Communicable diseases Flashcards
What is a pathogen?
A microorganism that can cause disease
What are the four types of pathogen?
- Bacteria
- Viruses
- Fungi
- Protists
Give three examples of viral diseases.
- HIV (which potentially leads to AIDS in humans)
- Measles (in humans)
- Tobacco mosaic virus (in plants)
Give two examples of bacterial diseases.
- Salmonella (in humans)
- Agrobacterium (in plants)
Give two examples of fungal diseases.
- Athlete’s foot (in humans)
- Rose black spot (in plants)
Give two examples of diseases caused by protists.
- Malaria (in humans)
- Downy mildew (in plants)
What is a communicable disease?
A disease caused by a pathogen that can be transmitted from one person to another
Name five ways that pathogens can be transmitted.
- Direct contact (e.g. sexual intercourse, shaking hands)
- Water
- Air (inhalation of droplets)
- Unhygienic food preparation
- Vector (an organism that spreads a disease)
What a viruses made up of?
- Short length of DNA
- A protein coat
How do viruses make new viral particles?
They replicate their DNA and protein coats inside of a host cell
Describe how tobacco mosaic virus affects plant growth.
- Destroys chloroplasts
- So less photosynthesis
- So less glucose is produced
Describe four ways that HIV can be spread.
- Unprotected sex
- Sharing needles
- Blood transfusions (using unscreened blood)
- From mother to baby
How can the spread of gonorrhoea be prevented?
- Abstain from vaginal, anal or oral sex
- Use a condom (or other barrier methods of contraception)
Describe three symptoms of gonorrhoea.
- Burning pain when urinating
- Thick yellow/green discharge from vagina or penis
- If untreated, can result in infertility
How is malaria spread?
Through mosquitos, an insect vector, which carry the Plasmodium protist.
They suck the blood of an infected person, then spread the disease through sucking the blood of an uninfected person.
What are some methods used to prevent malaria?
- Insecticides (to kill mosquitos)
- Insect repellents (to prevent being bitten)
- Mosquito nets (to prevent being bitten)
- Anti-malarial tables (to kill protist)
- Vaccinations (to create immunity to malaria)
In rose black spot, leaves turn yellow and drop off the plant.
How does this affect plant growth?
Most photosynthesis happens in the leaves
So affects the plant’s ability to photosynthesise
Less glucose is produced
How does the skin act as a non-specific defence against disease?
- Covers all parts of the body to prevent infection by pathogens
- If cut forms a scab, prevents infection as acts as a physical barrier
How do the eyes act as a non-specific defence against disease?
Produce tears which contain enzymes, acting as a chemical barrier to infection
How does the nose act as a non-specific barrier to disease?
- Contain internal hairs, which act as a physical barrier to infection
- Produce mucus, which traps pathogens before they enter the lungs
How do the trachea and bronchi act as non-specific defences to disease?
- Goblet cells in trachea produce mucus to trap pathogens
- Ciliated cells in trachea waft mucus towards throat where it can be swallowed (and pathogens destroyed by stomach acid)
How do phagocytes act in your immune system to protect you against communicable diseases?
In a process called phagocytosis:
- Phagocyte engulfs pathogen (membrane surrounds pathogen)
- Enzymes in the phagocyte break down the pathogen and destroy it
How do lymphocytes act in your immune system to protect you against communicable diseases?
- Lymphocytes recognise proteins on the surface of pathogens called antigens.
- Lymphocytes detect that these are foreign not naturally occurring within your body and produce antibodies.
How do antibodies produced by lymphocytes help to protect your body against pathogenic disease?
Antibodies cause pathogens to stick together and make it easier for phagocytes to engulf them.
