What is the human body is made of?
The human body is made up of systems, which are made up of organs, which are made up of tissues, which are made of cells and other biological materials made by cells.
The human body is made of various biological systems including the nervous system, cardiovascular system, digestive system (and many more). Each of these systems are made up of organs that allow that particular system to carry out its function.
For instance, the cardiovascular system consists of a heart, veins, arteries and capillaries that carry blood throughout the human body.
Each of these organs is made of tissues, for example the heart is made mostly of muscle and connective tissue. The tissues themselves are made of specialised cells (and their products) that allow those tissues to work together to help the heart pump blood.
Cells are made of biochemical molecules including lipids (eg. fats, membranes), carbohydrates (eg. sugars), nucleic acids (eg. DNA and RNA), and proteins. Smaller compartments within the cells are called organelles. Cells also contain a lot of water (H2O).
All these parts of the body are made by combining chemical elements. Roughly 60% of the adult male human body is made of water. Most of the mass of the human body (96%) is made of oxygen, carbon, hydrogen and nitrogen. Most of the rest is made of traces of the macronutrients calcium, phosphorous, magnesium, sodium, potassium, chlorine and sulphur. Of those macronutrients, calcium and phosphorous are the most common. There is a long list of micronutrients the human body needs a very small amount of to grow and function properly.