Two Billion Beats

The title of this post refers to the number of beats, on average, a heart makes during the lifetime of a person. 
  Today, I opened the chest of Betty and we looked for her heart.  The organ of romance, love, affection and all the emotions that people have.  The subject of poems, novels, songs and movies. 
  How many lines of prose has this muscle weighing between nine to ten ounces produced? 
  The day began as I took an electric circular saw, which is rather like a large Dremel, not the circular saw a carpenter uses, and began cutting through the ribs of the chest.  Around the thoracic cavity I went, through the clavicle, the sternum, the ribs until finally we could begin to lift off the entire anterior portion of Betty's chest. 
  Connecting the chest wall to the interior is a membrane called the parietal pleural membrane, with parietal meaning 'pertaining to wall' meaning the body wall.  This membrane surrounds the entire chest (thoracic) cavity, like a large bag.  Around each organ is a visceral membrane, for example around the heart is the visceral (organ) peri(around)cardial membrane.
  We cut this membrane from the body wall and lifted off the wall and looked inside Betty's body cavity and did not see what we expected.  This woman had an enlarged heart and the left side of it was so enlarge that the left lung was completely "squeezed" up into the upper left of her chest. 
  What crossed my mind when I saw this was 'wow!' and then, she must have been hypertensive and suffering from poor circulation.  I wouldn't have been surprised if she could not walk up a flight of stairs without stopping for or I should say, gasping for breath.
  This organ of romance has four major chambers-which I suspect every high school biology student has learned about-called the atrium and ventricles.  These chambers receive blood from the body and then pump it back out either to the lungs or to the body. 
  The heart has eight major blood vessels to carry the blood about, and between the chambers, the blood vessels, the heart's own blood supply (the cardiac system), the valves between the chambers, this organ receives a lot of scrutiny in life.
  For all the ink spilled on the heart, the simple fact is it is simply a pump.  Actually two pumps.  One moves blood to the lungs for oxygen and the other one to the body. 
  Because of Betty's health issues, it was her left ventricle (that pumps to the body)that was enlarged-to about the size of a baseball, which is large.
  The blood of the heart leaves through the very large aorta as it journey's to the body.  The first branch off of this tube are the coronary arteries-the right and the left.  These two arteries proceed to circle the heart and they too will provide more branches to reach this important organ's muscles so that oxygen and food reach their destinations.
  Descending down between the right and left ventricles is the left anterior descending artery (LAD for short) or known as the widow maker.  Any occlusion in this artery will provide instant relief from this world, hence it's moniker. 
  Far as I know, Betty hadn't suffered a heart attack, but with time she probably would have.
  While this is just a muscular pump, that beats about 2.5 billion times a life, we recognize its importance. 
  I guess the song writers got it right.

 

Six Hundred and Forty There Abouts

 There are about 640 muscles in the human body.  Some people have more, some less and I don't think we've counted everyone.  There seems to be a wide variance of how many.
  But the exact amount really doesn't matter, it just seems that as we descended down through the layers of the skin, we encountered the muscles that move us.
  Betty, laying prone, was in the posterior view (we were looking at her back) showed us her muscles that moved her head, arms and held her up right.
  What does a muscle look like, well, not to put you off, but sorta like roast beef.  Muscles are stringy, made of protein fibers wrapped around by fascia and put together just like strings form ropes.  So, muscle structure gives you a clue of what they do.
  For example, the trapezius muscle shown here (Wikipedia is the source) is named for its unique shape.  Any high school student can tell you what a trapezoid is and hence its name. This muscle  quite  big, moves the spine, moves your scapula, helps you throw a ball, lifts your head after looking down (extends the neck) are some of its actions.
  Muscle motions are called actions, the places they connect to bones are called insertion and origin.  The insertion is the bone that does not move when the muscle contracts and the insertion is the bone it moves.
  The main job of muscles is to move your bones, creating motion.  The other jobs muscle perform are keeping you warm (shivering for example), movement of materials inside your body (food in the gut for example) and posture-keeping standing erect.
  All muscles have nerves (called innervation) and a rich blood supply.  Muscle cells have many mitochondria as these organs need lots of energy.
  In Betty's body are three kinds of muscles, the skeletal muscles attached to bones, the smooth muscles of the organs and cardiac muscles of the heart.
  Betty's trapezius was rather large, but it was a thin muscle, meaning she didn't do a lot of lifting.  A person who does a lot of shoulder shrugs with weights will develop a "web" appearance in the neck, especially if you look at them from the front.
  Betty's muscles were not easy to separate.  One goal of our class was to "clean" (remove all fat and fascia) and separate the muscles from each other.  Some muscles were easy to separate, others not so well.
  While we didn't dissect all 640 muscles, it felt like it by the end of the term.  To be honest, I was looking forward to seeing something else beside muscles after a few weeks of nothing but, muscle this, muscle that.

Beauty Is Only Skin Deep

  The book, The Frontiersmen, crossed my mind as I proceeded with my task.  Today was the first day of dissection, Betty was lying face down (prone position) and our task was to dissect the muscles of the dorsal chest. 
  Studying a human cadaver was not new to me, but that cadaver had already been dissected (the purpose of this course), and so the question crossing my mind was, could I put scalpel to skin and make the cut? 
  I didn't volunteer in our group, I just picked up the scalpel and made the midsagittal  cut (down the middle of the  back) from the back of the head to the sacrum (bone between the hips).  It was actually fairly easy, the new blade was very sharp and the cut was made.
  Our group then sectioned the skin into large squares and proceeded to remove the skin-yes, we were skinning a human. 
  And that is where I  began to think of Eckert's book.  In the course of  his narrative, he writes about when both sides of the war, between white man and native, human prisoners were skinned alive. 
  This was indeed a very painful way to go.  For you see, the human skin is attached to the underlying body tissue by very tough connective fibers and this makes the task of removing the skin very hard. 
  Unlike skinning a deer, where the skin literally "unzips" off with a pull, the human skin is attached very strongly to the body.  This fibrous connective tissue can be seen running from the dermal layer of the skin, through the hypodermal layer to the layers underneath.  Then there is a connective tissue call fascia that seems to cover everything in the  body holding the hypodermis to the body.
  Let's just say that it takes a lot of pulling, and that is defined as a lot of pulling.
  Now image you are alive and undergoing this.  I shudder when I think of it. 
  And yes, while you are doing this task (on a cadaver, not a living person), you mind tends to wonder. 
  The human skin or integument, consists of three  basic layers.  The epidermis, the part you can see, the dermis just under it, and finally, deepest, is the hypodermis. 
  The main job of the epidermis is to protect you from your environment, the dermis is the actual living skin (epi means upon) and the hypodermis (hypo=down,meaning down; under dermis in this case) is the padding layer.
  Your sense of touch, pain etc. are located in the dermis, along with your blood vessels, sweat and oil glands.  Your hair grows out of the dermis, while the hair follicle is actually part of the epidermis, it is located in the dermis.  The main  business of the skin is located here.
  The hypodermis is mostly adipose-fat.   The function of subcutaneous fat is to provide energy storage, padding and insulation.  Elderly people lose this layer in their later years, resulting in the  complaint, "Its cold in here!" and frequent bruising of the arms and legs.
  The reason skin is attached so strongly is to make sure it stays in place.  You don't want it sliding around you know.  Most everyone knows what a "strawberry" is when they slide on the ground.  That wonderful friction burn on the skin, because the skin won't slide with you.
  But, where the skin must bend, elbows, knees, fingers, the skin will slide-so you can bend those joints!
   So, we proceeded to remove the skin from Betty's back, one piece at a time.  What we saw underneath I'll tell you next time.
   
  

Meeting Betty

  I met Betty in a cold, bright laboratory early in the morning, along with nine other of her companions.  I actually met her face down on the table, looking at her broad back and short legs.  Not quite how I pictured the first time I would see a complete cadaver.
  While, I have studied the human anatomy before using a cadaver, that cadaver was already prepared for students to study, this one was 'complete' in the sense and waiting for us to begin. 
   I had signed up for the class back in the spring and the purpose of the course was to prepare corpses for just such an activity-the study of the human body in anatomy classes.  
 Arriving early for the first day of class and watching the other students arrive, I couldn't help but thing that these students all look like the students I had just finished teaching last month.  Am I getting that old and the worst thought was 'will I be the oldest one in the class'?
 Fortunately for me, another grey hair showed up and we entered the laboratory.
 I'd like to say the entrance was dramatic, but it wasn't. 
  Instead of bodies laying on tables, I saw stainless steel coffins in neat rows through the room.   Our little group was assigned one nearest the door and it was time to begin.
  So, I met Betty.  This is not her name.  I don't know her name, only a number that tells me, when I look at the listed posted on the wall, how she died.  From the short sentence by her number, I figured it had to do something with her heart and kidneys.
  Most of the donated bodies were older and had passed on from pneumonia, COPD, just plain old age.  Not ours.  She was neither old nor a typical mortality.
 Inside her metal coffin, she was wrapped in plastic (twice) to preserve the tissues, and once we opened the metal lid, the smell wrapped itself around us.  I quickly deducted the purpose of the metal shell that each body is kept in, one to help preserve it, the other to keep the smell to a minimum.
  We were to start on the back (posterior) and begin by removing the skin and then cleaning the muscles on the back for future students to study.
  Little did we know what we were getting ourselves into.  And that is the subject of my next post.