Your Heart
http://healthguide.howstuffworks.com/aging-changes-in-the-heart-and-blood-vessels-dictionary.htm
The heart, one of the vital organs in the human
body, is a powerful pump located behind and slightly to the left of the breastbone and between the lungs. It is a muscle about
the size of your fist which contracts and expands using its own bio-electrical system, to continuously pump blood ar ound the body to nourish and provide energy.
The pumping of the heart is known as the cardiac cycle, which occurs about 72 times per minute and it pumps blood through
network of vessels in the body.
The heart lies at the
centre of these complicated network of blood vessels which include arteries and veins. The left side of the heart receives
oxygen filled blood from the lungs and pumps it out through the 'arteries' around the body and the right side receives
used up-blood containing carbon dioxide through the 'veins' and sends this blood to the lungs to get rid of the carbon
dioxide and take in fresh oxygen.
The heart, in the simplest
terms, consists of four chambers, two atria (upper chambers) and two ventricles (lower chambers). As the muscles of
the heart relax, blood (oxygen filled blood from the lungs and carbon dioxide filled blood from the rest of the body) enters
its various chambers. The atrium fill with blood and help move blood into the ventricle. The ventricle supplies the main force
that pumps the blood out, through either the lungs or to the rest of the body. As the blood enters the heart, Flaps
called valves close quickly to stop any blood leaking backwards and thus control the direction of blood flow. There are four
valves; mitral and the tricuspid between the atria and the ventricles and other two, aortic and pulmonary through which blood enters
and leaves the heart.
Heart functions begin to slow down with age.
The aging process reduces the heart muscle strength. So its pumping power declines, and the maximal heart rate (the highest
number of times your heart can contract in a minute) also decreases. When the amount of blood pumped by the heart in
a minute declines, systolic blood pressure tends to rise. Some of the common heart problems that can occur as we age are
·
Arteriosclerosis (hardening / clogging of the arteries due to excessive build up of fat and cholesterol known
as plaque). Fatty plaque deposits inside the blood vessels cause it to narrow and can totally block blood vessels and also
cause the valves that control the direction of blood flow to thicken and become stiff. Arteriosclerosis in turn is the
underlying cause of most cardio vascular diseases.
· The heart has to
work
harder due to decreased blood supply. Greater force is necessary to push blood through
narrowed vessels due to plaque build up. So high blood pressure develops and this buildup and shortage of oxygenated blood
over time, leads to heart attacks. In a heart attack, a part of the heart muscle becomes starved for oxygen and dies.
·
Angina (chest pain caused by temporarily reduced oxygenated blood flow to the heart muscle), causing pain
in the chest, in the left arm or between the shoulder blades.
· Dissecting
Aneurysm: The atherosclerosed aorta becomes brittle and can break much easier creating a life threatening situation.
·
Heart failure is very common in the elderly. In people older than 75, heart failure occurs 10 times more often
than in younger adults.
· Abnormal heart rhythms (arrhythmias)
of various types.
Probable
reasons for the change...
From
forty through seventy, the five major risk factors for heart disease are family history, smoking, high cholesterol, diabetes
and high blood pressure. But apart from family history and smoking, the others are related to diet, weight and inactivity. Directly,
age is not a risk factor but people tend to put on weight and become more inactive as they age and a combination of other
factors like continuing heart-unhealthy habits and diets takes its toll as people age and as such age is a risk factor for
the other risk factors. Apart from cholesterol; stress and the presence of Lp (a), a lipoprotein; homocysteine, an obscure
amino acid ; and triglycerides, a compound of fats in the blood are also involved in the development of heart diseases. Your
triglyceride levels tend to rise from forties through sixties. The higher the levels of triglycerides, the higher the probability
of reduced levels of good cholesterol (HDL). The body also converts the cellular carriers of triglycerides into forms of bad
cholesterol (LDL).
Ways
to delay effects of aging...
Risk factors that you have some control over include high blood pressure, cholesterol levels,
diabetes, obesity, and smoking. 'Atherosclerosis' once thought to be an aging disorder is now known to be
a progressive narrowing of arteries over time which is fed by rich diets, high in cholesterol and fats and aggravated by smoking
and high blood pressure.
People who work out seriously and continuously for most of a decade has been seen
to cut their age related decline of maximal heart rate in half. So maintaining a healthy
diet and regular activity level and stopping unhealthy habits like smoking go a long way in
controlling heart related problems.
http://longevity.about.com/od/longevityandillness/f/revheartdisease.htm
The Aging Heart:
Heart disease is a leading cause of death. As we age, our heart compensates for clogged arteries by working harder and raising blood pressure. These changes
put the heart at risk and impact our quality of life:
- 40 percent of deaths for people aged 65 to 74 are from heart disease
(60 percent for those over 80).
- From age 20 to 80, there is a 50 percent decline in the body's capacity for vigorous exercise
- In your 20s the maximum heart is between 180 and 200 beats per minute. At 80, it is 145.
- A 20-year-old's heart can output 3.5 to 4 times the heart's resting capacity. An 80-year-old
can output 2 times resting capacity.
Aging Arteries:
Arteries take oxygen-rich blood away from the heart and deliver it to the body. As we age, our arteries become stiffer
and less flexible. This causes our blood pressure to increase. The heart has to adjust to the increase in blood pressure by
pumping harder and changing the timing of its valves. These adjustments leave the heart more vulnerable. To stay young at heart, protect your arteries by:
- exercising
- controlling your blood pressure
- watching your cholesterol
Thickening of
the Left Ventricle:
Researchers have noted that the wall of the left ventricle of the heart becomes
thicker with age. This thickening allows the heart to pump stronger. As our blood vessels age, they become narrower -- causing
blood pressure to increase. The heart compensates for this by becoming stronger and pumping with more force.
Mitral
Valve Closes More Slowly:
The mitral valve closes more slowly with aging. This is because the rate of blood
flow from the left ventricle decreases as it relaxes more slowly. It relaxes slower because it grows thicker with age (see
above).
Exercise Capacity Shrinks:
As the heart ages, it becomes less able to respond
rapidly to chemical messages from the brain. Researchers do not know exactly why the heart does not respond as fast to messages
to speed up and adjust to increased activity. The result is the body cannot exercise as long or as intensely as before. This
shows up as shortness of breath -- a sign that oxygen-rich blood is not moving fast enough through the body because the lungs
are trying to breath in more oxygen.
"Sitting" Heart Rate Lowers:
The heart rate
of an older person while sitting is slower than a younger person (but the same when lying down). It is thought that this slower
rate is from a decline in the heart-brain communication because fibrous tissue and fatty deposits have built up on the on
nerves connecting the heart and brain. To compensate, the heart increases the volume of blood in circulation by raising the
diastolic blood pressure.
The Heart Can't Squeeze as Tightly:
Because of the increase
in diastolic blood pressure, the heart also stretches larger each beat, giving a stronger pump in order to have a stronger contraction
to pump the excess blood volume (called the Frank-Starling mechanism). But because of the greater diastolic pressure, the
heart can't squeeze as tightly.
Heart Enlarges:
The heart of a healthy 70-year-old
has 30 percent fewer cells than a 20-year-old's heart. When heart cells die, the other cells must stretch and grow to
stay connected. An older person's heart cells may be up to 40 percent larger than a younger persons.
Keep Your Heart
Healthy and Reverse Heart Disease
Your heart is only as healthy as your arteries. Work hard to
keep your arteries healthy by:
