Darwinism Vs. the real world XIII

Controlling Blood Pressure Requires an Irreducibly Complex System:
Howard Glicksman September 22, 2015 12:32 PM

Editor's note: Physicians have a special place among the thinkers who have elaborated the argument for intelligent design. Perhaps that's because, more than evolutionary biologists, they are familiar with the challenges of maintaining a functioning complex system, the human body. With that in mind, Evolution News & Views is delighted to present this series, "The Designed Body." Dr. Glicksman practices palliative medicine for a hospice organization.

The body is a multi-cellular organism that requires the circulation of blood within its cardiovascular system to give its cells what they need to live, grow, and work properly.

In the last article in this series, I explained what blood pressure is -- the force that blood exerts against the walls of the large systemic arteries as it flows through them.

Since blood has mass, its flow within the body is prevented by natural forces such as inertia, vascular resistance and gravity. The heart pumps the blood throughout the circulatory system and it is the blood pressure that represents the driving force for blood flow. When the left ventricle contracts, it pumps more blood into the systemic arteries, which causes the blood pressure to rise to a maximum, called the systolic pressure.

During diastole, while the heart is relaxed, the blood in the large systemic arteries rebounds back and forth between the arterioles and the closed aortic valve as some of it makes its way into the capillaries within the tissues. This causes the blood pressure to slowly drop, reaching its nadir just before systole and is called the diastolic pressure.

The three main factors that affect the blood pressure are the cardiac output, the blood volume and its distribution within the cardiovascular system, and the peripheral vascular resistance of the arterioles. In general, the more cardiac output, blood in the arteries, and peripheral vascular resistance, the higher the blood pressure and the less cardiac output, blood in the arteries and peripheral vascular resistance, the lower the blood pressure.

Life is a dynamic process in which the physiological functions of the body are always in a state of flux. Evolutionary biologists claim to have explained how human life has come about, but they only describe how it looks. What about how it actually works within the laws of nature to survive? Think about it. You are always on the move: going from lying down to sitting and standing up, from walking to running and jumping, from crouching and crawling to kneeling. All of these changes in position affect the blood pressure and how effective the cardiovascular system is in giving the tissues what they need to live and work properly. That's what the bodies of our earliest ancestors would need to have been able to do to survive. I will now look at some of the ways that the body takes control to maintain an adequate blood pressure.

Three of the most important chemicals involved in blood pressure control have already been mentioned within another context in previous articles. Norepinephrine and epinephrine, the neurohormones of the sympathetic nervous system, act quickly, within a split second. Angiotensin II, a hormone that comes about from the action of renin, secreted by the kidneys, and Anti-Diuretic Hormone, sent out by the posterior pituitary gland, are slower and usually act within a few minutes. It is important to realize that the effects of these chemicals is limited to only several minutes which allows the body to maintain moment to moment control of its blood pressure. The sensors, integrators and effectors that make up each of the systems for these chemicals to affect blood pressure will be looked at one at a time below.

There are sensors located in the main arteries directly supplying blood to the brain, which can detect wall distension. These are the baroreceptors, which by sensing the stretching within the arterial walls are able to detect the arterial blood pressure. They are a type of mechanoreceptor that senses movement, in contrast to the chemoreceptors which detect chemicals like oxygen, carbon dioxide and hydrogen ion. The baroreceptors send their data on the blood pressure by way of nerves to the brain. The brain integrates this information, and if the blood pressure is too low, it causes the release of more norepinephrine and epinephrine from the sympathetic nerves. By attaching to specific receptors, increased sympathetic stimulation affects all three of the factors mentioned above, which makes the blood pressure rise.

As noted previously, it makes the heart pump harder and faster, which increases the cardiac output. In addition, it causes the kidneys to absorb more Na+ ions and more water by the release of more ADH, which increases the blood volume. It also stimulates the systemic veins to send more blood back into the systemic arteries. Finally, it tells the muscles surrounding the arterioles to contract more which increases the peripheral vascular resistance. All of these actions combine to increase the blood pressure. However, if the blood pressure is where it should be or higher than normal, the sympathetic system releases less of these neurohormones, usually at only a basal rate.

As we've already seen, there are wall motion sensors located within specialized cells within the kidneys where the blood enters to be filtered. These sensory cells release a hormone, called renin, in an amount that is inversely related to how much wall motion they detect. The more the walls stretch, the less renin is sent out, and the less the walls stretch, the more renin is sent out. Renin is an enzyme that starts a chemical reaction which results in the formation of a hormone called angiotensin II. By attaching to specific receptors, angiotensin II affects two of the three factors that make blood pressure rise.

First, it causes the body to take in more salt and water and the kidneys to hold onto more as well. All of these actions increase the blood volume. And second, as its name denotes, angiotensin II makes the muscles surrounding the arterioles constrict, causing a rise in the peripheral vascular resistance. In fact, it is the most powerful vasconstrictor in the body, even more than norepinephine. Both of these actions make the blood pressure rise.

The osmoreceptors in the hypothalamus, which detect the water content of the body, are shrink sensitive and affect the release of ADH. The less water in the body, the more they shrink, and the more ADH they cause to be sent out by the posterior pituitary gland. And the more water in the body, the less they shrink and the less ADH is sent out. By attaching to specific receptors ADH affects two of the three factors that impact the blood pressure. More ADH causes the body to take in more water and the kidneys to bring back more from the urine in production, all of which increases blood volume. Another name for ADH is, vasopressin, which like norepinephrine and angiotensin II increases the peripheral vascular resistance by making the muscles surrounding the arterioles contract more as well. Both of these actions increase the blood pressure.

Each of the three systems mentioned above have their own sensors, integrators, and specific receptors, while using the same effectors to affect blood pressure. Dr. Michael Behe would call each of these systems irreducibly complex because without any one component, each system would fail and life would be impossible. But to anyone who has ever had a momentary feeling of dizziness on standing up, this experience tells us that just trying to explain the simultaneous development of each of these systems, or all of them at once, as difficult as that may be, should not be enough. For, when it comes to life, and being able to stand up to gravity, real numbers have real consequences.

Evolutionary biologists seek to tell us how life came into being. Yet they only even purport to explain how the different parts of the body supposedly came together -- without considering how biological function must also meet specific numerical benchmarks to work within the laws of nature. Maybe that's why the famous British journalist Malcolm Muggeridge was quoted as saying, "I myself am convinced that the theory of evolution, especially to the extent to which it has been applied, will be one of the greatest jokes in the history books of the future. Posterity will marvel that so very flimsy and dubious an hypothesis could be accepted with the incredible credulity it has."


With that in mind, next time we'll look at how, where blood pressure is concerned, the numbers must be just right for us to stay standing.

The menace of 'settled science'.

From the Folks Who Brought You Camels and Lucky Strikes: "Consensus"
Bruce Chapman May 5, 2015 6:56 PM 

Spend some time with old issues of TimeMagazine or Look circa 1950 and you'll find ad after ad touting the doctors who smoke Camels or Lucky Strikes ("More Doctors Smoke Camels than Any Other Cigarette"). The PR agencies surveyed the doctors, sometimes counting hundreds of thousands of them, then advised readers that such and such brand was "not irritating on the throat," was "soothing," and other euphemisms for scientific approval of what turned out to be a deadly product.
Most doctors smoked in those days. There was a kind of consensus that smoking was okay, especially if you bought a particular brand, one with filters, perhaps. That the incidence of lung and throat cancer was rocketing didn't register fully on medical practitioners for a long while. The connection with heart disease also was missed.
All those doctors testifying on behalf of cigarettes didn't matter to the truth, did it? The cigarette makers did not exactly announce a scientific consensus, but they implied it.
History tells repeatedly of scientific consensus or implications of same that were driven by self-interest, expedience, groupthink, or just plain ignorance. As SUNY brain surgeon Michael Egnor notes, the consensus is for man-made global warming (aka, climate change), Darwinian evolution, and whatever the latest fad headline attests that "Scientists Say." In the case of forensic science and the FBI, it has turned into a scandal.
But such is the prestige of scientists that you will hunt hard for universities that tolerate contrarian views on politically delicate science issues, or will even allow debate. But the careful reader can find out for himself.

Figuratively speaking, put out that cigarette.

The menace of 'settled science'. II

"Ninety-five Percent of Forensic Scientists Agree..."
Michael Egnor May 5, 2015 3:12 PM



 Firedoglake, on the scandal involving forensic science and the FBI:

In a stunning revelation the FBI has admitted that it provided flawed forensic testimony on hundreds of cases in the two decades prior to the year 2000. The FBI forensic experts falsely stated forensic matches that favored prosecutors 95% of the time in the over 200 cases reviewed so far.
In 14 of the cases the FBI experts offered that flawed testimony in the defendants have either died in prison or been executed. Four previous defendants have been exonerated so far thanks to new reviews of FBI forensic testimony...
The misleading testimony of the forensic scientists was pervasive:
The Justice Department and FBI have formally acknowledged that nearly every examiner in an elite FBI forensic unit gave flawed testimony in almost all trials in which they offered evidence against criminal defendants over more than a two-decade period before 2000. Of 28 examiners with the FBI Laboratory's microscopic hair comparison unit, 26 overstated forensic matches in ways that favored prosecutors in more than 95 percent of the 268 trials reviewed so far...
This scandal is of extraordinary importance, yet I suggest that its importance is generally misunderstood.
It is clearly a scandal involving the criminal justice system; the false testimony of these scientists has sent innocent men to prison and possibly to death. Yet it is only secondarily a scandal of the criminal justice system.
It is primarily a scandal of the scientific community. The testimony clearly reflected a consensus within the community of forensic scientists who testify for the FBI. The fundamental scandal is that the FBI took scientists at their word --that their scientific findings were consensus science, and therefore good science.
In the courtroom, scientists favored the prosecution (their employer) 95 percent of the time. This echoes government-funded global warming scientists' claim that "97% of climate scientists agree that anthropogenic climate change is occurring."
The parallel to the controversy about global warming and Darwinian biology is striking. Many climate scientists demand that we restructure the world economy and even world governance according to "consensus climate science," and many evolutionary biologists insist that it is the scientific consensus that Darwinian mechanisms explain all biological adaptation and that this consensus precludes discussion of the strengths and weaknesses of Darwinian theory in schools.
No doubt the forensic scientists insisted, as climate scientists and evolutionary biologists still insist, that their findings were facts, and that there is a scientific consensus to support their proclamations. No doubt defense experts were labeled deniers (or the forensic equivalent) for questioning the consensus science, just as skeptical climate scientists and biologists are labeled "deniers" for asking probing questions about climate science and evolutionary biology.
Consensus climate science and consensus evolutionary biology are no more credible than consensus forensic science. If anything, forensic scientists' ethical standards are higher than those of climate scientists and evolutionary biologists, who don't proclaim their theories in situations in which life and freedom are immediately at stake, who are unaccountable to the justice system, and who aren't under oath when they make their proclamations about scientific unanimity.
This lesson is clear: consensus science isn't science. Consensus science is groupthink, ideology-mongering, and censorship masquerading as science. Science is a continuous process of inquiry. We should reject "consensus science" in the courtroom, in the classroom, and in the public square.