Liver Function and Its Effects
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 is delighted to offer this series, “The Designed Body.” For the complete series, see here. Dr. Glicksman practices palliative medicine for a hospice organization.
Tim (not his real name) was a hard-working, hard-drinking man who had never stayed attached to anyone. He had contracted viral hepatitis which, combined with his alcohol abuse, had caused him to develop chronic liver disease. He had been hospitalized several times when I first met him at his sister’s home after he was placed in hospice care. He was lying in a recliner looking pretty weak with a yellowish tinge to the whites of his eyes and skin. He had marked muscle wasting, scattered scratches and bruises on his arms, and a large belly with swollen red legs. I saw that he was confused and had problems expressing himself, so I turned to his sister and her son to get the history.
They told me that Tim had been declining for the last several weeks and that, although he had stopped drinking a few months ago, each time he came out of hospital he was worse than the last time. Now he needed a lot of help to dress, bathe, and use the bathroom. He could barely stand, even with significant assistance, to pivot and transfer to a wheelchair. He was more prone to confusion and slept most of the time, seemed to be itchy, ate very little and complained of abdominal and leg swelling and pain. When I examined him, not only was he confused and jaundiced, I also found that he had a fever, a quick pulse, and a relatively low blood pressure. I also noted that not only was his abdomen full of fluid but the redness in his swollen legs was due to infection.
His sister brought out the results of some of his recent blood work, which showed a very low serum albumin, elevated bilirubin and ammonia levels, and a moderate delay in his clotting test. I sat down with Tim’s sister and nephew to explain the situation and what we might be able to do for him to keep him comfortable.
Next to the brain, the liver is the most versatile organ, performing over five hundred different tasks, and each is important for survival. Since the liver is capable of regeneration and has a large functional reserve, it usually requires a loss of over eighty percent of its cell function for the symptoms and signs of chronic liver disease to manifest. It is the liver that handles the metabolism of carbohydrates, proteins, and fats for the energy and nutrient needs of the body. It produces numerous different proteins for specific tasks and, using enzymes, chemically breaks down drugs, hormones and other substances so the body can maintain control of its chemical environment.
Evolutionary biologists are good at imagining how an ultra-complex organ like the liver could have come into being by talking about how it looks, but not how it actually works within the laws of nature to keep the body alive. But real numbers have real consequences and by using Tim’s case to highlight just five of the over five hundred functions of the liver, we will see what would have happened to our earliest ancestors without any one of them. After all, evolutionary biology claims that life came about by chance and laws of nature alone, so it must explain how transitional organisms survived as the liver gradually acquired these vital functions while macroevolution was taking place.
First, the liver helps the body break down red blood cells and, using enzymes, chemically converts hemoglobin into bilirubin. It then takes bilirubin and joins it with cholesterol and other chemicals it produces to form bile. The liver sends the bile into the intestine so it can absorb fats and with it fat-soluble chemicals like vitamin A, for vision, vitamin D, for bones and calcium metabolism, and vitamin K, for clotting, all of which were necessary for our earliest ancestors. Just as we see for Tim, when the liver cells aren’t working properly, the bilirubin they produce backs up and moves into the blood, making the bilirubin level rise and causing the whites of the eyes and the skin to turn yellow (jaundiced). People who are jaundiced often feel tired and weak, with a poor appetite and nausea, and may feel itchy.
Second, the liver produces albumin which represents over sixty percent of its entire protein output. One role for albumin is to help transport minerals like calcium and magnesium, fatty acids and other lipids, and steroid hormones like estrogen, progesterone, and testosterone in the blood so they can travel to where they are needed in the body. But one other very important function of albumin is to maintain the blood volume by keeping enough water in circulation. As blood enters the arterial side of the capillary under pressure and moves to the venous side, water is naturally pushed out of the circulation through the pores within the walls of the capillary and into the interstitial fluid, like soft boiled potatoes through a ricer.
Since albumin cannot escape from circulation through the walls of the capillary, it naturally applies an osmotic pull back on the water trying to leave, acting as a counterbalance to the pressure pushing the water out. The degree of osmotic power applied by albumin to pull back on the water trying to escape from circulation is directly related to how much albumin is in the blood. When the liver doesn’t produce enough albumin, more water tends to move out of the circulation and into the interstitial fluid, which reduces the blood volume and can cause blood pressure to drop. One of the main causes of Tim’s low blood pressure and increased fluid in his abdomen (ascites) and legs (edema) was due to a very low level of albumin in his blood.
Third, besides albumin and other transport proteins, the liver produces most of the clotting factors. Hemostasis is the process by which the body prevents itself from bleeding, something that would have been vital for the survival of our earliest ancestors. Damage to the blood vessel wall triggers the muscles surrounding it to contract and close off the opening as much as possible. It also causes the platelets in the blood passing by to stick together, forming a soft plug to cover the opening and limit blood loss.
But, for many blood vessel injuries, this is not adequate to achieve hemostasis. The clotting factors must swing into action to produce a fibrin clot strong enough to permanently seal the defect, stop the bleeding, and allow healing to take place. When the clotting factors are released from the liver into the blood they are inactive and do not interact with each other unless they encounter a damaged blood vessel. This is very important because if fibrin clots formed within normal blood vessels they could block blood flow and lead to organ damage and death. When the clotting factors encounter a damaged blood vessel, and the platelet plug trying to seal it, this triggers them to interact like dominos to form a fibrin clot in a process called the coagulation cascade. When the liver isn’t making enough clotting factors, this makes the body prone to bleed easier as we see with Tim, whose clotting test was prolonged. That was why his arms were bruised due to minimal trauma from scratching.
Fourth, another set of proteins the liver makes is complement which consists of over thirty proteins that, when activated, work together to help the immune cells fight infection. Just like the clotting factors, the complement proteins are inactive when the liver releases them into the blood. Encountering microbial infection triggers them to interact like dominos to aid in the immune defense of the body. They increase inflammation in the area of infection, kill microbes, and attract immune cells to the battlefield and help them attach to microbes so they can literally swallow and destroy them. When the liver isn’t working as well as it should, it produces less complement, which along with other factors, makes the body more susceptible to infection. Clinical experience shows that this would have made the survival of our earliest ancestors impossible.
Fifth, another important job for the liver is to convert ammonia, a highly toxic byproduct of protein metabolism, into urea, so it can be released from the body through the kidneys.
This requires five specific enzymes working together in what is called the urea cycle. Elevated blood levels of ammonia are toxic to the nervous system and the absence of any one of these five enzymes would have made life impossible for our earliest ancestors. When the liver isn’t working properly, it may allow ammonia, and other toxic substances that it usually metabolizes, escape into the blood, causing a condition called hepatic encephalopathy. In its milder form, this manifests as irritability, poor attention, anxiety, and insomnia. But if the ammonia level rises further, this can progress to imbalance, lethargy, confusion, slurred speech, difficulty swallowing, and be fatal. Returning to Tim, we see that with his confusion, difficulty speaking, and need for lots of assistance, that he is probably showing signs of hepatic encephalopathy.
Having detailed to his sister and nephew what was going on with Tim, I also explained that his leg infection could be responsible for his functional decline and confusion. In other words, if we could treat some of his problems with medications and provide him with good nutrition and support, he may improve and be able to live a little longer. We started him on antibiotics to treat his infection, diuretics to push excess salt and water out of his body and reduce the swelling in his legs and abdomen, and medication to reduce the ammonia level in his blood. Over the next several weeks Tim’s condition improved so that he was lucid, had a better appetite, and could be up on his own with a walker. The transformation was remarkable and he became very animated about how he had a “new lease on life.”
Tim’s nephew was due to go back to college for his pre-med courses in biology and he was perplexed. He believed in neo-Darwinism, and was exposed to the rhetoric that those who don’t believe Darwin really don’t understand science. But what he had learned about the liver and just five of its vital functions, and what he had seen happen over the last several weeks, gave him pause. He had seen someone who believes in intelligent design prove his knowledge of how science, and life, really works by bringing his uncle back from the brink. I told him that being a physician means having the responsibility to seek out and speak the truth so that those who are vulnerable will not be misled and being humble enough to admit that we don’t always have all of the answers, and probably never will.
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