcohol molecules can go between the phospholipids and disrupt the membranes.
When the membrane is disrupted it becomes more fluid and more permeable. some cells need complete membranes in order to function eg. the transmission of impulses in nerve cells. when the neural membranes are disrupted nerve impulses aren't transmitted normal.