The blogger’s note:
Thank you and good morning Prof Andrew for your Good Morning greetings that our heart is the only machine that works non stop.
Let us start the day working out how much our hearts have actually been working for us in terms of the amount of blood pumped out throughout our lives say, for about 90 years.
Let's us begin doing some calculations using these information.
The average weight of a healthy adult is about 70 kg.
His average heart rate is between 60 to 100 beats per minute, but let us say about 80 beats per minute maximum.
The volume of each ventricle left and right is about 95 mls each, hence both right and left ventricles have a capacity of about 190 mls, abut only about 66 - 67 % of this volume blood is ejected out with each beat. We call it as "ejection fraction".
Each time the heart or ventricles contract, the ejection fraction is called "stroke volume".
This volume of blood ejected out is about 70 mls after subtracting the amount of blood left in the ventricles at the end of each beat which we call it as "end-systolic volume".
We can now calculate out the amount of blood pumped out per minute by multiplying the stroke volume x heart rate if we want to be exact.
But since heart rate varies from hour to hour, person to person, from one physiological state to the next, let's not be that exacting which would not be scientific.
On the average this works out to be about 5 litres per minute for a stroke volume of about 70 mls for an average 70 kg healthy individual.
There are 60 minutes in an hour, 24 hours in a day, and 365.25 days in a year, and for 90 years of our life if we are lucky, there would be:
60 min x 24 hrs x 365.25 days x 90 years = 47,336,400 minutes
Multiply this by 5 litres per minute = 236,682,000 litres = 236, 683 cubic meters. Wow!
This is a whooping lot of blood gushing out, and is many times more the size of a large swimming pool.
If blood is not circulated in a closed system but allowed to bleed, hypovolumia and shock results with ensuring death, but thanks to the closed circuit circulation.
The density of blood is 1060 kg per cubic meter.
Hence the amount of blood pumped out by our heart is horrendous.
density x volume = 1060 x 236,683 = 250,882,920 kg = 250,883 metric tons
Wow! This is a massive amount of load our hearts have been pumping.
Bless our hearts if we can live for 90 years.
We thank the Good Lord and Shepherd for this whooping blessings.
Now we know how hard our heart labours and toil for us till it dies in harness.
It makes our morning so blessed to know this awesome blessings we receive from Him each morning.
The working of the heart is very interesting. Its rhythmatic contraction and relaxation throughout life is due to a very small electric current it generates.
This mini electrical current is detectable by using an electrocardiogram that detects mini electrical pulses called PQRST waves across the heart muscles.
This area is called electrocardiophysiology, and is applied in cardiology to diagnose heart diseases due to electrical disturbances of the heart.
The heart contracts due to an electrical transmission from the sinus atrial nodes (SA node) in the upper right chamber through the Bundle of His into the AV (atrio ventricular) nodes sitting between the upper atrium and the ventricles below and then down into the ventricles through the Purkinje fibres to initiate ventricular contraction and cardiac cycles.
Any interruption in this transmission may result in irregular heart beats called arrhymias such as heart block.
The extent of block in their electrical transmission may be classified either as 1st degree, 2nd degree Mobitz type, and 3rd degree Wenchkebach type as total heart blocks.
We could go on and on, but my leg is aching badly on a hospital bed for months now.
So I need to stop writing medical stories and rest, but not my blessed heart.
Thank you for reading.
Iim ju boo
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P/s: Dr. JB Lim insisted the blogger to add the following “acknowledgement” for his articles published here in this blog:
"I am indebted to my friend Sifu Ir. Lau Tai Onn for graciously illustrated all my articles he published in his blog with beautiful illustrations and photos for which I am not be able to do as I am not savvy in this artistic technology Thank you Ir Lau for your artistic efforts. Lim jb boo”
The blogger wishes to stress that it has always been a great honour to be entrusted by the Great Sifu Dr. JB Lim to publish his many articles par excellence in this blog all this while, so as to reach out to broad audience, though there is absolutely nothing in return, monetarily or otherwise, to the blogger.
It is the duty of a “publisher” to the best of his ability to proofread for any obvious grammatical or spelling errors before posting. Nothing worthy to shout about. The insertion of illustrations/photos inside Dr. Lim’s articles to make the posting colorful/attractive actually renders great pleasure/satisfaction to the blogger himself, something money can’t buy. Thank you, Doc.