Training. According to the American Physical Therapy Association, there were more than 200 accredited physical therapy programs in 2013. Master of Physical Therapy or Master of Science in Physical Therapy degrees are no longer offered in the U.S., and PTs in training now receive a Doctor of Physical Therapy degree.
Cell Membrane. The cell membrane (plasma membrane) is a thin semi-permeable membrane that surrounds the cytoplasm of a cell. Its function is to protect the integrity of the interior of the cell by allowing certain substances into the cell, while keeping other substances out.
A cell membrane is composed of two layers of phospholipids. Each phospholipid molecule has a hydrophilic phosphate head and two hydrophobic lipid tails. The heads line up along the inner and outer surfaces of the cell membrane, while the tails fill the middle space.