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Friday 25 March 2016

Darwinism vs. the real world XXIV



   Heat and Temperature -- What's the Difference? 

 see here . Dr. Glicksman practices palliative medicine for a hospice organization.

We live in a world made up of matter. Matter consists of atoms and molecules that follow the laws of nature. Organic life is made up of atoms and molecules that are organized into cells. Our body has trillions of them. Heat and temperature are physical phenomena and, although related to each other, they are not the same thing.


Heat is the transfer of energy from one object to another. When a machine uses energy, it naturally gives off heat. This applies to the body as well. When our cells use oxygen to release energy from glucose, they give off heat. The laws of nature not only cause the release of heat when energy is used, they also cause the transfer of heat from a warmer object to a cooler object when they come in contact with each other. When you touch a hot stove, the transfer of heat from it to your fingers will burn them. Grab an ice cube and the transfer of heat from your hand to it will cause it to melt.


In contrast, temperature is a measure of an object's internal energy, reflected in its amount of random molecular motion. This energy is often derived from heat but can come from other sources, like electrical and nuclear energy. The higher an object's temperature, the more random motion there is among its molecules. Conversely the lower an object's temperature, the less random motion there is among its molecules.


For some molecules, like H2O, the amount of random motion can affect its physical state. If the temperature of H2O is below 32oF (0oC), it is a solid -- ice. And when its temperature is between 32oF-212oF (0oC-100oC), H2O is liquid water. Finally, when the temperature of H2O is greater than 212oF (100oC) it is a gas called water vapor or steam. The effects of heat on an object's temperature, physical state, and functional capacity apply not only to working machines but to the cells of the body as well.


Everybody knows that going outside in the sun during the summer will make you feel hot. And going outside without a coat in the winter will make you feel cold. And most people know that the temperature inside the body (core temperature) is normally higher than on the skin (surface temperature). All you have to do is blow on your hands and feel the heat to figure that out. As humans, we are warm-blooded, while most reptiles, amphibians, fish, and insects, are cold-blooded. But most people do not understand why and how the body follows the rules and keeps its core temperature within a certain range to stay alive. That's what the next few articles in this series will explain.


Just as a machine can malfunction if it is too hot or too cold, so too, the cells that make up the organs of the body can malfunction if the core temperature is too high or too low. The core temperature of the body is a reflection of the amount of random molecular motion within its cells. Most of the enzymes the body uses for its metabolic processes work best within an ideal temperature range. For the human body the normal range for the core temperature is 97o-99oF (36o-37oC).


If the core temperature rises too high or drops too low, it may affect not only the function of the enzymes but also the integrity of the proteins and the plasma membrane. A core temperature greater than 107oF (42oC) usually causes structural and enzymatic protein breakdown, causing impairment of cellular respiration and destabilization of the plasma membrane. This ultimately results in brain malfunction, loss of temperature control, muscle breakdown, and multi-system organ failure. A core temperature below 91oF (33oC) usually causes a significant reduction in enzyme activity and metabolic function, resulting in a marked decrease in energy production. This too leads to brain malfunction, loss of temperature control, impaired muscle function, and multi-system organ failure.


Clearly, it is important for the body to control its core temperature. To understand how thermoregulation is accomplished, you must first understand how the laws of nature affect the body with respect to heat and temperature.


The core temperature of the body is affected mainly by two processes: how much heat the body produces from the energy its cells use to function and how much heat the body gains from, or loses to, its surroundings.


The chemical reactions in the body can either release or use up energy. The sum total of all these chemical reactions is called the metabolism. Chemical reactions that release energy while breaking down complicated molecules, like glucose (C6H12O6), into simpler ones, like carbon dioxide (CO2) and water (H2O), are called catabolic reactions. Chemical reactions that use energy to build more complex molecules, like proteins, from simpler ones, like amino acids, are called anabolic reactions. Both catabolic and anabolic reactions take place side by side in the cell.


The cell is only able to harness about one quarter of the energy that is released from the breakdown of complex molecules like carbohydrates, fats, and proteins. It places this energy in special energy-storage molecules (e.g., ATP). The remaining three-quarters of the energy is released into the body as heat. The energy-storage molecules, like ATP, then transfer their energy within the cell so it can be used for anabolic processes and functional activities. These include things like the synthesis of proteins for cell structure and enzymes that promote vital chemical reactions, ion pumps (like the sodium-potassium pump) for cellular integrity and function, muscle contraction, gland and nerve cell function, and gastrointestinal absorption. All of these processes ultimately result in the release of heat. So most of the energy the body uses eventually results in the release of heat.


When the body hasn't eaten for a while and is at total rest, the amount of energy it requires to maintain its cellular integrity and total organ function is called its basal metabolic rate (BMR). Think of the BMR as being like the amount of energy a car uses while idling in traffic. It needs a minimum amount of energy just to keep the engine running before the driver steps on the accelerator. So too, the BMR is a measure of the amount of energy the body uses just to maintain its cellular and organ function while it waits to be put into action. And just like a car, the faster the body moves and the more work it does, the more energy it needs, the more heat it releases, and the higher its internal energy and temperature. So the laws of nature regarding the release of heat when energy is used to do work affects the body's core temperature, not only when it is at complete rest (BMR) but with any level of activity.


Since the body is surrounded by air (or sometimes water) it is always losing heat to, or gaining heat from, its environment. Since most people prefer to stay in surroundings where their core temperature (97o-99oF, 36o-37oC) is higher than the ambient temperature, the body is usually constantly losing heat to its surroundings. In the same way that heat radiates from the sun, much of the heat produced by the body's metabolism is lost through the skin into the surroundings. This accounts for about one-half of the body's heat loss.


Conduction involves the transfer of heat from one object to another by direct contact. If the body comes in contact with something cooler or warmer than itself, as when swimming in a cold river or sitting in a hot sauna, then heat is transferred to or from the body by conduction. Heat loss by conduction usually takes place between the skin and the air surrounding the body and is often aided by convection. Convection is the phenomenon where heated air at the surface of the skin moves away from the body and is replaced by cooler air, which is more effective in taking away heat. This is why a cool breeze against the skin causes more heat loss. Conduction, aided by convection, generally accounts for about one-quarter of the body's heat loss.


Finally, evaporation takes place when water on a surface absorbs heat from it and is released into the air as water vapor. Heat loss by evaporation takes place from the lungs, the mouth, and, most importantly, from perspiration on the surface of the skin. Evaporation accounts for about one-quarter of the total heat lost from the body.


In summary, the laws of nature demand that heat be released when energy is used to do work. The body invariably produces heat from its metabolism, which allows it to live and function normally within its environment. The laws of nature also demand that a warmer object transfer heat energy to a cooler one when they come in contact with each other. Since the body is surrounded by air that is usually cooler than its core temperature, this means that it is usually losing heat to its environment. The body's core temperature is therefore determined by its total production of heat through its metabolism and how much heat it loses to, or gains from, its surroundings.


The molecules that make up the cells and perform the functions of the body work best within a given temperature range. To control its core temperature and stay healthy, the body must take into account these two laws of nature that naturally cause internal heat production and the transfer of heat to, or from, the environment. Next time, we'll look at how the body does it and whether, given this understanding of how life works, the explanations of evolutionary biology are satisfying.

Monday 21 March 2016

On irreconcilable differences between Darwin and God.

Character and Theology Aside, What About Denis Lamoureux's Science?

The appearance of evenhandedness?

Larry Moran -- Voice of Reason


The salmon vs. Darwin



Another Fine-Tuned Mechanism Gets Salmon Home


Evolution News & Views March


What is carbonic anhydrase and why does it matter? The presence of this enzyme in salmon hearts points to another case of intelligent design in these remarkable fish that were depicted in Illustra Media's film Living Waters. News via the Journal of Experimental Biology explains the challenge salmon face swimming upstream:
Fish plumbing is contrary. As the heart is the last organ that blood passes through before it returns to the gills, and with little direct blood supply to the ceaselessly contracting muscle, there are occasions when it could be on the verge of failure. 'We know this can happen under certain conditions like exhaustive exercise in combination with hypoxia or elevated water temperature', says Sarah Alderman from the University of Guelph, Canada. Added to the challenge of keeping the heart supplied with oxygen, Alderman explains that the haemoglobin that carries oxygen in fish blood is finely tuned to blood pH: the more acidic the red blood cells, the less able haemoglobin is to carry oxygen, which could prevent the red blood cells of exercising fish from picking up oxygen at the gills if they didn't have an effective pump to remove acid from the cells and restore the pH balance. [Emphasis added.]
Here we see a double challenge the salmon faces. It has to avoid excess acid so that the hemoglobin can carry oxygen, and it has to get the oxygen all the way from the gills through its entire body to the heart. Here's where carbonic anhydrase comes to the rescue:
But Alderman and her colleagues, Till Harter, Tony Farrell and Colin Brauner from the University of British Columbia, Canada, also knew that fish can take advantage of a sudden drop in red blood cell pH to release oxygen rapidly at tissues -- such as red muscle and the retina -- when required urgently. An enzyme called carbonic anhydrase -- which combines CO2 and water to produce bicarbonate and acidic protons, and vice versa -- lies at the heart of this mechanism. Normally there is no carbonic anhydrase in blood plasma; however, the enzyme has been found in salmon red muscle capillaries, where it facilitates the reaction of protons -- that have been extruded from the red blood cell -- with bicarbonate to produce CO2, which then diffuses back into the red blood cell. The CO2 is then converted back into bicarbonate and protons in the blood cell, causing the pH to plummet and release a burst of O2 from the haemoglobin. Could salmon take advantage of this mechanism to boost oxygen supplies to the heart when the animals are working full outPossibly, but only if carbonic anhydrase was accessible to blood passing through the heart.What is carbonic anhydrase and why does it matter? The presence of this enzyme in salmon hearts points to another case of intelligent design in these remarkable fish that were depicted in Illustra Media's film Living Waters. News via the Journal of Experimental Biology explains the challenge salmon face swimming upstream:
Fish plumbing is contrary. As the heart is the last organ that blood passes through before it returns to the gills, and with little direct blood supply to the ceaselessly contracting muscle, there are occasions when it could be on the verge of failure. 'We know this can happen under certain conditions like exhaustive exercise in combination with hypoxia or elevated water temperature', says Sarah Alderman from the University of Guelph, Canada. Added to the challenge of keeping the heart supplied with oxygen, Alderman explains that the haemoglobin that carries oxygen in fish blood is finely tuned to blood pH: the more acidic the red blood cells, the less able haemoglobin is to carry oxygen, which could prevent the red blood cells of exercising fish from picking up oxygen at the gills if they didn't have an effective pump to remove acid from the cells and restore the pH balance. [Emphasis added.]
Here we see a double challenge the salmon faces. It has to avoid excess acid so that the hemoglobin can carry oxygen, and it has to get the oxygen all the way from the gills through its entire body to the heart. Here's where carbonic anhydrase comes to the rescue:
But Alderman and her colleagues, Till Harter, Tony Farrell and Colin Brauner from the University of British Columbia, Canada, also knew that fish can take advantage of a sudden drop in red blood cell pH to release oxygen rapidly at tissues -- such as red muscle and the retina -- when required urgently. An enzyme called carbonic anhydrase -- which combines CO2 and water to produce bicarbonate and acidic protons, and vice versa -- lies at the heart of this mechanism. Normally there is no carbonic anhydrase in blood plasma; however, the enzyme has been found in salmon red muscle capillaries, where it facilitates the reaction of protons -- that have been extruded from the red blood cell -- with bicarbonate to produce CO2, which then diffuses back into the red blood cell. The CO2 is then converted back into bicarbonate and protons in the blood cell, causing the pH to plummet and release a burst of O2 from the haemoglobin. Could salmon take advantage of this mechanism to boost oxygen supplies to the heart when the animals are working full outPossibly, but only if carbonic anhydrase was accessible to blood passing through the heart.
Well, what do you know! That's what Alderman's team found: the enzyme is present on the surface of the heart chambers. Using the heart itself as their "reaction vessel," they were able to see the pH plummet as the enzymes went into gear. 
Working closely together, the duo painstakingly developed a technique where they could measure the pH in the beating heart with pH probes that were thinner than a human hair. Eventually, the duo's persistence paid off and the pH in the heart plummeted as they fed CO2 into the pulsating chambers. And when they added a carbonic anhydrase inhibitor (produced by Claudia Supuran) to the fluid, the pH fall slowed dramatically. Carbonic anhydrase was responsible for the drop in pH.
The Protein Data Bank 101 website shows pictures of this enzyme and describes its mode of action. 
An enzyme present in red blood cells, carbonic anhydraseaids in the conversion of carbon dioxide to carbonic acid and bicarbonate ions. When red blood cells reach the lungs, the same enzyme helps to convert the bicarbonate ions back to carbon dioxide, which we breathe out. Although these reactions can occur even without the enzyme, carbonic anhydrase can increase the rate of these conversions up to a million fold.
There's an evolutionary conundrum about this enzyme: functional equivalence without sequence similarity:
This ancient enzyme has three distinct classes (called alpha, beta and gamma carbonic anhydrase). Members of these different classes share very little sequence or structural similarity, yet they all perform the same function and require a zinc ion at the active site. Carbonic anhydrase from mammals belong to the alpha class, the plant enzymes belong to the beta class, while the enzyme from methane-producing bacteria that grow in hot springs forms the gamma class. Thus it is apparent that these enzyme classes have evolved independently to create a similar enzyme active site.
Further complicating the picture, there are different forms of the enzymes depending on the tissue or cellular compartment they are located in. These allow fine tuning of the enzyme's activity: "Thus isozymes found in some muscle fibers have low enzyme activity compared to that secreted by salivary glands," in the case of mammals.Carbonic anhydrase (CA) was the first enzyme found to contain zinc, abiochemistry textbook says; now, hundreds are known. Zinc and other metals are often essential for function in metalloenzymes. The PDB-101 article explains,
Zinc is the key to this enzyme reaction. The water bound to the zinc ion is actually broken down to a proton and hydroxyl ion. Since zinc is a positively charged ion, it stabilizes the negatively charged hydroxyl ion so that it is ready to attack the carbon dioxide.
It's not surprising that this enzyme is present in the salmon, since it exists in all three domains of life. What's amazing is that the salmon's heart is studded with these enzymes that are "at the ready" when the large fish is fighting with all its might to leap above cascades and waterfalls, facing daunting challenges without the benefit of food. (Living Waters says, "The sockeye are so focused on their objective that after leaving the ocean, they do not eat again.")
If the pH dropped too early as the blood travels through the salmon's body, it would be less able to carry its precious oxygen cargo. But right when it is needed during that Olympic high jump over a waterfall or away from a hungry bear, the fish uses its CA enzymes in its heart to drop the pH and release the oxygen it needs. The spent blood then travels to the gills to load up with more oxygen. In the original paper in the Journal of Experimental Biology, the authors summarize what they found:
Combined, these results support our hypothesis of thepresence of an enhanced oxygen delivery system in the lumen of a salmonid heart, which could help support oxygen delivery when the oxygen content of venous blood becomes greatly reduced, such as after burst exercise and duringenvironmental hypoxia.
How many independent systems do we see at work in the remarkable migration of the salmon? The fish has a built-in map of its destination. It has the ability to memorize waypoints by smell. It can navigate by the earth's magnetic field. It has a sixth sense, the lateral line. It can distinguish odors by parts per trillion. Each of its body systems contain thousands of molecular machines like carbonic anhydrase that are located just where they need to be, doing what they need to do to support the whole organism.
If any one of these systems is a testament to intelligent design, how much more the composite? The only fish story here is the notion that all this came together by unguided natural processes -- sheer dumb luck.


Thursday 17 March 2016

On taking on big science's gatekeepers.

Is There a Scientific Establishment?

Yet more on pre evolutionary design.

Collective Motion: A New Level of Design Found in Proteins

On Charles Darwin and Rube Goldberg

My Debate with Michael Ruse -- Evolution as a Rube Goldberg Machine