Malcolm H. Lader, OBE, LLB, DSc, MD, PhD, FRCPsych, FMedSci

• Emeritus Professor of Clinical Psychopharmacology,
• King? College London, Institute of Psychiatry,
• London, UK

Because the average reader is unaware that there simply is no Bermuda triangle "problem" or "mystery" to be explained prehypertension yahoo purchase prinivil 2.5 mg line, he or she can be taken in by the implication of these ads and the prestige of Time-Life Books and end up concluding that there must be something to the frequent reports of paranormal powers hypertension jnc 8 classification discount 10 mg prinivil visa. Those responsible for deciding how to present the paranormal in the popular media can be quite explicit about their interest in downplaying the skeptical position hypertension numbers order 2.5 mg prinivil with mastercard. A simple exercise supports this contention: the next time you are on vacation (and hypertension emergency treatment generic 2.5 mg prinivil mastercard, for academics arteriographic embolization purchase 5mg prinivil free shipping, no longer in a university town) hypertension word parts buy prinivil 10 mg, take a trip to the local bookstore and examine the offerings in the general science section. Small in absolute terms; small compared to the science fiction section; small compared to the paranormal section; small compared to almost any reasonable category one might name. The media, after all, merely try to boost circulation, and doing so requires adhering to the beliefs and preferences of the audience. Paranormal claims would not sell, the argument goes, if they did not tap some pre-existing belief, or will to believe, in the general population. Belief, or the desire to believe, creates a market for the coverage of the paranormal, and this coverage in turn creates or reinforces belief. Most important, it suggests a greater reality which we have yet to fully understand. This can be an extremely seductive "transcendental temptation" 27 because it opens up several inviting possibilities, such as the potential for some part of us to survive death. Parapsychology validated the existence of basic phenomena that could partially account for, and fit in with, some of the spiritual views of the universe. Most of us are prepared to believe such a doctrine if only the evidence could make it seem plausible. Perhaps we can more accurately predict the future through precognition, more efficiently communicate with others through telepathy, and more effectively control our physical health through something akin to psychokinesis. Perhaps many of the things we accomplish already through hard work and the application of our intelligence can be achieved more effortlessly through these special powers. It is worth noting that those who want psychic phenomena and parapsychological research to be more widely accepted in the general public often play upon this desire by emphasizing that psi is an undeveloped potential in everyone. For example, Targ and Puthoff say of their remote viewing research that: our laboratory experiments suggest that anyone who feels comfortable with the idea of having paranormal ability can have it. In our experiments, we have never found anyone who could not learn to perceive scenes, including buildings, roads, and people, even those at great distances and blocked from ordinary perception. So far, we cannot identify a single individual who has not suceeded in a remote viewing task to his own satisfaction. More important, there are many things we would like to believe, but reality gets in the way. As we saw in chapter 5, people do not willynilly believe what they want to believe. The wish may be father to the belief, but like all fathers it requires a mate-some supporting evidence in this case. Forty-one percent of the believers in a sample of Canadian undergraduates cited personal experience, or that of their friends and relatives, as the most important determinant of their belief, 30 as did 51% of the believers in a sample of readers of the British journal New Scientist. What type of personal experience do people have in mind, and how is it construed, or misconstrued, as evidence of psi? Given the widespread use of various randomizing devices in many gambling and board games, I am convinced that one of the most common (and for many people the earliest) apparent experiences of psi involves attempts to influence such random processes. Is there any reason to expect that they will be construed not as the occasional hits one can expect by chance, but as the product of paranormal powers? First of all, because psychic powers and the ability to harness them are considered so mysterious, the door is open to selective encoding of success and failure. As we saw in Chapter 2, people have a difficult time accepting the randomness of such streaks. They may thus walk away from the experience of these runs convinced that they have witnessed the operation of some special power. Another phenomenon which tempts many people to speculate about a transcendent force is the experience of a remarkable coincidence. Two friends who have not seen each other in years sit in adjacent seats in a theatre in a foreign town. A man dials a wrong number in a distant city, and the recipient turns out to be his college roommate. A woman is thinking about an event she has not thought of in years and intends to discuss it with her spouse; miraculously, he brings it up first. These events seem so improbable, and often produce such powerful emotion, that they strike many people as more than just coincidence. When asked to consider the probability that at least two people in a group of a particular size were born on the same day of the year, most people are shocked to learn that the odds are roughly 50-50 when the group is as small as 23. More shocking still is that the probability of a matching birthday is 85% when the group size is only 35. Thus, many people will be surprised by an outcome (a pair of matching birthdays) that is not unusual at all. This may be what Aristotle had in mind when he said that "the improbable is extremely probable. A telling example is provided by physicist and Nobel laureate Luis Alvarez, who was struck by a remarkable coincidence in his own life. After reading a brief passage in a newspaper, Alvarez began a series of associations that led him to think of a long-forgotten acquaintance from his college years. Turning the pages of the paper, he was amazed to see an obituary of that very same individual! Or might his recollection of this long-forgotten acquaintance been produced by a precognitive awareness of the obituary itself? Believing such paranormal explanations implausible, Alvarez proceeded to compute an approximate probability of such a coincidence by estimating the number of people the average person knows and how often the average person has such recollections. Thus, with the population of the United States as it is, we can expect there to be over 3,000 of these events every year, or almost 10 every day. Our misguided intuitions about the true likelihood of such events appear to stem from two sources-a failure to appreciate how often we "sample" from the population of all events, and a reluctance to consider how many different events we would consider to be coincidental. Given the vastness of our experience (how many thoughts we have, how many people we come in contact with, etc. Perhaps the key to this shortcoming of human intuition is that, unlike coin flipping, the repeated sampling is not obvious because it is not the same distribution being repeatedly sampled. By meeting a person here, thinking of someone there, receiving a phone call somewhere else, we are sampling from different distributions, and it is this difference that masks the repetitive element of the sampling process. Furthermore, people may be reluctant to think of their own experience, with all its attendant emotions, as a sample from a population of all possible experiences. Our intuitions about coincidental events also suffer from the problem of "multiple endpoints" discussed in Chapter 4. While the odds of a particular coincidence may indeed be vanishingly low, the odds of any of a set of equally remarkable coincidences is generally much higher. Suppose an amateur thespian takes in the theatre while visiting London and runs into his high school drama teacher. Or what if the encounter had taken place, not in the theatre, but at the opera house, a museum, or even a pub? By pulling back a bit like this, we quickly see that although the probability of any one coincidence is indeed quite low, the probability of the union of all such coincidental events can be quite high. Our sense of astonishment when confronted by coincidence can thus be traced to our intuitive tendency to assess the likelihood of the intersection of the specific events that did occur, rather than the union of all similar outcomes that might have occurred. Many people approach the problem with a fairly accurate sense of the long odds against a particular pair of people having the same birthdate (approximately 1/365), but they fail to appreciate how many different pairs of people there are (253) in a group of 23. Finally, people may be inclined to see some sort of guiding hand behind many coincidental events because of the powerful emotions these experiences often produce. Premonitions tend to elicit paranormal explanations as much or more as a startling coincidence. Someone dreams about a plane crash and then hears about precisely that event on the evening news. Someone reminisces about an old acquaintance, and the acquaintance suddenly walks in the room. Premonitions strike people as compelling for the same reason that underlies the impact of coincidence-they seem too improbable to occur by chance. But given how often an active mind thinks of people, places, and events, the briefest reflection informs us that a person is almost certain to experience quite a few premonitions in a full lifetime. Death, for example, is a very frequent topic of dreams, and so it is hardly surprising if one such dream should happen to correspond to a real-world fatality. Premonitions are also precisely the kind of "one-sided" events (chapter 4) for which the successes stand out and the failures go unrecognized. People daydream about long-lost friends all the time, but little of the specific content of such reveries can generally be recalled-unless they should happen to be followed by an unexpected visit by that very same person. Against this background of selective recall, any one premonition looms as a much more impressive event than it really is. A man has a vague, unpleasant dream about riding in a plane that is out of control (or was it a boat? Dreams are particularly suspect in this regard because their multi-faceted, kaleidoscopic nature makes them something of a "one size fits all" premonition that is easy to fulfill. Psychologist James Alcock cites intriguing evidence of the retrospective nature of many prophetic dreams: Those who claim to have such experiences report that their prophetic quality disappears after he has them record their dreams! His popularity is thus truly baffling, particularly when one learns that he essentially made this admission about his predictions himself! Suppose that after visiting a relative you depart with a vague sense of unease: Your relative looks "different" in a way that you cannot quite identify. This unease leads to anxious dreams about the person, perhaps one in which he or she is harmed. Suppose, in addition, that two days later you learn that this same relative has been hospitalized with a serious ailment. Under these circumstances, it is hard to resist the conclusion that you have forseen this bad turn of events-you have. A rumination about a particular person may be triggered by some external event with which he or she is associated. That same external event, of course, can lead that same person to think about you and thus prompt a phone call. Here again, though, the important question is whether they occur more frequently than one would expect by chance. The notion that it is just coincidence may be difficult to accept for anyone who has had such a premonition and experienced all the powerful emotion and sense of awe they inspire. Intuitively, such awesome events demand more than mundane causes-certainly more than the implication that there is no cause at all. People generally believe the scientific community, even when it makes claims that seem bizarre or that conflict with the apparent lessons of everyday experience. Few quarrel with the claim that the earth is round or that it revolves around the sun, despite immediate experience that seems to suggest otherwise. People also readily accept the existence of quarks, black holes, and gaps in the ozone layer-entities that can be difficult to fathom. Exciting phenomena either have one of several mundane explanations or they simply do not exist. Thus, the skeptic asks that what seems to be a unified-although not terribly deep- explanation of a host of phenomena. People act much like professional scientists who are willing to tolerate troublesome data in allegiance to a unifying theory-until a more elegant and unified theory is discovered. Logicians and philosophers are in virtual unanimous agreement that the burden of proof on any question lies not with the skeptic, but with the person making the positive assertion. The failure to supply a convincing "natural" explanation for an anomalous event may be more a reflection of the limits of our knowledge than an argument for psi. Skeptics and parapsychologists obviously differ in their assessments of this likelihood. Another way to frame the debate, however, is to ask, "if psi existed, and a research program were conducted to examine it, what would we expect to discover? For instance, what would those who started the scientific investigation of psi have expected to result from 130 years of research? The answer is of course impossible to know with certainty, but it is hard to resist the conclusion that they would have been disappointed with what has been obtained thus far. There is the "experimenter effect," whereby positive results are obtained by sympathetic investigators and inhibited by skeptics. There is the "decline effect," whereby Examples of Questionable and Erroneous Beliefs the psi powers of even the most gifted subjects decline and generally disappear over time. And there is "psi-missing," whereby gifted subjects sometimes reveal their powers of apprehending concealed targets by making significantly fewer correct responses than expected by chance. If psi existed, is it likely that this is what we would have to show for 130 years of continuous investigation? To be fair, others might quarrel with my characterization of what are the consistent findings of parapsychological research, and they may want to include additional results. But even with a more generous inclusion of a few additional findings, the overall assessment remains much the same. Pirsig, Zen and the Art of Motorcycle Maintenance M any treatment strategies and training efforts are designed to eliminate the source of the existing problem. When someone has an infection, for example, the underlying cause can be treated by administering antibiotics. When someone first learns to drive a car with a manual transmission, problems often arise from the predisposition to let out the clutch prematurely. With practice, however, the person gradually learns to let it out at the appropriate rate and the initial tendency to rush things simply disappears.

Syndromes

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• Asphyxiating thoracic dystrophy
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• Injections into the penis
• Pregnant women who have diabetes should try to get good control over their blood sugar levels.
• Pneumonectomy, to remove a lung
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The members of an omega family may have different lengths and different numbers of double bonds arteria rectal superior purchase 2.5 mg prinivil, but the first double bond occurs at the same point in all of them heart attack 5 days collections cheap 10mg prinivil mastercard. These structures are drawn linearly here to ease counting carbons and locating double bonds 000 heart attack buy prinivil 10 mg overnight delivery, but their shapes actually bend at the double bonds arteria opinie 2012 discount prinivil 10 mg fast delivery, as shown in Figure 5-8 (p hypertension quizlet purchase prinivil 10 mg free shipping. Similarly hypertension signs and symptoms treatment buy discount prinivil 2.5 mg, an omega-6 fatty acid is a polyunsaturated fatty acid with its first double bond six carbons away from the methyl end. Figure 5-2 compares two 18-carbon fatty acids-linolenic acid (an omega-3 fatty acid) and linoleic acid (an omega-6 fatty acid). When glycerol is part of a triglyceride, each carbon is attached to a fatty acid by a carbon-oxygen bond. H H C O H H C O H H C O H H Triglycerides Few fatty acids occur free in foods or in the body. Most often, they are incorporated into triglycerides-lipids composed of three fatty acids attached to a glycerol. Most triglycerides contain a mixture of more than one type of fatty acid (see Figure 5-5). The food industry often refers to these saturated vegetable oils as the "tropical oils. A section later in this chapter explains how these features affect health; this section describes how the degree of unsaturation influences the fats and oils in foods. Firmness the degree of unsaturation influences the firmness of fats at room temperature. Generally speaking, the polyunsaturated vegetable oils are liquid at room temperature, and the more saturated animal fats are solid. Cocoa butter, palm oil, palm kernel oil, and coconut oil are saturated even though they are of vegetable origin; they are firmer than most vegetable oils because of their saturation, but softer than most animal fats because of their shorter carbon chains (8 to 14 carbons long). Generally, the shorter the car* Research scientists commonly use the term triacylglycerols; this book continues to use the more familiar term triglycerides, as do many other health and nutrition books and journals. Triglyceride + 3 water molecules Three fatty acids attached to a glycerol form a triglyceride and yield water. In this example, all three fatty acids are stearic acid, but most often triglycerides contain mixtures of fatty acids (as shown in Figure 5-5). Polyunsaturated fats spoil most readily because their double bonds are unstable; monounsaturated fats are slightly less susceptible. Saturated fats are most resistant to oxidation and thus least likely to become rancid. The oxidation of fats produces a variety of compounds that smell and taste rancid; other types of spoilage can occur due to microbial growth. Manufacturers can protect fat-containing products against rancidity in three ways-none of them perfect. First, products may be sealed in air-tight, nonmetallic containers, protected from light, and refrigerated-an expensive and inconvenient storage system. First, it protects against oxidation (thereby prolonging shelf life) by making polyunsaturated fats more saturated (see Figure 5-7, p. Second, it alters the texture of foods by making liquid vegetable oils more solid (as in margarine and shortening). Hydrogenated fats make margarine spreadable, pie crusts flaky, and puddings creamy. Trans-Fatty Acids Figure 5-7 illustrates the total hydrogenation of a polyunsaturated fatty acid to a saturated fatty acid, which rarely occurs during food processing. Most often, a fat is partially hydrogenated, and some of the double bonds that remain after processing change from cis to trans. In nature, most double bonds are cis-meaning that the hydrogens next to the double bonds are on the same side of the carbon chain. Only a few fatty acids (notably a small percentage of those found in milk and meat products) are trans-fatty acids-meaning that the hydrogens next to the double bonds are on opposite sides of the carbon chain (see Figure 5-8, p. These arrangements result in different configurations for the fatty acids, and this difference affects function: in the body, trans-fatty acids that derive from hydrogenation behave more like saturated fats than like unsaturated fats. Polyunsaturated, omega-6 Polyunsaturated, omega-3 Saturated Monounsaturated © Polara Studios Inc. Animal fats and the tropical oils of coconut and palm are mostly saturated fatty acids. Coconut oil Butter Beef tallow Palm oil Lard Some vegetable oils, such as olive and canola, are rich in monounsaturated fatty acids. Olive oil Canola oil Peanut oil Many vegetable oils are rich in polyunsaturated fatty acids. Safflower oil Flaxseed oil Walnut oil Sunflower oil Corn oil At room temperature, saturated fats (such as those commonly found in butter and other animal fats) are solid, whereas unsaturated fats (such as those found in vegetable oils) are usually liquid. In contrast, naturally occurring fatty acids, such as conjugated linoleic acid, that have a trans configuration may have health benefits. Fatty acids vary in the length of their carbon chains, their degrees of unsaturation, and the location of their double bond(s). Those that are fully loaded with hydrogens are saturated; those that are missing hydrogens and therefore have double bonds are unsaturated (monounsaturated or polyunsaturated). Hydrogenation, which makes polyunsaturated fats more saturated, gives rise to trans-fatty acids, altered fatty acids that may have health effects similar to those of saturated fatty acids. Most often, fat is partially hydrogenated, creating a trans-fatty acid (shown in Figure 5-8). O H+ H+ H+ H+ H H C H C O H H O C O H conjugated linoleic acid: a collective term for several fatty acids that have the same chemical formula as linoleic acid (18 carbons, two double bonds) but with different configurations. H H H C H H O H C O H H C H H H O C O H cis-fatty acid A cis-fatty acid has its hydrogens on the same side of the double bond; cis molecules fold back into a U-like formation. The trans form typically occurs in partially hydrogenated foods when hydrogen atoms shift around some double bonds and change the configuration from cis to trans. The other two classes of lipids, the phospholipids and sterols, make up only 5 percent of the lipids in the diet. Notice that lecithin has a backbone of glycerol with two of its three attachment sites occupied by fatty acids like those in triglycerides. The fatty acids make phospholipids soluble in fat; the phosphate group allows them to dissolve in water. Such versatility enables the food industry to use phospholipids as emulsifiers to mix fats with water in such products as mayonnaise and candy bars. Phospholipids in Foods In addition to the phospholipids used by the food industry as emulsifiers, phospholipids are also found naturally in foods. The richest food sources of lecithin are eggs, liver, soybeans, wheat germ, and peanuts. Roles of Phospholipids the lecithins and other phospholipids are important constituents of cell membranes (see Figure 5-10, p. Because phospholipids are soluble in both water and fat, they can help lipids move back and forth across the cell membranes into the watery fluids on both sides. Thus they enable fat-soluble substances, including vitamins and hormones, to pass easily in and out of cells. The phospholipids also act as emulsifiers in the body, helping to keep fats suspended in the blood and body fluids. Its advocates claim that it is a major constituent of cell membranes (true), that cell membranes are essential to the integrity of cells (true), and that consumers must therefore take lecithin supplements (false). As for lecithin taken as a supplement, the digestive enzyme lecithinase in the intestine hydrolyzes most of it before it passes into the body, so little lecithin reaches the tissues intact. In other words, lecithin is not an essential nutrient; it is just another Reminder: Emulsifiers are substances with both water-soluble and fat-soluble portions that promote the mixing of oils and fats in watery solutions. Both nature and the food industry use lecithin as an emulsifier to combine water-soluble and fat-soluble ingredients that do not ordinarily mix, such as water and oil. Notice that a molecule of lecithin is similar to a triglyceride but contains only two fatty acids. Other phospholipids have different fatty acids at the upper two positions and different groups attached to phosphate. The fatty acid "tails" orient themselves away from the watery fluid inside and outside of the cell. Like other lipids, lecithin contributes 9 kcalories per gram-an unexpected "bonus" many people taking lecithin supplements fail to realize. Perhaps these symptoms can be considered beneficial-if they serve to warn people to stop self-dosing with lecithin. In the body, phospholipids are part of cell membranes; the food industry uses phospholipids as emulsifiers to mix fats with water. Inside cell Watery fluid Sterols In addition to triglycerides and phospholipids, the lipids include the sterols, compounds with a multiple-ring structure. Sterols in Foods Foods derived from both plants and animals contain sterols, but only those from animals contain significant amounts of cholesterol-meats, eggs, fish, poultry, and dairy products. Some people, confused about the distinction between dietary and blood cholesterol, have asked which foods contain the "good" cholesterol. Being structurally similar to cholesterol, these plant sterols interfere with cholesterol absorption, thus lowering blood cholesterol levels. Among them are bile acids, the sex hormones (such as testosterone), the adrenal hormones (such as cortisol), and vitamin D, as well as cholesterol itself. Despite popular impressions to the contrary, cholesterol is not a villain lurking in some evil foods-it is a compound the body makes and uses. Right now, as you read, your liver is manufacturing cholesterol from fragments of carbohydrate, protein, and fat. These deposits lead to atherosclerosis, a disease that causes heart attacks and strokes. Notice, too, how different cholesterol is from the triglycerides and phospholipids. The body faces a challenge in digesting and absorbing these lipids: getting at them. Reminder: An enzyme that hydrolyzes lipids is called a lipase; lingual refers to the tongue. In the Mouth Fat digestion starts off slowly in the mouth, with some hard fats beginning to melt when they reach body temperature. Mouth Stomach the acid-stable lingual lipase initiates lipid digestion by hydrolyzing one bond of triglycerides to produce diglycerides and fatty acids. The degree of hydrolysis by lingual lipase is slight for most fats but may be appreciable for milk fats. Salivary glands Tongue Sublingual salivary gland Stomach (Liver) Gallbladder Pancreatic duct Pancreas Common bile duct Small intestine Bile flows in from the gallbladder (via the common bile duct): Fat Bile Emulsified fat Pancreatic lipase flows in from the pancreas (via the pancreatic duct): Pancreatic (and intestinal) Monoglycerides, Emulsified fat lipase glycerol, fatty (triglycerides) acids (absorbed) Small intestine Large intestine Large intestine Some fat and cholesterol, trapped in fiber, exit in feces. In infants, this enzyme efficiently digests the short- and medium-chain fatty acids found in milk. In the Stomach In a quiet stomach, fat would float as a layer above the other components of swallowed food. But the strong muscle contractions of the stomach propel the stomach contents toward the pyloric sphincter. This churning grinds the solid pieces to finer particles, mixes the chyme, and disperses the fat into smaller droplets. These actions help to expose the fat for attack by the gastric lipase enzyme-an enzyme that performs best in the acidic environment of the stomach. Still, little fat digestion takes place in the stomach; most of the action occurs in the small intestine. The amino acid end is attracted to water, and the sterol end is attracted to fat (see Figure 5-13, p. There, the fats are fully digested as they encounter lipase enzymes from the pancreas and small intestine. The major fat-digesting enzymes are pancreatic lipases; some intestinal lipases are also active. Occasionally, enzymes remove all three fatty acids, leaving a free molecule of glycerol. Phospholipids are digested similarly-that is, their fatty acids are removed by hydrolysis. Most sterols can be absorbed as is; if any fatty acids are attached, they are first hydrolyzed off. The other possibility is that some of the bile can be trapped by dietary fibers in the large intestine and carried out of the body with the feces. Because cholesterol is needed to make bile, the excretion of bile effectively reduces blood cholesterol. As Chapter 4 explains, the dietary fibers most effective at lowering blood cholesterol this way are the soluble fibers commonly found in fruits, whole grains, and legumes. In addition to bile acids and bile salts, bile contains cholesterol, phospholipids (especially lecithin), antibodies, water, electrolytes, and bilirubin and biliverdin (pigments resulting from the breakdown of heme). Small molecules of digested triglycerides (glycerol and short- and medium-chain fatty acids) can diffuse easily into the intestinal cells; they are absorbed directly into the bloodstream. Larger molecules (the monoglycerides and long-chain fatty acids) merge into spherical complexes, known as micelles. Micelles are emulsified fat droplets formed by molecules of bile surrounding monoglycerides and fatty acids. This configuration permits solubility in the watery digestive fluids and transportation to the intestinal cells. Upon arrival, the lipid contents of the micelles diffuse into the intestinal cells. Once inside, the monoglycerides and long-chain fatty acids are reassembled into new triglycerides. Within the intestinal cells, the newly made triglycerides and other lipids (cholesterol and phospholipids) are packed with protein into transport vehicles known as chylomicrons. The chylomicrons glide through the lymph until they reach a point of entry into the bloodstream at the thoracic duct near the heart. It is then bound to an amino acid to improve its ability to form micelles, spherical complexes of emulsified fat.

Slight deviations in either direction can denature proteins heart attack quizzes trusted prinivil 10mg, causing metabolic mayhem understanding prehypertension generic prinivil 2.5mg without a prescription. Normal energy metabolism generates hydrogen ions arteria rectalis inferior buy 10 mg prinivil free shipping, as well as many other acids prehypertension while pregnant buy 5mg prinivil overnight delivery, that must be neutralized heart attack piano order prinivil 5mg fast delivery. Three systems defend the body against fluctuations in pH-buffers in the blood blood pressure beta blocker purchase 10mg prinivil with mastercard, respiration in the lungs, and excretion in the kidneys. Regulation by the Buffers Bicarbonate (a base) and carbonic acid (an acid) in the body fluids (as well as some proteins) protect the body against changes in acidity by acting as buffers-substances that can neutralize acids or bases. Carbon dioxide, which is formed all the time during energy metabolism, dissolves in water to form carbonic acid in the blood. The appropriate balance between carbonic acid and bicarbonate is essential to maintaining optimal blood pH. Regulation in the Lungs the lungs control the concentration of carbonic acid by raising or slowing the respiration rate, depending on whether the pH needs to be increased or decreased. If too much carbonic acid builds up, the respiration rate speeds up; this hyperventilation increases the amount of carbon dioxide exhaled, thereby lowering the carbonic acid concentration and restoring homeostasis. Conversely, if bicarbonate builds up, the respiration rate slows; carbon dioxide is retained and forms more carbonic acid. Recall from Chapter 7 that carbon dioxide and water are formed during energy metabolism. Excessive losses of fluids and electrolytes upset these balances, and the kidneys play a key role in restoring homeostasis. The distinction between the major and trace minerals does not mean that one group is more important than the other-all minerals are vital. The major minerals are so named because they are present, and needed, in larger amounts in the body. A few generalizations pertain to all of the minerals and distinguish them from the vitamins. Inorganic Elements Unlike the organic vitamins, which are easily destroyed, minerals are inorganic elements that always retain their chemical identity. Once minerals enter the body proper, they remain there until excreted; they cannot be changed into anything else. Iron, for example, may temporarily combine with other charged elements in salts, but it is always iron. In fact, the ash that remains when a food is burned contains all the minerals that were in the food originally. Minerals can be lost from food only when they leach into cooking water that is then poured down the drain. Recommended intakes for the major minerals are stated in hundreds of milligrams or grams, whereas those for the trace minerals are listed in tens of milligrams or even micrograms. Calcium Phosphorus Potassium Sulfur Sodium Chloride Magnesium Iron Zinc Copper 30 2. A pound is about 454 g; thus only calcium and phosphorus appear in amounts larger than a pound. Some minerals, such as potassium, are easily absorbed into the blood, transported freely, and readily excreted by the kidneys, much like the water-soluble vitamins. Other minerals, such as calcium, are more like fat-soluble vitamins in that they must have carriers to be absorbed and transported. And, like some of the fat-soluble vitamins, minerals taken in excess can be toxic. Some foods contain binders that combine chemically with minerals, preventing their absorption and carrying them out of the body with other wastes. Examples of binders include phytates, which are found primarily in legumes and grains, and oxalates, which are present in rhubarb and spinach, among other foods. The interactions between sodium and calcium, for example, cause both to be excreted when sodium intakes are high. These are just two examples of the interactions involving minerals featured in this chapter. Discussions in both this chapter and the next point out additional problems that arise from such interactions. Notice how often they reflect an excess of one mineral creating an inadequacy of another and how supplements-not foods-are most often to blame. Later sections describe the minerals most noted for their roles in bone growth and health-calcium, phosphorus, and magnesium. Reminder: Bioavailability refers to the rate at and the extent to which a nutrient is absorbed and used. Key fluid balance nutrients: · Sodium, potassium, chloride binders: chemical compounds in foods that combine with nutrients (especially minerals) to form complexes the body cannot absorb. They usually receive special handling and regulation in the body, and they may bind with other substances or interact with other minerals, thus limiting their absorption. Sodium People have held salt (sodium chloride) in high regard throughout recorded history. We describe someone we admire as "the salt of the earth" and someone we consider worthless as "not worth their salt. Cultures vary in their use of salt, but most people find its taste innately appealing. Salt brings its own tangy taste and enhances other flavors, most likely by suppressing the bitter flavors. You can taste this effect for yourself: tonic water with its bitter quinine tastes sweeter with a little salt added. Sodium Roles in the Body Sodium is the principal cation of the extracellular fluid and the primary regulator of its volume. Sodium also helps maintain acid-base balance and is essential to nerve impulse transmission and muscle contraction. Then, with great precision, the kidneys return to the bloodstream the exact amount of sodium the body needs. Normally, the amount excreted is approximately equal to the amount ingested on a given day. When blood sodium rises, as when a person eats salted foods, thirst signals the person to drink until the appropriate sodium-to-water ratio is restored. Sodium Recommendations Diets rarely lack sodium, and even when intakes are low, the body adapts by reducing sodium losses in urine and sweat, thus making deficiencies unlikely. Sodium recommendations are set low enough to protect against high blood pressure, but high enough to allow an adequate intake of other nutrients with a typical diet. Because high sodium intakes correlate with high blood pressure, the Upper Level for adults is set at 2300 milligrams per day, slightly lower than the Daily Value used on food labels (2400 milligrams). The average sodium intake for adults in the United States exceeds the Upper Level-and most adults will develop hypertension at some point in their lives. Sodium and Hypertension For years, a high sodium intake was considered the primary factor responsible for high blood pressure. Salt has a greater effect on blood pressure than either sodium or chloride alone or in combination with other ions. For some individuals, blood pressure increases in response to excesses in salt intake. People most likely to have a salt sensitivity include those whose parents had high blood pressure, those with chronic kidney disease or diabetes, African Americans, and people over 50 years of age. Overweight people also appear to be particularly sensitive to the effect of salt on blood pressure. For them, a high salt intake correlates strongly with heart disease, and salt restriction helps to lower their blood pressure. In fact, a salt-restricted diet lowers blood pressure in people without hypertension as well. Compared with others, salt-sensitive individuals have elevated concentrations of renin in their blood. The accompanying "How to" offers strategies for cutting salt (and therefore sodium) intake. Chapter 27 offers a complete discussion of hypertension and the dietary recommendations for its prevention and treatment. Sodium and Bone Loss (Osteoporosis) A high salt intake is also associated with increased calcium excretion, but its influence on bone loss is less clear. Some people can lower their blood pressure by avoiding highly salted foods and removing the saltshaker from the table. Foods eaten without salt may seem less tasty at first, but with repetition, people can learn to enjoy the natural flavors of many unsalted foods. Most people are surprised to learn that 1 ounce of cornflakes contains more sodium than 1 ounce of salted peanuts-and that 1/2 cup of instant chocolate pudding contains still more. Low potassium may be as significant as high sodium when it comes to blood pressure regulation, so processed foods have two strikes against them. Sodium Deficiency If blood sodium drops, as may occur with vomiting, diarrhea, or heavy sweating, both sodium and water must be replenished. Under normal conditions of sweating due to physical activity, salt losses can easily be replaced later in the day with ordinary foods. Salt tablets are not recommended because too much salt, especially if taken with too little water, can induce dehydration. During intense activities, such as ultra-endurance events, athletes can lose so much sodium and drink so much water that they develop hyponatremia-the dangerous condition of having too little sodium in the blood. Notice how potassium is lost and sodium is gained as foods become more processed, causing the potassium-to-sodium ratio to fall dramatically. Limiting sodium intake may help in two ways, then-by lowering blood pressure in salt-sensitive individuals and by indirectly raising potassium intakes in all individuals. Prolonged excessive sodium intake may contribute to hypertension in some people, as explained earlier. Dietary deficiency is rare, and excesses may aggravate hypertension in some people. When chlorine reacts with sodium or hydrogen, however, it forms the negative chloride ion (Cl­). Chloride Roles in the Body Chloride is the major anion of the extracellular fluids (outside the cells), where it occurs mostly in association with sodium. Chloride moves passively across membranes through channels and so also associates with potassium inside cells. In the stomach, the chloride ion is part of hydrochloric acid, which maintains the strong acidity of the gastric juice. One of the most serious consequences of vomiting is the loss of this acid from the stomach, which upsets the acid-base balance. Chloride Recommendations and Intakes Chloride is abundant in foods (especially processed foods) as part of sodium chloride and other salts. Because the proportion of chloride in salt is greater than sodium, chloride recommendations are slightly higher than, but still equivalent to , those of sodium. Chloride losses may occur in conditions such as heavy sweating, chronic diarrhea, and vomiting. The only known cause of high blood chloride concentrations is dehydration due to * Hydrochloric acid secretion into the stomach involves the addition of bicarbonate ions (base) to the plasma. When hydrochloric acid is lost during vomiting, these hydrogen ions are no longer available for reabsorption, and so, in effect, the concentrations of bicarbonate ions in the plasma are increased. In this way, excessive vomiting of acidic gastric juices leads to metabolic alkalosis. Reminder: the loss of acid can lead to alkalosis, an above-normal alkalinity in the blood and body fluids. In both cases, consuming ordinary foods and beverages can restore chloride balance. Potassium Roles in the Body Potassium plays a major role in maintaining fluid and electrolyte balance and cell integrity. During nerve impulse transmission and muscle contraction, potassium and sodium briefly trade places across the cell membrane. Controlling potassium distribution is a high priority for the body because it affects many aspects of homeostasis, including a steady heartbeat. Potassium Recommendations and Intakes Potassium is abundant in all living cells, both plant and animal. Because cells remain intact unless foods are processed, the richest sources of potassium are fresh foods-as Figure 12-11 (p. In contrast, most processed foods such as canned vegetables, ready-to-eat cereals, and luncheon meats contain less potassium-and more sodium (recall Figure 12-10, p. Potassium and Hypertension Diets low in potassium seem to play an important role in the development of high blood pressure. Low potassium intakes raise blood pressure, whereas high potassium intakes, especially when combined with low sodium intakes, appear to both prevent and correct hypertension. Potassium Deficiency Potassium deficiency is characterized by an increase in blood pressure, salt sensitivity, kidney stones, and bone turnover. As deficiency progresses, symptoms include irregular heartbeats, muscle weakness, and glucose intolerance. Potassium Toxicity Potassium toxicity does not result from overeating foods high in potassium; therefore an Upper Level was not set. It can result from overconsumption of potassium salts or supplements (including some "energy fitness shakes") and from certain diseases or treatments. Key: Breads and cereals Vegetables Fruits Milk and milk products Legumes, nuts, seeds Meats Best sources per kcalorie kidneys accelerate their excretion. Potassium is the primary cation inside cells; fresh foods, notably fruits and vegetables, are its best sources. Deficiency Symptomsa Irregular heatbeat, muscular weakness, glucose intolerance aDeficiency accompanies dehydration. It receives much emphasis in this chapter and in the highlight that follows because an adequate intake helps grow a healthy skeleton in early life and minimize bone loss in later life. First, it is an integral part of bone structure, providing a rigid frame that holds the body upright and serves as attachment points for muscles, making motion possible.

As Highlight 5 explained blood pressure headache buy prinivil 2.5 mg fast delivery, epidemiological and clinical studies have found that a diet high in unsaturated fatty acids often helps to maintain a healthy blood lipid profile arrhythmia 4279 diagnosis buy cheap prinivil 10mg on line. Now genetic studies offer an underlying explanation of this relationship: diets rich in polyunsaturated fatty acids activate genes responsible for making enzymes that break down fats and silence genes responsible for making enzymes that make fats blood pressure 300 over 200 order 5 mg prinivil with amex. To learn more about how individuals respond to diet blood pressure levels women purchase 10 mg prinivil, researchers examine the genetic differences between people blood pressure medication viagra generic 2.5mg prinivil visa. The quest now is to identify the genetic characteristics that predict various responses to dietary recommendations arrhythmia natural treatments generic 10mg prinivil with amex. Critics have questioned whether genetic markers for disease would be more useful than simple clinical measurements, which reflect both genetic and environmental influences. The long-range possibility is that many genetic markers will eventually be identified, and the hope is that the combined information will be a useful and accurate predictor of disease. Having the knowledge to prevent disease and actually taking action do not always coincide. Despite the abundance of current dietary recommendations, people seem unwilling to make behavior changes known to improve their health. For example, it has been estimated that heart disease and type 2 diabetes are 90 percent preventable when people adopt an appropriate diet, maintain a healthy body weight, and exercise regularly. Given the difficulty that people have with current recommendations, it may be unrealistic to expect that many of them will enthusiastically adopt an even more detailed list of lifestyle modifications. The debate over nature versus nurture-whether genes or the environment are more influential-has quieted. Scientists acknowledge the important roles of each and understand the real answers lie within the myriad interactions. Current research is sorting through how nutrients (and other dietary factors) and genes confer health benefits or risks. Answers from genomic research may not become apparent for years to come, but the opportunities and rewards may prove well worth the efforts. Keusch, What do ­omics mean for the science and policy of the nutritional sciences? Kaput, Nutrigenomics: An emerging scientific discipline, Food Technology 57 (2003): 60­67; R. Weinshilboum, Inheritance and drug response, New England Journal of Medicine 348 (2003): 529­537; A. Collins, Genomic medicine-A primer, New England Journal of Medicine 347 (2002): 1512­1520. Ordovas, Single nucleotide polymorphisms that influence lipid metabolism: Interaction with dietary factors, Annual Review of Nutrition 25 (2005): 341­390. Milner, Nutrigenomics, proteomics, metabolomics, and the practice of dietetics, Journal of the American Dietetic Association 106 (2006): 403­413. Kaput and coauthors, the case for strategic international alliances to harness nutritional genomics for public and personal health, British Journal of Nutrition 94 (2005): 623­632; J. Rodriguez, Nutritional genomics: the next frontier in the postgenome era, Physiological Genomics 16 (2004): 166­177. Watkins, Personal metabolomics as a next generation nutritional assessment, Journal of Nutrition 133 (2003): 4260­4266. Ordovas, Nutrigenetics, plasma lipids, and cardiovascular risk, Journal of the American Dietetic Association 106 (2006): 1074­1081. Ntambi, Polyunsaturated fatty acid regulation of genes of lipid metabolism, Annual Review of Nutrition 25 (2005): 317­340. Ordovas, the quest for cardiovascular health in the genomic era: Nutrigenetics and plasma lipoproteins, Proceedings of the Nutrition Society 63 (2004): 145­152. Willett, Balancing life-style and genomics research for disease prevention, Science 296 (2002): 695­698. Collins, Realizing the promise of genomics in biomedical research, Journal of the American Medical Association 294 (2005): 1399­1402; P. Learn how the cells of your body transform carbohydrates, fats, and proteins into energy-and what happens when you give your cells too much or too little of any of these nutrients. Discover the metabolic pathways that lead to body fat and those that support physical activity. C H A P T E R Metabolism: Transformations and Interactions Energy makes it possible for people to breathe, ride bicycles, compose music, and do everything else they do. All the energy that sustains human life initially comes from the sun-the ultimate source of energy. Although every aspect of our lives depends on energy, the concept of energy can be difficult to grasp because it cannot be seen or touched, and it manifests in various forms, including heat, mechanical, electrical, and chemical energy. In the body, heat energy maintains a constant body temperature, and electrical energy sends nerve impulses. This chapter answers that question by following the nutrients that provide the body with fuel through a series of reactions that release energy from their chemical bonds. As the bonds break, they release energy in a controlled version of the same process by which wood burns in a fire. When wood burns in the presence of oxygen, it generates heat and light (energy), steam (water), and some carbon dioxide and ash (waste). Similarly, during metabolism, the body releases energy, water, and carbon dioxide. By studying metabolism, you will understand how the body uses foods to meet its needs and why some foods meet those needs better than others. Readers who are interested in weight control will discover which foods contribute most to body fat and which to select when trying to gain or lose weight safely. Physically active readers will discover which foods best support endurance activities and which to select when trying to build lean body mass. The major fuels include glucose, fatty acids, and amino acids; other fuels include ketone bodies, lactate, glycerol, and alcohol. Energy metabolism includes all the reactions by which the body obtains and expends the energy from food. Metabolism is the sum of these and all the other chemical reactions that go on in living cells; energy metabolism includes all the ways the body obtains and uses energy from food. The Site of Metabolic Reactions-Cells the human body is made up of trillions of cells, and each cell busily conducts its metabolic work all the time. The Building Reactions-Anabolism Earlier chapters described how condensation reactions combine the basic units of energy-yielding nutrients to build body compounds. Each of these reactions starts with small, simple compounds and uses them as building blocks to form larger, more complex structures. Anabolic reactions are represented in this book, wherever possible, with "up" arrows in chemical diagrams (such as those shown in Figure 7-2). A protein-rich jelly-like fluid called cytosol fills the spaces within the lattice. When nutrients enter the body from the digestive tract, the liver receives them first; then it metabolizes, packages, stores, or ships them out for use by other organs. When alcohol, drugs, or poisons enter the body, they are also sent directly to the liver; here they are detoxified and their by-products shipped out for excretion. An enthusiastic anatomy and physiology professor once remarked that given the many vital activities of the liver, we should express our feelings for others by saying, "I love you with all my liver," instead of "with all my heart. Notice that the bonds connecting the three phosphate groups have been drawn as wavy lines, indicating a highenergy bond. Earlier chapters described how hydrolysis reactions break down glycogen to glucose, triglycerides to fatty acids and glycerol, and proteins to amino acids. When the body needs energy, it breaks down any or all of these four basic units into even smaller units, as described later. The Helpers in Metabolic Reactions-Enzymes and Coenzymes Metabolic reactions almost always require enzymes to facilitate their action. Coenzymes are complex organic molecules that associate closely with most enzymes but are not proteins themselves. The relationships between various coenzymes and their respective enzymes may differ in detail, but one thing is true of all: without its coenzyme, an enzyme cannot function. Some of the B vitamins serve as coenzymes that participate in the energy metabolism of glucose, glycerol, fatty acids, and amino acids (Chapter 10 provides more details). Reminder: Enzymes are protein catalysts- proteins that facilitate chemical reactions without being changed in the process. The general term for substances that facilitate enzyme action is cofactors; they include both organic coenzymes made from vitamins and inorganic substances such as minerals. The simultaneous occurrence of one reaction releasing energy and another reaction using the energy is called a coupled reaction. Aided by enzymes and coenzymes, the cells use these products of digestion to build more complex compounds (anabolism) or break them down further to release energy (catabolism). Breaking Down Nutrients for Energy Chapters 4, 5, and 6 laid the groundwork for the study of metabolism; a brief review may be helpful. During digestion, the body breaks down the three energy-yielding nutrients-carbohydrates, lipids, and proteins-into four basic units that can be absorbed into the blood: · From carbohydrates-glucose (and other monosaccharides) · From fats (triglycerides)-glycerol and fatty acids · From proteins-amino acids the body uses carbohydrates and fats for most of its energy needs. Look for these four basic units-glucose, glycerol, fatty acids, and amino acids-to appear again and again in the metabolic reactions described in this chapter. Alcohol also enters many of the metabolic pathways; Highlight 7 focuses on how alcohol disrupts metabolism and how the body handles it. Glucose, glycerol, fatty acids, and amino acids are the basic units derived from food, but a molecule of each of these compounds is made of still smaller units, the atoms-carbons, nitrogens, oxygens, and hydrogens. To follow this action, recall how many carbons are in the "backbones" of these compounds: · Glucose has 6 carbons: C C C C C C · Glycerol has 3 carbons: C C C · A fatty acid usually has an even number of carbons, commonly 16 or 18 carbons:* C C C C C C C C C C C C C C C C · An amino acid has 2, 3, or more carbons with a nitrogen attached: © Chris Cole/The Image Bank/Getty Images N C C C N C C C C C N C C All the energy used to keep the heart beating, the brain thinking, and the legs running comes from the carbohydrates, fats, and proteins in foods. As you will see, each of the compounds-glucose, glycerol, fatty acids, and amino acids-starts down a different path. Along the way, two new names appear-pyruvate (a 3-carbon structure) and acetyl CoA (a 2-carbon structure with a coenzyme, CoA, attached)-and the rest of the story falls into place around them. Two major points to notice in the following discussion: · Pyruvate can be used to make glucose. A key to understanding these metabolic pathways is learning which fuels can be converted to glucose and which cannot. The parts of protein and fat that can be converted to pyruvate can provide glucose for the body, whereas the parts that are converted to acetyl CoA cannot provide glucose but can readily provide fat. The body must have glucose to fuel the activities of the central nervous system and red blood cells. Without glucose from food, the body will devour its own lean (protein-containing) tissue to provide the amino acids to make glucose. Therefore, to keep this from happening, the body needs foods that can provide glucose-primarily carbohydrate. Giving the body only fat, which delivers mostly acetyl CoA, puts it in the position of having to break down protein tissue to make glucose. Giving the body only protein puts it in the position of having to convert protein to glucose. Clearly, the best diet provides ample carbohydrate, adequate protein, and some fat. First, the text describes how each of the energy-yielding nutrients is broken down to acetyl CoA and other compounds in preparation for their entrance into these final energy pathways. Fatty acids may have 4 to 20 or more carbons, with chain lengths of 16 and 18 carbons most prevalent. The figures in this chapter usually show amino acids as compounds of 2, 3, or 5 carbons arranged in a straight line, but in reality amino acids may contain other numbers of carbons and assume other structural shapes (see Appendix C). This discussion features glucose because of its central role in carbohydrate metabolism and because liver cells can convert the other monosaccharides (fructose and galactose) to compounds that enter the same energy pathways. Glucose-to-Pyruvate the first pathway glucose takes on its way to yield energy is called glycolysis (glucose splitting). Glycolysis: Glucose-to-Pyruvate To test your understanding of these concepts, log on to academic. This simplified overview of glycolysis illustrates the steps in the process of converting glucose to pyruvate. Galactose and fructose enter glycolysis at different places, but all continue on the same pathway. These 3-carbon compounds continue along the pathway until they are converted to pyruvate. The net yield of energy at this point is small; to start glycolysis, the cell uses a little energy and then produces only a little more than it had to invest initially. This discussion focuses primarily on the breakdown of glucose for energy, but if needed, cells in the liver (and to some extent, the kidneys) can make glucose again from pyruvate in a process similar to the reversal of glycolysis. Still, glucose can be made from pyruvate, so the arrows between glucose and pyruvate could point up as well as down. When the body needs energy quickly-as occurs when you run a quarter mile as fast as you can-pyruvate is converted to lactate in an anaerobic pathway. When energy expenditure proceeds at a slower pace-as occurs when you ride a bike for an hour-pyruvate breaks down to acetyl CoA in an aerobic pathway. Pyruvate-to-Lactate As mentioned earlier, coenzymes carry the hydrogens from glucose breakdown to the electron transport chain. If the electron transport chain is unable to accept these hydrogens, as may occur when cells lack sufficient mitochondria (review Figure 7-1, p. The process of converting lactate from the muscles to glucose in the liver that can be returned to the muscles is known as the Cori cycle. Working muscles break down most of their glucose molecules anaerobically to pyruvate.

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