The Human Body
The human body is not just a matter of anatomy and physiology, of biology on an organismal and cellular level. Anatomy and physiology are each fascinating subjects. But there is so much more to explore.
You are an ecosystem. There are more microbes on and in you than you have human cells. You have protozoans living in the microbial biome that is your gut. There is bacteria all over your skin, producing a microbial cloud around yourself. Your mouth is a microbiome with bacteria unique to you. There are a plethora of microbial species living together in your stomach and intestines - including E. coli. (Your E. coli is a strain specific to you. It's when you get a foreign strain of E. coli, like one accustomed to living in pigs, that you become ill.) You even have bacteria in your lungs. What's more, these microbes are all beneficial ones. They boost your immunity, make you healthier, keep you from getting sick. And while eating yoghurt can help, it isn't enough because such a source usually only contains one species of probiotic; your body's microbial biome contains entire ecosystems of various species of microbes. Furthermore, exposure to bacteria at a young age can prevent allergies, autoimmune disorders, and asthma later in life.
You are a chemical factory. The biochemistry going on in your cells allows them to communicate with each other and manage their inner worlds. Chemistry allows cells to work together in a tissue, and to send out an alert when a protective white blood cell is needed. Cellular respiration is a complex chemical process that keeps you energized. Your senses work by translating external stimuli into chemical signals your brain can understand. A blot clot forms on your skin as a result of a parade of chemical reactions.
You are a living circuit. Your neurons connect with electrical connections, making your brain a constantly changing electrical pathway. The electricity that runs from your brain or spinal cord depends on the flow of ions that create an electric gradient, which is an electric potential - a voltage. This culminates with the electrical stimulation of muscle cells. Electric principles play a role in other parts of your body, too: your DNA is negatively charged, and is stored in your cells around histones. Histones are molecules that are positively charged to attract DNA and keep it wound tight.
You are a mechanical machine. The study of how your bones and muscles work together to produce movement is called biomechanics. Your arms work as levers, your muscles work against gravity with tensile strength, your knees bend when you land from a jump to absorb the shock.
All of these things work together on the various levels that construct you - cells, tissues, organs, systems. You are a masterpiece for biologists, ecologists, chemists, electricians, and physicists to marvel over.
Which leads to the most remarkable thing of all. You are a conscious being, capable of marveling over your own remarkable design.
Check it Out:
Jonathon Eisen's TED Talk: Meet Your Microbes
'Good Bacteria' Key to Stopping Asthma by James Gallagher, BBC News
"The Inner Life of the Cell" at https://www.youtube.com/watch?v=wJyUtbn0O5Y shows what goes on inside your cells on a cellular/molecular level; chemistry is largely what determines what goes on on a molecular level
Idan Segev's course Synapses, Neurons and Brains from Hebrew University of Jerusalem; a MOOC on Coursera.org
Quick video on biomechanics of human arm: https://www.youtube.com/watch?v=ny8k7LUUIEk