What are the levels of organization?
The human body is a biological wonder with trillions of cells working together to sustain life. Each cell within the body carries out a small job and when these small jobs are compounded by all the other cells you get a living human that can walk, talk, think, and live. With so many cells, it only makes sense to organize the human body in some capacity.
The most basic organization of the human body is into its components that increase in complexity and specificity as you go up the levels of organization. At its most basic you have a single cell, and at its most complex, you have an organ system that carries out a specific job.
Understanding the levels of organization of the human body can allow for a better understanding of ways that you can support your health.
Cells
Cells are the most basic unit of life. Every living thing must be made up of at least one cell for it to be classified as living. Eukaryotic cells are quite complex and contain many different structures known as organelles which aid in their survival. In the case of humans, you have about 30 trillion eukaryotic cells and many more organelles.
Cells can be specialized to carry out a wide variety of functions. Some cells like muscle cells can physically move while other cells like goblet cells in the digestive tract secrete mucus. While these cells have drastically different functions, they both need a steady supply of energy through the mitochondria and cellular respiration.
Tissues
Tissues represent several cells that come together. An example of tissue is muscle tissue. When in isolation a single muscle cell wouldn’t be very useful since it doesn’t have a usable amount of force. When many muscle cells come together, the amount of force generated by the muscle is more useful and can allow for bodily movement.
Organs
Organs are the next classification in which two or more tissues come together to carry out a specific function. In the case of muscles, skeletal muscle would be considered an organ. Nerves innervate muscle tissue and these muscle tissues are attached to the bones of the body. The interaction of two or more tissues is what makes an organ an organ.
The heart, lungs, kidneys, brain, and stomach are examples of organs. A key aspect of organs is that they play assistive roles in bodily functioning and in isolation they are not very useful. For instance, the heart would be useless without the accompanying blood vessels and blood.
Organ system
An organ system level of organization occurs when two or more organs work together to perform a bodily function. As an example, the heart works with the lungs, veins, and arteries to effectively deliver oxygen to all of the cells in the body. The digestive, immune, nervous, endocrine, and integumentary systems represent the major organ systems within the human body.
Organ systems are reliant on one another for optimal functioning so if the health of one organ system declines it will most likely impact other systems. As an example, high blood pressure can place strain on more than just your cardiovascular system and can cause issues with your kidneys, brain, and even your eyes.