An Independent Practice Association, or IPA, is an organization comprised of physicians who maintain their independent practices and also join together as an association. The IPA negotiates with organizations, like HMOs, which will supply both patients and income to physicians.
There are 11 major organ systems in the human body, which include the circulatory, respiratory, digestive, excretory, nervous and endocrine systems. The immune, integumentary, skeletal, muscle and reproductive systems are also part of the human body.
There are approximately 7 x 1027 atoms in the average human body. This is the estimate for a 70 kg adult human male. Generally, a smaller person would contain fewer atoms; a larger person would contain more atoms. On average, 87% of the atoms in the body are hydrogen or oxygen. Carbon, hydrogen, nitrogen, and oxygen together account for 99% of the atoms in a person. There are 41 chemical elements found in most people. The exact number of atoms of the trace elements varies widely according to age, diet, and environmental factors.