1
1.4 Extending skills
The publication of a book by William Harvey in 1628
describing the circulation of blood in the body could be seen as the next landmark stage of development, essentially marking the basis of modern physiology. Along with developments in chemistry which took place around the same time, this meant that the body could be studied rationally as a functioning system for the first time. Another significant development was the discovery
of vaccination. This was in use in England from the 1730s. Children were deliberately infected with small amounts of smallpox so that they would develop a resistance to the disease. Unfortunately, this could sometimes be fatal: exposure to smallpox in the vaccination could lead to the contraction of the disease itself. The process was refined in 1796 when Edward Jenner discovered that cowpox – a non-fatal disease – could provide immunity to smallpox, which was much more dangerous. Further developments came in the 1870s, when Louis Pasteur was able to produce weak strains of viruses in the laboratory and develop vaccines for anthrax. The introduction of antiseptics by Joseph Lister
in 1865 gave medicine another tool with which to fight infection. Maintenance of good levels of hygiene had long been recognized as important in preventing illness, but Lister outlined the mechanisms by which infection could spread in a clinical setting and introduced carbolic acid as an effective way of preventing this. His work led to the widespread acceptance of the theory that microorganisms caused disease. Finally, I’d like to mention the significant development
in the fight against microorganisms represented by the discovery of penicillin, which is usually attributed to Alexander Fleming. While the action of penicillin on bacteria was known about from 1928 onwards, it was not until 1942 that it began to be used more routinely on patients. Its success in treating a very wide range of diseases meant that, for perhaps the first time, doctors had a tool which was easy to use and which could quickly bring about enormous improvements in a patient’s condition. The modern era of medicine had dawned.
12 Lecture 3
In stage one of the disease, the changes are very similar to those which occur with the onset of old age. For example, short memory lapses, mild aphasia – I mean, not being able to think of the correct word – and not being able to find everyday items, such as glasses and keys. Even though the individual notices some decline in cognition, it is not noticed by those around them. At this stage, Alzheimer’s is very rarely diagnosed. Stage two of progression is marked by a significant
decline in memory function and the beginnings of a personality change. There is difficulty in remembering the names of new acquaintances, difficulty in remembering items which have been read, and difficulties in organizing and planning. Towards the end of this stage, the symptoms become more and more evident to others around the individual. A small proportion of individuals are diagnosed with Alzheimer’s at this stage. By stage three of the disease, individuals are unable
to function without assistance. There is great difficulty in remembering information such as their address or phone
28
number, and sometimes even the date, day of the week or month. While they may be able to remember the names of people near to them, they forget the names of those they see on a less regular basis. Often, they may not recognize their surroundings. By this stage, a significant proportion of patients will be diagnosed. In stage four, patients will require help with most of
their daily functions. Personality changes also become evident, and there may be expressions of inappropriate emotions. Patients can still distinguish between familiar and unfamiliar faces but have difficulty identifying individuals. They can wander off and get lost if not kept under observation. Frequently, they may need help with their bodily functions and can become doubly incontinent. They appear lost and confused for most of the time, though there may be periods of lucidity. The final stage of the disease is characterized by
a catatonic-like state, which means that patients are unable to speak or respond to others, though they may occasionally utter words. Their muscles become rigid, and they are unable to sit up, smile, swallow or hold their heads up. Death eventually intervenes, typically around eight years after the initial diagnosis of Alzheimer’s.
13 Lecture 4
The problem that Dr Snow faced was that he did not know what was causing his patients to contract cholera. At this time, the dominant theory regarding the transmission of disease was that it came from breathing foul air or ‘miasma’ which contained harmful particles. However, Dr Snow was convinced that the miasma theory did not provide a convincing answer to the cholera outbreak. On the contrary: he felt that the water people drank might be making them ill. He did not, however, have a model of the mechanism involved, since the theory that microorganisms caused disease would not be fully formulated until 1875. Dr Snow had a number of tools at his disposal to help
identify the cause of the problem. The first step he took was to look at where the people who contracted cholera obtained their water. Initially, he looked at samples of the water from these pumps, using a microscope and chemical analysis. However, this did not reveal anything of significance. His next step was to identify where those who died of
cholera had lived; he created a spot map to show this. The map showed that most of the people who died lived very close to one of the public water pumps, on Broad Street. Another cluster was close to a separate public water pump elsewhere. Snow then interviewed residents of both areas. By
talking to people who lived near the second pump, he found that some of those who had died actually obtained their water from the Broad Street pump, as they preferred the taste. The remainder had children who went to school in the vicinity of the Broad Street pump. As a result of this, Dr Snow concluded that the water from the Broad Street pump was a common factor in all the deaths. He took his results to the local authorities, and as a result of his investigations, the handle was taken off the pump so that no more water could be taken from that source. The outbreak came to an end shortly afterwards.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151 |
Page 152 |
Page 153 |
Page 154 |
Page 155 |
Page 156 |
Page 157 |
Page 158 |
Page 159 |
Page 160 |
Page 161 |
Page 162 |
Page 163 |
Page 164 |
Page 165 |
Page 166 |
Page 167 |
Page 168 |
Page 169 |
Page 170 |
Page 171 |
Page 172 |
Page 173 |
Page 174 |
Page 175 |
Page 176 |
Page 177 |
Page 178 |
Page 179 |
Page 180 |
Page 181 |
Page 182 |
Page 183 |
Page 184 |
Page 185 |
Page 186 |
Page 187 |
Page 188 |
Page 189 |
Page 190 |
Page 191 |
Page 192 |
Page 193 |
Page 194 |
Page 195 |
Page 196 |
Page 197 |
Page 198 |
Page 199 |
Page 200 |
Page 201 |
Page 202 |
Page 203 |
Page 204 |
Page 205 |
Page 206 |
Page 207 |
Page 208 |
Page 209 |
Page 210 |
Page 211 |
Page 212 |
Page 213 |
Page 214 |
Page 215 |
Page 216 |
Page 217 |
Page 218 |
Page 219 |
Page 220 |
Page 221 |
Page 222 |
Page 223 |
Page 224 |
Page 225 |
Page 226 |
Page 227 |
Page 228 |
Page 229 |
Page 230 |
Page 231 |
Page 232 |
Page 233 |
Page 234 |
Page 235 |
Page 236 |
Page 237 |
Page 238 |
Page 239 |
Page 240 |
Page 241 |
Page 242 |
Page 243 |
Page 244 |
Page 245 |
Page 246 |
Page 247 |
Page 248 |
Page 249 |
Page 250 |
Page 251 |
Page 252 |
Page 253 |
Page 254 |
Page 255 |
Page 256 |
Page 257 |
Page 258 |
Page 259 |
Page 260 |
Page 261 |
Page 262 |
Page 263 |
Page 264
