Volume
The volume of the cell is variable and oscillates within broad limits. In plants and in animals, cells are found which are visible to the naked eye and which possess a very great volume. Thus, the eggs of certain birds may have a diameter of several centimeters and are composed, at least at first, of a single cell.
This is nevertheless the exception, the great majority of cells being visible only with the microscope since their diameter is only a few thousandths of a millimeter (micron). The smallest cells have a diameter of 4 microns (4 one-thousandth of a millimeter). In the tissues of the human body, with exception of the nerve cells, the volume varies between 200 cubic microns and 15,000 cubic microns. In general, the volume of the cell is fairly constant for any one cell type and independent of the size of the individual. For example, the renal or hepatic cells of a bull, of a horse, or of a mouse have an almost equal size. The differences in the total mass of the organ are due to the number and not to the volume of the cells.
This is nevertheless the exception, the great majority of cells being visible only with the microscope since their diameter is only a few thousandths of a millimeter (micron). The smallest cells have a diameter of 4 microns (4 one-thousandth of a millimeter). In the tissues of the human body, with exception of the nerve cells, the volume varies between 200 cubic microns and 15,000 cubic microns. In general, the volume of the cell is fairly constant for any one cell type and independent of the size of the individual. For example, the renal or hepatic cells of a bull, of a horse, or of a mouse have an almost equal size. The differences in the total mass of the organ are due to the number and not to the volume of the cells.
Size
The size of cells is also related to their functions. Eggs (or to use the latin word, ova) are very large, often being the largest cells an organism produces. The large size of many eggs is related to the process of development that occurs after the egg is fertilized, when the contents of the egg (now termed a zygote) are used in a rapid series of cellular divisions, each requiring tremendous amounts of energy that is available in the zygote cells. Later in life the energy must be acquired, but at first a sort of inheritance/trust fund of energy is used.
Cells range in size from small bacteria to large, unfertilized eggs laid by birds and dinosaurs. The relative size ranges of biological things is shown in Figure 2. In science we use the metric system for measuring. Here are some measurements and convesrions that will aid your understanding of biology.
1 meter = 100 cm = 1,000 mm = 1,000,000 µm = 1,000,000,000 nm
1 centimenter (cm) = 1/100 meter = 10 mm
1 millimeter (mm) = 1/1000 meter = 1/10 cm
1 micrometer (µm) = 1/1,000,000 meter = 1/10,000 cm
1 nanometer (nm) = 1/1,000,000,000 meter = 1/10,000,000 cm
The size of cells is also related to their functions. Eggs (or to use the latin word, ova) are very large, often being the largest cells an organism produces. The large size of many eggs is related to the process of development that occurs after the egg is fertilized, when the contents of the egg (now termed a zygote) are used in a rapid series of cellular divisions, each requiring tremendous amounts of energy that is available in the zygote cells. Later in life the energy must be acquired, but at first a sort of inheritance/trust fund of energy is used.
Cells range in size from small bacteria to large, unfertilized eggs laid by birds and dinosaurs. The relative size ranges of biological things is shown in Figure 2. In science we use the metric system for measuring. Here are some measurements and convesrions that will aid your understanding of biology.
1 meter = 100 cm = 1,000 mm = 1,000,000 µm = 1,000,000,000 nm
1 centimenter (cm) = 1/100 meter = 10 mm
1 millimeter (mm) = 1/1000 meter = 1/10 cm
1 micrometer (µm) = 1/1,000,000 meter = 1/10,000 cm
1 nanometer (nm) = 1/1,000,000,000 meter = 1/10,000,000 cm
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