Health and Disease I
Diseases
A condition where part of an organism doesn't function properly
Health: A state of complete physical, mental and social well-being, and not merely the absence of disease or infirmity
Communicable diseases
Can be spread from person to person
Cause by pathogens
Common cold and cholera
Non-communicable diesease
Can't be spread from individuals
Asthma and cancer
Pathogens
Organisms that cause disease
Bacteria
Very small cells which can reproduce rapidly inside your body through binary fission
Produce toxins which damage your cells and tissues
Viruses
Not cells, not alive
Reproduce rapidly inside your body
Live inside cells and replicate using the cells machinery to produce many copies
Protists
mostly eukaryotic and single celled
Some are parasites, use humans and animals as their hosts
Fungi
More complex than bacteria
Eukaryotic
Some cause disease, but many are harmless and beneficial
Prokaryotic
Bacterial diseases
Tuberculosis
Caused by the Mycobacterium tuberculosis
Symptoms include: excessive coughing, fatigue, lung damage, and weight loss
It's spread through the air in droplets through coughing and sneezing
Spread can be reduced using quarantines and face masks
Treatment is 2 antibiotics for 6 months
Cholera
Spread by the bacterium Vibrio cholerae
Symptoms include: diarrhoea, vomiting, severe dehydration
Spread through contaminated water sources
Spread can be controlled by drinking safe water only, washing hands regularly and using proper toilets
Treatments include: cholera vaccines which provide 6 months of protection and oral or intravenous hydration antibiotics
Stomach Ulcers
Caused by the bacterium helicobacter pylori
Symptoms include: inflammation of stomach lining, stomach pain, nausea and vomiting
Spread through oral transmission and contaminated food
Spread can be reduced by having clean water supplies and washing hands regularly, thoroughly cooking food
Treatments include antibiotics and histamine blockers
Viral diseases
Ebola
Caused by the Ebola Virus
Symptom include: Haemorrhagic fever, vomiting, Diarrhoea and rashes
Spread through coming into contact with the bodily fluids of an infected individual
Spread can be reduced by isolating infected individuals and sterilising and areas where the virus may be present. Medical staff should regularly wash their hands and wear protective clothing
Treatments include the mAb114 vaccine
HIV
Caused by the Human Immunodeficiency Virus, attachks white blood cells, a key part of the immune system
Symptoms include: fever, sore throat, body rash, joint pain
Spread through unprotected sex and sharing needles
Spread can be controlled by wearing condoms and not sharing needles
Treatments include antivectorial medicines which stop the virus replicating
Overtime, it will lead to AIDS, where the immune system eventually fails
Fungal and protist diseases
Chalara ash dieback
Caused by the Hymenoscyphus fraxineus fungi
Symptoms include loss of leaves and bark lesions
Spread by air and wind and when ash trees already infected are moved between areas
Spread can be reduced by removing young infected ash tress and placing restriction on the movement of ash trees
Malaria
Caused by the plasmodium taciparcum protist
Symptoms include high fever, sweating, loss of appetite
Spread by mosquitoes which are vectors, they pick up the protect when they feed on an infected animal, then they feed on another animal, inserting the protist into its vessels
Spread can be reduced by stopping mosquitoes from breeding, using mosquito nets and mosquito repellant
Treatment includes anti malarial medication
Virus reproduction
Viruses have to infect living cells in order to reproduce
Lytic pathway
1) Virus attaches itself to a specific host cell and injects its genetic material
2) Virus then uses proteins and enzymes in the host cell to replicate its genetic material and produce the components of new viruses
3) Once all the viral components are produced, they assemble to form new viruses
4) The host cell splits open, releasing the new viruses, which can go and infect new cells
Lysogenic pathway
1) The virus attaches itself to a specific host cell and injects its genetic material into the cell (called a provirus)
2) The genetic material is incorporated into the genome (DNA)of the host cell
3) The viral genetic material gets replicated along with the host DNA every time the cell divides, at this point the virus is dormant and no new viruses are made
4) A trigger, presence of a chemical causes the viral genetic material to leave the genome and enter the lytic pathway
Presence of one disease can lead to increase susceptibility to other disease