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The hu man body is a very complex set of systems that can withstand enormous challenges as well as accomplish dramatic feats. It can be described chemically, biologically, physically, and in terms of its functions. Chemically, the body is mostly water with additional elements including calcium, nitrogen, oxygen, sodium chloride, iron, phosphorus, potassium, trace minerals, and carbon. The human body is composed of a number of organic compounds that include carbohydrates, lipids, nucleic acids, and proteins.

The carbohydrates supply energy to the body’s cells. The body is maintained by energy derived from chemical reactions with carbohydrates. Lipids are fats that store energy for future use. Some lipids are the material used by the body to make the living cells of the body. Nucleic acids supply cells with instructions to perform their jobs. Proteins also serve as building blocks for cells. Some proteins are enzymes, which perform a variety of functions such as speeding chemical reactions within the body.

Biologically, the human body is composed of cells, which is the basic unit of living things. Cells are mostly composed of proteins and nucleic acids in addition to water. The cells in the human body perform many functions such as providing food and oxygen, eliminating wastes, defending against disease organisms, and regulating body temperature.

They stimulate growth and other activities as well. Each cell, such at blood cells, muscle cells, or brain cells, have unique features.

There are four major kinds of tissue cells. Connective tissue cells join together various parts of the body and also provide support. Most of the connective tissues, such as those attaching bones to muscles, are very strong and can withstand rugged use. The elastic connective tissues attach muscles to bones, or in the case of cartilage, support bones and act as support for motion.

Muscle tissue is fibrous and threadlike, and can contract or stretch in actions that enable a variety of motions, such as work or play. Nervous tissue transmits electro-chemical impulses that act as signals to the brain, muscles, sensory organs, and to other parts of the body. The epithelial tissue covers the body with skin and orifices such as the mouth and throat with a lining. The epithelial tissues protect the body from invasive organisms or from harmful substances.

Some of the tissues in the human body are organized into organs, which perform specialized functions. Groups of organs create networks to perform major functions in the body, such as the digestive system and the nervous system. Organs are composed of two or more types of tissue. The heart is an organ composed of muscle tissue, nervous tissue, and connective tissue.

The human body can be compared to a complex process organized into systems. The major systems include the skeletal, muscular, nervous, respiratory, circulatory, digestive, lymphatic, urinary, endocrine, reproductive, and epidermis (integumentary).

The skeletal system is the body’s framework. It supports the body, protects its vital organs, and enables it to do activities. The skeletal system is composed of 206 bones. Marrow forms the inside of bones and serves as an intricate microstructure fed by the blood. Bones also make red blood cells.

The muscular system consists of 600 muscles of three types that enable the body to move. Skeletal muscles are attached to the bone and are voluntary, meaning they can usually be controlled by the mind. The body’s internal organs have smooth muscles which, unlike skeletal muscles, do not have striations. Smooth muscles are involuntary muscles; they move automatically. Cardiac muscles in the heart are like both smooth and skeletal muscles. They have striations, but operate like smooth muscles with continuous, automatic, rhythmic actions. The heart beats, on average, 70-80 times per minute.

The respiratory system supplies oxygen to the body and removes carbon dioxide, which is a waste gas produced by respiration. The respiratory system includes the trachea (windpipe) and the lungs. Oxygen is needed by the cells of the body to release the energy supplied by food.

The circulatory system is composed of the heart, blood vessels, blood, and the lymphatic system. The heart is a four-chambered hollow muscle that pumps blood throughout the body. The right side receives the oxygen-poor blood and sends it to the lungs. The lungs then return blood to two chambers in the left side of the heart, which then send the oxygen-rich blood out to the brain and the body. The lymphatic system uses lymph, a milky liquid drawn from watery fluids collected around cells. Taken from blood vessels, lymph move slowly into the lymph system running throughout the body. The lymph collects wastes from cell activities, carries nutrients, and delivers white blood cells to various parts of the body. The thymus gland in the upper chest and the spleen are the main glands involved in the lymph system.

Another system that cleanses the body is the urinary system. The kidneys are the pair of organs that do most of the work in the urinary system; they are composed of millions of tiny filtering nephrons that filter salt, urea, and other wastes and water to be removed in the form of urine.

The glands in the endocrine system regulate growth, reproduction, digestion, and other hormonal functions. The major glands are the pineal gland, the hypothalamus, pituitary gland, thyroid gland, adrenal gland, the pancreas, the ovaries or testes, and the placenta during pregnancy. The body produces over 50 hormones that act as messengers to stimulate certain tissues.

The nervous system manages the activities of the other systems with chemical messages. These are transmitted through nerve cells (neurons). The central nervous system, the brain and spinal cord, controls the actions of the body. It receives information from the peripheral nervous system, which is composed of the eyes, ears, nose and other sense organs. The autonomic nervous system communicates messages from the brain’s subconscious to the involuntary muscles and to other automatic bodily functions.

The digestive system enables food and water to be used for the health of the body. Food taken into the mouth is passed down the esophagus into the stomach, where it is converted into chime. This thick liquid passes into the first part of the small intestines, where enzymes from the liver and the pancreas finish the digestion. The second part of the small intestines absorbs substances that can be used by the body. The remainder is passed to the large intestines, which extract water and minerals. What is left is eventually expelled as waste.

The reproductive system ensures the continuation of the species by bringing together the male sperm and the egg for growth in the uterus to produce a baby. Human gestation is nine months.

The skin or integumentary system has three layers. The outer layer, the epidermis, is tough and constantly shedding dead cells as new ones are replaced every several weeks. The skin protects the body from invasive bacteria, viruses, chemicals, and the sun. The middle layer is the dermis. It regulates body temperature; sweat glands are part of the dermis layer. The third later contains subcutaneous tissues that provide storage for fat, act as a cushion, and aid in the retention of heat.

Bibliography:

Anne M. Agur, Grant’s Atlas of Anatomy (Lippincott Williams & Wilkins, 2004);
Ann Baggaley, Jim Hamilton, and Jane Perimutter, Human Body (DK Publishing, , 2001);
Deni Brown, The Visual Dictionary of the Human Body (Eyewitness Visual Dictionary Series), (DK Publishing, 1991);
Carmine D. D. Clemente, Anatomy: A Regional Atlas of the Human Body (Lippincott Williams & Wilkins, 2006);
Barbara Janson Cohen and Jason James Taylor, Memmler’s The Human Body in Health and Disease (Lippincott Williams & Wilkins, 2005);
Henry Gray, Gray’s Anatomy (Barnes & Noble, 2000);
Barbara Herlihy and Nancy K. Maebius, Human Body in Health and Illness (Elsevier Health Sciences, 2002);
Armand Marie Leroi, Mutants: On Genetic Variety and the Human Body (Penguin Group, 2004);
Joseph E. Muscolino, The Muscular System Manual: The Skeletal Muscles of the Human Body (Elsevier Health Sciences, 2004);
Johannes W. Rohen, Chihira Jokochi, and Elke Lutien-Drecoll, Color Atlas of Anatomy: A Photographic Study of the Human Body (Lippincott Williams & Wilkins, 2006);
Gary A. Thibodeau, Anatomy and Physiology (Times Mirror/Mosby College Publishing, 1987);
Gerard J. Tortora and Bryan H. Derrickson, Principles of Anatomy and Physiology with Brief Atlas (John Wiley & Sons, 2005);
Funk & Wagnalls, Atlas of the Body (Rand McNally & Company, 1980).