The Human Body – An Incredible Human Machine

Healthy Eating Habits and Exercise

The human body is an extraordinary machine. Designed to house our soul and spirit, it is also the vehicle that transports us through life’s journey. There is nothing more mysterious, more breathtaking in its conception, marvellous in its mechanics, exquisite in its range of senses and staggering in our ability to understand the daily miracle routines of the human body. Our instruments, engines, infrastructure, roadways and circuitry – through 10 000 blinks – 20 000 breaths – 100 000 beats are mere ordinary functions in the life of the incredible human machine.

More than 7 billion human bodies live on earth, and while the blueprint is 99.9% identical, no two of us are the same. Your cells, sensors, muscles, bones, heart and brain must marshal all their forces together to get you through your daily activities. Your skin is the body’s largest organ that keeps you in and the world out. It’s your armour, your radiator, your entry to pain and pleasure.

In microseconds, your eye sights, follows, focuses and processes images fractions of an inch long or moving at hundreds of miles per hour, enabling us to access and appreciate the world around us more than any other sense. Not only are they the window to our soul, but there are more than a hundred and twenty million photoreceptors converting light into electrical impulses before processing and shipping them off to the brain.

Not only are our ears the body’s microphones, but they also give us balance and tell us where we are in space. Walking, cycling, diving, or just playing a game of tennis would be impossible without the intricate gadgetry deep inside our ears. We hardly ever think of the trauma we cause in our voice boxes when we laugh or scream. High performer vocalist vocal cords are slamming together at an average of 170 times a second to produce the magical melodies that we enjoy listening to.

Without taking a breath, we will not be able to survive. More than three hundred million tiny alveoli are spread across both our lungs. In less than one second, oxygen molecules exit the lungs through walls just one cell thick. They then cross into a surging bloodstream and are whisked throughout the body to provide precious resources to every one of our trillion of cells. Being a smoker, oxygen can’t empty properly into the lungs due to damaged bronchioles. On the exhalation, carbon dioxide, the waste product of breathing, makes the opposite journey back out.

The heart is a muscular pump to its core. Even if it is removed, it can still function on its own. Every breath we take deliver oxygen to our trillions of power-hungry cells that get our heart to pump. More than a gallon of blood needs to travel through some 60 000 miles of arteries, veins and capillaries, and only one little 10-ounce heart has the mammoth task of driving the whole system. It begins with a heartbeat that sends fresh oxygenated blood from the lungs streaming into the heart. Its genius lies in its millions of cardiac cells beating in unity. Blood circulates in less than a minute all around the body every minute of our lives. The more oxygen our cells burn, the harder our heart and blood vessels have to work to deliver more. When we eat, blood rushes to our stomach and when we run to our muscles. Even when you read a book, more oxygen must get to your brain.

It takes more than air to feed the body machine. It takes fuel. Every time you swallow a morsel of food, we send it out on a journey designed to suck everything useful out of it. Sitting down for lunch, we convert plants or animals into energy and absorb their chemical building blocks into our own flesh and blood. Carbohydrates, proteins, fats, vitamins, minerals and nutrients all come from what we eat. Just the idea of food can get your mouth to water. Once we swallowed our food from thereon, it gets squeezed like toothpaste through the digestive system. Highly acidic gastro juices are released from the walls of your stomach, which is only about a fist-size big. But after a big meal, it can expand to about 20 times its size. It breaks down the protein in our food while muscle contractions knead and chard it into a pulp. It absorbs very few nutrients, though. Food now passes through the 20-foot disassembly line of the small intestine. For approximately 5 hours, the foods building blocks are pushed, prodded and sprayed with digestive juices until their vital elements are forced through the intestinal wall and into the bloodstream. From here, most of the nutrients will flow directly to the liver, the body’s largest internal organ. The liver breaks down, repackages and delivers nutrients to our cells for growth and power. Our body ultimately tries to balance energy intake but sometimes more goes in than goes out. As a result, you get fat. It doesn’t take a lot of excess calories to allow weight gain. Only 15 calories more a day, the amount in just 4 pistachio nuts, will add a pound and a half of fat (700 grams) over a year.

Once the small intestine has done its work, food is pushed through to the large intestine. The last of the water is absorbed for the next couple of hours, and billions of bacteria work to break down the remaining contents. In the end, anything we can’t digest gets flushed out of our bodies. The complicated journey of food has a larger purpose. Once we’ve extracted what we need to feed the incredible machine and our engines are humming, it is nothing but astounding what we can do with it thanks to amazing contractions called muscles.

From the soles of our feet to the tips of our fingers, 650 muscles – about 40% of our body mass, power every move we make. As our day pushes on, our skeletal muscles lift us through it, usually without us thinking about it. Without them, we cannot run, blink, smile or speak. Just muttering a single word involves muscles in the face, lips, tongue, jaw and throat. 34 Muscles in the face are needed to deliver a kiss. Walking, which we take for granted, requires 200 skeletal muscles. Back muscles keep you from falling forward, and abdominal muscles keep you from falling backwards. It takes 40 muscles to raise one leg and move it forward. Add onto that running, shooting, riding and fencing, and you get an idea of how many muscles are being used.

If we zoom into a muscle fibre, we find 2 proteins, actin and myosin, and their action couldn’t be simpler. They link up, squeezing together like cox on a wheel, and then they relax, releasing their grip and going back to normal. From binding and releasing all our skeletal muscles, we get our every motion. The more we work our muscles, the more actin and myosin we make and the bulkier our skeletal muscles become.

Nerves to muscles are an intricate and delicate system and marvellous to behold. To lift a dumbbell, your brain sends an electrical impulse down to your skeletal muscle, telling the actin and myosin to bind and release. But for our muscles to work, that signal from the brain must get through. Follow any muscle to its base, to a bundle of strong, flexible fibres called tendons, down to the very point where it is anchored, and you will find one of the world’s most remarkable materials – bone.

Some 206 of these engineering marvels are strewed throughout the body. Strong enough to support up to 20 times our body weight, light enough to defy gravity, however briefly, flexible enough to absorb impacts and connected in such a way to provide an unseeingly endless range of movement. Bones are what give us our shape, and it provides 15% of our body mass. Deep in the centre of many bones is this tissue called marrow. Some 20 million oxygen-carrying red blood cells and 7 million micro fighting white blood cells are born every minute and shipped off to the rest of the body. Towards the surface, specialised cells continually lay down new bone while others whisk away layers of old bone. This is how we grow in our youth and how bone keeps itself strong in our adult life. Bone is made up of two substances, and they are a match made in heaven. Without flexible collagen, the bone would be as brittle as glass. Without calcium phosphate, it would be as unstructured as rubber. Together they are light enough to manoeuvre, strong enough to shelter our most delicate organs and resilient enough to last a lifetime.

The unsung heroes of all this movement are not our bones but what brings them together – ingenious devises called joints. From our knees to our knuckles, some 187 separate joints allow our bones to slide back and forth, side to side, up and down, and also round and round like a well-oiled machine. Bones almost have a miraculous tendency to heal themselves, but joints are prone to break down.

Billions of neurons are buzzing around in your head with all the nerve cells you will ever need. Throughout your childhood, your neurons will reach out to other neurons in your brain to make connections with them through each new experience. With each connection, your mind and body fuse to form the thing that is you, and at the helm of this, the most remarkable command centre in the world. All systems in the body are complex, but there is only one presiding over everything we do. The second your day begins, your brain has been guiding, guarding, giving orders defining nothing less than what you are. Through the information superhighway of nerves fanning throughout our bodies, our brain keeps tab of every part of us, eyes and ears, skin and bones, heart and muscles. 100 Billion specialised cells called neurons, millions of electrical and chemical signals move up to 200 miles per hour. This 3 pounds blob of fat and water let us think, feel, want, remember and act. It is our brains that set us apart from any other species and one another. Thoughts, feelings and selfhood are fragile. Even though the brain is only 2% of our body weight, it exhausts 20% of our oxygen. Unlike other cells in our body, when neurons get damaged, they are replaceable.

From its surface to its core, amongst its billions of cells, roadways and circuitries, at the end of the day, somehow all of these systems converge into one truly incredible design. While we sleep, our bodies are always working, always breathing, always beating and always ready to begin another day.

Humans want more out of life than merely to survive – We are built to thrive!