and how different types of
disease can interact with each other
Doc Brown's biology exam revision study notes
There are various sections to work through, after 1 they can be read and studied in any order.
Sub-index of notes on non-communicable diseases
(2) Examples of risk factors for
and how different types of
disease can interact
Just a few general points as a 2nd introduction to
non-communicable diseases - including when diseases coincide and cause
other medical situations - physical conditions or mental health
All diseases have risk factors.
Risk factors are anything that can be
associated with an increase in likelihood of developing a
non-communicable disease, but that doesn't been you will automatically
contract the disease!
They can be often related to a person's
lifestyle or whether they are exposed to a pollutant in the
environment or place of work - air pollution has always been linked with
bronchial and lung diseases including asthma.
Age or gender
Certain medical conditions become more likely to older you get -
e.g. arthritis or Alzheimer's disease - these are unavoidable as the
body ages, but susceptibility varies from one individual to another.
Males and females have different susceptibilities to certain
Alcohol - a lifestyle choice
Too much a in your alcohol in your diet can
cause liver damage e.g. cirrhosis of the liver (scarring of the
live). This happens because alcohol is broken down by enzymes in the
liver and some of the products of this process are toxic.
With excessive drinking over a long period
time results in permanent liver damage - in some cases a liver
transplant is required to keep the person alive - needs a donor -
may not be available.
Heavy drinking raises blood pressure to
increase the likelihood of cardiovascular disease.
Excessive drinking of alcohol can affect brain function,
nerve cells are damaged and brain volume decreases.
High alcohol consumption is being linked to
cancers of the bowel, liver, mouth and throat.
When pregnant women drink to much alcohol
there is an increased risk of health problems for an unborn baby
e.g. abnormal foetal brain development.
Quite a few diseases can be linked to genetic factors - what we
become from our inherited genes, which may include particular
Unfortunately, you can inherit faulty genes
that you a person more susceptible to cancer or coronary heart
e.g. mutations to the BRCA genes have been
linked to increased chance of women developing breast cancer or
Immune system responses
The presence of a pathogen infection in your body can trigger an
allergic reaction from your immune system e.g. asthma sufferers
experience more intense symptoms or skin rashes.
You can also have problems if a disease you
have lowers your immune system response and you become susceptible
to another disease. See
HIV virus infection
as an example.
Other lifestyle choices and your personal situation
Lack of regular exercise is one of several
factors that increase your chance of contracting cardiovascular
disease - especially if you have a poor diet too rich in fatty
and sugary foods leading to obesity - overweight.
Physically inactive people are more likely
to develop high blood pressure and heart disease, and an
increased risk of certain kinds of cancer.
The human circulatory system - causes/treatment of cardiovascular disease
Eating a good balanced healthy diet helps maintain your
body in good shape and your immune system to fight communicable
disease infections and reduce the risk of contracting
non-communicable diseases such as
cardiovascular disease and cancers.
The human circulatory system - including the causes
and treatment of cardiovascular disease
If you do not get the right balance of
nutrients in your diet, you have a condition called
The poorer you
diet (poor nourishment), the more susceptible you are to these kinds of diseases and
mental health issues.
Eating a balanced nutritious diet, not too
high in fats and sugars, plenty of minerals and vitamins from
whole grains, fruit and vegetables.
Lack of vitamin C in your diet causes
non-communicable disease with harmful consequences.
e.g. lack of vitamin C inhibits the
body's ability to make collagen - an important protein found
in bone and tendon tissue.
Symptoms of scurvy include painful
joints and muscles and bleeding gums.
Vitamin D is both a nutrient in
food we eat and a hormone our bodies make in our skin cells from
the action of sunlight.
It is a fat-soluble vitamin that helps
the body absorb and retain calcium and phosphorus; both are
critical for building bone.
Laboratory studies show that vitamin D
can reduce cancer cell growth, help control infections and
Interestingly, many of the body’s
organs and tissues have receptors for vitamin D, which
suggest important roles for Vitamin D other than bone
Lack of vitamin D may help your body fight the covid-19
viral infection, people low in vitamin D seemed to have been
more susceptible to the disease.
A diet too high in fat an sugar can lead
to obesity - being overweight makes your more susceptible to
non-communicable diseases such as cardiovascular disease and
type 2 diabetes - the latter can often be dealt with by changing
to a more healthy balanced nutritious diet.
Smoking - completely avoidable to reduce your chance of
developing lung cancer.
BUT, smoking is now linked to cardiovascular disease and lung diseases including cancer.
in tobacco smoke harm your blood cells and can damage the
function of your heart and the structure and function of your
Smoking reduces the body's defences
against particles you breathe in.
Substances in tobacco smoke cause damage to
lung tissue. Cigarette smoke contains four
potentially harmful substances - (i) carbon monoxide, (ii) nicotine,
(iii) particulates and (iv) tar.
This damage increases your risk of
atherosclerosis - a disease in which a waxy substance called
plaque builds up in the arteries.
(i) Carbon monoxide molecules (CO)
combines with haemoglobin more strongly than do oxygen molecules
This displaces oxygen from oxygenated
haemoglobin and reduces the oxygen supply to your cells
affecting your respiration.
(ii) Nicotine makes smoking addictive.
Nicotine in cigarette smoke
increases heart rate which increases blood pressure -
increasing the chance of a heart attack, stroke or blood
clot formation. Increased blood pressure damages the walls of arteries
which contributes to the build up of fatty deposits on the
walls of the arteries - leading to
heart disease and circulation problems which further
increase the risk of a stroke or heart attack when the blood
supply to the brain or heart is cut off.
lungs are also subjected to fine particulates that lodge in the
alveoli of the lungs - the latter will affect the efficiency of
lungs to deliver oxygen to the cells of your body.
smoking causes inflammation of the lining of the bronchi and
bronchiole tubes in the lungs giving you chronic bronchitis -
persistent cough, wheezing i.e. breathing problems!
The damage builds up and can eventually lead to
bronchitis - a disease that inflames the lining of the
bronchial tubes and also emphysema - a disease that destroys
the alveoli (air sacs) in the lungs.
(iv) The cells in the lining of the
lungs can be coated in tar (which also contains carcinogens).
The tar covers the cilia hairs on the
lining of airways inhibiting from moving mucous along, which
sticks to the lining of the airways making you cough as you
try to get rid of the mucous - 'smokers cough'.
This causes various serious lung conditions
- breathing problems because of less efficient oxygen intake, mutations
of the DNA of lung cells to form tumours which can become
cancerous. Smoking is now related to cancer of the
mouth, oesophagus and throat as well as the lungs.
Cells that line the
trachea and bronchi have cilia and others produce
You can think of it as the mucous
The cilia, hair-like
structures, can move the
mucous along from the lungs up to the nasal passage and back of the throat
where it can be swallowed, coughed out or blow
your nose, into a tissue!
Note that smoking can
damage and paralyse the cilia reducing the ciliated cell's
capacity to remove harmful particles, so another reason why
smokers are more susceptible to respiratory diseases.
When pregnant women smoke there is an
increased risk of health problems for an unborn baby.
I can't understand why anyone
smokes cigarettes these days, but they do!
Asthmatics are people who suffer from asthma because
their lungs are much too sensitive to certain materials.
If an asthmatic breathes these substances in the muscles
around the bronchioles contract, narrowing the airways in the
The lining of the airways becomes inflamed and fluids build
up in the airways making it harder to breathe - this what is
called an asthma attack.
The symptoms are difficulty in breathing, wheezing and a
feeling of tightness in the chest.
When an asthmatic attack occurs, e.g. symptoms above, the
asthmatic can treat themselves with an inhaler containing drugs
that open up the airways to allow normal efficient breathing.
Access to your needs?
The risk of a non-communicable disease
starting and progressing increases if you have limited access to
good healthcare systems and health education.
When you have access to a quality
healthcare system, your medical condition is more likely to be
diagnosed and receive appropriate treatment.
Education provides you with knowledge
about how non-communicable diseases develop and strategies for
prevention e.g. diet and exercise.
means lack of proper nutrition, caused by not having enough to eat,
not eating enough of the right things, or being unable to use the
food that one does eat.
Usually no problem in rich developed countries - your
choices, BUT not so for people living in poorer underdeveloped
countries - an undernourished body is more likely to be fatigued
and more susceptible to the effects of infections and
e.g. to help prevent or reduce the risk of non-communicable
diseases in the first place - an you afford to buy healthy
food? Is 'healthy shopping' readily available?
If you have contracted a non-communicable disease, do you
have access to appropriate medicines?
Perhaps surprisingly?, non-communicable
diseases are more likely with people of higher income in developed
countries because they can afford to buy richer food higher e.g. in
saturated fats - obesity related.
However, ALSO, people from poorer areas
are poor likely to have a poorer diet (not balanced) and exercise
less. Therefore in deprived areas, you find higher rates of
cardiovascular disease, obesity, type 2 diabetes due to less healthy
Statistics and a note of caution!
Medical scientist do their best correlate
data connecting risk factors with disease incidence.
However, correlation doesn't simply mean
you can relate incidence to cause.
Just because you eat a poor diet and have
little exercise doesn't mean to say you automatically get e.g.
cardiovascular disease (CVD).
Your diet and lack of exercise does not
cause CVD directly. What these two factors cause is high blood
pressure and increase in the blood levels of bad LDL cholesterol
- and it is these which actually cause the CVD.
Mental health and stress
If can develop a mental health condition such as depression while
enduring some physical health problem e.g. lack of mobility reducing
your ability to participate fully in everyday life.
If you are
constantly under mental stress e.g. 'high-powered' job or caring for
a very sick relative, then your physical well-being can be affected
- ulcers can develop or a mental health condition like extreme
anxiety - both of which are non-communicable.
When you are stressed, hormones are released,
your blood vessels constrict (narrow) and your blood pressure is
Stress can lead to depression, and increased
risk of obesity and diabetes, also increasing the risk of
cardiovascular disease, diabetes and Alzheimer's disease.
Obesity usually involves lifestyle factors,
but 'body chemistry' is naturally quite variable and not all down to
Poor diet and 'over-eating' lead to excess
weight in the body - obesity!
This increases your susceptibility to type 2
diabetes when your body is less responsive to your own insulin and
reduced control of blood sugar levels - which can be very dangerous.
Obesity can also affect your breathing -
reduces your respiratory function.
Obesity is a risk factor in other
non-communicable diseases e.g. cardiovascular disease and type 2
Some types of
cancer are triggered by particular
This is a communicable disease causing the development of a
Keywords, phrases and learning objectives for this part on risk factors and
Be able to describe and discuss non-communicable
diseases in terms of risk factors such as age, gender, consumption
of alcohol, genetic factors, diet, smoking, lack of exercise,
malnutrition, viral infections, obesity and stress.
Understand how different types of disease interact
with each other.
Appreciate the importance and need for access to
good medical care and have good mental health.
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