Historical Examples. 1  It will be seen that the valves v on the other side of the annular chamber are closed. 2  The angle of the anterior chamber is a true angle and not an annular sinus. 3  Johnston suggests that the reference is to an annular eclipse which he finds occurred on August 14, at about 8Â¼ h. in the morning.
Cellular nutrients come in many forms, including sugars and fats. In order to provide a cell with energy, these molecules have to pass across the cell membrane, which functions as a barrier â but not an impassable one.
Cells are surrounded by a membrane called a plasma or cell membrane. The membrane consists of phospholipids and proteins. Phospholipids make up the membrane and create the barrier between the cell's contents and area outside the cell. Two types of proteins are found in the cell membrane: integral and peripheral proteins.