The human body has a highly complex structure that is still not fully understood, and even after the huge revelations from the human genome investigations, there is still a very long way to go.
Although the body is just one structure, its composition involves countless structures within it which have to work in full orchestration and unity.
A HUNDRED TRILLION CELLS
Our bodies are miraculously composed of close to a hundred trillion cells which are the smallest units essential to life. There are various types of cells, all with a specific function, for example: stem cells, red blood cells, white blood cells, skin cells, nerve cells (neurons), muscle cells, gametes (sex cells for reproduction), liver cells, and so on, running into hundreds of variations. All cells work in unison 24/7 to carry out the body’s myriad of intricate functions.
Many cells are protected by a membrane which has numerous purposes including identifying other cells, and cell to cell communication. Some cells generate chemicals such as the hormone insulin; and others take in chemicals such as oxygen. The vast communication of electrical and chemical signals between the central nervous system (the brain and spinal cord) and the rest of the body, is billions of times more complex than the most technologically advanced computer system any where in the world!
Tissues are a concentration of similar cells that execute a common function. They are classed into four categories: connective tissue, epithelial tissue, muscle tissue, and nervous tissue.
Organs are composed of several types of tissue which carrying out a specific function; one good example is the stomach which comprises a combination of: connective, muscle, nervous and epithelial tissues.
Systems are the most intricate units in the entire body. They are an amalgamation of different organs which work in unison to carry out complicated functions. There are ten main systems: the endocrine (hormonal), nervous, muscular, skeletal, respiratory, cardiovascular, urinary, digestive, lymphatic, and reproductive system.