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.
All cells have a membrane. Cell membranes are the outer layers that hold the cell together. They let nutrients pass into the cell and waste products pass out. Not everything can pass through a cell membrane. What gets through and what doesnât depends on both the size of the particle trying to get in and the size of the opening in the membrane. Cells also have a nucleus. This is the cellâs control center. Cells continually divide to make more cells for growth and repair in your body. The nucleus contains the information that allows cells to reproduce, or make more cells. Another important part of a cell is the mitochondrion. This is the part of the cell where food and oxygen combine to make energy. You know that you need air to breathe. It is the oxygen in air that your body really needs.