B2 - Keeping Healthy Flashcards
Define health
A state of physical and mental well-being
Define disease
A disorder of the body or mind that
negatively affects an individual’s health
What are the causes of disease?
● Infection by a pathogen
● Gene mutation
● Conditions in the environment e.g. pollution
● Lifestyle e.g. lack of exercise, alcohol, stress
● Trauma
What is a communicable disease?
● A disease that is passed directly
between individuals.
● Caused by a pathogen
Define pathogen
A disease-causing organism e.g. virus,
fungi, bacteria, protists
What is a non-communicable disease?
● A disease that is not transmitted between
individuals
● Generally long-lasting with a slow-onset
● Caused by lifestyle, environmental conditions,
genetic mutations etc.
Give some examples of
non-communicable diseases
● Cancer
● Diabetes
● Cardiovascular diseases
● Chronic respiratory diseases e.g. asthma
What is a symptom?
A change experienced by an organism
that indicates disease
What is the ‘incubation period’?
The period of time between contracting
an infection and the development of
symptoms
List the ways in which communicable
diseases can spread
● Water ● Air ● Body fluids ● On surfaces ● Animal vectors ● Soil ● Food
How do bacteria cause disease?
They produce toxins which damage cells
and cause disease symptoms.
Give an example of a disease caused by
bacteria
● Cholera
● Food poisoning
● Crown gall disease
Describe how cholera is spread between
humans
Spread by drinking water or washing in
water than has been contaminated with
infectious faeces
Describe how Salmonella is transmitted
to humans
● Transmitted to humans in undercooked or out
of date food (generally animal products)
● Causes food poisoning
Describe how crown gall disease is
spread between plants
Spread in soils contaminated with
Agrobacterium tumefaciens. Bacteria
infect plant wounds.
Describe the effects of crown gall
disease in plants
Growths develop at plant crowns,
reducing water flow and damaging plant
tissue. This can result in plant death.
How do viruses cause disease?
They enter host cells and replicate inside
of them. The host cells rupture, releasing
new viruses.
Give an example of a disease caused by
a virus
● Influenza
● HIV/AIDS
● Chicken pox
● Tobacco mosaic virus
How do viruses differ from other
microorganisms e.g. bacteria, fungi?
Viruses are not living organisms. They
do not reproduce and can only replicate
inside a host cell.
Describe how influenza is spread
between humans
It is an airborne virus which is spread
via droplet infection.
How is HIV spread between humans?
HIV is passed on by direct contact with
infected body fluids e.g. blood, semen,
breast milk.
How does the HIV cause disease?
It destroys white blood cells making the
individual immunodeficient and
increasingly susceptible to other
diseases. This leads to AIDS.
Describe how the tobacco mosaic virus
(TMV) is spread between plants
TMV is spread between plants when
contaminated leaves come into contact
healthy leaves.
How does TMV affect plants?
It infects the chloroplasts, causing
discolouration and the wrinkling of plant
leaves. This reduces their ability to
photosynthesise.
What are protists?
Eukaryotic, single-celled microorganisms
Give an example of a disease caused by
protists
● Malaria
● Dysentery (causes severe diarrhoea)
Describe how malaria is transmitted
between humans
Spread by mosquito vectors which pick up the
plasmodium protist when feeding on the blood of
an infected organism. They transmit malaria to
other organisms during feeding.
How do fungi cause disease?
● Produce spores which spread to other
organisms
● Hyphae break through the surface of
plants and human skin
Give an example of a disease caused by
fungi
● Athlete’s foot
● Ash dieback disease
Describe how athlete’s foot is spread
between humans
It is spread by touching contaminated
surfaces e.g. shower floors, towels.
Describe how ash dieback disease is
transmitted between plants
It is spread via airborne spores which
are carried by the wind.
How does ash dieback disease affect
plants?
It causes dark lesions on bark and
blackened leaves which wilt and
eventually die.
What is a non-specific defence?
● Always present
● Same for all organisms
● Prevent pathogens from entering the body
Name the three types of non-specific
defence
● Physical - barrier to pathogens
● Chemical - chemicals damage or kill pathogens
● Microbial - microorganisms compete with pathogens
Give some examples of the body’s
physical defence system
● Skin - protective surface barrier
● Blood clotting - platelets seal wounds preventing entry of
pathogens into the blood
● Respiratory tract - mucus traps pathogens, cilia waft
mucus to the back of the throat where it is swallowed
Describe how platelets are adapted to
their function
● Small and flexible (no nucleus) allowing easy movement through capillaries
● Surface proteins enable adhesion to other platelets or to rough edges around the site of damage
● Can change shape to form a plug that seals the wound
● Contain other chemicals which aid blood clot formation
Give some examples of the body’s
chemical defence system
● Tears - contain lysozyme which digests bacterial cell
walls, killing bacteria and protecting the eye
● Hydrochloric acid in stomach - acidic pH kills pathogens
● Saliva - contains chemicals that destroy pathogens in the mouth
Give an example of the body’s microbial
defence system
Bacteria in the gut and on the skin
compete with pathogens, reducing their
chance of survival.
Describe the physical defence system
within plants
● Waterproof waxy cuticle - surface barrier preventing the entry of pathogens
● Cellulose cell wall - further barrier against pathogens
What is the immune system?
● The body’s defence against pathogens
once they have entered the body
● Aims to prevent or minimise disease
caused by pathogens
How do white blood cells detect
pathogens in the body?
● Pathogens have unique antigens on their
surface
● WBCs have specialised receptors which can
detect these ‘non-self’ antigens on
pathogens
How do white blood cells destroy
pathogens?
● Phagocytosis
● Antibody production
● Antitoxin production
Describe phagocytosis
A phagocyte (type of WBC) engulfs a pathogen and digests it
How is a phagocyte adapted to its
function?
● Flexible membrane allows it to engulf foreign
material
● Contains enzymes that digest the pathogen
What are antibodies?
● Proteins produced by B-lymphocytes (type of WBC) in response to an antigen
● Each antibody is specific to an antigen and binds to it
● ‘Tags’ pathogens or causes them to clump together,
disabling them and aiding phagocytosis
How do white blood cells produce
antibodies?
● WBCs detect ‘non-self’ antigens on foreign material
● Receptors on WBCs bind to antigens
● WBCs produce antibodies specific to the antigens
● WBCs divide by mitosis, producing copies of
themselves, enabling the rapid production of antibodies
What are memory cells?
● WBCs that remain in the body after a pathogen has
been destroyed
● Provide immunity - if the body is re-infected, antibodies are produced more rapidly and the pathogen is destroyed before it can produce disease symptoms
What are antitoxins?
Proteins produced by WBCs to
neutralise toxins released by pathogens
Describe the chemical defence system
within plants
● Produce antimicrobial substances in
response to pathogens
● These destroy or prevent the growth of
pathogens
Why are plant defence systems
important?
● Plants are producers so all organisms higher
up in food chains rely upon their survival and
ability to fight disease
● Important in maintaining human food security
Outline the methods used to reduce
infections in animals
● Hygiene (washing hands, sneezing into tissues etc.)
● Sanitation
● Treating wounds
● Isolating infected individuals (isolation unit, limiting travel etc.)
● Killing infected animals
● Contraception
● Vaccinations
How can sanitation be improved to
reduce disease in humans?
● Access to clean water
● Sewage systems
● Reduces the spread of diseases e.g. cholera
(spread by drinking or washing in dirty water)
Why is it difficult to improve sanitation in
a community?
It is expensive
Why must wounds be sterilised?
● Antiseptic kills pathogens around the wound
● Covered to prevent further entry of
microorganisms into the wound
Why does the isolation of infected
individuals reduce disease?
● Reduces the transmission of airborne diseases (e.g. TB)or diseases that are spread through surface contact
● Prevents the infection of healthy individuals
● Reduces the risk of epidemics or pandemics
Outline the benefits vs risks of placing
travel restrictions on infected individuals
Benefits:
● Prevents the transmission of disease across borders
● Protects the health of uninfected individuals
Risks:
● Shouldn’t an individual have the right to travel freely?
Why are infected animals often killed?
To prevent the transmission of disease to
other members of the herd.
What are the disadvantages of killing
infected animals to reduce disease
transmission?
● High cost
● Some animals may already be infected
but not display disease symptoms
How does the use of contraception
reduce the spread of disease?
Using condoms prevents the spread of
STIs which are present in body fluids
such as semen.
What is a vaccination?
● Deliberate exposure of an individual to ‘non-self’ antigens
● Triggers an immune response (produces antibodies) and provides immunity (due to memory cells)
● The individual does not contract the disease that is being immunised against
Describe the components of a vaccine
Dead, weakened or inactivated
pathogens with their surface antigens
still present
What are the benefits of vaccinations?
● Herd immunity - vaccination of a significant
proportion of the population gives some
protection to individuals who are not immune
● Helps to prevent epidemics and pandemics
What are the drawbacks of vaccinations?
● The high mutation rate of viruses changes the structure of viral antigens, making vaccines that are already available ineffective
● Inactivated pathogens may mutate and become pathogenic
● May cause an adverse reaction
● Vaccination programmes are costly
Outline the methods used to reduce
infections in plants
● Controlling the movement of plants ● Killing infected plants ● Sourcing healthy seeds and plants ● Polyculture ● Crop rotation ● Chemical and biological control
How does killing infected plants reduce
the spread of disease?
It prevents infected plants spreading
disease to healthy plants
Why is it important to control the
movement of plants?
● Ensures that infected plants do not spread
disease to healthy plants
● Plants from other regions of the world may carry
pests or diseases that could be harmful to plants
in the UK
What is polyculture?
The cultivation of several crop species at
once
How does polyculture reduce the
transmission of disease?
There is greater variation between
plants, reducing the likelihood of a
pathogen infecting an entire crop.
What is crop rotation?
Growing different types of crops in the
same area each season.
Why does crop rotation reduce the
transmission of disease?
● After a crop has been harvested, soil-borne pests and diseases may remain which have the potential to infect the next crop
● Pests and diseases are often specific to a certain crop
● Changing the type of crop grown reduces infection by soil-borne pathogens remaining from the previous year
Give an example of chemical control
Using fungicides
What is biological control?
When a new organism (often a predator)
is introduced into an ecosystem to
control a pest or pathogen
What is the risk of using biological
control?
Risk of the control organism becoming a
pest itself
How can diseases be detected andw
identified in the field?
● Observation of symptoms
● Symptoms may be specific to a disease and easily
identifiable e.g. TMV causes discolouration of leaves,
chicken pox causes red, blistering spots
● Books and online resources aid identification
Why is it difficult to identify a disease
using symptoms alone?
Many diseases may have similar
symptoms
How can a disease be detected from a
sample in the laboratory?
● Counting cells
● Culturing cells
● Microscopes and staining
● Testing with antimicrobials
● Genome analysis
● Isolation and reinfection (plants)
● Using monoclonal antibodies
How does counting cells help diseases
to be identified?
● Low RBC count indicates anaemia
● High WBC count shows that the body is fighting off an
infection
● Low WBC count may indicate diseases such as HIV,
leukaemia etc.
How does culturing cells enable the
identification of disease?
● It increases the number of microorganisms, making it easier to identify the colonies present.
● Antibiotics can be added to a colony. The reaction of the pathogen to the antibiotics can help identify it.
How do microscopes help to identify
pathogens?
They enable the structure of pathogens
to be observed in greater detail
How can staining be used to identify a
pathogen?
Staining differentiates between different types
of pathogens e.g. Gram stain distinguishes
Gram negative (stains pink) from Gram
positive (stains purple) bacteria.
Describe how genome analysis is used
to identify a pathogen
● The microorganisms genetic material can be
analysed and compared to the genomes of known
pathogens
● Gene probes added to determine whether a specific
pathogen is present
What is a gene probe?
● A single strand of DNA (often bound to a fluorescent molecule) that is used to identify a specific base sequence in a DNA sample
● Complementary to a base sequence in a pathogen’s DNA
● If the pathogen is present, the gene probe will bind to the pathogen’s DNA
Describe the process of isolation and
reinfection in plants
● Microorganism thought to be the cause of disease is isolated and cultured
● Used to infect healthy plants
● If the healthy plants develop the same symptoms as the infected plants, the pathogen has been identified
What is important when handling
samples containing microorganisms in
the lab?
Aseptic techniques
What are monoclonal antibodies?
● Antibodies that are clones from one
parent cell
● Specific to one type of antigen
Describe how monoclonal antibodies are
produced
● Specific antigen injected into an animal
● WBCs producing complementary antibodies extracted
● WBCs fused with tumour cells
● Resulting cells cultured
● Monoclonal antibodies collected
Outline the uses of monoclonal
antibodies
● Detect pathogens
(e.g. malaria diagnostic stick)
● Treat cancer
● Pregnancy test kits
What does a malaria test consist of?
A diagnostic stick containing monoclonal antibodies
(MAs) specific to the antigens on the plasmodium:
● MAs attached to a dye (free to move)
● MAs fixed to the test stick
Describe what happens to the test stick if
the pathogen is present
● Blood sample placed at one end of the stick and
diffuses up the stick
● MAs attached to a dye and MAs fixed to the stick bind to the plasmodium antigens
● Test strip changes colour
Describe what happens to the test stick if
the pathogen is not present
No change
What is the advantage of using
monoclonal antibodies to test for
diseases?
● Specific to one particular antigen
● Very accurate
● Quick results
What is a risk factor?
A variable associated with a greater
chance of developing a disease or
infection
Outline the factors that can affect the risk
of developing a non-communicable
disease
● Lifestyle factors e.g. diet, exercise, alcohol, smoking
● Environmental factors e.g. exposure to pollution
● Genetics e.g. alleles that increase the risk of cancer
“Correlation does not mean causation.”
Explain this statement.
Correlation between a risk factor and a
disease does not mean that the risk factor
causes the disease. Other factors may be
involved and some may be linked.
Describe how exercise affects the risk of
some non-communicable diseases
● Regular exercise decreases fat stores, reducing
obesity (a risk factor of CVD and type 2
diabetes)
● It decreases heart rate, recovery time and blood
pressure, lowering the risk of CVD
Describe how diet affects the risk of
some non-communicable diseases
● Diet high in saturated fat raises blood cholesterol levels, increasing the deposition of fatty deposits in the arteries ∴ greater risk of CVD
● Obesity and the consumption of large amounts of simple-sugars increases the risk of type 2 diabetes
● Malnourishment increases the risk of deficiency diseases
Give an example of a deficiency disease
● Scurvy (vitamin C deficiency)
● Anaemia (iron deficiency)
Describe how alcohol affects the risk of
some non-communicable diseases
● Alcohol broken down into toxic products in the liver which build-up and cause cirrhosis (scarring of liver tissue)
● Alcohol raises blood pressure therefore increasing the risk of CVD
● Toxic products in alcohol can cause mutations to DNA, increasing the risk of cancer (mouth, throat, liver etc.)
Describe how smoking affects the risk of
some non-communicable diseases
● Nicotine raises heart rate, increasing the risk of CVD
● Carbon monoxide lowers the ability of red blood cells to carry oxygen, heart rate increases, increasing the risk of CVD
● Carcinogens in tar can cause mutations to DNA, increasing the risk of cancer (mouth, throat, lung etc.)
● Smoking increases the risk of lung diseases e.g. chronic bronchitis
How do environmental factors affect the
risk of some non-communicable
diseases?
● Long-term exposure to pollution damages the airways, increasing the risk of lung diseases and lung cancer
● Exposure to UV radiation damages DNA, increasing the risk of DNA mutations and skin cancer
How do genetics affect the risk of some
non-communicable diseases?
The risks of some diseases such as type 2 diabetes,
lung cancer and CVD are increased if a family member has had these conditions.
Faulty genes can be inherited which increase the risk of conditions such as breast cancer.
How do diseases interact with each
other?
● Some diseases may cause other infections to develop e.g. HIV weakens the immune system, making an individual more susceptible to other infections such as TB.
● Some diseases reduce the risk of contracting other
infections e.g. Trichinosis reduces the development of
Crohn’s disease.
What is the function of painkillers?
They reduce the severity of symptoms
(i.e. pain) rather than curing the disease
itself.
What is an antibiotic?
● A substance that kills or inhibits the
growth of bacteria (no effect on viruses)
● Produced by living organisms e.g. fungi
Why are bacteria becoming increasingly
resistant to antibiotics?
Due to over prescribing and antibiotic
misuse e.g. not completing the entire
course
How does the failure to complete an
antibiotic course increase resistance?
● Most resistant bacteria survive
● Less competition for resources between remaining
bacteria
● Reproduce rapidly, increasing antibiotic resistance
What is MRSA?
● Highly resistant strain of bacteria
● Resistant to almost all available antibiotics
● Found in hospitals
How can we reduce the spread of
antibiotic-resistant bacteria?
● Prescribe antibiotics only when necessary
● Ensure patients complete their antibiotic courses
● Reduce the use of antibiotics in farming
● Improve hygiene in hospitals
What are antivirals?
● Used to treat viral infections
● Slow down the reproduction of viruses
Why must new antivirals constantly be
produced?
Viruses have a high mutation rate so
their surface antigens (targeted by
antivirals) are constantly changing.
Why is it difficult to produce antivirals?
● Viruses reproduce inside living cells
● Antivirals must be produced that do
not harm living cells
What is coronary heart disease?
● Type of cardiovascular disease (CVD)
● Build up of fatty deposits on the walls of the
coronary arteries forms atheromas which reduce
blood flow to the heart muscle
How can coronary heart disease lead to
a heart attack?
● Obstruction of a coronary artery due to an atheroma or
blood clot
● Results in loss of blood supply to an area of heart muscle
● This causes death of the cells and leads to a heart attack
How can CVD be treated?
● Improving diet and lifestyle
● Medication
● Surgery
What changes to diet and lifestyle can be
made to reduce the risk of CVD?
● Regular exercise ● Reduce intake of saturated fat ● Maintenance of a healthy weight ● Diet low in salt ● Reduce stress ● Stop smoking and drinking alcohol
How effective are changes to lifestyle
and diet in treating CVD?
Although not themselves effective in the
treatment of CVD, they can enhance the
efficiency of other methods of treatment.
Which medicines are used to treat CVD?
● Statins
● Anticoagulants
● Antihypertensives
Outline the benefits vs the risks of using
statins to treat CVD
● Statins lower the level of LDLs (cholesterol that
contributes to atheromas) in the blood
● However, they can cause liver damage, kidney failure or problems with memory
Outline the benefits vs the risks of using
anticoagulants to treat CVD
● Anticoagulants reduce blood clotting, lowering the risk of a heart attack or stroke
● However, they can cause excessive bleeding
Outline the benefits vs the risks of using
antihypertensives to treat CVD
● Antihypertensives lower blood pressure, reducing
damage to artery walls and the build up of atheromas
● However, they can have unpleasant side-effects such as headaches, dizziness or fainting
What are stents?
● Small, hollow tubes inserted into the
lumen of arteries to keep them open
● Require surgery to insert
What are the problems with the use of
stents to treat CVD?
● Stents cause the growth of scar tissue in the
arteries over time, further narrowing the artery
lumen
● Blood clots may stick to stents
What is a coronary bypass?
Using a blood vessel from another region
of the body (e.g. leg, arm) to divert blood
around a blockage in the coronary artery.
What does a heart transplant involve?
● Replacing a damaged heart with a
donated heart
● Immunosuppressant drugs taken to
prevent organ rejection
Describe the benefits of heart surgery
● Lifesaving
● Can provide a permanent solution to a
disease
Describe the risks of heart surgery
● Major surgery involving many risks e.g. excessive
bleeding, infection etc.
● Difficult to find a suitable donor
● Risk of rejection
● Immunosuppressant drugs must be taken for life
● Long recovery time
● Expensive
Describe how ‘targets’ for new medicines
can be identified
● Comparisons of the genomes of unaffected
individuals and those who are affected by a disease
to identify potential disease-causing alleles
● The alleles themselves or the proteins that they code
for can be used as a target
Outline the stages of drug development
- Screening
- Preclinical trials
- Clinical trials
Describe the process of screening
● Uses a machine to test large libraries of chemical
substances
● Enables identification of pre-existing chemicals which may
affect the target molecule
● Chemicals may be altered, allowing scientists to produce
a drug that reacts with target molecules in a specific way
What do preclinical trials involve?
● Drug tested on cultured human cells and using
computer models to determine its toxicity (potential to cause damage) and efficiency
● Drug then tested on live animals to establish a safe
dose for humans and observe any side effects
What happens during clinical testing?
● The drug is first tested on healthy human volunteers to
ensure that it is safe to use and has no other unwanted
effects on the body
● Drug then tested on patients with the disease to determine
its efficacy. Dosage is slowly increased until an upper limit
is established.
What are placebos?
A substance that appears just like the
real drug but has no effect on the
recipient
What is a blind trial?
● It is where the participants don’t know whether
they are receiving the new drug or the placebo
● Prevents the patient’s bias affecting the results
What is a double-blind trial?
● Neither the participants nor the doctors know
who is receiving the new drug or the placebo
● Prevents bias from doctors when analysing
the results
What are open-label trials?
A trial in which both the patients and the
doctors know who is taking the placebo
and who is taking the new drug.
What is the problem associated with
using placebos on patients with a
disease?
Is it ethical to prescribe a sick patient
with a placebo knowing that it will not
help their condition improve?
Why can monoclonal antibodies be used
to target cancer cells?
● Cancer cells have specific antigens called ‘tumour
markers’ on their membranes
● Monoclonal antibodies are specific to one type of
antigen so can be targeted to ‘tumour markers’
without damaging other cells
What are the two ways in which
monoclonal antibodies can be used to
treat cancer?
● Trigger an immune response
● Carry drugs to tumour cells
Why don’t tumour cells trigger an
immune response?
The immune system doesn’t identify
‘tumour markers’ as non-self antigens
How can monoclonal antibodies trigger
an immune response?
● MAs injected into the patient’s bloodstream
● MAs are specific to ‘tumour markers’ so bind to cancer cells
● WBCs now recognise the cancer cells as foreign
● Immune response triggered
● Cancer cells destroyed
How can monoclonal antibodies target
drugs to cancer cells?
● MAs attached to an anti-cancer drug
● MAs injected into the patient’s bloodstream
● MAs bind to ‘tumour markers’ on cancer cells
● Anti-cancer drug destroys cancer cells
Why are cancer treatments that use
monoclonal antibodies favoured over
traditional treatments?
● Radiotherapy and chemotherapy target rapidly dividing cells
● Healthy cells (e.g. hair follicle cells, bone marrow cells) are damaged as a consequence, producing unpleasant side effects
● MAs only target cancer cells, reducing damage to normal cells
