What is the average size of cells

A human is, according to the most recent estimates, an assortment of 3. The identities of the human cells are distributed amongst more than different cell types BNID , which perform a staggering variety of functions. The shapes and sizes of cells span a large range as shown in Table 1.

Size and shape, in turn, are intimately tied to the function of each type of cell. Red blood cells need to squeeze through narrow capillaries and their small size and biconcave disk shape achieve that while also maximizing the surface area to volume ratio.

Cells that serve for storage, like fat cells and oocytes have very large volumes. Figure 1: Dividing HeLa cells as seen by a scanning electron micrograph colored. The image is taken during cell division cytokinesis.

The transient connecting midbody formed by microtubules can be seen. The different shapes also enable us to recognize the cell types. For example, the leukocytes of the immune system are approximately spherical in shape while adherent tissue cells on a microscope slide resemble a fried egg with the nucleus analogous to the yolk. The two approaches not only arrive at very different results. They also neglect the fact that the complex structure of the human body is composed of some different cell types.

Each of these cell types is present in the body in different quantities. In addition, they differ in size and weight. At about 0. It is big enough to be just barely visible with the naked eye. The smallest human cells, on the other hand, are sperm — at least if you count the cell body without the flagellum.

The reason for this significant difference is that, unlike sperm, an egg cell holds large amounts of cytoplasm and yolk-containing nutrients.

However, sperm are ahead if you count the number of mature cells per month: on average there is one mature egg cell compared to 3,,, mature sperm cells each month. The longest cells in the human body are nerve cells. Their projection, the axon, can be up to one meter long. In its study, the international team of researchers considered the differences between cell types in terms of size, volume, and quantity. As the basis of their calculations, they used a year-old average man, who is 1.

For this man, the researchers determined the number of blood cells, liver cells, bone cells, and skin cells as well as the cells of other organs. Finally, they added the numbers. The primary source for that ratio dates back to the s, when American microbiologists used a series of assumptions to calculate the number of bacteria inside the intestinal tract.

New data show that the number of bacterial cells inside a human body is around 38 trillion. This turns out to be much closer to the estimated 30 trillion human cells in the body. There are three types of blood cells: red blood cells, white blood cells, and platelets. Red blood cells RBCs are by far the most abundant type of cell in the human body, accounting for over 80 percent of all cells.

Adult humans have somewhere around 25 trillion RBCs in their body, on average. Women usually have fewer RBCs than men, while people living at higher altitudes will usually have more.

There are also about million platelets and another 45 million lymphocytes a type of white blood cell in the body, based on recent calculations. There are roughly billion cells in the average male brain according to new research, including about 86 billion neurons. Neurons are cells that help transmit signals throughout the brain. There are also 85 billion other cells in the brain, called glial cells, that help support the neurons. The lifespan of each of the types of cells varies considerably, so not every type of cell is produced at an equal rate.

A good start is to look at the number of RBCs that are produced each day, as RBCs are the most abundant type of cell in the body. RBCs live for about days, at which point they are removed from circulation by macrophages in the spleen and liver. At the same time, specialized stem cells are replacing the dead red blood cells at roughly the same rate. The average body makes about 2 to 3 million red blood cells every second, or about to billion red blood cells per day.

Most, but not all, cells in the body will eventually die and need to be replaced. Fortunately, a healthy human body is capable of maintaining a precise balance between the number of cells produced and the number of cells that die.

For example, as the body is producing between and billion RBCs per day, roughly the same number of RBCs are dying off. For example, white blood cells only live for about 13 days, whereas red blood cells live for about days.

Liver cells, on the other hand, can live up to 18 months. Using more sophisticated methods than before, new research estimates that there are about 30 trillion human cells in the average person. Red blood cells comprise the majority of these cells. Of course, human cells are not the only cells in our bodies. New research has also learned that there are around 38 trillion bacteria in the average human as well.

This brings the grand total to over 68 trillion cells human or not. Over time, scientists will continue to fine-tune these calculations.