B6.3 Flashcards
3e
What is a communicable disease?
A communicable disease is a disease that can spread between individuals and is caused by pathogens (micro-organisms)
What is a non-communicable disease?
- a non communicable disease is one that is not caused by pathogens and cannot be spread between individuals
- the effects of these diseases tend to be longer lasting
- e.g asthma
What are some factors that increase the risk of developing non-communicable diseases?
- Smoking (lung + cardiovascular diseases)
- Obesity (Type 2 Diabetes, excess consumption of sugar reduces the sensitivity of body to insulin )
- Alcohols (liver disease + brain impairment, breakdown of alcohol by liver produces large amounts of toxins+ neurones of brain are also damaged)
- Carcinogens (cancer, exposure to ionising radiation can lead to uncontrolled cell division, e.g cancer)
- Smoking/Drinking while pregnant (poor development of fetus, smoking means less oxygen transported to baby as there is more carbon monoxide + alcohol can impair the brain development of a fetus)
- Location in the world
- Constantly being under stress (can lead to High BP)
- A person’s Income
What is susceptibility and why does it occur?
- if an individual has one disease then they are more likely to be more susceptible to other deasies
- this is because the immune system can be compromised in some way (e.g individuals with HIV will have a reduced number of lymphocytes (white blood cells), which reduces the body’s ability to tackle infections (such as pneumonia)
What can viruses lead to?
- Viruses in cells can be triggers for cancer (e.g HPV cells in the cervix can lead to cervical cancer)
What can a knockon effect of physical ill health be?
- mental illnesses which can negatively impact the immune system and also lead to the individual making poorer choices
How does HIV affect lymphocytes (4 Steps)?
- HIV attaches to the receptors on the lymphocyte
- The HIV then injects it’s genetic material into the lymphocyte, which becomes the host cell
- The HIV uses the cell’s machinery to replicate and produce more copies of itself
- After making many copies the host cell is destroyed
What does a HIV infection mean for the body?
- reduced number of lymphocytes to tackle infections, as less antibodies can be made
- leads to AIDS
How does HIV avoid being recognised and destroyed by lymphocytes?
The HIV constantly changes its protein coat to avoid detection
What are 4 types of microorganisms that can be pathogens?
- Bacteria
- Protoctists
- Fungi
- Viruses
Which type of microorganism is always pathogenic?
VIRUSES
How do pathogenic bacteria harm the cells?
- pathogenic bacteria do not always enter the target cell
- they can release toxins which damage cells
- they are small and can reproduce rapidly
- e.g cholera
How do pathogenic fungi harm the cells?
- mostly harm plants, not animals
- can be single or multicellular
- they produce spores that allow them to infect other organisms (via touching contaminated surfaces)
- fungal diseases can threaten entire crops for plants and are serious
- e.g athletes foot
How do pathogenic protists harm the cells?
- eukaryotic organisms
- parasites, so require a host to live
- small number of protists are pathogenic but those that are are serious
- e.g malaria
What are 7 modes of transmission for communicable diseases?
- Water - drinking/bathing in dirty water (cholera)
- Air - spores can be distributed by wind (barley powdery mildew)
- Body Fluids - sharing needles (blood), semen, breast milk (HIV)
- Through Contact - (Athletes Foot)
- Ingestion - not cooking food properly or old food (salmonella)
- Animal Vectors - mosquitos (malaria)
- Soil
What are the 2 ways the spread of disease can be prevented?
- behaviour in social situation: (density of population, poor diet, availability of healthcare, education)
- individual behaviour (personal hygiene, self isolating, cleaning, vaccination)
What are 4 ways of detecting disease?
- antigens detected in a persons bloodstream or body fluids - e.g COVID 19 testing kits
- DNA testing - can see whether some alleles that could mean the disease later in life (non-communicable)
- Visual Identification of the disease (from trained professionals)
- Reporting plant diseases
What are the 4 main physical plant defences?
- waxy cuticle - keeps leaf waterproof and also prevents pathogens from getting in through the surface
- cell wall - can act as a physical barrier to pathogens within the leaf
- Callose Production - presence of pathogens can cause callose to form which makes a temporary extra cell wall
- production of anti-microbial substances - some plants produce anti-microbial substances to defend agaisnt pathogens, which may kill the pathogen or prevent reproduction
What are the first lines of defence against pathogens for the body?
- nose hairs - barrier against pathogens going up nostrils
- mucus(goblet cells) in trachea/bronchi traps the pathogens/bacteria and cilia waft it up where it is swallowed and destroyed by hydrocloric acid
- hydrocoloric acid in the stomach
- enzymes in tears that kill bacteria
- enzymes in sebum and sweat
How do white blood cells detect the presence of pathogens?
- all cells have marker proteins on them called antigens
- White blood cells recognises them, sees foreign antigens and knows
What is a phagocyte and what does it do?
- it is a white blood cell that engulfes unknown antigens
- enzymes are released into the pathogen which destroy it
What type of immunity are phagocytes used for ?
NON SPECIFIC
What type of white blood cell is used for specific immunity?
LYMPHOCYTES
There is a different lymphocyte…
for every antigen
What do lymphocytes do and what are they?
- lymphocytes produce proteins called antibodies which directly fit the corresponding antigen
- will clone mutiple copies of the antibody
- will release antibodies into bloodstream and body
What do antibodies do?
- they will fit onto the antigen and clump many antigens together
- this means phagocytes can engulf many antigens at once
