Rebecca, I do appreciate your posts and discussing this important issue. I will again attempt to address your questions but I am rather pressed for time so I will need to keep it short.

Rebecca Bradley wrote:
I was interested enough to have a look at the link you provided to your website. I see a degree in history and politics, jobs in tourism, banking/insurance, teaching ESL, sales, shearing sheep, and running a roadhouse. Nothing wrong with any of that, but I'm curious: on what basis do you claim special technical expertise in hydraulic systems?

I do not claim any special expertise in hydraulics. I have however worked a lot with hydraulics and heavy machinery. If people are suggesting the living human body is merely a machine then the basic principles that apply to machines (Newtonian physics) should also apply to the cardiovascular system. The way I see it; no amount of muscle movement etc. could possibly account for the energy that would be required the move blood through such a small diameter tube, and over such a great distance.

Rebecca Bradley wrote:
That's a little disingenuous. You referred several times to the blood having to be pushed 128,000 km through an 8-micron tube.

I did try to clarify that point. Yes; the blood does not have to go through a single tube of 128,000 klms – what I have said is that 128,000 klms is the total length of all combined capillaries.

Rebecca Bradley wrote:
Nope. You seem to think that 10 billion individual teeny pipes link the arterioles to the venules. This is incorrect. As I said above, the capillaries form a mesh, an intricate fractal network. There is nothing like 10 billion individual paths that blood must be pushed through. Furthermore, only an estimated 5-10% of the capillary beds are flooded at any given time, controlled by precapillary sphincters that can shut off little local networks while blood is shunted to parts of the system that need it - the digestive system after eating, the muscles during exercise, etc.

Okay, I have no formal education in biology – I would love to have done some courses but every time I mention that I am not completely in agreement with the Darwinian model I get pointed to the door. However, in relation to the above, please tell me if there are 128,000 klms of capillaries – that the diameter of those capillaries is 8 microns, and that blood needs to go through all of it. If the answers to the above is yes – then that system is not sourcing the energy needed solely from the heart.

Rebecca Bradley wrote:
I don't think any sane mechanical engineer would claim expertise about the cardiovascular system. Or draw a false analogy between a system of rigid pipes and a network of flexible blood vessels. You do realize, don't you, that the elasticity of the vessel walls, muscle action, and even skeletal motion all have an effect on circulation?

As mentioned earlier, if people were to relate the human body to a machine the expertise of a mechanical engineer should equally apply to biological systems. I do not agree with your claim that the ‘elasticity of vessel walls, muscle action and skeleton motion’ would play a significant part here. And the first thing a mechanical engineer is going to ask is about the valves. There are no valves in the arteries or capillaries - only the veins have valves. The elasticity of vessel walls, muscles action, pulses in our arms and legs etc., cannot direct the blood away from the heart. So without valves in the arteries and capillaries there is nothing preventing back-flow – and nothing accounting for the circulation of blood around the body. Also; people lay near motionless for years in a coma but this does not appear to prevent blood flow.

We must also take into consideration the fact that the energy from the heart (and all our body movement) is dependent on the energy supplied by the food we eat. I find it difficult to believe we can get all that energy from what we eat!



Edited 2 time(s). Last edit at 12-Feb-20 02:15 by Robert Jameson.