is a pump that provides the energy to drive blood through the circulatory system.
Parity of the heart is understandable
from the embryological point of view. Separation of the left and right hearts ensures supply of well-oxygenated blood to the
Control of the heart rate is by the electrical conduction system.
THE BLOOD CIRCULATORY SYSTEM
The circulatory system is an
illustration of the natural physical laws of equilibrium and control.
Blood circulation follows biophysical
principles and is another illustration of the unity of creation because physical and biological phenomena follow the same
The efficiency of the heart’s energy conversion is 20%, better than many machines.
The circulatory system adjusts to changes. Blood flow to the skin increases in hot temperature
to release heat. During digestion more blood flows into the GIT. During exercise cardiac output increases ten-fold and work
done by the heart can increase 500-fold.
The lungs are the main organs of respiration. The lungs provide a big opportunity for exchange
between the internal and external environments.
The term respiration can be
used in 2 different ways to mean ventilation or tissue respiration.
Coughing and sneezing expel
irritants. In coughing the glottis is closed raising intra-ductal pressure to 100mm of mercury. When the glottis is opened
suddenly, a jet of air under high pressure is released accompanied by the familiar sound of coughing. The glottis is not closed
in sneezing but pressure still builds up.
Respiratory movements have been used over the millennia as indicators of life. Death was
pronounced when breathing stopped. This is no longer the situation because of modern life support technology.