1.3.1 Communicable diseases

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a type of cell that can infect plants and animals. They can reproduce quickly in warm, moist conditions and they cause damage by producing harmful toxins Salmonella Salmonella is a bacterial disease that is caused by contaminated food that hasn't been cooked well enough. It can give the body symptoms such as a fever, cramps, vomiting or diarrhoea. Gonorrhoea Gonorrhoea is an STD transmitted through unprotected sex. It can cause thick discharge and pain while urinating, and if left untreated it can lead to pelvic pain and infertility. It can be treated with antibiotics, and prevented by using contraception. Fungal Diseases There are few fungal diseases that affect humans, but one is athletes foot which can be transferred by physical contact with an infected surface. Fungal infections are worse in plants, and in extreme cases they can destroy the plant or crop Rose Black Spot Disease Rose black spot disease is a fungal disease that can be carried over wind or in water. It causes purple or black spots to appear on a plants leaves which then lead to the leaves turning yellow and falling off. This limits photosynthesis which means the plants won't be able to get as much nutrients as they need. Protist Diseases Protists are unicellular, eukaryotic organisms (which means they have a nucleus) can carry diseases. These diseases often need a vector to carry it from one host to the next. Malaria Malaria is a protist disease that is transferred using the vector of a mosquito, which doesn't carry the disease but does carry the harmful pathogens. Malaria causes recurrent episodes of fever/ The spread of malaria can be prevented by preventing the mosquitos from biting and breeding MOSQUITO ● SEXUAL REPRODUCTION OF THE MALARIA PARASITE MOSQUITO CONSUMES INFECTED BLOOD WHEN FEEDING FEMALE ANOPHELES MOSQUITO BITES THE HUMAN MALARIA PARASITE INFECTS THE LIVER AND REPRODUCES ASEXUALLY MALARIA PARASITES IN THE BLOOD OF HUMANS HUMAN Copyright © Save My Exams. All Rights Reserved RED BLOOD CELL uman Defence Systems The human body has a lot of features that make it less susceptible to pathogens and disease in the first place. There are 4 non-specific defence systems we have in place: The skin which is a barrier to harmful pathogens while also secreting antimicrobial substances to kill them • The hairs and mucus in your nose block some harmful particles from getting in • The trachea and bronchi create mucus that traps pathogens • The cilia in the bronchi also move the mucus up to the throat where is can be swallowed by into the stomach • The hydrochloric acid in our stomach is used to kill off any pathogens that reach it Note Whenever a pathogen enters the body, the immune system tries to destroy that pathogen White Blood Cells in the Immune System There are a number of things which white blood cells do to defend against pathogens. ● Phagocytosis This is where white blood cells engulf and digest foreign pathogens Production of antitoxins Antitoxins are substances created by white blood cells that help to offset the damage caused by the toxins of the pathogen They neutralise the affect of toxins on the brain ● Production of antibodies This is where a type of white blood cell (lymphocytes) produce a type of protein called antibodies to lock onto a new type of invading pathogen so they can be found and destroyed by other white blood cells - antibodies are y-shaped and they are specific to the antigens of the pathogen they bind to Antibodies are complimentary to their antigens antigens new pathogen Vaccination white blood cell antibodies produced new pathogens attacked by new antibodies Vaccinations work by trying at achieve artificial immunity. They expose the individuals to the antigens of the pathogen, which triggers an immune response to form a memory cell which can make antibodies against the pathogen. Ideally this means that if a vaccinated person would become infected, they should be able to destroy the pathogen before it became infectious. This is what gives us the concept of 'herd immunity', if enough of a population is vaccinated, it should stop the spread of a disease Antibiotics and Painkillers While painkillers are drugs that can reduce pain they don't treat any of the causes of a disease, they only treat the symptoms. Antibiotics are a different kind of drugs that tackle bacterial disease by killing the harmful bacteria without killing your own cells. This helps destroy the disease from your system. It is important that there are different types of antibiotics for different types of disease. Antibiotics cannot treat a viral infection because it is hard to kill these viruses without killing your own cells. Antibiotics have saved numerous lives but when they are used too often, bacteria develops a resistance to the antibiotics which can become serious as it leads to a disease that cannot be treated. U.S. INFECTION DEATH RATE PER 100,000 POPULATION ● 300 ● 200 100 ANTIBIOTICS CAUSED U.S. DEATHS TO DECLINE BY ~220 PER 100,000 IN 15 YEARS SULFA 1940 PENICILLIN 1960 Copyright © Save My Exams. All Rights Reserved ALL OTHER MEDICAL TECHNOLOGIES REDUCED DEATHS BY ~20 PER 100,000 OVER THE NEXT 45 YEARS Discovery and Development of Drugs Traditional drugs were extracted from plants or microorganisms. Nowadays we can synthesis new drugs in a lab. After doing this, all drugs must be thoroughly tested. 1980 Preclinical testing This is the testing done in a lab, it may include computer simulations They also test Efficacy and Toxicity at this stage Whole organism testing • These are tests (required by UK law) on at least two animals • This is where Efficacy, Toxicity and Dosage Clinical testing This is where real humans test the drug at low dosages to make sure it has no negative side effects They sometimes use double blind trials where some of the patients are given a placebo This is where the final dosage testing can be done