lifestyle and disease

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What is a disease?

What is a disease?

An abnormal condition of an

organism that impairs its function

and which is accompanied by a

set of characteristic signs and

symptoms.

A disease is different from

physical trauma due to an

accident (e.g. breaking a rib in a

fall).




Classifying diseases

Diseases can be classed in several ways:

by timescale – acute (develops quickly and lasts a shorttime, e.g. acute angina) vs. chronic (develops slowly and

lasts a long time, e.g. chronic bronchitis)

by number of causes – single factor (have a single

cause, such as a single mutated gene, e.g. sickle-cell

anaemia,) vs. multifactorial (have many causes, genetic

and environmental, e.g. cardiovascular disease).

Diseases can also be classified according to whether theyare infectious (e.g. HIV), non-infectious (e.g. lung cancer),

inherited (e.g. cystic fibrosis), caused by a deficiency (e.g.

scurvy), a mental disorder (e.g. schizophrenia), etc.




UK deaths, 2005




Genetics and environment

Many non-infectious diseases develop as a result of the

interaction between a person‟s environment/lifestyle and their

genes – they are multifactorial diseases.

These diseases have a genetic component, which means

they may be:

partly inherited – inheriting the „faulty‟ genes will make yougenetically predisposed (more susceptible) to develop

the disease, but environmental factors still play a role.

Examples include heart disease, cancer and Alzheimer‟s.

completely inherited – inheriting the „faulty‟ genes is

certain to make you develop the disease. Examples

include cystic fibrosis and Huntington‟s chorea.




Calculating the risk of diseases

In 2005 in the UK, 100,936 people died from coronary heart

disease (CHD), and the population was 60,209,500. Whatwas the risk of death from CHD in the UK in 2005?

= 0.0017

= 0.17%

= 1 in (60,209,500 / 100,936)

= 1 in 597

Risk = 100,936 in 60,209,500 Or, risk = 1 / 597

Health risks are not the same for everyone, however,

because people have different risk factors.

What is the risk of developing a disease?

no. people with the disease at any one timetotal no. people who could develop the disease

risk =




What are risk factors?

A risk factor is anything that increases the chance of

developing a disease.

Smoking is a major risk

factor for lung cancer,

which means smokers

have a much higher riskof developing lung cancer

than non-smokers.

Risk factors are correlational with a disease, not

necessarily causal. For example, international travel is a riskfactor for malaria, but it is not the travel itself that causes

malaria – it just increases the chance of coming into contact

with the malarial parasite.


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Types of risk factor

Risk factors may be modifiable or non-modifiable.

Modifiable risk factors are

those that can be prevented and

controlled. These are essentially

environmental or lifestyle risk

factors, such as smoking, dietand physical activity.

Non-modifiable risk factors are

those that cannot be preventedor controlled. These are age and

genetic risk factors, such as

gender and family history.



Take a vote: lifestyle and health



is commoninvolves a spectacular outcome

is familiar is unfamiliar

is an accidentis the result of an intentional

action

occurs over the long-termoccurs over the short-term

is done voluntary by youis out of your control

Underestimate the risk of

an event if it…

Overestimate the risk of an

event if it…

Perceived risk vs. actual risk

A person‟s perceived risk of a particular event can be

markedly different from the actual risk. What factors do you

think make an event seem more risky than it actually is?



Worldwide deaths due to CVD, 2002



What is coronary heart disease?

Coronary heart disease (CHD) is a disease of the arteries

supplying the heart (coronary arteries). Almost one-fifth of

all deaths in the UK in 2005 were due to CHD.

The major cause of CHD is

atherosclerosis: a thickening of

arteries caused by a build-up of

fatty plaques (atheromas) on the

inside walls.

Atherosclerosis can eventuallylead to a reduced blood supply

(ischaemia) to tissues, with

potentially fatal consequences.



Trends in CVD death rates



Gender, age, CHD and stroke



Scientist case study



Development of atherosclerosis



others: stress, alcohol

diabetes mellitus

obesity

ethnicity/racephysical inactivity

family history of the diseasetobacco smoking

male gender high blood cholesterol

advancing agehigh blood pressure

CHD risk factors

Hundreds of risk factors for CHD and stroke have been

identified. The major ones are:

Non-modifiableModifiable



Hypertension and CHD

High blood pressure (hypertension) is a major risk factor for

CHD and other cardiovascular diseases.

Hypertension is defined as

systolic blood pressure above

140 mmHg and/or diastolic

blood pressure above 90 mmHg.

Hypertension puts strain on the

heart and blood vessels,

increasing the risk of

aneurysm or thrombosis. It issometimes called the „silent

killer‟ because it can develop

without symptoms.



Hypertension and CHD



Cholesterol and lipoproteins

Cholesterol is a soft waxy lipid that has a vital role as a

component of cell membranes, where it regulates fluidity.

Cholesterol is insoluble in blood, so

it is transported by lipoproteins.

These are spherical complexes

consisting of:

Two major types of lipoprotein are low-density lipoprotein

(LDL) and high-density lipoprotein (HDL).

an outer layer of phospholipids,

studded with proteins

an inner core of trigylcerides

and cholesterol.



High blood cholesterol levels and CHD

LDLs generally transport cholesterol fr om the

liver to body tissues, depositing it on the

walls of blood vessels. In high levels,it contributes to atherosclerosis.

HDLs generally transport cholesterol away from the tissues

to the liver, where the cholesterol is metabolized. High levels

of HDL cholesterol are linked to a reduced risk of CHD.

Eating a diet high in saturated fat

is the biggest cause of elevated LDL cholesterol levels.

LDL cholesterol levels can be reduced by regular exercise,

eating plenty of fibre and a diet rich in polyunsatured fats.



Smoking and CHD

Smoking tobacco is a major cause of CHD, and smokers are

at a higher risk of developing CVD than lung cancer.

Smoking increases the risk of CHD in several ways:

it damages and weakens the endothelial lining of blood

vessels

nicotine increases blood pressure and heart rate, andconstricts blood vessels

it increases clotting and the development of atheromas

carbon monoxide reduces the amount of oxygen that

blood can carry.

it lowers HDL cholesterol and raises LDL cholesterol levels



Effects of CHD: heart attack

The most dangerous symptom/result of CHD is a heart attack,

known as a myocardial infarction (MI).

An MI occurs when the blood

supply to part of the heart muscle

(myocardium) is interrupted.

This causes oxygen deprivationand subsequent tissue damage.

The most common symptom is

chest pain, but shortness of breath,excessive sweating, nausea and

weakness may also be present. Loss

of consciousness and death can occur.



Effects of CHD: angina

A less severe symptom of

CHD is angina pectoris.

This is a tight, grippingchest pain or ache, similar

to indigestion, which

commonly occurs during

physical activity.

The narrowing of the coronary arteries results in inadequate

blood and oxygen supply, forcing the heart to respire

anaerobically, and causing a build-up of lactic acid.

The pain normally subsides with rest, once the demand on

the heart has dropped and it can respire aerobically.

Di i h di



Diagnosing heart disease

H d CHD d l ?




How does CHD develop?

Id tif i CHD i k f t




Identifying CHD risk factors

R d i th i k f CHD




Reducing the risk of CHD

Ensuring a healthy lifestyle can make a significant difference

to a person‟s risk of developing CHD.

stopping smoking

These changes aim to reduce blood pressure and blood

cholesterol, and reduce weight if overweight or obese. Key

steps include:

regular cardiovascular exercise – about 30 mins of

moderate exercise several times a week

a healthy diet – low in saturated fats (including trans fats)

and salt, high in fibre, fresh fruit/vegetables, and

moderate mono/polunsaturated fats

reducing alcohol intake.

T ti CHD di ti




Treating CHD: medication

T ti CHD




Treating CHD: surgery

Surgery is used in the treatment or prevention of CHD, stroke

or MI. The type of operation depends on the severity and

location of atherosclerosis, and factors such as whether thepatient has diabetes.

A coronary artery bypass

graft (CABG) is an operationin which arteries from

elsewhere in the body (e.g.

legs or chest) are grafted on

to coronary arteries to

bypass blocked regions.

Single, double, triple bypass refers to the number of coronary

arteries that are bypassed.

T ti CHD i l t




Treating CHD: coronary angioplasty




Respiratory diseases




Respiratory diseases

Respiratory diseases are one of the biggest causes of death

worldwide.

Respiratory diseases affect the lungs, bronchi, trachea and

throat. They can be mild (e.g. cold) or life-threatening (e.g.

pneumonia, lung cancer).

Chronic obstructive pulmonary disorder (COPD) is aterm for a group of diseases that cause a reduction in the

airflow in the lungs and which are not fully reversible.

Two of the more serious types of COPD are chronicbronchitis and emphysema, and are both usually caused

by smoking.

COPD: chronic bronchitis




COPD: chronic bronchitis

Chronic bronchitis is a

narrowing of the bronchi. It

is characterized by:

a persistent cough that

produces phlegm - due

to an increased number

and size of goblet cells

shortness of breath and wheezing - irritants in cigarettesmoke cause inflammation in the lining of the bronchioles.

Over time this leads to scarring and narrowing of the

bronchioles, reducing airflow.

normal

airway

inflammed

airway

mucus

bronchi

COPD: emphysema




COPD: emphysema

Emphysema is a gradual breakdown of alveolar walls and

damage to terminal bronchioles and alveolar capillaries.

This reduces the efficiency of gas exchange, causing

chronic breathlessness and hyperventilation.

Using this photo of healthy lung tissue

(left ) and emphysema

lung tissue (right ), can

you explain why gas

exchange is less

efficient in

emphysema?

Diagnosing COPD




Diagnosing COPD

There is no one single test for COPD. Diagnosis depends

on taking into account a patient‟s risk factors (e.g. whether

they smoke, their age), their symptoms and clinical tests.

Testing the patient‟s lung

function using spirometry

is essential. It can

determine whether there is

airway obstruction and can

help exclude the possibility

of other respiratorydiseases, such as asthma

or lung cancer.

Determining lung function




Determining lung function

Treating COPD




Treating COPD

Stopping smoking is the single most important step in

slowing the decline in lung function in people with COPD.

Medicines commonly prescribed to treat COPD include

bronchodilators, which widen the airways by relaxing

smooth muscles, and corticosteroids, which act as anti-

inflammatories.

Oxygen therapy,

especially for people

with emphysema, may

be required for most of each day.

What is asthma?




What is asthma?

Asthma is a chronic condition in which the airways

occasionally narrow and become inflamed, limiting airflow.

Asthma causes difficulty

breathing, wheezing and

chest tightness, and can

be mild or life-threatening.

Treatment is with bronchodilators, corticosteroids, or a

combination of the two.

Asthma is triggered by a

range of stimuli, such as

allergens, dust, exercise,

stress and infections.

Lung cancer




Lung cancer

Lung cancer is the biggest cause of cancer-related deaths in

men and second-biggest cause in women. About 90% of

cases are caused by smoking.

Symptoms include shortness of breath, coughing (including

coughing up blood) and loss of weight.

Most incidences of lung

cancer are due to

uncontrolled growth of epithelial cells lining the

airways. Cancers arising

from these cells are

called carcinomas.

Lung cancer




Lung cancer

Lung cancer generally develops quite slowly. By the time it

has been diagnosed, the cancer may have spread to other

areas of the body. This is called metastasis, and makes itdifficult to treat successfully.

Lung cancer can be seen

on an X-ray or a CT scan,and diagnosis is usually

confirmed after a small

sample of tissue is taken

(a biopsy) and analysed.

Like many other cancers, lung cancer is treated by surgery,

chemotherapy and/or radiotherapy.

Cancer statistics




Cancer statistics

Smoking and lung cancer




Smoking and lung cancer

Smoking and lung cancer: epidemiology




Smoking and lung cancer: epidemiology

The first solid epidemiological evidence that smoking

increased the risk of lung cancer came from a 1950 study by

Richard Doll, a British doctor and epidemiologist, and AustinBradford Hill, a British epidemiologist and statistician.

Their study of over 1,700 men and women in London

concluded that: “The risk of developing the diseaseincreases in proportion to the amount smoked. It may be

50 times as great among those who smoke 25 or more

cigarettes a day as among non-smokers.”

Before their study, it was unclear whether the rapid rise in

lung cancer was due to smoking or other atmosphericpollution, such as exhaust fumes, industrial plants or tarmac.

Smoking and health: epidemiology




Smoking and health: epidemiology

Following Doll and Hill‟s research, a large-scale study into the

health and smoking habits of British male doctors began in

1950, continuing with periodic updates until 2001.

Two of the main findings of this British Doctors Study were:

life-long smokers died, on average, 10 years earlier than

non-smokers

the earlier smokers stop smoking, the more chance they

have of avoiding reduced life expectancy.

Which respiratory disease?




Which respiratory disease?




Glossary




Glossary

What’s the keyword?




What s the keyword?

Multiple-choice quiz



Multiple choice quiz

lifestyle and disease

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