Communicable Diseases (3.1) (M) Flashcards
What is health?
the state of physical and mental well-being
What is the difference between communicable and non-communicable diseases?
Communicable diseases are spread from person to person and caused by pathogens, whereas non-communicable are not caused by pathogens and cannot be spread
What are pathogens?
microorganisms that cause infectious disease
What are the 4 types of pathogen?
- viruses
- bacteria
- protists
- fungi
How can communicable diseases spread in plants and animals?
by direct contact, by water or by air
Why can bacteria and viruses be hard to control once inside the body?
they reproduce rapidly inside the body
How do bacteria make us feel ill?
produce poisons (toxins) that damage tissues
also reproduce rapidly inside the body
How are viruses harder to treat than bacteria?
they live and reproduce inside cells, causing cell damage
How can the spread of communicable disease be reduced or prevented?
by being hygienic (e.g. washing hands after being sick), destroying vectors, isolating infectious people/plants, and by using vaccinations
What type of disease is measles?
Viral
What are the symptoms of measles?
fever and a red skin rash
What is the danger of measles?
Measles is a serious illness that can be fatal if complications arise
What prevention takes place against measles?
most young children are vaccinated against measles
How is measles spread?
The measles virus is spread by inhalation of droplets from sneezes and coughs.
What type of disease is HIV?
Viral
What are the symptoms of HIV?
initial flu-like symptoms
How is HIV controlled?
with antiretroviral drugs
cure is extremely rare
What is the danger of HIV?
Unless successfully controlled with antiretroviral drugs the virus attacks the body’s immune cells.
Late stage HIV infection, or AIDS, occurs when the body’s immune system becomes so badly damaged it can no longer deal with other infections or cancers.
How is HIV spread?
HIV is spread by sexual contact or exchange of body fluids such as blood which occurs when drug users share needles
What type of disease is tobacco mosaic virus (TMV)?
Viral
What is tobacco mosaic virus (TMV)?
a widespread plant pathogen affecting many species of plants including tomatoes
What is the effect of TMV? What does this lead to?
It gives a distinctive ‘mosaic’ pattern of discolouration on the leaves which affects the growth of the plant due to lack of photosynthesis
What type of disease is salmonella food poisoning?
Bacterial
How is salmonella food poising spread?
it is spread by bacteria ingested in food or on food prepared in unhygienic conditions
How is salmonella food poisining prevented?
In the UK, poultry are vaccinated against Salmonella to control the spread
What are the symptoms of salmonella food poisoning? How are they caused?
Fever, abdominal cramps, vomiting and diarrhoea are caused by the bacteria and the toxins they secrete.
Give both pathogen name and umbrella term associated with it
What type of disease is Gonorrhoea?
Bacterial
Sexually-transmitted disease (STD)
How is Gonorrhoea spread?
Through direct sexual contact
What are the symptoms of Gonorrhoea?
a thick yellow or green discharge from the vagina or penis and pain on urinating
How was Gonorrhoea treated?
It was easily treated with the antibiotic penicillin until many resistant strains appeared
How can the spread of Gonorrhoea spread be controlled?
The spread can be controlled by treatment with antibiotics or the use of a barrier method of contraception such as a condom
What type of disease is rose black spot?
fungal
What are the symptoms and effects of rose black spot?
Purple or black spots develop on leaves, which often turn yellow (chlorosis) and drop early. It affects the growth of the plant as photosynthesis is reduced (due to less green chlorophyll to take in light energy)
How is rose black spot spread?
It is spread in the environment by water or wind
How can rose black spot be treated?
It can be treated by using fungicides and/or removing and destroying the affected leaves
Which 2 diseases (that we have studied) only affect plants?
TMV and Rose black spot
all others only effect humans (animal)
Which pathogen causes malaria?
Protist
The malarial protist has a life cycle that includes which vector?
mosquitos
What are the symptoms and danger of malaria?
Malaria causes recurrent episodes of fever and can be fatal
How can malaria be prevented?
The spread of malaria is controlled by preventing the vectors, mosquitos, from breeding and by using mosquito nets to avoid being bitten
4 needed
What are the the non-specific defence systems of the human body against pathogens?
- Skin
- Nose
- Trachea and bronchi
- Stomach
specific = tailored to specific pathogen type, non-specifiic - all pathogens equally
How does the nose defend against disease?
Has internal hairs, which act as a physical barrier to infection. Cells in the nose produce mucus, which traps pathogens before they can enter the lungs.
How does skin defend against pathogens?
acts as physical barrier; if cut, a scab will be formed to prevent pathogens from entering and will heal itself
How do the trachea and bronchi defend against disease?
They have smaller hair cells called cilia which waft up mucus to mouth to go down into stomach
How does the stomach defend against disease?
It contains hydrochloric acid, which kills the pathogen (in the food)
If a pathogen enters the body, what does the immune system try to do?
the immune system tries to destroy the pathogen
How do white blood cells help to prevent against disease?
- Phagocytosis - [phagocytes] engulfing pathogens
- Antibody production - [lymphocytes] attaching to specific markers (antigens) on pathogens, killing them
- Antitoxin production - neutralising the toxins produced by bacteria
How do vaccinations work?
The introduction of small quantities of dead or inactive forms of a pathogen into the body will stimulate the white blood cells to produce antibodies, that are specific to the antigens of the pathogen, so the pathogen is destroyed
If re-infected memory cells will respond quickly to produce antibodies rapidly
This will be similar for traditional re-infection
How can the spread of pathogens be prevented by vaccination?
the spread of pathogens can be reduced by immunising a large proportion of the population so they are immune to a certain pathogen (herd immunity)
Ulcers are caused when the mucus lining in the stomach is damaged, how does this occur when an acid-resistant bacteria enters the stomach?
bacteria not killed (by stomach acid / HCl) and so they damage mucus lining
so acid / HCl damages stomach tissue / causes an ulcer
How may a disease spread from the roots of one plant to the roots of another plant?
in the soil
6 marker
How do different types of organism prevent against microorganims?
Animals:
- skin - dead layer that is difficult to penetrate
- nose - hairs keep out dust and microbes
- trachea - mucus traps microbes and cilia moves microbes
- stomach - hydrochloric acid kills bacteria
- white blood cells - e.g. engulf pathogens
Plants:
- cell wall - difficult to penetrate
- wax cuticle - difficult to penetrate
- dead cells/bark - fall off taking pathogens with them
- production of antibacterial chemicals - kills microorganisms
How can scientists use a plant with a TMV-resistant gene to produce many plants with this?
Take stem cells from meristem
3 marks - so only 3/4 needed
Explain how some people in the same place could die from influenza and the other group didn’t show any symptoms?
- One group of people were immune
- One group of people had antibodies
- One group of people were vaccinated
- The infected group caught disease off the non-infected group
Explain why someone with AIDS may take longer to recover from salmonella food poisoning than a person without AIDS
Immune system is weakened
So white blood cells cannot kill salmonella/bacteria
2 marks
How would increased phagocytosis of pathogen help the patient?
more pathogens will be engulfed by white blood cells/phagocytes
therefore less damage to cells/tissue
Why will a measles virus not protect someone from the rubella virus?
antibodies are specific or needs different antibodies
