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Human Anatomy and Physiology


Organs Systems

There are 11 organ systems in the human body.   Each organ system has 2 or more organs.   Note that the eyes, ears, nose, tongue, finger, etc., contain parts of different organ systems.

Integumentary System

The integumentary system is composed of skin, sweat and oil glands, hair, and nails.   This system covers the entire body, regulates body water and heat, and protects the body from harmful substances in the environment.

Skeletal System

This system is composed of bones, cartilage, tendons and ligaments.   It provides support for the body, protects internal organs and provides attachment sites for the organs.

Muscular System

This system is composed of skeletal and smooth muscles.   It provides body movement and protection to other organs.   It also controls the movement of materials through some organs, such as the stomach, intestines, and the heart.

Circulatory System

This system is composed of heart, blood vessels and blood.   It transports nutrients contained in food, water, oxygen, carbon dioxide, hormones, antibodies and wastes through the body.   Blood also transmits heat to the skin for removal, thus maintaining a safe body temperature.


Blood consists of a fluid called plasma and bodies contained in the blood called erythrocytes (red blood cells), leukocytes (white blood cells) and platelets.   Erythrocytes exchange oxygen and carbon dioxide between the lungs and the body tissues.   To combine with oxygen, the erythrocytes must contain a red protein pigment called hemoglobin, which depends on the iron level in the body.   Leukocytes defend the body against infecting organisms and foreign agents, both in the tissues and in the blood itself.   Platelets form blod clots to arrest bleeding.

Blood is classified into 4 groups: A, B, AB and O.   Each group contains A, B, both A and B, or neither (O) antigens (agglutinogens), which are located on the surface of red blood cells.   Antigens stimulate antibodies (agglutines) that destroy invading substances or organisms that do not contain its antigen.   Thus, Group A contains anti-B antigens, Group B contains anti-A antigens, Group AB contains no anti-A nor anti-B antigens, and Group O contains both anti-A and anti-B antigens.   When Group A red cells are mixed with serum (blood having no red calls and clotting agents) containing anti-A antibodies, the red cells agglutinate.   When Group B red cells are mixed with serum containing anti-B antibodies, the read cells agglutinate.   Group AB red cells agglutinate with either anti-A or anti-B antibodies, and Group O red cells do not agglutinate at all.   Therefore, when blood of different types is mixed, illlness or death may occur.   In addition, some blood may contain an Rh (for Rhesus monkey in which it was first discovered) antigen.   This blood is called Rh+.   Other blood is without the Rh antigen and is called Rh-.   Transfusions by people of one type into people with another type can cause serious immune reactions.   For example, women with Rh+ fetal blood can develop reactions to the baby's blood, causing medical problems in the fetus.   A person with AB Rh+ can receive a donation from anyone (a Universal Recipient).   A person with O Rh- can donate blood to anyone (a Universal Donor). How 278

Nervous System

This system is composed of brain, spinal cord and peripheral nerves.   It relays electro-chemical signals to direct muscle movement and, along with the endocrine system, controls physiological processes such as digestion, circulation, sensation, etc.

Respiratory System

The respiratory system is composed of nose, trachea and lungs.   It provides gas exchange between the blood and the environment.   Oxygen is absorbed from the atmosphere into the body and carbon dioxide is expelled from the body.

Digestive System

This system is composed of mouth, esophagus, stomach, small and large intestines.   It breaks down and absorbs food that the cells use for growth and maintenance.

Excretory System

This system is composed of kidneys, ureters, bladder and urethra.   It eliminates those substances that are not used by the cells.   The 2 kidneys separate urea, mineral salts, toxins, and other waste products from the blood.   They also conserve water, salts, and electrolytes.

Endocrine System

This system is composed of many glands, including hypothalamus, pituitary, thyroid, pancreas and adrenal glands.   It sends chemical messages through the body to control physiological processes.

Reproductive System

In the female, this system is composed of ovaries, oviducts, uterus, vagina and mammary glands.   In the male, it is composed of testes, seminal vesicles and penis.   It manufactures cells that result in reproduction when male sperm cells fertilize female egg cells.

Lymphatic and Immune System

This system is composed of lymph, lymph nodes and vessels, white blood cells, and T- and B- cells.   It destroys and removes invading microbes and viruses from the body.   It also removes fat and excess fluids.

Below is a history of significant events about anatomy and physiology:

To 1790

Human body dissection was done in Greece by 500 BCE.   In 180 CE, Galen, a Greek physician, advanced knowledge of animal, including human, physiology by severing animal spinal cords in different places to obtain the effects body functions.   In 1242, the Arabian scholar, Ibn an-Nafis, wrote a book in which he described the heart as two separate ventricles and the lesser circulation through the lungs, but the book was not discovered by Europeans until 1924, so it had no effect on subsequent knowledge of physiology.   In 1316, the Italian anatomist, Mondino de Luzzi, published the first book on anatomy, which was the definitive work on the subject for two centuries.   The eustachian tube was first described by the Italian anatomist, Bartolommeo Eustachio in 1552.   In 1553, a Spanish physician, Miguel Serveto, published a book in which he described the lesser circulation, but the book and author were mostly destroyed by the ruling Calvinists.   In 1559, Realdo Colombo, an Italian physician, was the third person to describe the lesser circulation, and his book became well known.   Vein valves were discovered in 1603 by the Italian physician, Girolamo Fabrici.  In 1623, the English physician, William Harvey, published a book in which he described blood circulation throughout the entire body.   Modern physiology is said to have begun at this point in time.   Lymphatics were discovered in 1653 by the Swedish naturalist, Olof Rudbeck.   Red blood corpuscles were discovered by the Dutch naturalist, Jan Swammerdam in 1658.   Capillaries were discovered by the Italian physician, Marcello Malpighi, in 1660, using the newly invented microscope.   Using the microscope, Robert Hooke, an English physicist, discovered cells in cork   Using the microsope, the Dutch microscopist, Antoni van Leeuwenhoek, discovered microorganisms in 1676.   In 1683 he discovered what we now know to be bacteria. Asimov 45-172






















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