The heart sends oxygen and nutrients through all those blood vessels to our extremities .... and at the same time is removing waste products such as carbon dioxide.
There are some amazing engineering feats happening
No engineering. Creation. By nature, as God says. Let's take a look at that system; it's a lot more wonderful than you thought.
Very early living things were sufficiently small that most of their nutrient, waste, and gas exchange were by diffusion. The Ediacaran biota, for example, showed evidence of "quilting" and other means to keep a large surface area/mass ratio.
Cnidarians and flatworms got bigger and more complex, and for them a common digestive/circulatory system was sufficient.
Arthropods have a modification of this system, where blood circulation and lymphatics are in a single system, a low pressure "hemolymph" system that bathes the internal tissues.
Annelids like earthworms have a slightly more advanced system, based on the arthropod/onychophoran model, but with pressurized blood vessels and primitive "hearts" which work sort of like the superficial blood vessels in your legs. One-way valves, and intermittent contraction, moves the blood.
In primitive chordates, there arises a problem. The circulation, which originally was adequate for smaller organisms, became less efficient with size. Since in fish, the circulation is heart to gills, to muscles, to heart, the heart receives less-oxygenated blood. Lungs were apparently one way to resolve that issue, which explains why lungs preceded land-living animals:
In primitive fish, the process involved two paths:
- Gills to muscles to heart
- Gills to lungs to heart
In lungfish, the splitting of the ventrical to two chambers allowed a more complete isolation, with the above modified to
- Gills to to lungs to heart to gills
- heart to muscle to heart.
1. There are actually two circuits of blood vessels.
a) The first circuit of blood vessels takes blood from the body to the lungs, so oxygen can be added, and carbon dioxide removed.
b) The second circuit takes the oxygen rich blood out to all your body parts.
But how does one heart pump in 2 different directions?
This existed in more primitive fish, but in a less complete way. The double circulation existed, but oxygenated and unoxygenated blood mixed in the heart, making it less efficient. With lungfish (which were not the first fish to have lungs), the ventricles were beginning to form into two chambers, partially isolating the two flows.
This is accomplished because our hearts basically is two pumps within one.
Rather, it's one pump, with two separate chambers. It pumps as one unit. It might be more efficient to have two functional pumps, but given the evolutionary history of the chordate heart, it wasn't possible.
It is very cool how this happens in the womb, but basically there is a tube that gets kinked forming two compartments that end up functioning as two separate pumps.
See above. Notice from where that comes. Cool, um? This is why we can't have 2 separate pumps. Less efficient, yes. But it works well enough, and evolution doesn't have the luxury of tossing out the original design and starting over; it has to modify what's already there.
3. This is so cool..... Our hearts all have a built in pacemaker.
The "pacemaker" is actually a population of cells in the heart. They 'vote' to determine contractions, which are coordinated by nervelike muscle cells called Perkunje fibers. Not haveing a central decision maker, the heart is vulnerable to a sudden disruption in the pattern of contraction, leading to ventricular fibulation, a pattern of uncoordinated contractions that will lead to death if not corrected.
It would have been better to have a central coordinator, which was immune to such disruption, but that wasn't an option.
And amazing evidence of design.
And now you know better.
