physiological support systems in the body all work together simultaneously
to provide a sustained energy release during physical activity
to achieve a specific task. The three major systems which actively
participate in this effort are the pulmonary
system, cardiovascular system and the neuromuscular system.
The Pulmonary system is primarily
responsible for controlling breathing and volume of air that enters
the lungs. Lung volumes vary with age, gender, and body size,
especially stature. As the body becomes more physically fit for
endurance, the pulmonary system becomes more efficient in exchanging
the volume of gas between its internal and external environment.
The process of this exchange is extremely quick with a healthy
lung taking about 1 second to exchange gas with blood. The alveoli
are the final branchings of the respiratory tree and act as the
primary gas exchange units of the lung. The alveoli are the final
branchings of the respiratory tree and act as the primary gas
exchange units of the lung. The alveolar pressure is determinant
to whether air will flow into or out of the lungs. When alveolar
pressure is negative, as is the case during inspiration, air flows
from the higher pressure at the mouth down the lungs into the
lower pressure in the alveoli. When alveolar pressure is positive,
which is the case during expiration, air flows out. At end-inspiration
or end-expiration, when flow temporarily stops, the alveolar pressure
is zero (i.e., the same as the atmospheric pressure).
you know that the surface area of the lungs is the same as a tennis court?
Carbon dioxide (CO2) is the primary gas which is expelled from
the body, while oxygen (O2) is primary gas which is inhaled and
absorbed. In an average, moderately fit human being, the exchange
of these two gases is very efficient and ventilation capacity
is rarely taxed.
you know that their are 700 million alveoli in an adult lung?
Even during maximal exercise, a considerable breathing reserve
exists because pulmonary ventilation at this level of exercise
rarely exceeds 85% of a healthy person's maximum capacity for
breathing. After only 4 weeks of submaximal training, a considerable
reduction in the amount of oxygen needed to maintain the same
energy output is observed.
you know you lose about 1/2 liter of water a day through breathing?
Theoretically, endurance exercise would benefit the pulmonary
system for two main reasons: (1) It would reduce the fatiguing
effects of exercise on the ventilatory musculature (primarily
the lungs), and (2) any oxygen freed from use by respiratory muscles
becomes available to the exercising muscles.
The Cardiovascular System consists of the heart and blood vessels which develop the vascular
circuit of the body. This system serves four important functions
during physical activity: 1) It delivers oxygen to the exercising
muscles and removes wastes; 2) It returns blood to the lungs for
aeration; 3) It transports heat, a byproduct of cellular metabolism,
from the body's core to the skin; and, 4) It delivers fuel nutrients
to the active issues.
you know that 8 million blood cells die every second, and the
same number are born each second.
The blood is sometimes compared to a river, but the arteries are
more like a river in reverse. Arteries are thick-walled tubes
with a circular covering of yellow, elastic fibers, which contain
a filling of muscle that absorbs the tremendous pressure wave
of a heartbeat and slows the blood down. This pressure can be
felt in the arm and wrist - it is the pulse. The largest artery
in the human body is the aorta which distributes the highest volume
of blood. Eventually arteries divide into smaller arterioles and
then into even smaller capillaries, the smallest of all blood
vessels. One arteriole can serve a hundred capillaries. Here,
in every tissue of every organ, blood's work is done when it gives
up what the cells need and takes away the waste products that
they don't need. Now the river comparison really does apply. Capillaries
join together to form small veins, which flow into larger main
veins, and these deliver deoxygenated blood back to the heart.
Veins, unlike arteries, have thin, slack walls, because the blood
has lost the pressure which forced it out of the heart, so the
dark, reddish-blue blood which flows through the veins on its
way to the lungs oozes along very slowly on its way to be reoxygenated.
Back at the heart, the veins enter a special vessel, called the
pulmonary arteries, into the wall at right side of the heart.
It flows along the pulmonary arteries to the lungs to collect
oxygen, then back to the heart's left side to begin its journey
around the body again.
you know you the adult human body contains
5-6 quarts of blood?
Physician will regularly measure your blood pressure as an assessment
when you go for your annual checkup. Blood
pressure is equal to the forces exerted by the blood against the
walls of the arteries during a cardiac cycle and is written as or, for example, 120/80 mm Hg (stated as 120 over 80).
you know you the adult human body contains
5-6 quarts of blood?
High blood pressure, or hypertension, imposes a chronic
and excessive strain on the normal function of the cardiovascular
system. Chronic hypertension that is not corrected can eventually
lead to heart failure. Hypertension is defined as: systolic
blood pressure (SBP) of 140 mm Hg or greater; or diastolic blood
pressure (DBP) of 90 mm Hg or greater. Regular aerobic training
brings about modest reductions in systolic and diastolic blood
pressure at rest and during submaximal exercise. Systolic blood
pressure increases in proportion to oxygen uptake and cardiac
output during exercise, whereas diatolic pressure remains relatively
unchanged or increases slightly. At the same relative exercise
load, systolic pressures are greater when exercise is performed
with arms and legs.
you know you that your heart beats 40
million times a year?
output reflects the functional capacity of the circulatory system.
Heart rate and stroke volume (quantity of blood
ejected with each stroke) are the two factors that determine
the heart's output capacity. The relationship is: Cardiac output
= Heart rate X Stroke volume.
know you that your heart will increase in size with strength training?
short and long term cardiac performance and adaptation are significant
via aerobic (utlizing O2) and anaerobic (without O2) exercise. Training changes may, enable the
heart to function at a lower percentage of its total oxidative
capacity during exercise. In addition, exercise may provide some
protection from the degenerative process of heart disease.
The Neuromuscular System consists
of the integrated network of nerves and muscles in the body. Muscles
are composed of thousands of individual cells called muscle fibers
held together with a network of connective tissue that becomes
continuous with the tendons at each end of the muscle. Tendons
serve to connect skeletal muscle to bones, and it is through this
connection that muscle can actively change its length and produce
joint and limb movement.
you know you that the strongest muscle in your body is located
at your jaw - the masseter?
Muscle fibers are innervated by motor neurons. A motor neuron
can innervate as few as one or several hundred muscle fibers.
When a motor neuron fires, all the fibers that it serves are simultaneously
activated and develop force. A motor neuron and all of the muscle
fibers that it innervates are referred to as a motor unit, the
basic functional entity of muscular activity. The extent of control
of a muscle is usually dependent on the number of muscle fibers
within each motor unit. Muscles that must function with great
precision, such as eye muscles, may have motor units with as few
as one muscle fiber per motor neuron. In contrast, the quadriceps,
which performs much less precise movements, may have several hundred
fibers served by one motor neuron.