Growth Hormone

• In multicellular organisms, the distance for substances to enter cells is larger due to a higher surface area to volume ratio
• Multicellular organisms require specialised exchange surfaces for efficient gas exchange of carbon dioxide and oxygen
• Growth hormone, also known as somatotropin, is an anabolic peptide hormone that stimulates growth
• Growth hormone acts directly to reduce the formation of adipose cells, leading to fewer nutrients stored as fat
• Growth hormone acts indirectly via insulin growth factor (IGF), produced by the liver, to increase muscle mass and bone size
• Due to its role in promoting growth and regeneration, some athletes use growth hormone as a performance enhancer
• The use of human growth hormone in sports is banned, with proven cases of doping strictly punished
• Traditional urine testing could not detect doping, historically making bans difficult to enforce
• Recent blood tests can now identify between natural and artificial variants of growth hormone