7.1 Human Diseases


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UBC Bio 111 - Intro to Biology

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7.1 Human Diseases

  1. 1. 7.1 Human Diseases Learning Outcomes: 1. Categorize diseases by causation Readings: 18:467-476, 2: 41-46, 3: 66-69 and http://encarta.msn.com/encyclopedia_761566075/human_disease.html PDF files in Learning Module 7 “Historical Intro to Disease” and “History of the Flu” Reminder: Reading Quiz #7 has been reopened and will be due before class Wed Oct 21st Disease – abnormal condition(s) of an organism that impair normal bodily functions. Diseases can be caused by external or internal factors External: Toxins egs. 2nd hand smoke (cancer), heavy metals eg. lead (poisoning) Infectious: 1. Microbes (pathogens) =disease causing organisms a) Viruses egs. SARs, West Nile, AIDS, smallpox, polio b) Bacteria egs. bird flu, cholera, plague, TB c) Protists egs. malaria, Lyme disease, dysentery 2. Prions (infectious proteins) eg. mad cow disease Internal 1. Poor nutrition egs. rickets, scurvy, spina bifida, 2. Genetic conditions egs. Huntington’s, Muscular dystrophy, some forms of cancer Although a number of pathogens have likely been with us through our evolutionary history a great change occurred in the makeup of human disease 8 to 10 000 years ago as humans made the switch from being hunter-gatherers to farmers 1. We domesticated animals as livestock and pets. This led to animal to human disease transmission Eg. Rabies, influenza 2. We began domesticating and cultivating plants for food crops Both actions changed our diet and had a big effect on type and diversity of human diseases eg. ergot in grain  St. Elmo’s Fire, Food storage ailments eg. Salmonella spp., 3. Increases in human population size led to diseases whose success depends on direct person to person transmission. QUESTION 1: What might be some examples of these type of diseases? a. stomach ulcers b. tuberculosis c. malaria d. b and c e. all of the above Other Examples: MRSA, Mono, The common cold, H1N1, SARS, SDIs, smallpox, any flu
  2. 2. 4. The build up of human and animal wastes led to contaminated water/environment. This brought humans (and sometimes our animals) in contact with a new array of pathogens including both bacteria and eukaryotic parasites Egs. Cholera, typhoid fever, dysentery, tapeworms 5. We made profound changes to the natural environment and this favoured some pathogens For example, slash and burn agriculture (deforestation) increased the number of breeding spots for mosquitoes carrying malaria BIG QUESTION 2: From your study of biology so far what would say is the “prime directive” of all living organisms? (What do all organisms do while they are alive?) a. Find a suitable habitat in which to live and grow b. Acquire energy for their metabolic needs c. Reproduce d. A and c e. All of the above Most pathogens are alive. (Question 3: Which ones are not considered to be alive?) As living organisms, pathogens also follow this prime directive. Viruses Habitat = whatever organism they infect mostly get energy from organism they infected so they can grow and reproduce. While doing this, many pathogens produce toxins which can make the host ill. We will focus on the Biology of infectious diseases in this unit. Above are listed some major causes of infectious diseases through the development of human society. New diseases continue to emerge. QUESTIONS 4: What are some of the necessary conditions for the spread of new disease-causing organisms such as HIV, SARS or swine flu. 5. Where do new diseases often originate? 6. How do diseases become more lethal or more infectious? 7. How do pathogens spread to uninfected organisms? 8. How do pathogens evade immediate destruction by the host’s immune system? Historical disease treatment
  3. 3. Causes of ailments Treatments Water (phlegm) Air (blood) Cold + wet Hot + wet Displeased gods Sacrifices to gods Phlegmatic sanguine Eg in China smallpox goddess, gourds hung New Years Eve to get infected instead Evil spirits, sorcery Shamanic healing (village healer), trephination (=drilling a hole in the skull to let out the evil spirits) Imbalance of the 4 Blood-letting humours Herbal medicine Earth (black bile) Fire (yellow bile) Cold + dry Hot + dry Melancholic Choleric Commonly used herbal remedies that you know: Notes of caution: The purity and concentration of herbal supplements is not regulated Some herbal remedies can be toxic…eg ephedra (ma huang) taken as a decongestant and a weight loss supplement: cases of heart attack, stroke, seizures Research into the usefulness of traditional remedies is ongoing. Taxol is an effective drug in treating many cancers because it inhibits cell division. Taxol has some adverse side effects for eg. it can adversely affect liver function. Taxus brevifolia – Pacific Western Yew