KIN 140 Section 5 Dr Mike Walsh
CHRONIC DISEASES (Rust of Our Body)
Chronic diseases are diseases that progress very slowly, often for more than 20 years
before the body finally succumbs. Often these diseases were not as prevalent in past
history because we died of other things sooner before a chronic disease could fully
bloom. In addition, some things we have today, like pollution and super size fries, our
bodies have never been prepared for. Such an attack upon our physiology becomes a
chronic disease. We can usually treat the conditions of a chronic disease but we cannot
Always remember, we are designed by evolution.
Chronic diseases account for 75 % of the mortality currently in our Canadian society. The
chronic diseases below all have associated risk factors determined from epidemiological
studies. Some of the risk factors are immutable (cannot be changed) such as age, gender,
and genetics whereas others are mutable such as diet and exercise.
I. Cardiovascular Disease
Cardiovascular disease encompasses any disease of the heart or blood vessels.
Arteriosclerosis is a hardening of the arteries and atherosclerosis is a type of
arteriosclerosis. Atherosclerosis is a fatty plaque accumulation that occurs at the inner
most layer of a blood vessel: the endothelium.
Atherosclerosis is the leading killer of cardiovascular disease. If it occurs in the heart, it
is called coronary heart disease. If it occurs in the brain it is called a stroke, and if it
occurs in a limb it is called peripheral vascular disease. The heart locus accounts for over
2/3 of atherosclerosis.
B. Generic Mechanism
In atherosclerosis, a lesion occurs on the inner lining of an artery. This leads to an
accumulation of lipids creating a fatty streak. Proliferation of smooth muscle cells can
occur further narrowing the blood vessel. Calcium and fibrous tissue invade the lipids and
it becomes hardened. Blood clotting factors can also invade the fat forming a thrombus
which can create a serious blockage of blood flow. Tissues downstream of the artery will
suffer ischemia and can die.
A piece of the thrombus can break off creating an embolus that will block a vessel further
C. Risk Factors 2
The risk of atherosclerosis is 3x higher at 60 than 45 yr. This of course is partly due to the
chronic nature of the disease progressing with time. It also reflects that as one ages, the
repair mechanisms do not work as well.
Estrogen, a female sex steroid, is believed to have protective effects.
Family history plays an important role in CVD. In BC, the Medical Services Commission
will normally only reimburse for a total cholesterol test and not for different lipoprotein
fractions. If your total cholesterol is lower than 5.2 mmol/L (200 mg %) for under 30 yr
and lower than 6.2 mmol/L (240 mg %) for over 30 yr, you only get a paid test every 5
years. If you are above these levels, MSC will pay for more frequent and specific testing.
Males of African descent have a higher incidence of CVD, especially if they have
Hypertension, or high blood pressure, is a disease in and of itself. Normal blood pressure
is about 120 mm Hg/80 mm Hg. Hypertension is often said to exist when blood pressure
is >140/>90. We only know about 10 % of the causes of hypertension but we do know
that if you have hypertension, the chances of getting atherosclerosis increases
dramatically. The abnormally high blood pressure levels create a lot more work for the
heart to perform and changes blood flow patterns.
Hypertension is enhanced by salt intake.
b. Type 2 Diabetes
see III. Diabetes
High fat, high alcohol, high simple sugars, low fibre, low antioxidants, and excessive
calories are all thought to contribute to atherosclerosis. 3
Cholesterol is transported in the blood by lipoproteins. These molecules have various
amounts of lipid and protein in them: the greater the density, the greater the relative
amount of protein. Density is used to classify groups of lipoproteins. We will just classify
2 groups: low density lipoproteins (LDL) and high density lipoproteins (HDL). LDLs
transport cholesterol from the liver to the rest of the body and HDLs transport cholesterol
from the body back to the liver. A high ratio of LDL/HDL is a risk factor for
atherosclerosis even if total cholesterol is under the age-specific limit. If you have too
much LDL, it gets deposited in the fatty plaques in the arteries.
Often people are asked to reduce their dietary cholesterol. This is good advice if you are
cholesterol sensitive, but only about 30 % of people are. Therefore, for most people can
decrease their intake of eggs, organ meats, and shellfish with very little effect on the
plasma cholesterol levels. Furthermore, for the average person, their liver makes about 80
% of their plasma cholesterol; only about 20 % comes directly from dietary intake. In
cholesterol-sensitive people, the liver does not respond ‘normally’ to an increase in
dietary intake. Their liver continues to make cholesterol rather than reduce its production
Reducing a high fat intake is a good idea, especially saturated fats. The relation between
percent of calories from saturated fats and either CHD death rates or serum cholesterol is
A moderate consumption of alcohol is associated with higher HDL and reduced heart
High levels of plasma homocysteine (an amino acid) are correlated to arteriosclerosis.
More recent evidence indicates this may be due low levels of B vitamins and folic acid.
d. Physical Activity
Lack of physical activity can lead to diabetes, hypertension, and an increase in the
Research shows physical activity increases the branching of the arterial tree. Thus if an
arteriole becomes block, another arteriole will be in close proximity and can supply the
endangered downstream tissue.
e. Central Obesity
Having fat located on your abdomen (e.g., beer gut for males) is associated with a higher
risk of atherosclerosis than having fat located on other parts of your body. Although there
are different patterns of obesity, the abdominal pattern is more often associated with
males than females. 4
f. Type A Personality
A person with a type A personality is one who is quite hard-driving, intense, and
competitive. People with type A personality have a greater chance of suffering
atherosclerosis that those with a type B personality.
g. Other Psychological Stressors
Isolation, pessimism and repressed emotions (type D) and people with low self-esteem
and confidence also have a greater incidence (3x) of atherosclerosis.
Smoking leads to a decrease in HDL and an increase in platelet stickiness. Furthermore,
the carbon monoxide produced binds to hemoglobin with 250x the affinity of oxygen.
Second hand smoke is unfiltered and thus is more cardiotoxic than the smoke that goes
inside a smoker’s lungs.
Smoking as a risk factor is interesting. Some people have smoked 3 packs a day for 70 yr
and have never had a heart problem. People use such individual-type evidence to show
that a relation between smoking and atherosclerosis does not exist. This type of evidence
has been used to discount many other types of health problems. However, in this case,
what is true for the individual is not true for the population
Infection with chlamydia pneumonia, H. pylori, and herpes simplex leads to greater heart
problem risk. In general, it is found that people with a high level of inflammation as
determined by a high white blood cell count have a higher risk of heart disease.
Identification of high risk individuals and putting them on a proper prevention program is
very important for extending the health of the high risk individual.
Such a program could include avoiding tobacco and regular exercise. A healthy heart diet
will include replacing saturated fat with unsaturated fat, high fibre content, lots of fruit
and vegetables, reducing salt (i.e., help reduce hypertension for some), and omega-3 fats
Do what you were designed to do!
A. Overview 5
Cancer is a term for a group of over 200 diseases that are characterized by uncontrolled
cell growth. Cancer accounts for about 25 % of deaths in our society.
A tumor or neoplasm is an abnormal increase in cell division. The tumor can be either
benign or malignant. A benign tumor (is not a cancer) usually does not present any health
problems other than size related ones. A malignant tumor is a cancer and can spread to
other tissue beds by 2 mechanisms: direct invasion of malignant cells into neighbouring
tissues or by metastasizing in which malignant cells enter the blood or lymph and then
can enter other tissues.
One reason there are so many different diseases that characterize cancer is that