Group+2

=Medicine= Esna Ong (9), Tracy Gani (10), Joanne Tan (13), Rebekah Lee (16), Lidia Wong (18)

__Timeline of key events__
200 A.D. - Medicine field was dominated by Galen, a Greek physician and philosopher 1500 - Paracelsus, a Swiss physician experimented with chemistry 1543 - Andreas Vesalius, wrote //On the Fabric of the Human Body// 1602 - William Harvey received a doctorate of medicine in 1602. 1628 - William Harvey wrote //On the Motion of the Heart and Blood// 1660 - William Harvey's ideas gained greater recognition in this period 1674 - Antonie van Leeuwenhoek made the first observation of microbes 1677 - Antonie van Leeuwenhoek made the first observation of spermatozoa 1700 - Discovery of Smallpox vaccine

__Brief Biographies__
Galen was a Greek physician who specialised in the fields of anatomy, physiology, disease, medicing and philosophy. He mainly relied on animal dissection, specifically apes and monkeys because human dissection was banned. Galen wrote //That the Best Physician is also a Philosopher// which emphasizes the importance of grounding medical practice in theoretically sound knowledge or 'philosophy'. This echoed the belief then, where philosophers used philosophy to tried to explain 'natural philosophy', or science. **
 * Galen (AD 129 - 199/217)

Paracelsus (1493-1541)
Paracelsus was a Renaissance physician, botanist, alchemist, astrologer and general occultist (a notable person involved in a practice). He gave the element Zinc its name, calling it 'zincum' and is regarded as the first systematic botanist. Paracelsus is sometimes referred to as the "Father in Toxicology".

Andreas Vesalius was a Belgian anatomist and physician in the 1530s. He ventured in the field of anatomy, specifically and most significantly, the vascular and circulatory systems. Vesalius was most famous for //De humani corporis fabrica,// which means On the Workings of the Human Body. Vesalius is given the common address as the "Founder of Modern Human Anatomy".
 * Andreas Vesalius (1514 - 1564)**

William Harvey was an English physician who was known for his findings in the fields of medicine and physiology. He was the first to describe correctly and in detail, the systemic circulation and properties of blood. He also established that the blood circulates, while the heart acts as a pump. Harvey was most well known for //On the Motion of the Heart and Blood.//
 * William Harvey (1578 - 1657)**

Antony van Leeuwenhoek is commonly known as the “Father of Microbiology” and is considered to be the first microbiologist. The skill he developed was one of a kind, one which none his profession could surpass during his day. While the compound microscope had already been invented a generation before he was born, they were not practical for magnifying objects more than about 20 or 30 times their natural size. Instead, Leeuwenhoek carefully ground small lenses of very short focal length in order to attain a resolving power greater than that of any of the early compound microscopes. With the great skill he had at grinding lenses, together with his naturally acute eyesight and great care in adjusting the lighting where he worked, he had successfully ground over 500 optical lenses, and created over 400 different types of microscopes (only 9 exist today), which were made of silver or copper metal frames holding the lenses. Out of all his surviving lenses, the highest magnifying power is up to 275 times, and there are indications that he had made even more powerful ones. Hence, it can be said that Leeuwenhoek had contributed significantly to the Microbiology area as his handcrafted microscope was able to examine more tiny things, as compared to before where it was only able to enlarge things.
 * Antonie van Leeuwenhoek (1632 – 1723)**

__Major discoveries & achievements__
In the field of anatomy, Galen taught that there was a group of blood vessels near the back of the brain which was common in humans, but this was later disproved. It turned out that this was found in the primate/monkey anatomy he dissection and based his observations on, but untrue in the case of humans. Galen categorized blood into two categories. 1) Venous blood, which was dark red in colour, originated from the liver. 2) Arterial blood, which was brighter and thinner, originated in the heart.
 * Galen**

In the field of physiology, Galen mused that there were two separate blood systems. 1) One system controlled muscular activities and contained bright red blood moving upward and downward through the arteries. 2) The other system maintained the digestive functions and contained dark red blood that ebbed and flowed in veins.

Galen taught that the body was composed of 4 bodily humors, which when in imbalance, will result in sickness and disease. 1) Blood was warm and moist 2) Yellow bile was warm and dry 3) Phlegm was cold and moist 4) Black bile was cold and dry

**Paracelsus**
He pioneered the use of chemicals and minerals in medicine and believed that man's health was determined by his analogy of the harmony of Man and Nature and that man needed respective balances of minerals in their bodies and chemical remedies could cure illnesses. Paracelsus also came out with the concept that illnesses was the result of the human bod being attacked by outside agents. Paracelsus also came out with the theory that "All things are poison and nothing is without poison, only the dose permits something not to be poisonous." This is true, as even water can be dangerous if over-consumed. And toxic substances may be harmless if consumed in small doses. He also came up with his theory about psychotherapy, or rather unconsciousness that sight and hearing are so strong that humans unconsciously have fantasies about what they have seen or heard.

Vesalius discovered, through human dissection, that the heart had four chambers, and the liver had two lobes. Blood vessels originated in the heart and not the liver, as was believed. He noted that the right atrium linked to the inferior and superior venae cava and the left atrium continued into pulmonary vein. He deduced that the cardiac systole is synchronous with arterial pulse.
 * Andreas Vesalius**

Vesalius disproved Galenic theories and methods using human cadaver dissection. He also disproved medical theories made by Aristotle and Mondino de Liuzzi. He found out that the interventricular septum of the heart was impermeable, and that blood did not pass through the interatrial septum. Unlike what Galen taught, the lower jaw was only one bone, not two. Most importantly, Vesalius disproved the fact that the large blood vessels originated from the liver, because he observed that they came from the heart instead. However, he still believed Galen's theories about the kinds of blood, until William Harvey disproved this theory.

Harvey observed the structure of the heart, as well as analysed the arteries. He saw that contraction of the left ventricle affects pulsation, while contraction of the right ventricle propels blood into the pulmonary artery, and that the two ventricles move together almost simultaneously.
 * William Harvey**

Using mathematics, Harvey disputed Galen's theory about blood circulation. Galen thought that the liver was the origin of venous blood, but Harvey estimated the capacity of the heart, that the amount of blood expelled through each pump of the heart and the amount of times the heart beats in half an hour.

//"He estimated that the capacity of the heart was 1.5 ounces, and that every time the heart pumps, 1/8 of that blood is expelled. This led to Harvey's estimate that about 1/6 of an ounce of blood went through the heart every time it pumped. The next estimate he used was that the heart beats 1000 times every half an hour, which gave 10 pounds 6 ounces of blood in a half an hour, and when this number was multiplied by 48 half hours in a day he realized that the liver would have to produce 540 pounds of blood in a day.

Having this simple but essential mathematical proportion at hand, Harvey proved the overall impossible aforementioned role of the liver."//

Harvey was the one who conducted the famous, Vein Experiment.

"Harvey noticed that as he tied the veins, the heart would become empty, while as he did the same to the arteris, the organ would swell up. //This process was later performed on the human body: the physician tied a tight ligature onto the upper arm of a person. This would cut off blood flow from the arteries and the veins. When this was done, the arm below the ligature was cool and pale, while above the ligature it was warm and swollen. The ligature was loosened slightly, which allowed blood from the arteries to come into the arm, since arteries are deeper in the flesh than the veins. When this was done, the opposite effect was seen in the lower arm. It was now warm and swollen.// //The veins were also more visible, since now they were full of blood. Harvey then noticed little bumps in the veins, which he realized were the valves of the veins, discovered by his teacher, Hieronymous Fabricius. Harvey tried to push blood in the vein down the arm, but to no avail. When he tried to push it up the arm, it moved quite easily. The same effect was seen in other veins of the body, except the veins in the neck. Those veins were different from the others - they did not allow veins to flow up, but only down. This led Harvey to believe that the veins allowed blood to flow to the heart, and the veins maintained the one way flow."//

Arguably Leeuwenhoek’s greatest discovery would in 1674, when he made the first observation of microbes, which comprised of red blood cells as well as Infusoria (diverse group of eukaryotic microorganisms). In addition, 3 years down the road, he was also the first to describe spermatozoa (more commonly known as the sperm cell) from insects, dogs and man. Leeuwenhoek was able to calculate the sizes of bacteria and protozoa.
 * Antonie van Leeuwenhoek**

Inside a small drop of water, he found very little animalcules. He described the green Charaphyte alga Spirogyra: “Passing just lately over this lake, ... and examining this water next day, I found floating therein divers earthly particles and some green streaks, spirally wound serpent-wise, and orderly arranged, after the manner of the copper of tin worms, which distillers use to cool their liquors... whole circumference of each of these streaks was about the thickness of a hair...all consisted of very small green globules joined together: and there were very many small green globules as well.”

Upon studying them, he discovered that microbes could be found in many places (wells, ponds, in rain water, in the mouths and intestines of human beings). Along with other men (such as Robert Hooke), Leeuwenhoek contributed to the Cell Theory, which states:

1. A cell is the smallest unit able to carry out life processes (cells are the basic unit of structure and function of living organisms). 2. All living things or organisms are made up of one or more cells. 3. All cells come from only other living cells (new cells are created by old cells dividing into two).

__Significance of discoveries & achievements__
**Andreas Vesalius The significance and impact that Vesalius made in the field of anatomy in his discoveries were great, but even greater was the method and way in which he went about his experimentation. Vesalius yearned to provide the most accurate form of the human body, and often recorded his observations in neat and accurate drawings or other visual representations. By disproving Galenic tradition and overcoming them, Vesalius created a new scientific method by depending on his own observations. He corrected his own claims and continually reshaped his thoughts on the human body. His close observation and attention to details allowed him to provide clear description and unprecedented anatomical drawings.

Antonie van Leeuwenhoek** The invention of a more powerful microscope by Leeuwenhoek contributed to 17th century intellectual arguments about the origins of life. The discovery of the microscope has enabled man to learn a great deal about life on the atomic and microscopic level. Leeuwenhoek’s microscopes were far superior to any previous models, and enabled him to discover capillary systems, protozoa and bacteria. He also observed various plant and muscle tissue as well as the life cycle of ants. Currently, modern microscopes allow the intense study of organisms and life on atomic levels. Hence, it can be seen from here that progress in science owes much to the advent of the microscope, which Leeuwenhoek had played a great part in. As mentioned earlier, Leeuwonheok had contributed to the Cell Theory, which still remains largely true today. In fact, it is very important as it provides one of the great unifying theories in biology: regardless of the vast diversity of organisms, they are all united at a very fundamental level, namely the presence of cells. It is this basis which future scientists carried out their research, and hence it can be seen that Leeuwenhoek had contributed much to this aspect.


 * __References__**

http://www.strangescience.net/leeuwenhoek.htm http://en.wikipedia.org/wiki/Anton_van_Leeuwenhoek http://www.whonamedit.com/doctor.cfm/1593.html http://www.essentialvermeer.com/dutch-painters/dutch_art/leeuwenhoek.html http://en.wikipedia.org/wiki/Infusoria http://www.ucmp.berkeley.edu/history/leeuwenhoek.html http://en.wikipedia.org/wiki/Microscope http://www.microscope-microscope.org/basic/microscope-history.htm http://www.bio.miami.edu/~cmallery/150/unity/cell.text.htm http://biology.about.com/od/biologydictionary/g/celltheory.htm http://leeuwenhoek.wordpress.com/2010/01/16/leeuwenhoeks-zoological-researches/ http://en.wikipedia.org/wiki/Paracelsus