The Concise Human Body Book
The number of humans in the world has raced past seven billion (7,000,000,000). More than 250 babies are born every minute, while 150,000 people die daily, with the population increasing by almost three humans per second. Each lives and thinks with, and within, that mostcomplex and marvelous of possessions—a human body.
LEVELS OF ORGANIZATION
To understand the inner structure and workings of the human body, this book takes the “living machine” approach, borrowed from sciences such as engineering. This views the body as a series of integrated systems. Each system carries out one major task. In the cardiovascular system, for example, the heart pumps blood through vessels, to supply every body part with essential oxygen and nutrients. The systems are, in turn, composed of main parts known as organs. For example, the stomach, intestines, and liver are organs of the digestive system. Moving down through the anatomical hierarchy, organs consist of tissues, and tissues are made up of cells. Cells are often called the building blocks of the body. Active and dynamic, they continually grow and specialize, function, die, and replenish themselves, by the millions every second. The whole body contains about 100 trillion cells, of at least 200 different kinds. Science is increasingly able to delve deeper than cells, to the organelles within them, and onward, to the ultimate components of ordinary matter—molecules and atoms.
The study of the body’s structure, and how its cells, tissues, and organs are assembled, is known as human anatomy. For clarity, its elements are often shown in isolation because the inside of the body is a crowded place. Tissues and organs press against one another. Body parts shift continually as we move, breathe, pump blood, and digest food. For example, swallowed food does not simply fall down the gullet into the stomach; it is forced down by waves of muscular contraction.
For a rounded understanding of the body, we need to see human anatomy in combination with physiology—the study of how the body functions. Physiology focuses on the dynamic chemical minutiae at atomic, ionic, and molecular levels. It investigates the workings of such processes as enzyme action, hormone stimulation, DNA synthesis, and how the body stores and uses energy from food. As researchers look closer, and unravel more biochemical pathways, more physiological secrets are unlocked. Much of this research is aimed at preventing or treating disease.
HEALTH AND ILLNESS
Medical science amasses mountains of evidence every year for the best ways to stay healthy. At present, an individual’s genetic inheritance, which is a matter of chance, is the given starting point for maintaining health and well-being. In coming years, treatments such as preimplantation genetic diagnosis (PGN), which is carried out as part of assisted reproductive techniques such as in-vitro fertilization (IVF), and gene therapy will be able to remove or negate some of these chance elements. Many aspects of upbringing have a major impact on health, including factors such as diet—whether it is too rich or too poor. The body can also be affected by many different types of disorders, such as infection by a virus or bacteria, injury, inherited faulty genes, or exposure to toxins in the environment.
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|August 21, 2020|
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