Display #14:  Heart models

When one is presented with evidence for evolution, it is almost invariably with skeletons.  There is no mechanism for skeletal changes in the first place, but something else that you will never hear about is the changes required with internal organs and the systems (energy, reproduction, etc...) within the organism. Take for example, the heart.  This is a fascinating study.  Here we have a simplified model of a fish heart.  The reason these models are simplified is because the real thing is incredibly complex and difficult to follow. Fish have  a simple two chambered heart.  They pump high pressure blood straight to the gills, which then goes to the body, then back to the heart.   If you pumped high-pressure blood to your lungs, you would drown in your own blood!  To maximize gas transfer between your blood and the air, the Creator has designed the capillaries (extremely fine blood vessels) in your lungs to be as small and as thin walled as possible.  So pumping high pressure blood to your lungs would burst the capillaries and you would drown on your own blood. However, fish live underwater and the pressure from the surrounding water allows them to pump high-pressure blood straight to their gills without bursting the capillaries. The fish heart for designed and created for fish.

The Frog heart (and many amphibian hearts) are a three chambered heart. Frogs breath both with their lungs, and through their skin.  Blood returning from the body and organs returns into two chambers, marked A and B.  One blood is oxygen starved while the other has some oxygen in it.  The two blood flows enter the pumping chamber through a common, one-way valve they share. Because of laminar flow, the blood doesn't mix!  So the two types of blood leave the pumping chamber still separated, through a common valve again.  The squiggly valve, C, keeps the two blood flows separate so that the oxygen starved blood gets directed to the lungs and skin while the blood which has oxygen in it get directed to the body.

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The Crocodile heart is really interesting.  It has a four chambered heart, much like you.  However, it has some interesting plumbing. There are two unique things about the crocodile heart at points A and B.  B is the foramen of Panizza and A is a cogged valve that the two halves actually mesh together. The crocodile can actually lock the A valve completely closed, which completely cuts off blood flow to the lungs.  This works in conjunction with the foramen of Panizza to allow blood flow to completely bypass the lungs when the valve is shut off. Why would the crocodile want to do this?  Because it wants to go underwater!  Once submerged and the lungs have already given up all the oxygen they can, the lungs will actually rob oxygen from the blood.  So, the crocodile closes off blood flow to the lungs, enabling it to stay underwater for up to two hours! Want to try to stay underwater for two hours?  The Croc was designed for this, not you.

Now we come to the human heart.  The adult human heart is a four chambered heart.  Like the crocodile (and for the same reasons) it has a low-pressure side, and a high-pressure side. The low pressure side pumps low pressure blood to the lungs, to maximize gas transfer without damaging the lungs, then the blood returns to the high-pressure side of the heart where it is pumped under high pressure to the rest of the body so that even the extremities get a good supply of blood. A very interesting thing occurs during development as a fetus.  The lungs obviously are not used while in the mother's womb.  The heart is a muscle, and like all other muscles, needs to be used to develop.  So the Creator, in His incredible wisdom, designed some plumbing changes for development which are then removed at birth.  This allows both sides of the heart to work like two separate pumps on the same job during development.

The first thing you'll notice is the two halves of the heart are joined together at the main blood vessels leaving the heart (A).  It's called the Ductus Arteriosus. This simple, joining vessel is quite remarkable:  the arteries are made of a very flexible and stretchy tissue while the foramen ovale is made up of a stiff, muscular material. Upon birth, the doctor gives you your well deserved spanking, welcoming you into the world.  This gets you to cry, which causes you to use your lungs for the first time in your life.  This produces the first real dose of heavy oxygen in your blood. The Ductus Arteriosus then has a strange reaction when it sees high oxygen:  It shrivels up!  It will completely close off and actually grow closed after birth!

If you were to look at the back of the fetal heart, you'll see that there's a "door" open between the two chambers that receive blood coming back to the heart. The Crista Dividens (A) is the wall between the two chambers, and B is the door. Some of the blood returning to the heart is from the umbilical cord from the mother - this has the highest oxygen content of all the blood in the heart and is the reddest in the model. There is some blood returning from some of the major organs, and it has a little bit of oxygen remaining in it, it is show as purple in the model. The blood returning from the body is oxygen starved and is shown as blue. Like we saw in the amphibian heart, the blood returning is in laminar flow and doesn't mix.  The Crista Dividens separates the two flows just right so that the oxygenated blood goes first to the heart, then to the brain, then to the body.  The oxygen starved blood is directed into the other chamber where it gets pumped to the umbilical cord to get oxygen. The heart is brilliantly engineered.  During development, the right hand side of the heart (on the left in this photograph, we're looking at the back) is the low-pressure side.  But after birth, the right hand side of the heart becomes the high-pressure side.  So what happens?  The door was pushed "open" during development and is now pushed "closed" after birth by the high pressure on the right side! Combine this with the Ductus Arteriosus which is sealing off up above simultaneously and our temporary plumbing is removed.

The consequences of the fall and the non-evolution of the heart:

Sadly, in this fallen world, sometimes the door joining the two atriums does not close, and you wind up with what is commonly called a baby with a hole in its heart.  This often kills the baby, and is debilitating to an adult who survives with it.
Sometimes people are killed instantly in adulthood when an artery fails - an aorta ruptures.

Evolutionarily speaking, we were supposed to have evolved from protobacteria to fish, to amphibians, to land animals, birds, etc....  Compare the different hearts, understand and realize the changes that need to take place in order for a fish to become an amphibian.  You need to grow new blood vessels, which for a time at least will go nowhere.  Why would an animal develop a lung it doesn't need?  How would it?  Lungs are incredibly complex!  One hole developing in an artery to make way for a new blood vessel going nowhere kills the organism! Changes and mutations kill, they do not develop into more complex structures which is precisely what is needed for the "evolution" of the cardiovascular system. The heart was designed for the animal it was built into, and will not work for other animal types.  The heart was carefully engineered - evidence of a Creator.

Let's haul out the hogwash-o-meter® and test this hypothesis: Can the cardiovascular system can evolve in small, incremental steps? Oh, MAN!  Another meter bites the dust.... Those things are expensive too!