B5 Communicable diseases Flashcards
What is your health?
a state of physical and mental well-being, not just an absence of disease
What are examples of communicable diseases
tuberculosis, flu, diarrhoeal diseases and malaria
What are communicable diseases caused by?
pathogens such as bacteria and viruses that can be passed from one person to another
What can non-communicable diseases not do?
cannot be transmitted from one person to another
Give examples of non-communicable diseases
Heart disease and arthritis, cancer
What three other factors affect ill health
Diet, stress and life situations
What do life situations include
the part of the world where you live your gender your financial status you ethnic group the level of free health care provided where you live how many children you have local sewage and rubbish disposal
Give an example in which viruses living in cells can trigger changes that lead to cancers
the human papilloma virus can cause cervical cancer
What may be the cause of a defect in the immune system that helps the body to destroy pathogens?
genetic makeup, poor nutrition or infections such as HIV/AIDS; more likely to suffer other communicable diseases
Immune reactions initially caused by a pathogen, even something like the common cold, can trigger allergies to factors in the environment. What can these allergies be called?
skin rashes, hives, or asthma
What can severe physical ill health lead to
depression and other mental illness
What health conditions is malnutrition often linked to
deficiency diseases, a weakened immune system, obesity, cardiovascular diseases, type 2 diabetes, and cancer
What are the microorganisms that cause disease called?
pathogens, infecting animals and plants
What can pathogens be?
bacteria, viruses, protists, or fungi
How are communicable diseases caused?
either directly by a pathogen or by a toxin made by a pathogen
What are pathogens able to do?
can be passed from one infected individual to another individual who does not have the disease
What are known as fairly mild communicable diseases
common cold and tonsillitis
What are known as killer diseases
tetanus, influenza, and HIV/AIDS
Sometimes communicable diseases can be passed between different species of organisms. What is an example.
- infected animals such as dogs or bats can pass rabies onto people
- tuberculosis can be passed from badgers to cows, and from cows to people
What causes the majority of communicable diseases in people?
bacteria and viruses
In pplants, what are the most common pathogens
viruses and fungi
What are bacteria
single-celled living organisms that are much smaller than animal and plant cells
What is bacteria used for?
to make food such as yogurt and cheese, to treat SEWAGE, and to make medicines
Bacteria are important where?
in the environment, as a decomposer, and in the body
How much bacteria do scientists estimate that most people have in their guts?
between 1 and 2 kg of bacteria; having a major effect on our health and well-being
Pathogenic bacteria are the minority
but they are significant because of the major effects they can have on individuals and society
What sort of shape does viruses have?
regular shapes and are even smaller than bacteria
What causes diseases in every type of living organism?
viruses
What happens once bacteria and viruses are inside your body?
they may reproduce rapidly
How may bacteria divide rapidly?
splitting in two (binary fission); may produce toxins (poisons) that affect your body and make you feel ill; sometimes they directly damage your cells
What do viruses do?
take over the cells of your body
What do viruses do once they have taken over the cells of your body?
they live and reproduce inside the cells, damaging and destroying them
What are some common disease symptoms?
high temperature, headaches. and rashes
Why do symptoms happen
by the way your body responds to the cell damage and toxins produced by the pathogens
The more pathogens that get into your body, the more likely..
you will develop an infectious disease
Give three ways in which pathogens spread from one individual to another
by air (including droplet infection)
direct contact
by water
What causes infectious diseases?
microorganisms known as pathogens
How do pathogens make you ill?
as a result of reaction to toxins produced,
or damage caused to cells
By air- droplet infection
droplets full of pathogens expelled in
coughing, sneezing, or talking, droplets breathed in by others,
direct skin contact
pathogens spread from skin of one person to skin of another
direct contact of body fluids
pathogens pass directly from inside
one person’s body into another
by contaminated water
taking in pathogen through digestive
system
by under-cooked or contaminated food-
taking in pathogen through digestive system
By air in plants
fungal spores carried in air from one plant to another
by direct contact-
- pathogens on traces of plant material come into contact with new plants in the soil and infect them
by contaminated water
fungal spores carried in splashes of
water from one plant to another
Describe and explain the main differences between bacteria and viruses and how they cause diease
Bacteria are single-celled organisms much smaller than plant and
animal cells.
Viruses are even smaller than bacteria.
Bacteria divide rapidly by splitting in two (binary fission).
Viruses take over body cells and reproduce inside them.
Bacteria may produce toxins or directly damage body cells.
Viruses damage and destroy cells.
To culture (grow) microogranisms, you must..
provide them with everything they need
what is a culture medium
giving bacteria a liquid or gel containing nutrients
What do culture mediums contain?
carbohydrate as an energy source, various minerals, a nitrogen source so they can make proteins, and sometimes other chemicals
What do most micro-organisms also need to grow?
warmth and oxygen
How does one culture bacteria
Hot agar gel is poured into a Petri dish.
It is then left to cool and set before the micro-organisms are added
Where can you also culture micro-organisms?
in a flask of sterile nutrient broth solution
What sort of cultures of microorganisms do you need to investigate the effects of chemicals such as disinfectants and antibiotics
uncontaminated
Where can contamination come from?
your skin, the air, the soil, or the water around you
Why is it important to avoid any unnecessary contamination?
The bacteria growing may be harmless, however always the risk that a mutation (change in the DNA) will take place and produce a new and dangerous pathogen
Why do scientists culture microorganisms in the labratory
To find out what nutrients they need to grow
and to investigate which chemicals are best at killing them.
Explain why agar gel is important in setting up bacterial cultures
Agar gel is a culture medium
giving microorganisms everything they need to grow
Suggest why bacteria are grown at 25 degrees Celsius or below in the school lab when this is not their optimum temperature for growth
reduces risk of growing dangerous pathogens
Explain why bacteria are often cultured at much higher temperatures in industrial plants and hospital laboratories
Higher temperatures enable microorganisms to grow much more rapidly so that they can be identified sooner (e.g., in hospital labs) or to produce products more quickly in industry (e.g., insulin-producing
GM bacteria).
Explain why petri dishes are not opened before incubation once they have been inoculated and sealed.
To prevent contamination of culture by microorganisms from the environment and to prevent release of potentially harmful microorganisms that might
grow.
Suggest what might limit the growth of bacteria in a culture on a Petri dish because these ideal conditions do not last forever
Petri dish- limited supplies (nothing new added), bacteria use up available food and oxygen (limiting growth).
Petri dish has no mechanism for removal of waste products (build-up of carbon dioxide and other toxins can poison bacteria and stop growth)
What are you surrounded by all the time?
disease causing bacteria
What happens if bacteria have the right conditions, including enough nutrients and a suitable temperature?
They can grow very fast, dividing every 20 minutes
What factors may affect growth rate of a bacteria population
temperature, available nutrients, oxyygen levels, and pH
You can calculate the number of bacteria in a population after a given time as long as you know the mean division time
This varies greatly, from 15-20 minutes to hours, days or even years
What is the formula for calculating bacteria at the end of the growth period?
bacteria at the beginning of the growth period x 2ⁿᵘᵐᵇᵉʳ ᵒᶠ ᵈᶦᵛᶦˢᶦᵒⁿˢ
What are the ways to prevent the growth of bacteria?
- raise/ lower the temperature
- chemicals to stop them growing or kill them
What is a disinfectant?
chemicals used to kill bacteria in the environment around us
What is an antiseptic?
a disinfectant that is safe to use on human skin
What are antibiotics?
chemicals that can be used inside our bodies, which kill bacteria or prevent them from growing
In the mid-1850s, who was Semmelweis?
a doctor at ime where many women in hospital died from childbed fever a few days after giving birth; nobody knew why
What was something important that Semmelweis noticed?
his medical students went straight from dissecting a dead body to delivering a baby without washing their hands
What did Semmelweis wonder?
If they were carrying the cause of disease from the corpses to their patients
What did Semmelweis also notice from another doctor?
another doctor died from symptoms identical to childbed fever after cutting himself while working on a body. This convinced him that the fever was caused by some kind of infectious agent
As a result of Semmelweis’ discovery, what did he insisted to his medical students?
wash their hands before delivering babies; fewer mothers died from the fever. However, other doctors were very resistant to Semmelweis’s ideas
In the mid-to late-19th century, who are two other people who made scientific discoveries in terms of medicine
Louis Pasteur and Joseph Lister
What did Louis Pasteur do?
showed that microorganisms cause disease; developed vaccines against diseases such as anthrax and rabies
What did Joseph Lister do?
started to use antiseptic chemicals to destroy pathogens before they caused infection in operating theatres
As microscopes improved…
it became possible to see pathogens more clearly. This helped convince people that they were really there
What is another way to help us prevent from disease happening?
understanding how communicable diseases are spread from one person to another
What are the four ways to prevent the spread of communicable diseases?
Hygiene
Isolating infected individuals
Destroying or controlling vectors
Vaccination
What are some simple hygiene measures?
Hand washing; using disinfectants on kitchen work surfaces, toilets, etc, to reduce the number of pathogens; keeping raw meat away from food that is eaten uncooked; coughing or sneezing into a tissue; maintaining the hygiene of people and agricultural machinery to help prevent the spread of plant diseases
Explain ‘isolating infected individuals’
The fewer healthy people who come into contact with the infected person, the less likely it is that the pathogens will be passed on
Why may isolating infected individuals may be difficult for plants
only those plants that are small and can be moved and destroyed easily can this be possible
Give a 3 examples of a vectors?
- mosquitoes carry a range of diseases, such as malaria and dengue fever
- Houseflies can carry over 100 human diseases
- rats
What happens when vectors are destroyed?
The spread of disease can be prevented
What happens when the numbers of vectors are controlled?
the spread of disease can be greatly reduced
What happens during vaccination?
doctors introduce a small amount of harmless form of a specific pathogen into your body
How do vaccinations work
If you come into contact with the live pathogen, you will not become ill as your immune system will be prepared
