"Keep thy heart with all diligence; for out of it are the issues of life." Prov. 4:23
The issues of life (physical as well as spiritual) are all dependent on the heart. All functions of the body rely on it as, beating some 100,000 times a day, it pumps about 600 tons of blood through the body each year at the rate of about a quart every minute.
What keeps it going? Medical scientists do not know, but think it may be brought about by certain chemical impulses. The real answer is that this is another wonder of God's creation. Only He could devise so intricate and reliable a machine out of flesh and blood.
The ten pints of blood that is in the adult body is pumped to the lungs by the heart. The blood passes through arteries on its way to the lungs. These arteries increase in number but reduce in size. By the time the blood finally reaches the lungs it has passed through about 600 million tiny capillaries. Each of these is less than half the diameter of a hair! As air rushes into the lungs when we breathe, this blood picks up oxygen from the air, at the same time discarding carbon dioxide, which the lungs exhale through the nose.
Enriched with oxygen, the blood travels a different route back to the heart where it is again pumped through the aorta into other arteries and capillaries. Thousands of miles of capillaries are needed to bring the blood to the cells, organs, muscles, tissues and every part of the body.
As the blood makes this long journey, the oxygen content gets less and less. By the time the blood has circulated through the system and returns to the first pump of the heart, there is practically no oxygen left, and it must be refueled before it can be useful to the body again. It contains large amounts of carbon dioxide which the cells of the body have given off. Once more the blood is sent to the lungs where the carbon dioxide is released and oxygen is absorbed.
How wise is the master plan of the Creator as seen in this most amazing system! If man tried to duplicate it, he would be totally unable to do so.
The heart is often spoken of in the Bible to describe our feelings and reasonings of the mind. God describes it this way: "The heart is deceitful above all things, and desperately wicked: who can know it?" The answer is immediately given: "I the Lord search the heart" (Jer. 17:9-10). It is very solemn to know that nothing is ever hidden from Him. Since God knows the heart, shouldn't we trust in God with our heart? "Trust in the Lord with all thine heart; and lean not unto thine own understanding. In all thy ways acknowledge Him, and He shall direct thy paths" (Prov. 3:5-6). What a wonderful invitation this is, and those who accept it and find the Lord as their Savior can say with the Psalmist, "I have trusted in Thy mercy; my heart shall rejoice in Thy salvation" (Psa. 13:5). Have you asked the Lord to put this joy in your heart?