August 29 Notes / September 3 Notes

Answers to question in Semmelweis reading:

Pueperal fever is a disease which symptoms include abdominal pain, pritonitis, high fever, delirium and shock; major cause of death to mother after labor in the 1800's. While performing an autopsy, one of Semmelweis's collegues cut himself with a scalpel; he became ill with the same symptoms as the dying mothers. An autopsy of his freinds body gave him the same findings. Semmelweis concluded medical students coming from the First clinic were transmitting cadaveric matter into the pregnant women by failing to wash their hands in between performing vaginal and postmortem examinations. He tested his hypothesis by requiring all students and physians to wash their hands and scrub their finger nails, before entering the clinic; deaths dropped significantly. Obstetricians vehemently opposed his hypothesis and fought his ideas. Eventually he died from blood poisening. (Colin O'Sullivan 9/17/07 late, late, late….)

I. Bacteria is the dominant form of life on planet earth because bacteria have an overwhelming dominance in the world in terms of numbers and in living matter.

a. Example: Numerical (in every colony there exists over a billion bacteria in some many more, like 10 or 20 billion) and mass dominance (total mass of bacteria is > the total mass of all other living organisms). Bacteria out weighs everything else
b. In a single colony there are more individual bacteria than there are humans in the entire world.

c. Longevity dominance: Bacteria has existed for 3.5 billion years ( largely in change). Bacteria are not only stable, but are good competitors. They can stay alive in many changes and conditions for example:
i. a single individual rock crystal, the rock layer was found to be about 250million year old and the bacteria was found; still alive. This is also why scientists search for bacteria in outer space, because if anything was living it would be bacteria. Bacteria=stable

Here is a link to an article about bacteria living in permafrost for half a million years. Here is another link to a magazine article describing the 1999 discovery of the 250-million year old (possibly) bacteria.

d. Environmental dominance 20% of the O2 in our atmosphere is entirely the work of bacteria, and is why the earth now has an oxygen rich environment, in the beginning the atmosphere was 2% and because of the byproduct of bacteria’s metabolism it increased to 20%.

e. The leading cause of death for every multi cellular, including humans to this day is infection because of:
2) virus
3) single celled eukaryotes.

e. On the contrast bacteria is essential to life and functions of organisms, known as (Normal flora).
1) e-coli in the gastro-intestinal tract that helps us digest food and aids in the production of vitamins we cant get on our own.
2) Immune system : immune system learns from bacteria. Bacteria primes it and teaches it how to attack things ie.- White Blood. cells. They also occupy areas of the body which could otherwise be occupied by harmful bacteria (competition against pathogens-causes disease)
3) Bacteria is essential for human body to work

II. Spontaneous generation (something from nothing) matter + life force = living organisms
a. The evidence for spontaneous generation (evidence was found to support not to disprove)
i. Of mice and maggots (put in a closed container, then mice can not get to area)
-the theory that hay in barns turns into mice
ii. “Putrefaction” of food (boiling)
iii. Falsifiability and the nature of science (Hypothesis can be falsified. Originally humans looked for evidence to prove; "what can prove me right?" vs. "what can prove me prove me wrong?"- science seeks to disprove)
Was it reasonable for people to believe in spontaneous generation? NO!!!!
-Again, I would have to disagree. People believed that spontaneous generation was true because they were looking for proof to prove them correct. The hypotheses presented seemed to come true. Mice did seem to appear in hay lofts and maggots did "magically" appear on meat on the counter. This sort of thinking lead them to believe that spontaneous generation was logical. It wasn't until they started looking for evidence to disprove their beliefs that they finally were able to look beyond the belief in spontaneous generation. This line of reasoning was acceptable based on their view of science. For their time period, I would say that people were reasonable in believing that spontaneous generation was a believable hypothesis.

b. Spallanzani experiment- melted the top of flask closed with boiled chicken broth inside, and in turn it stayed good. critics said the lack of air disproved this trial)

c. Pasteur’s swan-necked flasks: Pasteur conducted his experiments about 150 years ago. He bent the top of the flask instad of sealing it shut. The curve in the pipe aloud air to pass but not bacteria, allowing the broth to remain sterile. The broth stayed clear. This theory is almost just like if you would drop a ring down a bathroom drain. because the s-shape of the drain the ring is traped in the hump and the water is LESS dense than the ring therefore the water can not sweep the ring down the drain.

III. The Germ Theory of Disease
a. Previous ideas about disease causation: Humors: 4 humors: bile, blood, phlegm, and lymph. It was believed that an imbalance of these four humors lead to disease; The doctor would then bleed the pateint to try to balance them again.
Was it reasonable to believe in humoral imbalances as a cause for diseases? What support did doctors have for that belief? NO~!
-I believe that the correct answer here is YES. Although today's modern science warrants us to throw these beliefs out the window as ridiculous statements, there was reason for doctors in that day to believe these imbalances were correct. This goes back to "looking for the answers". They performed a "surgery" or a bleeding and then sought out whether or not bleeding someone would cause the persons sickness to change. For many ppl this sort of treatment did work… but not because of the treatment. Some of these sicknesses simply needed time for their immune systems to respond the virus or bacteria that had invaded their body. They may have been bled, but the real reason for their cure was a reaction by their immune system, not an imbalance of blood. The doctors weren't exactly capable of seeing this at the time (no knowledge of how our immune systems work, or even the presense of an immune system) but they saw that after they bled someone, the person generally got better. Therefore I do not believe that it is correct to assume that the people in the time had unreasonable beliefs, they were simply misguided by their lack of knowlegde in anatomy & physiology. -Chad

b. Previous ideas about disease causation: Miasmas = "Bad air" that if you breathed in you would get sick, closer to todays concept of transfer of diseases, but not there yet.
Was it reasonable to believe in Miasmas as a cause for epidemics? What support is there for this belief?
-It was very reasonable to believe that Miasmas were causes for epidemics. Today we know that viruses and bacteria can be transferred via close contact between two or more human beings… "bad air"… If someone was carrying a virus or bacteria that was pathogenic, they had the potential to breath on people, or make physical contact with a large group of people before the symptoms actually kicked in. This chain could go on and on without people knowing that they were carrying a virus or bacteria that was causing the illness, especially in largely populated areas. The idea of "bad air" was pretty close to being correct, considering that the air was potentially full of bacteria and viruses that caused the symptoms, although their ideas about getting rid of the sickness caused by miasmas was far from correct.
I think the idea of 'bad air' is reasonable to give caution, many viruses are spread through droplets, contact, or are air born. We went over Tb in class, a person with an active virus needs to be kept in near isolation, with their own heating and cooling units so it does not spread through ventilation, extremely air born contagious… creating bad air.-Michaela

c. John Snow and the Broad Street Pump 1849 cholera (sever diarhea, causing death due to dehydration)epidemic in London. Many people thought cholera was a miasma (bad air) . BUT Snow mapped out the spread of cholera, circled out from a central point. In the center of this point was a water well. Snow then broke the well and the people got better: the first recorded public health intervention.
d. Robert koch was first people to develope a set of criteria to determine if a particulare germ can cause a particular disease.
Koch developed 4 rules to determine if a certian germ can cause a certian desease, These for rules are called Koch's Postulates.
*Kotch's Postulates:
i. microbe causing disease must be found in each pateint with the disease
ii. must be able to grow in pure culture
iii. germ must be able to be inoculated in a healthy experimental host; then host must exhibit the same symptoms as the host
iv. Must be able to re-culture same culture from host you infected
Are there diseases caused by microorganisms that are exceptions to Koch’s Postulates? Why?

September 3rd Notes

I. Eukaryotes
- cells that have a nuclei
- nucleus holds DNA
a. Parasites - microbes that cause diseases (ex. sleeping sickness, malaria)
b. Fungi - macroscopic (ex. mushrooms, mold)
(microbe is any organism too small to be seen with the naked eye)
(macroscopic can be seen with the naked eye
II. Prokaryotes
-lacks a nucleus
-DNA bunched up in cell
a. Archaea
-cell membrane is = to eukaryotes
-RNA polymerase is like that of eukaryotes
-Extremophiles - organisms that live in EXTREME conditions (very hot, high pressure, high/low pH)
b. Bacteria
- gram positive
-Plasma membrane is a phospholipid bi layer
- Peptidoglycan (alanine sugar) cell wall with lipoteichoic acid (LTA)
-gram negative
-plasma membrane
-Peptidoglycan cell wall with no LTA
-Periplasmic space
-outermembrane containing lipopolysaccharide (LPS) - made of fats and sugars

Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-ShareAlike 3.0 License