Surface Area of Cells

Surface Area of Cells

The ratio between the surface area and volume of cells and organisms has an enormous impact on their biology. In order for cells to survive, they must constantly exchange ions, gases, nutrients, and wastes with their environment. Nutrients and oxygen need to diffuse through the cell membrane and into the cells. These exchanges take place at the cell's surface. To perform this function efficiently, there must be an adequate ratio between the cell's volume and its surface area.

Since the importance of the surface area to volume ratio of a cell is to ensure the efficiency of the transport of the nutrient and waste substance throughout the whole system, small cells function more efficiently than large cells. Small cells can exchange substances more readily than large cells because small objects have a higher surface area-to-volume ratio than larger objects. If the cell's surface area-to-volume ratio is too low, substance cannot enter and leave the cell in numbers large enough to meet the cell's needs. An increased surface area to volume ratio also means increased exposure to the environment.

Smaller single celled organisms have a high surface area to volume ratio, which allows them to rely on oxygen and material diffusing into the cell in order to survive. The higher the surface area-to-volume ratio they have, the more effective this process can be. Larger animals require specialized organs that effectively increase the surface area available for exchange processes, and a circulatory system to move material and heat energy between the surface and the core of the organism.

Increased surface area can also lead to biological problems. For small organisms with their high surface area to volume ratio, friction and fluid dynamics (wind, water flow) are relatively much more important, and gravity much less important, than for large animals.

High surface area-to-volume ratios also present problems of temperature control in unfavorable environments. More contact with the environment through the surface of a cell increases loss of water and dissolved substances for small organisms. Being large helps warm-blooded animals to maintain body temperatures different from their surroundings. Small organisms have a hard time keeping cooler than their surroundings.

Knowing all of this, surface area has obvious pros and cons, but regardless, this is a vital part of a cell's way of surviving. The process that it goes through to have a flow in nutrients is what makes a cell function effectively and to help us, living organisms, survive as well.