The Cardiovascular Circulatory System
Body Systems
Working Together toMaintain Homeostasis:^
The Cardiovascular System
Integumentary System
●● Blood flow to the skin aids in temperature control
for the body.^
●● Blood flow to the skin brings oxygen and nutrients to
and removes waste from skin tissue and glands.^
●● Dilation of blood vessels in the dermis occurs when
we are embarrassed, resulting in blushing seen in
light-skinned individuals.
Skeletal System
●● Bones store and release calcium to maintain plasma
levels of calcium.^
●● Bones are the sites of hematopoiesis.
●● Bones (sternum and ribs) protect the cardiovascular
organs.
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Muscular System
●● Exercising muscles receive increased blood flow
-delivering oxygen and nutrients and removing
waste.^
●● Cardiac and smooth muscle contractions maintain
blood flow and blood pressure.^
●● Exercise helps prevent cardiovascular disease.Nervous System
●● The brain and spinal cord depend on blood flow for
survival and maximum function.^
●● The autonomic nervous system regulates heartbeat
rate and blood pressure.Endocrine System
●● The bloodstream transports hormones to their target
organs.^
●● Epinephrine, thyroxine, and antidiuretic hormone
affect- blood pressure rates.As The Body Ages
As we age, our maximum heart rate gradually decreases. These conditions in car-diac
muscle lead to this situation: a decrease in the rate of calcium transport and a
corresponding increase in the rate of the breakdown of ATP molecules, a decrease in
the rate of aerobic metabolism, and a decrease in the effects of adrenalin and
noradrenaline on heartbeat rates. These conditions cause longer relaxation and
contraction rates of the heart, decreasing in maximum heartbeat rates. By 70 years of
age, there can be as much as a 75% decrease in cardiac output.^
The left ventricle can enlarge as we age. There is increased pressure in the
aorta caused by a decrease in its elasticity and that of other large arteries, causing the left
ventricle to work harder thus building up mass. During the aging process, the heart cells also
accumulate collagen fibers and lipid molecules, producing stiffness and less elasticity. The re-
sulting increases in pressure due to increased volume of the left ventricle lead to individuals
feeling out of breath when they exercise vigorously.
The heart valves are also affected by age. Calcium deposits increase and the connective
tissue becomes stiff, resulting in abnormal valve function. A narrowing of the aortic semilu-nar
valve and the bicuspid valve is especially common.
The development of coronary artery disease occurs as we age, as does congestive heart
failure. Coronary artery disease is the major cause of death and heart disease in older
Americans-. This especially occurs in people in their 80s, resulting in an inability to deal with
stress, blood loss, and infections. Changes in the frequency of the electrical conduction sys-tem
of the heart lead to a higher rate of arrhythmias or irregular heartbeats in older adults.
The best way to maintain a healthy heart, at any age, is to exercise regularly. Assuming no
heart disease conditions, maintaining a consistent level of aerobic exercising improves the
working capability of the heart muscle. In older adults, a daily walking regimen is one of the best
exercises to maintain good heart performance.