CONCLUSION
Discoveries in the field of epigenetics, which increase every year, convince us that genes are not a sentence: it does not matter whether we inherit "good" or "bad" genes, it is important how we use them. Most people probably have the potential for active long life in their genes. And in the future, no doubt, we will find a way to unlock it.
CHAPTER 4
BODY
IF YOU WANT TO PROPERLY USE SUCH A COMPLEX MECHANISM AS THE HUMAN BODY, IT IS NECESSARY TO UNDERSTAND HOW IT IS BUILT. A HUMAN IS VULNERABLE TO DISEASE WITHOUT KNOWING THEIR PHYSIOLOGY. THE MAIN TASK OF THOSE WHO WANT TO BE HEALTHY AND LIVE LONGER IS TO SUPPORT THE WORK OF THE BODY.
WHAT OUR BODY IS
CELLS
The human body is made up of cells, the basic structural units, which work together and perform the various functions necessary to sustain life.
The human body weighing 70 kilograms consists of an average of 30 trillion cells. And most of them are erythrocytes they account for 84 %. Then there are thrombocytes 4.9 %, bone marrow cells 2.5 %, vascular endothelial cells 2.1 %, lymphocytes 1.6 %, and hepatocytes 0.8 %. Muscle and fat cells account for 0.1 % of the total cell number[42].
For the body to function properly, there is a continuous process of replacing old cells with new ones. About 3.8 million cells are renewed every second, and almost 330 billion cells per day. Even when a human dies, it will be a while before all the cells in the body die.
Researchers at the Karolinska Institute (Sweden), led by biologist Jonas Friesen, calculated the lifespan of individual cells, finding that they change differently depending on the type[43]. For example, the epidermal cells that make up human skin are renewed every two weeks. Erythrocytes, which carry oxygen from the lungs to the tissues of the body, live for four months, while neutrophils, a type of white blood cell, live only for two days.
The life of liver cells is between 300 and 500 days. The epithelial cells lining the intestine last only five days and then are replaced by new cells they are among the shortest-lived in the body. Without them, the average age of all intestinal cells is 15.9 years. Skeletal tissue cells live about 10 years, while cells of rib muscles live 15.1 years[44].
But not all cells are renewed: for example, the cells of the retina and lens do not change throughout life. This explains the natural deterioration of vision with age. For a long time, it was believed that nerve cells also live as long as humans, die with aging, and do not renew. However, recent data have shown that new neurons are formed from stem cells, but it is not yet known how functionally full-fledged they can be. Scientists estimate that the adult male brain contains 86.1 ± 8.1 billion neurons[45].
According to Friesen, the average lifespan of a human cell is 710 years. This statement has caused the popular misconception that "the human body renews every seven years." This is not true, because cell replacement is a continuous process: the body renews in different parts at different rates depending on the needs and functions.
ATOMS
At a more fundamental level, cells consist of molecules, which, in turn, consist of atoms (from Greek ἄτομος "uncuttable"). An adult human body weighing 70 kg contains about 6.7 octillion (6.7 × 10
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Most of the chemical elements come from the environment. When we eat, drink, or breathe, atoms enter the body. They not only compose cellular structure but also ensure the flow of chemical processes, supporting vital activity.
When we exhale, sweat, or lose body tissues, i.e., excrete anything into the environment, the atoms return to the Earth's biosphere. From there they enter the bodies of other people, animals, and plants. Thus, most of the atoms in the body are constantly replaced. And they do it differently some in a few hours, others in a few years.
All these atoms are not regenerated every day. They have been around for billions of years and existed long before the Earth was formed. The first atoms formed in the early days of the universe, 13.7 billion years ago, about 380,000 years after the Big Bang. By that time, the universe had already cooled enough for electrons and protons to combine and form hydrogen and helium. The first stars were born from these atoms, and because of nuclear reactions in them, other heavier elements were formed.
Every particle of our body was once inside such stars or was formed because of its death. "Every atom in your body came from a star that exploded. It is the most poetic thing I know about physics. And, the atoms in your left hand probably came from a different star than your right hand. You are all stardust," writes physicist Lawrence Krauss in his book "A Universe from Nothing."
BODY SYSTEMS
Cells composed of atoms form tissues: epithelial, connective, muscular, and nervous. And tissues form organs. The latter, in turn, are combined into systems.
All systems interact closely with each other. For example, the digestive system provides the intake of nutrients in the blood for energy. However, the cells can produce energy only with oxygen, which is supplied by the respiratory system.
HOMEOSTASIS
Each cell can only function under certain conditions: temperature, acidity level (pH), a certain concentration of fluids, electrolytes, and oxygen there are a lot of factors. Maintaining the balance of the body's systems necessary to sustain life is called homeostasis.
Under the influence of harmful factors which can damage the body, there is a redistribution of innate resources: with hypothermia, the body provides a flow of extra blood and, consequently, heat to the vital organs by narrowing the blood vessels of the skin. When overheated, on the contrary, skin vessels expand, which increases heat loss and remains constant internal temperature.
A well-established system of self-regulation is the most crucial component for a long and healthy life. The functioning of the body allows it to respond adequately to dangers and adapt to changing environmental conditions. Dysfunction in one organ inevitably affects the functioning of other organs and systems. For this reason, in old age people often face several diseases at once, each of which provokes and accelerates the progression of other disorders. A complication of diabetes mellitus, which is often associated with obesity, is a vascular disruption in the whole body, which in turn increases the risk of cardiovascular disease. Joint problems limit a person's mobility, which contributes to weight gain, which, in turn, puts stress on the joints. It is a developmental factor of a wide range of diseases.
It is very important to bear in mind that even a small health issue may result in a cascade of abnormal changes that lead to serious diseases. Even a small nidus of persistent infection, such as a decayed tooth or chronic tonsillitis, provokes the development of inflammation in the digestive tract and creates determinants for intestinal issues. Any violation in the supply of macro and micronutrients will affect every body's cell function with time.
Both physical and mental aspects are important for keeping a healthy body. It is known that chronic stress is an equally important contributor to disease than, for example, nutritional disorder, physical inactivity, or bad habits. On the background of distress, the level of cortisol a hormone of chronic stress increases, which negatively affects the immune system, provokes obesity and increases the risk of depression.