Modern Medicine Flashcards
Ideas about the Causes of Disease at the Start of the 20th Century
-By 1900, Germ Theory had been around for 40 years and microbes had been clearly linked to the outbreak of disease. People widely understood what caused common diseases.
-Doctors no longer referred to miasma, the Four Humours or the supernatural when diagnosing disease. They now worked solely with scientific discoveries and evidence- not just ideas.
-However, it was also clear that microbes did not cause all disease. For example, some babies were born with conditions that seemed to develop inside the womb. This fact stumped doctors for the first half of the 20th century.
Early Research into Genetics
-By 1900, a German scientist, Mendel, theorised that genes come in pairs and one is inherited from each parent. These were called the fundamental laws of inheritance.
-However, there was no scientific proof for that these laws were correct. This was because microscopes were not yet powerful enough to identify gene pairs.
-In 1902, an English doctor, Archibald Garrod theorised that hereditary diseases are caused by missing information in the body’s chemical pathway.
-In 1941, Garrod’s theory was proved correct by two American scientists, Beadle and Tatum.
Research into Genetics During the 1950s
-By 1951, scientists knew that characteristics were passed down from parents to children, as children often look like their parents.
-They also theorised that a substance in human cells passed this information on from one person to the next. This substance also passed on a variety of hereditary diseases.
-In 1951, at King’s College London, Rosalind Franklin and Maurice Wilkins created images of DNA using x-rays.
-However, it was not until 1953 that technology finally made it possible for scientists to finally find DNA.
Watson, Crick and the Discovery of the Human Gene
-In 1953, Watson and Crick were sharing an office whilst working at Cambridge University. They both had a strong interest in researching human biology.
-They saw the x-rays produced by Franklin and Wilkins and built their model of DNA. They shared it with Franklin who made corrections. Wilkins also shared clearer photographs of DNA.
-Watson and Crick were then able to discover the structure of DNA- shaped like a double helix which could then unzip itself to make copies. They published their paper in 1953.
-Understanding the shape of DNA meant they could now look at its structure and identify the parts that caused hereditary diseases.
The Mapping of the Human Genome
-Once the structure of DNA was understood, teams of scientists began to break it apart to understand how it worked.
-Understanding that information -mapping the DNA’s code- was vital to helping scientists understand the cause of genetic diseases such as haemophilia.
The Human Genome Project
-The Human Genome Project was launched in 1990 and was originally led by Watson. For a decade, 18 teams of scientists worldwide worked together to map the human genome.
-Despite hundreds of scientists working towards this, it was not until 2000 that the first draft was completed.
-Once the human genome was mapped, it was possible for scientists to use this blueprint of DNA to look for mistakes in the DNA of those suffering from hereditary diseases.
-For example, a gene often found in women with breast cancer can now be identified. This can’t treat breast cancer but gives women the opportunity to prevent it by having a mastectomy.
The Role of Technology in the Development of Genetics
-Advances in microscopes and the ability to produce higher-powered images enabled scientists to identify the DNA and then start to examine how it is formed.
-In 1931, the electron microscope was first developed.
-It could produce an image clearly 10,000,000 times magnified whereas an optical microscope could only clearly magnify a sample up to 2000 times.
The Role of Science in the Development of Genetics
-Understanding DNA required a lot of collaboration on the part of the scientific community.
-The Human Genome Project was an example of a new kind of ‘big science’ -thousands of scientists all over the world collaborating to solve the same puzzle.
-All the data produced from the study was made public so that it could benefit as many people as possible.
The Impact of the Science of Genetics
-A better understanding of DNA and how the genome affects the body has helped scientists recognise genetic disorders such as Huntingdon’s and Down Syndrome.
-This could theoretically lead to treatments in some cases if scientists could somehow put the missing genetic information back in the genome. However, this is not a current treatment.
-A good understanding of genetics has led to a better understanding of the causes of disease but science is not yet at the stage where treatments of this nature are readily available.
The Influence of Smoking on Health
-Smoking became popular during the 1920s and was associated with being young and free. During the 1950s, doctors saw a rise in the number of men suffering from lung cancer. This was linked with smoking.
-Doctors now recognise that smoking is associated with a large variety of diseases, including high blood pressure, cancer (e.g lung and mouth), heart disease, gum disease and tooth decay.
-Smoking is the biggest cause of preventable disease in the world. It is even dangerous to those who inhale the smoke second-hand.
-Studies show children who are exposed to second hand smoke are more likely to develop asthma than those who do not.
The Influence of Diet on Health
-Due to the Theory of the Four Humours, our Medieval ancestors believed what we ate had a huge impact on our health.
-Although the Theory is rejected today, we now recognise that diet has a huge impact on health (but in different ways to those suggested in the Middle Ages).
-It is important to have a balanced diet including plenty of fruits and vegetables with other foods in moderation.
-Too much sugar can lead to type 2 diabetes, an incurable disease where the body is unable to process sugar in the blood. Too much fat can cause heart disease.
The Influence of Alcohol, Tanning and Unprotected Sex on Health
-Alcohol is a liquid drug. Drinking too much either through binge drinking or drinking a lot over a long period of time can lead to diseases and kidney problems.
-People now recognise that sharing bodily fluids with other people, either through intravenous drug use or unprotected sex can lead to the spread of certain diseases.
-The fashion of tanning, either naturally or using sun beds, has led to a rise in the number of cases of skin cancer worldwide.
Diagnosis at the Beginning of the 20th Century
-At the start of the 20th century, diagnosis would happen between a doctor and patient.
-The doctor would observe the patient and consider the symptoms.
-He would consult medical textbooks and diagnose based on this knowledge.
Changes in Diagnosis During the 20th Century
-During the 20th century, there was a move towards laboratory medicine with more examination of samples. These samples might include skin or blood or detailed samples of flesh gathered in a biopsy.
-These samples would be examined by medical scientists in a lab using microscopes and other technology. An x-ray of the patient may also be taken so doctors could see inside the body and use the images to identify a cause of disease.
-This additional information means diagnosis is now more accurate. The exact microbe causing disease can be identified and targeted. Diagnosis is based on medical testing rather than the doctor’s knowledge and experience.
New Methods of Diagnosis
-The enormous leap forward in technology since 1900 has made diagnosing disease much more accurate. This has, in turn, had a huge impact on the doctor’s ability to treat patients.
-The development of computers and machines has enabled doctors to have a better understanding of a patient’s disease than in any previous time.
-For example, x-rays and CT scans mean that doctors no longer have to use surgery to diagnose all diseases.
The Use of X-rays, MRI and CT scans to Diagnose Disease
-X-rays (from the 1890s) help to see inside the human body without cutting into it. Since the start of the 20th century, they have helped diagnose problems such as broken bones.
-MRI scans (from the 1970s) use magnets and radio waves to create an internal image of the body. They are better suited to diagnosing soft tissue injuries, such as ligament damage, than x-rays.
-CT scans (from the 1970s) are a more advanced form of x-rays. They can be used to diagnose tumours and other growths in the body.
The Use of Endoscopes, ECGs and Ultrasound scans to Diagnose Disease
-Endoscopes (from the 1900s) use a camera on the end of a thin, flexible tube to see inside the body. They are most commonly used to investigate digestive symptoms such as vomiting blood.
-Sometimes, they can be used in treatment, by carrying small surgical instruments into the body.
-ECGs (1900s) use electrical impulses to track heart activity.
-Ultrasound scans (from the 1940s) use sound waves to build up a picture of the inside of the body. They are helpful for diagnosing things like galls tones and kidney stones.
The Use of Blood Tests, Blood Pressure Monitors and Blood Sugar Monitoring to Diagnose Disease
-Blood pressure monitors (from the 1880s)help to diagnose high and low blood pressure.
-Blood sugar monitoring (from the 1960s) allows people who suffer from diabetes to check their blood sugar regularly to ensure they manage their condition.
-Blood tests (from the 1930s) use blood samples to test for an enormous number of conditions without the need for invasive diagnosis methods.
The First Chemical Cures: Magic Bullets
-The term ‘Magic Bullet’ was used to describe a chemical cure that would attack the microbes in the body causing disease, whilst at the same time leaving the body unharmed.
-In the late 1800s, more microbes causing specific diseases were being discovered. This meant scientists could now search for substances to attack and destroy these microbes.
-Doctors now understood that the body produces antibodies to fight diseases. They tried to find artificial or chemical antibodies that would work in the same way- attacking the infection without harming the body.
The Development of the First Magic Bullet: Salvarsan 606
-In 1900, Paul Ehrlich came up with a theory that a chemical compound could be developed that targeted one specific microbe without damaging other cells in the body.
-Between 1906 and 1909, he systematically tested different compounds to find any that killed the bacteria which causes syphilis. By 1907, he had tested over 600 compounds with no success.
-In 1909, Ehrlich’s assistant, Hata, retested all of the compounds and discovered that the 606th cured syphilis. This was the first ‘magic bullet’. Ehrlich’s worked later helped more effective medicines to be developed.
-However, Salvarsan 606 was hard to administer and could be harmful to the patient too.
The Development of the Second Magic Bullet: Prontosil
-In 1932, scientist Gerhard Domagk discovered that a bright red dye called Prontosil ( a sulphonamide antibiotic medicine) killed bacterial infections in mice. He tested it on his daughter who had blood poisoning and it cured her.
-Scientists at the Pasteur Institute in Paris discovered that Prontosil worked by preventing the bacteria from multiplying inside the body. This made it possible for the body’s own immune system to kill the bacteria.
-Scientists began looking for other drugs that worked in the same way. In 1938, British scientists developed M+B 693. It was successfully used to treat Churchill for Pneumonia during WW2.
Problems with Sulphonamides
-The chemical that worked is Prontosil was a sulphonamide. They killed lots of germs so other sulphonamides were developed.
-However, they caused liver damage and were totally ineffective against particularly strong diseases.
-This meant the wait for truly effective antibiotics continued until the discovery of Penicillin.
The First Antibiotic: Penicillin
-The term antibiotic is used to describe any treatment that destroys or limits the growth of bacteria in the human body.
-The first true antibiotic was penicillin. Penicillin was different to Salvarsan 606 as it was created using microorganisms, not chemicals.
-Penicillin had been seen before but not developed. Lister has used it on a patient in 1871 and it had been note that mouldy bread had healing properties in the Middle Ages.
-Fleming published his work at a time when chemical cures were being actively looked for so people took more notice of penicillin than before.
-Penicillin was isolated from a mould sample by Fleming and developed into a usable treatment by Florey and Chain.
The Second Antibiotic: Streptomycin
-Inspired by the discovery of antibiotics, other scientists investigated moulds and fungi in the search for more antibiotics.
-Streptomycin was discovered by scientist Selman Wakston in 1943. This antibiotic was so powerful that it was even effective against tuberculosis, which had previously been thought incurable.
-During the 1950s and 1960s, even more antibiotics were discovered.
Recent Developments into New Antibiotics
-In the 21st century, pharmaceutical companies continue to test substances to develop new antibiotics. This is because some bacteria have developed a resistance to the antibiotics we already have.
-If new treatments are not developed, scientists fear that old antibiotics will become totally ineffective against diseases that we think we have beaten such as septicaemia.
-Therefore, in the short term, antibiotics have been a miracle cure for a variety of diseases. However, their long-term impact is yet to be measured.
The Impact of Science on Advances in Medicine
-Scientists have now developed medicines that pinpoint and treat specific diseases.
-Even if they are unable to cure some diseases, such as diabetes and lung cancer, treatments have been developed to help patients manage their illnesses.
-Improved scientific understanding has also led to better testing and trialling of new treatments. It now takes several years for a new drug to be trialled and released. This slows down progress but ensures drugs are safe for everyone.
-Before, drugs did not have to go through this process, meaning mistakes were made. In the 1960s, thalidomide was used to treat pregnant women for morning sickness but caused birth defects instead.
The Impact of Technology on Advances in Medicine
-The mass production of pills has made the distribution of drugs much easier.
-The development of capsules which dissolve in the stomach to release the drug means taking taking drugs is easier.
-Hypodermic needles allow the precise dose to be introduced directly into the bloodstream.
-Insulin pumps for young people suffering from diabetes deliver insulin without the need for injections.
Alexander Fleming
-Fleming was a British doctor working in a hospital in London.
-He had a particular interest in studying bacteria and had been one of the first doctors to use the first ‘magic bullet’ to treat syphilis.
-He had worked in battlefield hospitals during WW1 to improve treatments for soldiers with infections which often killed them.
-He rejected the idea that infection and the death it caused were unavoidable medical problems. He was dismayed at the number of soldiers dying from simple infection and believed there must be a way to avoid it.
