Cell Classification And Its Effect On The Human Body

2403 Words Sep 15th, 2016 10 Pages
While water is commonly referred to as the “elixir of life” because of its universal qualities, cells are credited as being responsible for making the human organism “alive”. It is the difference between a cluster of organic atoms or molecules that can react chemically, and a single living cell, the smallest unit of life.
The study of cells is called cytology, and any research usually requires the use of a high-definition microscope, as most cells in the human body are between 1 micrometer (μm) and 100 μm in diameter. However, some cells, such as red blood cells (erythrocytes) or the human oocyte, can theoretically be observed directly as they are larger in size.
Human adults have hundreds of different cell types in their body. A quick search on Wikipedia resulted in a long list of more than 100 types of cells. They are classifed in three broad categories:
1. Cells that are derived primarily from endoderm
2. Cells that are derived primarily from ectoderm
3. Cells that are derived primarily from mesoderm

Endoderm-derived cells are secreting cells, and are subdivided by function into exocrine epithelial cells and hormone-secreting cells. Exocrine epithelial cells are usually gland cells whose function is to secrete fluid, from milk secretion (mammary gland cell), lacrimal gland cell (tear secretion), to salivary gland cells or stomach-lining mucuous cells. Hormone-secreting cells are manifold as well, including thyroid gland and adrenal gland cells,…

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