Can Exercise Really Improve Your Mental Health? Yes, Studies Have

8/14/2019 Can Exercise Really Improve Your Mental Health? Yes, Studies Have

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Can exercise really improve your mental health? Yes, studies have shown that exercise bringsabout both short- and long-term psychological enhancement and mental well-being. Some of thepsychological benefits from physical activity include improvement in self-confidence, relief oftension and feelings of depression, positive changes in mood, increased alertness, clearerthinking, and positive coping strategies. Individuals of all ages and gender can realize thesebenefits from exercise.

Are those so-called "sports drinks" beneficial during exercise? The composition of thesedrinks is basically water, electrolytes (minerals capable of carrying an electrical charge), andglucose. Sweat consists mostly of water and electrolytes. In prolonged endurance events, glucose(carbohydrate) replacement may be beneficial. Also, endurance exercise in heat contributes toheavy losses of water and electrolytes which need to be replenished.

Is it O.K. to drink water while exercising? Yes, your body's circulation system must get foodand nutrients to the working cells to carry out their chemical reactions. Sweating during exercisedepletes your body's water supply, which may lead to dehydration. Do not depend on your thirstto tell you to drink water. Try to drink at least 8 ounces of cool water for every 30 minutes of

vigorous exercise. Use that water bottle!

What are free radicals and antioxidants? Free radicals are unstable molecules produced bychemical reactions utilizing oxygen in the body's cells. A variety of external factors can promotefree radical formation including smoking, drinking alcohol, and pollution. Antioxidants (vitaminC, E, and beta carotenea precursor to vitamin A) protect the cells from free radicals byneutralizing the process of molecular oxidation that leads to their formation.

Does the distribution of body fat have any health consequences? Yes, people who gain fat inthe abdominal area have a higher risk of coronary heart disease, high blood pressure, diabetesand stroke as compared to individuals who gain fat in the hip area. Men tend to gain fat aroundthe waist and women at the hip.

What are the leading causes of death in the United States? According to the National Centerfor Health Statistics, they are heart disease, cancers, strokes, injuries, chronic lung diseases,pneumonia, diabetes, suicide, AIDS, and homicide.

Is it O.K. to drink beer after working out? Alcohol is a diuretic, which means that itstimulates urine production. Following a workout you want to replenish your body with lostfluids. Consequently, drinking any alcohol beverage before or after exercise is notrecommended.

Do you burn more calories when you are hot or cold, or does it even make a difference?

Shivering in clold weather requires more energy but not enought to enhance a weight lossprogram.

What are the limiting factors of flexibility? With the muscles relaxed, and reflex mechanismsminimally involved, researchers have found the relative contributions of soft tissue to jointstiffness to be the following: joint capsule, including ligaments (47%), muscles and their fascialsheaths (41%), tendons (10%), and the skin (2%).


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Why does the mirror show your change of shape before the scale? Muscle is denser than fat.A pound of fat bulges out 18% more than a pound of muscle. Since you are adding muscle toyour body as you shape up, you will often notice a loss of inches before a loss of weight.

Why do people who exercise have fewer colds and viral infections? It has been observed thatexercise may boost the immune system and that physically active people take better care ofthemselves. It should be noted that regular, strenuous exercise has also been shown to have anopposite effect on the body's immune system. This adds support for an exercise prescriptiondirected towards regular, moderate levels of exercise participation.

Why do you perspire more after you stop working out? During exercise your muscles needmost of the blood to get oxygen for the activity. Upon the cessation of exercise, more blood isdiverted to the skin to cool the body by means of sweat production. Also, during most modes ofexercise you are moving allot, which helps sweat evaporate more efficiently during the activity.

What is cholesterol? Cholesterol is a fat-like substance used to help build cell membranes,make some hormones, synthesize vitamin D, and form bile secretions that aid in digestion. Since

fat can't mix with water, which is the main ingredient of blood, cholesterol's most important jobis to help carry fat through your blood vessels. Before cholesterol can enter the bloodstream it iscoated with a protein, referred to as a lipoprotein. Lipoproteins are transport vehicles in thecirculation plasma that are composed of various lipids such as cholesterol, phospholipids,triglycerides and proteins known as apoproteins. The major classes of lipoproteins arechylomicrons, very low-density lipoprotein cholesterol, low-density lipoprotein cholesterol andhigh-density lipoprotein cholesterol.

Which is the 'bad' and 'good' cholesterol? The low-density lipoprotein cholesterol (LDL-C) isthe primary transport carrier of cholesterol in the circulation. It is referred to as the 'bad'cholesterol because too much cholesterol, from eating foods high in saturated fat, often leads toLDL-C pieces adhering to the inner walls of the blood vessels, narrowing the blood passages. Onthe other hand, the high-density lipoprotein cholesterol's (HDL-C) primary function is totransport cholesterol from the tissues and blood to the liver for excretion or recycling. It isreferred to as the good cholesterol.

Are natural vitamins better for you than manufactured vitamins?No, your body can'tdistinguish the difference between vitamins manufactured in a laboratory and natural vitaminsextracted from food.

Does cold weather give you colds? People exposed to chilling temperatures often feel they aremore susceptible to colds. However, it is viruses that give you colds, not the weather. Colds areactually more common in cold weather because people are inside more, and thus more exposed

to germs.

What's a good substitute for those high-fat potato chip snacks? Try pretzels. They are almostfat-free. As a matter of fact, pretzels are one of the fastest growing snack foods in the U.S.However, there is good news for you 'chip' lovers. There are now some new and improved chipsthat are low in sodium, fat and calories. Read the labels at your supermarket. Look for the chipsthat are baked, not fried, and avoid chips made in hydrogenated oil. Remember to check the totalfat content and serving size, too.


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Can you drink too much caffeine? Most people have internal regulators that tell them when tostop drinking caffeine. However, drinking 4-6 cups of coffee a day may result in symptomsreferred to as caffeinism: breathlessness, headache, lightheadedness and irregular heartbeat. Toomuch caffeine may also trigger a panic attack. For college students, caffeine-containing softdrinks have overtaken coffee as the primary source of caffeine. Most experts advice no morethan 200 milligrams of caffeine consumption, which is about the same as two to three 5-ouncecups of coffee.

Are these low-carbohydrate, high-protein diets any good? Initially these diets help peoplelose weight because the body loses water; approximately 3 parts of water to 1 part ofcarbohydrate. A low carbohydrate diet is fairly unappetizing. However, the body cannot handlethe extra amounts of proteins and will end up storing much of it as fat.

How do you avoid repetitive strain injuries? With the wonderful benefits of computer usethere are also some physical perils to know. Repetitive strain injury (RSI) results from hand,wrist, arm and neck injuries from a repetitive (fast) work. Carpal tunnel syndrome is a form of

RSI which results from pain in the tendons and nerves across the wrist. To avoid, take frequentbreaks during your typing and make sure your computer set-up avoids any neck, back, wrist andeye strain (see Sitting at your Computer Station).

Are vegetarian diets more healthful than diets that include animal foods? Vegetarian dietsare higher in fiber and lower in saturated fats and cholesterol. Studies also show that vegetarianssuffer less from high blood pressure, diabetes, heart disease and obesity. However, manyvegetarian foods such as chips and candy contain allot of fat and calories, with little nutrientvalue. Also, vegetarians need to be conscious of deficiencies in iron, calcium, vitamin D, vitaminB12, and zinc.

What are triglycerides? Triglycerides (TG) are fats that circulate in the bloodstream thatprovide energy for the body. It is uncertain whether high TG levels are associated with coronaryheart disease. However, high TG levels are associated with diabetes, kidney diseases, andobesity. Steps to lower TG levels include cutting down on saturated fat, losing weight, exercise,and quitting smoking.

What is this creatine supplement craze? Creatine is an amino acid found predominantly in themuscles in the form of creatine phosphate, where if facilitates energy production. It also helps toreduce the lactic acid accumulation during intense exercise. Most investigations have shown thatcreatine supplements boost short-term muscle strength and power. However, it is important tonote that the long-term effects of high doses of creatine are unknown.

Are the sunless tanning lotions safe? According to the U.S. Food and Drug Administrationthey are safe. The main ingredient in self-tanning products is dihydroxyacetone, which reactswith the top layer of skin to form a light brown tan stain. Remember that these lotions do notgive you any sun protection, however.

How successful are all the stop smoking interventions? The interventions range fromacupuncture, nicotine gum and patches, hypnotism, anti-depressants and behavior modificationapproaches. None of the methods has outstanding long-term effects, with each method showing a


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20% success rate after one year. Quitting smoking is essential. A person needs the support of thefamily and friends as well as a sustained effort to find the intervention that works.

What causes your limbs to "fall asleep?" A limb will become numb when you remain seatedor lying in a position that compresses a nerve in the limb or stops the blood flow to the nerve.This sometimes happens when you cross your legs or arms for an extended period of time. Whenyou remove the pressure the tingling is the nerve sensitivity returning. Moving the limb helps tospeed up the recovery. Men who carry a thick wallet in their back pocket (with tight pants) canput pressure on the sciatic nerve, causing a similar numbness and pain.

Will exercise reduce a womans risk to breast cancer?Exercise reduces the risk of heartdisease, diabetes, stroke and obesity. It appears to have a protective effect against breast cancerbut more research is needed. However, the best advice for men and women is that they shouldexercise.

What dietary substances are needed to prevent osteoporosis besides calcium and vitaminD? Two other substances of importance are magnesium and potassium which are both found in

fruits, vegetables, milk and whole grains.

Is it true that when you eat out, you usually eat more calories than at home? Yes, largeportion sizes and high-fat entrees burden most of this responsibility. Be aware that when you goout you are less likely to eat nutritious food. Forego eating appetizers as they add to the calories.Perhaps split a desert as opposed to ordering one for yourself. Also, most Americans neglectfruits and vegetables when eating out.

I read a recent study that said high-fiber diets dont cut colon cancer? Even if the study waswell-conducted research, it is still only one study. Decades of research suggest that high-fiberfoods are a protection against colon cancer. Remember, stay away from those sugary sweets thatare consistently associated with colorectal cancer.

I read allot about the health benefits of soy. Are they true? Soy has been shown to be veryhealth beneficial. For instance, research shows that soy consumption will lower triglycerides andLDL-cholesterol (lousy cholesterol) in people with high blood lipids, while raising the HDL-cholesterol (helpful cholesterol). Note also that heart disease is much lower in Asian countries,where soy is a dietary staple. Soy also has been shown to play a role in lowering breast anduterus cancer.

How does soy improve ones health? It is felt that the hormone phytoestrogen mimics some ofthe effects of estrogen, actually blocking off some of the harmful effects associated withestrogen. Also, remember soy foods are low in saturated fat and are cholesterol free. For an

internet source on soy-based foods and products go to www.soyfoods.com/

Is it true that tea may possibly be a healthful beverage? Yes, black and green tea (sorry, notherbal teas) appears to lessen cholesterols damaging affect on your arteries, as well as protectagainst cancers of the skin and gastrointestinal tract. Make sure you step tea for 3 minutes for thebeneficial antioxidants in the leaves to enter in the beverage.

How effective is the supplement creatine? Creatine is made by your body and supplied in


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foods such as fish and vegetables. It is beneficial when your muscles need short, quick spurts ofenergy for activities like resistance exercise and sprinting. However, the weight gain experiencedby some individuals may actually be more attributable to an uptake of water by the muscle cells.

What are the effects of removing the cool-down from your exercise routine? The purpose ofthe cool-down is to restore all cells,tissues and organs of the body that have been stressed (orchallenged) from the exercise workout. Removing the cool-down removes this process and thushinders the bodys ability to restore itselt to homeostasis.

I am so rushed to get things done I am contemplating taking some of these liquid mealreplacements on a regular basis. Many of these liquid meals provide plenty of calories as wellas a number of minerals and vitamins. But typically they do not provide the health-promotingfiber and phytochemicals that are found in fruits and vegetables. So, this is not to discouragetheir consumption, but make sure you balance the intake with real meals.

What does it mean when a food has the American Heart Association logo on it? The redheart with white check mark means no more than 3 grams of fat, 20 milligrams of cholesterol,and 480 milligrams of sodium. The food must also have at least 10% of the daily value for one ormore of these nutrients: protein, vitamin A, vitamin C, calcium, iron, or dietary fiber.

As you age, is there anything you can do to slow the decline in mental PROCESSES? Thedegree of decline varies from person to person, but the age-related changes are due to alterationsin the brains frontal lobe, right behind the forehead. However, new research suggests thatsedentary older people who take up aerobic exercise (such as walking) can slow the loss inmental agility even if they never exercised before in their lives. Researchers believe that theaerobic activity improves mental functioning by increasing the supply of oxygen to the brain.

How can I, as a young man, protect against prostate cancer? Very wise preventativemeasure. Prostate cancer is the second leading cause of cancer in American men. Research

confirms that diets high in fat, calories, and animal products are strongly associated with thisdeadly disease. Diets high in grains, cereals, soybeans, nuts and fish, on the other hand, appear tohave protective effects.

Whats the final scoop: Butter or Margarine? Good question. While margarine is indeedlower in saturated fat than butter, its higher in trans fatty acids, which do contribute to highlevels of cholesterol. Recent research does suggest that margarine is healthier. Also, it appearsthat soft tub margarine may be the best overall choice.

What are the most common types of arthritis? There are actually more than 100 differentforms. Osteoarthritis is a wearing and tearing form that affects the fingers and weight-bearingjoints (knees, back, hips). Rheumatoid arthritis causes irritating joint stiffness and swelling.Fibromyalgia leads to pain at different points of the body as well as insomnia, morning stiffnessand constant fatigue. Gout is caused when uric acid accumulates in the joints, specifically the bigtoe, knees and wrists. Lupus can damage the kidneys, heart, skin, lungs and joints.

What is the most common nutritional deficiency in the U.S? Iron deficiency. It affects some 8million women of childbearing age and upwards of 700,000 toddlers.

I only have time right before bed to exercise and am worried that it will impair my evening


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sleep patterns. Interestingly enough, recent research has shown that vigorous exercise ending 30minutes before bedtime failed to disrupt sleep.

I have trouble sleeping. Do you have any suggestions to get a better nights rest? Try toestablish a sleeping schedule of going to bed every night and getting up at the same time eachmorning. Work on the stress levels in your life as this can dramatically affect sleep. You sleepbetter if the room temperature is slightly cooler than other parts of the house. Try to avoiddrinking too many fluids before bedtime so that your bladder isnt full. Remember, spicy foodsfor dinner, or as snacks, may cause heartburn or stomach acidity and impair your quality ofsleep. Also, avoid alcohol near bedtime. While it may help you fall asleep, when the alcoholwears off your brain actually becomes more alert. Finally, stay away from sleeping pills as theymay lead to unwanted side effects and health-related risks.

I use a computer everyday. Are there any exercises that will help prevent and controlcarpal tunnel syndrome? Carpal tunnel syndrome is a condition that develops from repetitivewrist motions such as typing at a computer terminal. This motion may lead to pressure on themedian nerve in the wrist, and great pain and discomfort. Do the following exercises throughout

the day. Frequently take your wrists through a complete range of motion in both directions.Make a tight fist with both hands, hold for 6 seconds, and repeat 3 to 4 times. Also, circle yourwrists in both directions while holding your hands in a fist. Make sure you take short breaks fromyour typing to do these exercises (and to rest your wrists) in order to safeguard from developingcarpal tunnel syndrome.

What causes muscle cramps? New research on exercise-associated muscle cramping suggeststhe cramp occurs as a result of abnormal nerve activity from the spine, probably related tofatigue. Although not well understood, it is believed that tired muscles going through repeatedshortening contractions are more vulnerable to cramping. Avoiding over fatiguing workouts andincorporate regular stretching to best ward off muscle cramps.

What is this new concept of training called periodization? Although not really new, it is nowbeing used regularly with recreational resistance training enthusiasts. Periodization is mostwidely used in resistance training and involves systematically alternating high loads of trainingwith decreased loading phases in order to improve components of muscular fitness. The systemis typically divided into three cycles: 1. The microcycle, which lasts up to seven days 2. Themesocycle, which can be from two weeks to a few months, is subdivided into preparation,competition, peaking and transition phase. 3. The macrocycle is the overall yearly trainingperiod.

What is carbo loading and how do you do it? Carbo loading is a method of super saturatingyour muscles with glycogen. It has been shown to improve endurance performance in events

lasting over 90 minutes and is often used in competitive events. About seven days out from theevent, begin by eating a diet high (60% to 70%) in high-glycemic carbohydrates such as rice,pasta and potatoes. Make sure you are getting adequate amounts of fat and protein as well. Drinkplenty of water and increase your water intake four to eight cups (ABOVE NORMAL) about twodays before the event. Avoid dehydrating drinks and foods. As the event comes closer, rememberto taper down your training so you body will be appropriately rested for the contest.

What does the term MET mean? This term is used to describe energy expenditure of an


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activity. One MET is equivalent to the energy expenditure of a person at rest. It is expressed interms of oxygen uptake (i.e., 3.5 ml O2/kg/min). It is very much like a shorthand method ofdescribing energy requirements. For instance, running 6 miles per hour is about 10 METs whilewalking 3 miles per hour is about 3.3 METs.

What are phytochemicals? They are not vitamins. They are not minerals. Phytochemicals, areplant chemicals that offer great health benefits. The have been shown to project against heartdisease, cancer, diabetes, osteoporosis, and other medical conditions. The only way to getphytochemicals is to eat or drink them in fruits, vegetables, juices, nuts and whole grainproducts.

Is Yo-Yo dieting risky for you? Lets face it, many well-intentioned diets do fail, which hasconcerned researchers that the losing and regaining of weight might be harmful to the body.However, new research with high blood pressure, which is a major risk factor for heart disease,shows that Yo-Yo dieting doesnt appear to have any physiological damage. However, in termsof emotional wellness, Yo-Yo dieting may be most detrimental.

What is hypoglycemia? Hypoglycemia means low blood sugar. Most individuals may beaffected by what is referred to as reactive hypoglycemia, a condition resulting from glucoselevels dropping after a meal or when you havent eaten for several hours. Symptoms includedizziness, anxiety, shaking, and uneasiness. Eating small, but frequent meals and avoidingconcentrated sources of sugar is recommended.

Can you tell me in minutes or days how much smoking reduces life? According to someresearch, every cigarette a man smokes reduces his life by 11 minutes. Each carton of cigarettesrepresents a day and a half of lost life. For every year a man smokes a pack a day, he shortens hislife by about two months.

Why dont diets work? Most diets, especially fad diets, are poorly designed plans thatunrealistically restrict caloric intake. People lose weight initially, but these plans are notpermanent weight loss eating strategies which people can incorporate into a regular lifestyle.Consequently, INDIVIDUALS usually return to their previous eating habits that encouraged theweight gain in the first place. Eating habits (and exercise) must be changed permanently for dietsto be successful.To some degree, the answer depends on what type of workout you are about to do. The typical30 minute workout of easy jogging or brisk walking really doesn't have specific macronutrientrequirements. However, if your workout is going to be more intense or enduring, here are Somesuggestions. To keep fueling your metabolic engine you need more complex-carbohydrates afew hours prior to the workout. Your goal is to help maintain your body's blood glucose andcarbohydrate (glycogen) stores in the muscles. Also, make sure you drink fluids before the

workout. ACSM recommends 14 to 20 ounces of fluid two to three hours before the event andpossibly another 7 to 10 ounces right before an endurance event.

How can older people improve their memory?The University of California, Berkely Wellness Letter cites recent research that shows thataerobic exercise can help sharpen the memory and reduce depression in men and women aged 50to 77. The aerobic exercise helps to pump the blood more efficiently though the body and brain.Results show that meaningful results can occur in as little as 4 months.


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Should I eat before I workout?To some degree, the answer depends on what type of workout you are about to do. The typical30 minute workout of easy jogging or brisk walking really doesn't have specific macronutrientrequirements. However, if your workout is going to be more intense or enduring, here are Somesuggestions. To keep fueling your metabolic engine you need more complex-carbohydrates afew hours prior to the workout. Your goal is to help maintain your body's blood glucose andcarbohydrate (glycogen) stores in the muscles. Also, make sure you drink fluids before theworkout. ACSM recommends 14 to 20 ounces of fluid two to three hours before the event andpossibly another 7 to 10 ounces right before an endurance event.

LECTURE 3Copyright 2000 by Bowman O. Davis, Jr. The approach and organization of this material wasdeveloped by Bowman O. Davis, Jr. for specific use in online instruction. All rights reserved. No part of thematerial protected by this copyright notice may be reproduced or utilized in any form or by any means,electronic or mechanical, including photocopying, recording, or by any information storage and retrievalsystem, without the written permission of the copyright owner.

FLUIDS AND ELECTROLYTESReview of Lecture 2By this time, you should be comfortable with the three fluid compartments of thebody and the partitions that separate them and control their compositions. The roles ofhydrostatic and osmotic pressures in the shifting of fluids from one compartment toanother should be second nature to you. You should have also practiced workingthrough the basic physiology underlying a number of fluid imbalances and you should becapable of assessing a client experiencing a fluid imbalance.Now it is important to realize that fluids of the body do not exist independently.They have a number of chemical or cellular elements dissolved or suspended withinthem. Electrolytes, capable of conducting electrical current, exist dissolved in the fluidcompartments of the body. It is because of these dissolved electrolytes and their capacity

to conduct current, that it is possible to measure brain activity (EEG) as well as heart(EKG) and other muscle (EMG) by placing electrodes on the body surface. However,electrolytes also serve major physiological functions which are in danger of failingshould an electrolyte imbalance occur.Continue your text reading through Chapter 10 before proceeding.

Normal Electrolyte FunctionsBy chemical definition, electrolytes are charged particles (ions). These particlesexist dissolved in the various fluid compartments of the body (intravascular, interstitial,and intracellular) and perform a variety of functions in the total physiology of the humanbody. The electrolytes of importance at this point in the course are: (1) Sodium; (2)Potassium; (3) Calcium; (4) Hydrogen; and (5) Bicarbonate. Since hydrogen and

bicarbonate ions are primarily involved in pH balance, their discussion will be delayeduntil that point. Sodium, potassium and calcium will be considered here. Recall from theprior discussion of fluid composition that sodium is primarily an extracellular ion, thatpotassium occurs primarily intracellularly, and that calcium performs a variety offunctions. The important role of calcium in this discussion is its control of membranepermeability. Being a positive ion, calcium that associates with the plasma membraneand serves to repel other positive ions (like charge repulsions) to help control themembranes permeability to positive ions.


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Recall from your background study of excitable cells, such as nerve and muscle,that sodium and potassium are essential for the action potentials conducted along thesurface membranes of these cell types. Sodium, an extracellular ion, enters an excitablecell during the depolarization phase of the action potential. Whereas potassium, anintracellular ion, leaves an excitable cell during the repolarization phase of the actionpotential. All cells, including excitable cells in the resting state (not conducting anaction potential), are polarized such that the interior is negative relative to the exterior.This difference in net charge across a cells membrane is due in part to the intracellularproteins and body pH. Since normal body pH is slightly alkaline (7.4), proteins losehydrogen ions (behave like acids) and show a net negative charge. Since most proteinsare intracellular, when body pH is normal the positively charged intracellular potassiumions are offset by the negatively charged intracellular proteins to give the cells interior anet negative charge compared to the outside where proteins are deficient.REVIEW QUESTIONS:1. How do excitable cells differ from other cells of the body regarding their responseto stimulation?2. Refamiliarize yourself with the four phases of an action potential: (1)

depolarization; (2) repolarization; (3) hyperpolarization; and (4) return toresting state.3. What are the ion movements associated with each phase of the action potential?4. What would you predict might occur with an excitable cell if the normal locationsof sodium and potassium were to be reversed?

Electrolyte Disorders / AssessmentPeople who have disturbances in either sodium, potassium, or calcium areprobably going to show signs and symptoms of these disturbances in organ systemswhose normal functions depend upon action potentials, particularly neuromuscularsystems. Consequently, clients showing lethargy and muscle weakness or those withincreased irritability may have an electrolyte imbalance. The assessment problem then

becomes one of identifying the electrolyte(s) involved and whether they are abnormallyhigh (hyper-) or low (hypo-).Electrolyte imbalances may be primary or seconday in origin. A primaryelectrolyte imbalance usually affects only one electrolyte and typically involves anabnormality in either the intake or output of the ion of interest. For example, a high saltdiet can result in hypernatremia while some diuretics waste potassium and can causehypokalemia. Since electrolytes are assayed in blood samples, you are seeing theintravascular concentrations expressed on a lab report. Because of capillary porepermeability, these changes probably also appear in the interstitial fluid as well and can,in some instances, affect intracellular concentrations. Consequently, you must knowwhere each of the three electrolytes occur normally so you can predict the causes andeffects of their changing concentrations. Since electrolytes are osmotically active, they

can cause fluid shifts as well.REVIEW QUESTIONS:1. Why would hyperkalemia cause cardiac arrest?2. How does an EKG change with increasing potassium concentrations?A seconday electrolyte imbalance is one resulting from an abnormality in someother physiological function. Secondary imbalances usually affect more than oneelectrolyte and are common with fluid imbalances since they occur as a result ofconcentration or dilution of body fluids. For example, in renal failure the kidneys fail to


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output urine and can result in increased concentrations of all electrolytes normallyexcreted in the urine. Secondary imbalances are usually detected by looking first forfluid imbalances. Skin turgor (tenting in dehydration and pitting in edema) is a goodfluid balance indicator as are sudden weight changes, blood pressure abnormalities, andperipheral or pulmonary edema. Fluid imbalances often appear on lab reports as changesin hematocrit (percentage of formed elements in blood). A high hematocrit suggests apossible concentration of blood maybe due to dehydration while a low hematocrit canappear with fluid overloads.The table below covers electrolyte imbalances that involve Na, K, and Ca. Workthrough the table as you did in previous exercises being certain that you can explain thebasic physiology underlying each cause and each clinical manifestation appearing in thetable.You should take each one of the imbalances and be sure that you can explain theunderlying physiological abnormality underlying each cause and each clinicalmanifestation. This is an excellent review of basic physiology!!

ELECTROLYTE IMBALANCESSODIUM IMBALANCES (PRIMARY AND SECONDARY)

CONDITION CAUSE CLINICAL MANIFESTATIONSHyponatremia Decreased intake and adrenalinsufficiency (10); inappropriateADH; diaphoresis with waterreplacement; diuretic therapyCellular swelling with cerebral edemaleading to headache, stupor and coma;muscle weakness; decreased thirst; edemaif secondary to hypervolemia;Hypernatremia Increased intake or renal failure Cellular shrinking with increased CNS(10); water deprivation; decreasedADH secretion; increased

aldosterone; liver failure;hypothalamic lesionirritability; increased thirst; hypotensionwith oliguria if secondary to hypovolemia

POTASSIUM IMBALANCES (PRIMARY AND SECONDARY)CONDITION CAUSE CLINICAL MANIFESTATIONSHypokalemia Decreased intake, adrenal cortexhyperfunction and diuretictherapy (10); alkalosis;vomiting/gastric suctionCardiac arhythmia (lower T andappearance of U wave due to slowrepolarization) and muscle weakness;Hyperkalemia Increased intake or renal failureand hypoaldosteronism (10);acidosis; RBC hemolysis;Cardiac depression (shallow, wide QRSwith elevated T due to exaggeratedrepolarization); paresthesia and/orparalysis

CALCIUM IMBALANCES (PRIMARY AND SECONDARY)


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CONDITION CAUSE CLINICAL MANIFESTATIONSHypocalcemia Decreased intake (10), vit. Ddeficiency, hypoparathyroid;hypoalbuminemia; alcohol abuseor liver failureIncreased neuromuscular activity

(possible convulsions); skeletal muscletetany;Hypercalcemia Increased intake (10); immobility;hyperparathyroidism; bonemalignancies; renal failureDecreased neuromuscular activity (stuporto coma); renal calculi; increased fracturerisk

DISCUSSION QUESTIONS: (Post answers to the Patho Discussion Group)1. Explain why hyponatremia could cause cerebral edema.2. How could it be treated in order to get the most rapid results?

INTRODUCTION

To maintain good health, a balance of fluids and electrolytes, acids and bases must

be normally regulated for metabolic processes to be in working state.

A cell, together with its environment in any part of the body, is primarily composed

of FLUID.

Thus fluid and electrolyte balance must be maintained to promote normal function.

Potential and actual problems of fluid and electrolytes happen in all health care

settings, in every disorder and with a variety of changes that affect homeostasis.

The nurse therefore needs to FULLY understand the physiology and pathophysiology

of fluid and electrolyte alterations so as to identify or anticipate and intervene

appropriately.

Fluids

a solution of solvent and solute

Solvent


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Normal valuesPrematureTerm25 yrs45 yrs65 yrsTBW Male: Female:

80%75%60%50%

55%47%

50%45%

ICF35%35%40%Blood Volume90-100 ml/kg85 ml/kg70 ml/kg

neonates reach adult values by 2 yrs and are about half-way by 3 months

average values ~ 70 ml/100g of lean body mass

percentage of water varies with tissue type,A.lean tissues ~ 60-80%B.bone ~ 20-

25%C.fat ~ 10-15%

D.Tonicity of Body Fluids

Tonicity refers to the concentration of particles in a solution

The normal tonicity or osmolarity of body fluids is 250-300 mOsm/L1.Isotonic

Same as plasma2.Hypotonic

have a lesser or lowers solute concentration than plasma3.Hypertonic

higher or greater concentration of solutes

Common Intravenous Solutions

SolutionNaCl-K+CaGluOsm.pHLactkJ/l

D5W

000027825350840


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NaCl 0.9%

1501500003005.700

NaCl 3.0%

5135130008555.700

D4W/NaCL 0.18%

3030002222823.5 5-5

0672

Hartmans

1291095002746.72837.8

Plasmalyte

1409852945.52784

Haemaccel

1451455.16.2502937.300

Mannitol20%

000001086.200

Dextran 70

1541540003004-700Osmole

the weight in grams of a substance producing an osmotic pressure of 22.4 atm.

when dissolved in 1.0 litre of solution

(gram molecular weight) / (no. of freely moving particles per molecule)

Osmolality

the number of osmoles of solute per kilogram of solvent

Osmolarity


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the number of osmoles of solute per litre of solution

Mole

that number of molecules contained in 0.012 kg of C12, or,

the molecular weight of a substance in grams =

Avogadro's number

= 6.023 x 1023

Molality

the number of moles of solute per kilogram of solvent

Molarity

is the number of moles of solute per litre of solution

THE

Normal

DYNAMICS OF BODY FLUIDS

The methods by which electrolytes and other solutes move across biologic

membranes are Osmosis, Diffusion, Filtration and Active Transport. Osmosis,

diffusion and filtration are passive processes, while Active transport is an active

process.

1.OSMOSIS

This is the movement of water/liquid/solvent across a semi-permeable membrane

from a lesser concentration to a higher concentration

Osmotic pressure is the power of a solution to draw water across a semi-permeable

membrane


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Colloid osmotic pressure (also called oncotic pressure) is the osmotic pull exerted

by plasma proteins

TE DISTURBANCES

MANIFESTATIONS OF DISORDERED WATER, ELECTROLYTE AND ACID-BASE

STATUSPrimary disturbanceAltered physiologyClinical effect

SodiumECF volumeCirculatory changesWaterECF osmolalityCerebral

changesPotassiumAction potentialNeuromuscular weakness, cardiac

effectsHydrogen ionAcid-base Balance (pH)Altered tissue function, respiratory

compensationMagnesiumCell membrane StabilityNeuromuscular, vascular and

cardiac effects

Phosphate

Cellular energeticWidespread tissue effects

1)

What percentage of body weight in men is water?a.15b.30

c.

60T [ About 50% of body weight in women and 60% in men is water. Body fat

content influences the proportion of body weight that is water. As body fat

increases, water declines as a proportion of body weight. As muscle mass increases,

water increases as a proportion of body weight. Intracellular fluid (ICF) is the largest

compartment and is 60% of total body weight. Extracellular fluid (ECF) is 40% of

TBW. The solutes in the ICF and ECF compartments are different. See figure below.

In ICF the main cation is potassium and the anions are phosphates and bicarbonate.

In ECF the main cation is sodium, and chloride and bicarbonate are the anions.]

d.90

2)

What percentage of total body water is intracellular fluid?

a.30


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b.40

c.60T [ 55 to 75% of total body water is intracellular and 25 to 45% is extracellular.

The total body water is approximately 40 liters. About 25 liters is inside cells (ICF

compartment). Some 15 liters is in the extracellular fluid (ECF) compartment. The

ECF is further subdivided into intravascular and extravascular spaces in a ratio of1:3. Of the ECF, the plasma is only 3 liters. 12 liters is interstitial fluid outside the

cells. See figure below.]

d.80

3)Plasma volume is ------------- L

a.

3T [ 25% of the ECF is intravascular subcompartment. This corresponds to 3 - 3.5 L

of plasma. The remaining 75% of ECF volume is in the interstitial spaces. This

corresponds to 10 12 L.]b.6c.9

d.

12

4)

If 1 L of solute-free water is lost from the body, how much fluid is lost by the ICF

compartment?a.333 mL

b.

667 mL T [ Water is distributed between the ICF and the ECF in a 2:1 ratio.

Therefore, a given amount of solute-free water loss will result in a twofold greater

reduction in the ICF compartment than the ECF compartment. If 1 L of water is lost,

the ICF volume will decrease by 667 mL, whereas the ECF volume will fall by only

333 mL. If the 1L of fluid lost is isoosmotic, ECF compartment will decrease by 1 L

because Na+ is largely restricted to the ECF.]c.1 Ld.None

5)

Extracellular osmolality in a healthy adult

a.

More than intracellular osmolality

b.

Less than intracellular osmolality


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c.

Same as intracellular osmolality[ Osmolality is a measure of the total number of

solutes per mass of water. Osmolality is the solute or particle concentration of a

fluid. It is expressed as milliosmoles per kilogram of water (mosmol/kg H

2

O). The normal plasma osmolality is 275 to 290 mosmol/kg. The extracellular and

intracellular solutes (or osmoles) are markedly different, but water crosses cell

membranes to achieve osmotic equilibrium. Water moves across cell membranes

and distributes between ICF and ECF until the osmolality in these two compartments

is the same. Therefore, ECF osmolality is equal to ICF osmolality.]

d.

Any of the above depending on fluid intake

6)

ECF osmole(s)a.Na+

b.

Cl-c.HCO3-

d.

All of the aboveT [ Sodium is the predominant cation in ECF and associates with the

anions chloride and bicarbonate. These three electrolytes account for more than90% of the active osmoles in ECF. The predominant cation in ICF is potassium. K+ is

electrochemically balanced primarily by organic phosphates. In addition, DNA, RNA,

and phosphate esters (ATP, creatine phosphate, and phospholipids) are anionic and

provide a negative charge to balance the positive charge of potassium in

intracellular water (ICF). K+ and phosphate esters are the predominant ICF

osmoles. Solutes that are restricted to the ECF or the ICF determine the effective

osmolality (or tonicity) of that compartment. Na+ is largely restricted to the

extracellular compartment. Therefore, total body Na+ content is a reflection of ECF

volume. Hyponatremia or hypernatremia is due to disorders of water homeostasis.]

7)

ICF osmole(s)a.ATP

b.

Creatine phosphate

c.


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K+d.Phospholipids

e.

All of the aboveT [ K+ is predominantly limited to the ICF. The major intracellular

anions are phosphates and negatively charged proteins. These are necessary for

normal cell function. Therefore, the number of intracellular particles is relatively

constant. Therefore, any change in ICF osmolality is usually due to a change in ICF

water content.]

8)

The main extracellular cation

a.

Potassium[ Potassium is the dominant cation in the ICF.] b.Calciumc.Magnesium

d.

SodiumT [ Sodium is the dominant extracellular cation. Chloride and bicarbonate

are the dominant ECF anions. A typical diet contains more sodium than daily

requirements. Therefore, dietary intake of Na+ results in ECF volume expansion.

This in turn promotes increased renal Na+ excretion to maintain Na+ balance. The

amount of sodium excreted is equal to the amount ingested per day.]

e.

Albumin[ An important difference between the plasma and interstitial

compartments of the ECF is that only plasma contains significant concentrations ofprotein.]

9)

What maintains the difference in cation concentration between the ICF and ECF?

a.

Sodium-potassium pumpT [ Themajor force maintaining the difference in cation

concentration between the ICF and ECF is the sodium-potassium pump (Na,K-

activated ATPase) See figure below. Na

+

,K

+


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-ATPase moves three sodium molecules out of the cell while concurrently two

potassium ions in ECF enter the cell. With three cations transported out and two

cations transported into the cell, the consequence of Na

+

,K

+

-ATPase activity is a net negative intracellular charge.]b.RMPc.Osmotic

pressured.Intracellular proteins

10)

What maintains the difference in cation concentration between the ICF and ECF?

a.

Na

+

, K

+

-adenosine triphosphate

b.

Cell membrane sodium conductance pathways

c.

Cell membrane potassium conductance pathways

d.

Free movement of water

e.

All of the aboveT [ Sodium is the major cation in the ECF. Chloride and bicarbonate

are the major accompanying anions in the ECF. Potassium is the major cation in the

ICF. Negative charges on organic molecules maintain electroneutrality with

potassium in the ICF. The difference in cationic solute composition between these

two compartments is maintained by the activity of Na

+


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, K

+

-adenosine triphosphate (ATPase) operating in concert with cell membrane sodium

and potassium conductance pathways. The free movement of water ensures that

the sodium concentration in ECF is nearly equivalent to the potassium concentration

in ICF.]

11)

What regulates Na+ balance

a.

Sodium intake and thirst[ Na+ balance is regulated by varying Na+ excretion.]

b.

GFR[ Na+ excretion is mainly regulated by tubular Na+ reabsorption (not by GFR).]

c.

Sodium reabsorptionT [ About 65% of filtered Na+ is reabsorbed in the proximal

convoluted tubule. Further reabsorption (30%) occurs in the thick ascending limb of

the loop of Henle. About 5% of filtered Na+ is reabsorbed in the distal convoluted

tubule. Final Na+ reabsorption occurs in the cortical and medullary collecting ducts.

The amount of sodium excreted is equal to the amount ingested per day.]

d.

AVP [ Water metabolism is controlled primarily by arginine vasopressin. Sodium

metabolism is predominately regulated by the renin-angiotensin-aldosterone

system.]

12)

Osmotic adaptation occurs ina.Placenta during delivery

b.

Glomeruli during water load

c.

Normal brain T [ Brain cells can vary the number of intracellular solutes to protect

against large water shifts and resultant change in intraneuronal osmolality. This

process is called osmotic adaptation and occurs in chronic hyponatremia and


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hypernatremia. Osmotic adaptation is mediated initially by shifts of K+ and Na+

and later by osmolytes.]

d.

Muscles during exercise

13)

True statement(s)

a.

Osmolality refers to the concentration of all solutes

b.

Tonicity refers to the concentration of solutes that are effective in eliciting a water

shift between body fluid compartments

c.

Urea is not an effective solute [ Osmolality refers to the concentration of all solutes.

Tonicity refers to the concentration of solutes that are effective in eliciting a water

shift between body fluid compartments. Addition or removal of solutes causes shift

of water to restore the equality of solute concentrations. Therefore, they are

considered effective solutes. Solutes such as urea do not elicit such a sustained

shift in water. Therefore, urea is not considered effective solute, although they

contribute to the laboratory measurement of fluid osmolality.]

d.

Addition of water without solutes results in reduction in both osmolality and tonicity

[ The addition of water without solutes results in reduction in both osmolality and

tonicity of all body fluid compartments. The removal of water without solutes results

in increase in both osmolality and tonicity of all body fluid compartments.]

e.

All of the aboveT [ All are false statements.]

14)

Ineffective osmole

a.

Sodium[ The ECF volume is a reflection of total body Na+ content. Na+ excess or

deficit are manifest as edematous or hypovolemic states, respectively.]


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b.Potassium

c.

UreaT [ Urea and glucose do not contribute to water shift across cell membranes.

Therefore, they are known as ineffective osmoles.]

d.

Osmolytes [ Osmolytes are organic solutes (e.g., inositol, betaine, and glutamine).]

15)

Which of the following is the least important source of obligate water loss?

a.

Urine[ Metabolism of a normal diet generates about 600 mosmol/d. Therefore, 600

mosmols must be excreted per day through urine, primarily as urea andelectrolytes. The maximal urine osmolality that can be achieved is 1200 mosmol/kg.

Thus, a minimum urine output of 500 mL daily is required for excreting the daily

solute load. Oliguria is urine output < 500 mL/day. Water intake must equal water

excretion to maintain a steady state. Daily water intake exceeds physiologic

requirements in normal physiological conditions.]

b.

Stool T [ Gastrointestinal excretion is only a minor component of total water output.

It becomes an important route of water loss in patients with vomiting, diarrhea, or

high enterostomyoutput states.]

c.

Evaporation from the skin [ Evaporative or insensitive water losses are important in

the regulation of body temperature.]

d.

Evaporation from the respiratory tract

16)

What is the primary stimulus for drinking water?

a.

Thirst T [ The primary stimulus for drinking water is thirst. The thirst center is

situated in the organum vasculosum of the anterior hypothalamus. Thirst is caused

by an increase in effective osmolality or a decrease in ECF volume or blood


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pressure. The osmotic threshold for thirst is about 295 mosmol/kg and varies among

individuals. Reduction of ECF volume also stimulates thirst by means of angiotensin

2, even when body tonicity is not elevated.]

b.

Reduction of ECF volume [ Reduction of ECF volume is a very potent stimulus for

release of AVP (carried by the ninth and tenth cranial nerves), even when body

tonicity is not elevated. Reduction of ECF volume also stimulates thirst by means of

angiotensin 2.]

c.

Hypothalamus [ Osmoreceptors are located in the supraoptic and paraventricular

nuclei of the hypothalamus. They are stimulated by a rise in tonicity. The

osmoreceptors stimulate the release of AVP from storage sites in the posterior

pituitary gland. Even very small changes in tonicity (in the range of 2%) cause

changes in release of AVP and the perception of thirst. An increase or decrease in

tonicity is sensed by hypothalamic osmoreceptors, leading to enhancement or

suppression of AVP secretion.]

d.

Glucose[ Urea and glucose are ineffective osmoles. They do not stimulate thirst.]

e.

Urea

17)

What is the primary determinant of extracellular fluid osmolality?

a.

WaterT [ Body water is the primary determinant of extracellular fluid osmolality and

disturbances in water balance primarily affect body fluid tonicity. Disorders of body

water balance can cause hypotonicity or hyperotonicity. When there is an excess of

body water relative to body solute, hypotonicity results. When there is a deficiency

of body water relative to body solute, hyperotonicity develops. The main constituent

of plasma osmolality is sodium. Therefore, hypotonic disease states arecharacterized by hyponatremia and hypertonic disease states are characterized by

hypernatremia. Disturbances in sodium balance primarily affect ECF volume]

b.Glucosec.Uread.Hemoglobin

18)

What determines plasma osmolality?a.Glucoseb.Urea


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c.

Sodium T [ Sodium is actively pumped out of cells by the Na+, K+-ATPase pump. As

a result, 90% of all Na+ is extracellular. The major ECF solutes are Na+ salts.

Therefore, plasma Na+ concentration determines osmolality. The normal plasma

osmolality is 275 to 290 mosmol/kg. The plasma osmolality does not vary by morethan 2%. The intake of solute-free water must be balanced by the loss of the same

volume of electrolyte-free water. Impaired free water excretion will lead to

hyponatremia.]d.Potassiume.Calcium

19)

What determines ECF volume?

a.

Sodium T [ Total body sodium is the principal determinant of ECF volume. Most of

the body's sodium is located in the ECF. The regulation of sodium excretion by thekidney maintains normal ECF and hence plasma volume. The glomerular filtration

rate is 125 ml/min (80 liters/day) in a typical adult. Over 99% of this filtered fluid is

reabsorbed as a result of tubular reabsorption of sodium.]b.Reninc.Aldosterone

d.

Baroreceptors

20)

What is the osmotic threshold for AVP release?a.275

b.

285 mosmol/kgT [ The major stimulus for AVP secretion is hypertonicity. The

osmotic threshold for AVP release is 280 to 290 mosmol/kg. Arginine vasopressin

(AVP) is a polypeptide synthesized in the supraoptic and para-ventricular nuclei of

the hypothalamus and secreted by the posterior pituitary gland. An increase or

decrease in tonicity is sensed by hypothalamic osmoreceptors, leading to

enhancement or suppression of AVP secretion.]

c.300

d.

325

21)

What regulates water homeostasis


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a.

Thirst [ Fluid homeostasis depends on proper water intake (regulated by thirst

mechanism) and on urinary excretion of free water (regulated by AVP).]b.Arginine

vasopressinc.Kidneys

d.

All of the aboveT [ The serum sodium concentration and thus serum osmolality are

controlled by water homeostasis. Water homeostasis is mediated by thirst, arginine

vasopressin, and the kidneys. Abnormal water balance manifests as an abnormality

in the serum sodium concentration (hypernatremia or hyponatremia).]

CLINICAL FEATURES OF HYPOVOLAEMIA AND HYPERVOLAEMIA

HypovolaemiaHypervolaemia SymptomsThirstDizziness on standingWeakness

Edema BreathlessnessSignsTachycardiaHypotensionDry tongue Reduced skinturgorReduced urine outputConfusion

Peripheral edemaRaised JVPLung crepitationsPleural effusionAscitesWeight gain

HYPOVOLEMIA

CAUSES OF SODIUM AND WATER DEPLETION

MechanismExamplesInadequate intakeEnvironmental deprivation, inadequate

therapeutic replacementGastrointestinal sodium LossVomiting, diarrhea,

nasogastric suction, external fistulaSkin sodium lossExcessive sweating, burnsRenal

sodium lossDiuretic therapy, mineralocorticoid deficiency,tubulointerstitialdiseaseInternal sequestrationBowel obstruction, peritonitis,

pancreatitis, crush injury

In internal sequestration total body sodium and water may be normal or increased.

1)

What is/are the cause(s) of hypovolemia with normal renal function?

a.

High-protein hyperalimentation[ Hypovolemia is volume depletion leading to ECFvolume contraction due to loss of both salt and water exceeding intake. Increased

renal filtration of non-reabsorbed solutes (e.g., glucose, urea) impairs tubular

reabsorption of Na+ and water, leading to an osmotic (solute) diuresis. This occurs

in poorly controlled diabetes mellitus and in patients receiving high-protein

hyperalimentation.]

b.


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Mannitol IV[ The renal tubule is impermeable to mannitol. Therefore, mannitol

produces an osmotic diuresis because mannitol can be excreted along with water

only.]

c.

Hypoaldosteronism [ Mineralocorticoid deficiency (hypoaldosteronism) causes salt

wasting.]

d.

Central diabetes insipidus [ Central diabetes is due to impaired secretion of AVP.

Nephrogenic diabetes insipidus is due to renal unresponsiveness to AVP.]

e.

All of the aboveT [ Excessive renal losses of Na+ and water may also occur during

the diuretic phase of acute tubular necrosis and following the relief of bilateralurinary tract obstruction.]History can determine the cause of hypovolemia

(bleeding, vomiting, diarrhea, polyuria, medications, diaphoresis).

2)

How much fluid enters the gastrointestinal tract daily?a.2 Lb.5 L

c.

9 LT [ About 9 L of fluid enters the GIT daily, 2 L by ingestion and 7 L by secretion.

Almost 98% of this volume is reabsorbed so that fecal fluid loss is only 100 to 200

mL/d. Impaired gastrointestinal reabsorption or increased secretion leads to volumedepletion.]d.14 L

e.

20 L

3)

Diarrhea causes

a.

Metabolic alkalosis T [ Diarrhea often causes metabolic alkalosis because biliary,

pancreatic, and intestinal secretions are alkaline (high HCO3- concentration).]

b.

Metabolic acidosis [ Gastric secretions have high H+ concentration (low pH).

Therefore, vomiting often causes metabolic acidosis.]c.Lactic acidosis


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d.

Hyperkalemia 4)Sweat

a.

Usually hypertonic but may be isotonic

b.

Usually isotonic but may be hypertonic

c.

HypotonicT [ Sweat is hypotonic. Therefore, excessive sweating (e.g., febrile

illnesses, prolonged heat exposure), more loss of water than Na+, but continued

Na+ loss is manifest as hypovolaemia. The Na+ concentration of sweat is normally

20 to 50 mEq/L and decreases with profuse sweating due to the action of

aldosterone.]d.Hypertonic

5)

Third-space is in equilibrium witha.ECFb.ICFc.Both

d.

NeitherT [ Examples of third-space are peritoneal space, retroperitoneal space,

lumen of GIT, and subcutaneous tissue. Third space compartment is extracellular

but is not in equilibrium with either the ECF or the ICF. In pathologic conditions, ECF

can be sequestered into third-space compartments within the body without ahistory of fluid loss. In such cases, the clinical manifestations are those of real

hypovolemia because the sequestered compartment is not in hemodynamic

equilibrium with the ECF. The fluid is lost from the ECF and can result in

hypovolemia. Examples include sequestration of fluid in the bowel lumen in

gastrointestinal obstruction, in the subcutaneous tissues in severe burns or trauma,

in the retroperitoneal space in acute pancreatitis, and in the peritoneal cavity in

peritonitis or malignant ascites. These extrarenal causes of absolute hypovolemia

stimulate renal sodium and fluid retention.]

6)

ECF volume contraction results in

a.

Hypotension [ Clinically ECF volume contraction manifest as a decreased plasma

volume and hypotension. Hypotension is due to decreased venous return (preload)

and diminished cardiac output.]


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b.

Stimulation of baroreceptors [ Hypotension stimulates baroreceptors in the carotid

sinus and aortic arch.]

c.

Stimulation of sympathetic nervous system[ Hypotension activates the sympathetic

nervous system and the renin-angiotensin system.]

d.

Stimulation of renin secretion

e.

All of the aboveT [ The net effect is to maintain mean arterial pressure and cerebral

and coronary perfusion. In contrast to this cardiovascular response, the renal

response attempts to restore the ECF volume.]

7)

Renal response(s) to ECF volume contraction

a.

Increased GFR[ The GFR and filtered load of Na+ is decreased.]

b.

Vasodilatation of afferent arterioles[ Increased sympathetic tone decreases GFR bycausing preferential afferent arteriolar vasoconstriction.]

c.

Increased reabsorption of sodiumT [ There is increased tubular reabsorption of Na+.

Increased sympathetic tone increases proximal tubular Na+ reabsorption.]

d.

Increased atrial natriuretic peptide [ Sodium is also reabsorbed in the proximal

convoluted tubule. Enhanced reabsorption of Na+ by the collecting duct is in

response to increased secretion of angiotensin 2, aldosterone and AVP and

suppressed ANP secretion.] e.All of the above

CLINICAL FEATURES OF ECF VOLUME CONTRACTION

Symptoms (nonspecific and secondary to electrolyte imbalances and tissue

hypoperfusion)


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31/78

Severe degrees of hypovolemia (intravascular volume contraction > 15%) cause

hypotension, peripheral cyanosis, cold extremities, and reduced levels of

consciousness.

Thirst may be an early manifestation but more likely reflects a concomitant

hypertonic state.

Reduced skin turgor and dry mucous membranes are not reliable indicators of

hypovolemia.

8)

Laboratory finding(s) in loss of sodium and water

a.

Normal plasma sodium concentration[ Plasma sodium concentration may be normal

if losses of salt and water are parallel.]

b.

Raised plasma urea [ The plasma urea concentration rises because urea excretion is

reduced. Hypovolemia decreases GFR and urea excretion.]

c.

Normal plasma creatinine [ Plasma creatinine may be relatively normal early in

hypovolaemic states.]

d.

Raised plasma uric acid

e.

All of the above [ The urine specific gravity and osmolality increases because urine

concentrating mechanisms are activated to conserve water. Urine sodium

concentration falls]

9)

BUN:creatinine ratio of 20:1

a.

Normal [ Normally, the BUN:creatinine ratio is about 10:1.]

b.

Glomerulonephritis


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33/78

2

O.]

11)

A patient has quickly lost 1 L of whole blood following an accident. What featurescan you expect in such a patient? [ Answer all choices given below are true]

a.

Tachycardia

b.

Postural hypotension

c.

Peripheral vasoconstriction with cool extremities

d.

Oliguria - When fluid loss is extrarenal, there is water and sodium retention by the

kidneys. This normal renal response results in oliguria with an elevated urine

specific gravity (>1.020) and osmolality (>400 mOsm/kg), a sodium concentration

less than 20 mEq/L and a fractional excretion of sodium < 1%.

e.

Collapsed neck veins - Jugular venous pressure may fall (CVP < 5 cm H

2

O)

f.

Normal hemoglobin Hemoglobin may remain constant initially. Normal hemoglobin

levels do not rule out bleeding as a cause of hypovolemia. Later, hemoglobin falls

due to movement of ECF from the interstitial to the intravascular compartment

g.

Normal blood urea - Blood urea may also remain constant initially. Later, blood urea

may increase reduced renal blood flow and the effects of destruction of

erythrocytes in the gastrointestinal tract

h.


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35/78


36/78

1)

Hypernatremia is plasma Na+ concentration greater than -------- mEql/La.135

b.

145T [ Hypernatremia is plasma Na+ concentration > 145 mEql/L. Patients havemoderate hypernatremia if their serum Na+ is 146 to 159 mEq/L. Patients with Na+

greater than 160 mEq/L have severe, life-threatening hypernatremia.

Hypernatremia may be due to primary Na+ gain or water deficit. Water loss is the

most common cause of acute hypernatremia. Hypernatremia can develop in

patients who do not replace the water lost after excessive sweating in a hot

environment, vomiting or diarrhea.]c.155

d.

165

CAUSES OF HYPERNATREMIA

Net water lossPure water

Unreplaced insensible losses (dermal and respiratory)

Hypodipsia

Diabetes insipidus

Hypotonic fluid

Renal causes

Diuretics

Osmotic diuresis (glucose, urea, mannitol)

Postobstructive diuresis

Polyuric phase of acute tubular necrosis

Intrinsic renal disease


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Gastrointestinal causes

Vomiting

Diarrhea

Nasogastric drainage

Cutaneous causes

Burns

Excessive sweating

Hypertonic sodium gain

Hypertonic sodium bicarbonate or sodium chloride infusion

Hypertonic feeding preparation

Ingestion of sodium chloride (e.g., sea water)

Hypertonic saline enemas

Intrauterine injection of hypertonic saline

Hypertonic dialysis

Primary hyperaldosteronism

Cushings syndrome

2)

Hypernatremia - True statement

a.

Hyperosmolar sate [ Na+ and its accompanying anions are the major effective ECF

osmoles. Therefore, hypernatremia is a state of hyperosmolality and results in ICF


38/78

volume contraction. Sodium is impermeable. It contributes to tonicity and induces

the movement of water across cell membranes. Therefore, hypernatremia invariably

denotes hypertonic hyperosmolality and always causes cellular dehydration, at least

transiently.]

b.

Results in ICF volume contraction[ Hypernatremia causes hypertonicity of ECF.

Therefore, water shifts out of cells, leading to a contracted ICF volume. Neurologic

damage as a result of contraction of brain cell volume is the primary risk associated

with hypernatremia.]

c.

Stimulates thirst [ Hypernatremia stimulates thirst and thus increases water intake.

The severity of hyperosmolality is typically mild unless the thirst mechanism is

abnormal or access to water is limited (infants, postoperative state, impaired

mental status, and intubated patients in the intensive care unit.]

d.

Stimulates AVP secretion[ Another response to hypernatremia is excretion of a

minimum volume of maximally concentrated urine. This is due to increased AVP

secretion in response to hypertonia.]

e.

All of the aboveT [ The first question to be answered in any patient with

hypernatremia is why there has been inadequate intake of water.

Hypernatremia is rare in conscious patients who have free access to water because

of the extreme sensitivity of the thirst mechanism.]

3)

If 1 L of water is lost from the body, how much fluid is lost by the ICF compartment?

a.333 mL

b.

667 mLT [ Water is distributed between the ICF and the ECF in a 2:1 ratio.Therefore, a given amount of solute-free water loss will result in a twofold greater

reduction in the ICF compartment than the ECF compartment. If 1 L of water is lost,

the ICF volume will decrease by 667 mL, whereas the ECF volume will fall by only

333 mL. If the 1L of fluid lost is isoosmotic, ECF compartment will decrease by 1 L

because Na+ is largely restricted to the ECF.]c.1 Ld.None

4)


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What is the most common cause of hypernatremia?

a.

Gain of sodium[ A primary Na+ gain is an uncommon cause of hypernatremia. For

example, inadvertent administration of hypertonic NaCl or replacing sugar with salt

in infant formula can produce this complication.]

b.

Hyperemesis gravidarum[ Pregnant women, in the second or third trimester, may

develop nephrogenic diabetes insipidus due to excessive elaboration of

vasopressinase by the placenta.]

a.

Loss of waterT [ Most cases of hypernatremia are due to loss of free water.

Hypernatremia with hypovolaemia results from fluid losses that is more thansodium loss. Renal water loss (e.g., diuretics) is the most common cause of

hypernatremia. Diarrhea is the most common gastrointestinal cause of

hypernatremia. Profuse sweating is also a major cause of fluid loss resulting in

hypernatremia with hypovolaemia.]

b.

Renal failure

c.

Primary hypodipsia[ Primary hypodipsia results from damage to the hypothalamicosmoreceptors that control thirst. Thirst is impaired. Primary hypodipsia may be due

to granulomatous disease, vascular occlusion, or tumors.]

5)

Which of the following is a cause of diarrhea with hyponatremia?

a.

Lactulose [ Osmotic diarrheas (induced by lactulose, sorbitol, or malabsorption of

carbohydrate) and viral gastroenteritides cause more water loss than Na+ and K+

loss.]b.Sorbitolc.Malabsorption

d.

Viral gastroenteritides

e.


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CholeraT [ Secretory diarrheas (e.g., cholera, carcinoid, VIPoma) have a fecal

osmolality similar to that of plasma. Diarrhea due these present with ECF volume

contraction and a normal plasma Na+ concentration or hyponatremia.]

6)

Fecal osmolality

a.

Equal to the sum of stool concentrations of Na+ and K+

b.

Half the sum of stool concentrations of Na+ and K+

c.

Twice the sum of stool concentrations of Na+ and K+T [ The stool osmolality isassumed to be 300 mosmol/kg H

2

O. When the calculated difference is > 50, an osmotic gap is present. This suggests

that the diarrhea is due to a nonabsorbed dietary nutrient, e.g., a fatty acid and/or

carbohydrate. When this difference is < 25, it is presumed that a dietary nutrient is

not responsible for the diarrhea.]

d.

Thrice the sum of the stool concentrations of Na+ and K+

7)

Insensible losses are increased witha.Feverb.Exercise

c.

Severe burns

d.

Mechanical ventilation

e.

All of the aboveT [ Insensible loss of water is due to evaporation from the skin and

respiratory tract. Insensible losses are increased with fever, exercise, heat

exposure, and severe burns and in mechanically ventilated patients. The Na+


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concentration of sweat decreases with profuse perspiration, thereby increasing

solute-free water loss.]

8)

What is the most common cause of hypernatremia?

a.

Renal water lossT [ Renal water loss is the most common cause of hypernatremia.

The normal renal response to hypernatremia is for the nephron to generate

hyperosmolar urine and retain water. However, renal correction of hypernatremia

depends on the patient having access to water. Severe hypernatremia rarely occurs

in conscious patients because intense thirst compels them to drink water. In

contrast, severe hypernatremia can develop in sedated patients, disoriented

patients, or patients in delirium tremens.]

b.

Insensible lossc.Rota virus

d.

Diabetes insipidus

9)

Cause(s) of hypervolemic hypernatremia

a.

Administration of hypertonic sodium bicarbonate [ Hypernatremia with

hypervolemia can be caused by iatrogenic administration of hypertonic sodium

chloride or hypertonic sodium bicarbonate.]b.Administration of hypertonic sodium

chloride

c.

Mineralocorticoid excess [ Mineralocorticoid excess is suggested by the presence of

hypertension and hypokalemic metabolic alkalosis. Urine sodium concentration will

vary according to dietary intake.]

d.

All of the aboveT

10)

What is the most common cause of osmotic diuresis?


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a.

Diabetes insipidus[ Failure to synthesize and release ADH or failure of the renal

tubular cells to respond to ADH can result in hypernatremia.

Hypernatremia can develop in patients with diabetes insipidus who have sustained

a large water loss. Diabetes insipidus causes nonosmotic urinary water loss and

hypernatremia. Total solute excretion must equal solute production. Persons eating

a normal diet generate about 700 mosmol/d of solutes. Therefore, daily solute

excretion in excess of 750 mosmol is an osmotic diuresis. This can be confirmed by

measuring the urine glucose and urea.]

b.

Diabetes mellitusT [ Osmotic diuresis is water loss in excess of Na+ and K+. The

most common cause of an osmotic diuresis is hyperglycemia and glucosuria in

poorly controlled diabetes mellitus.]

c.

IV mannitol

d.

High-protein diet [ Intravenous administration of mannitol and high-protein diet

(increased production of urea) can also result in an osmotic diuresis.]

11)

The main symptom of hypernatremia is due to

a.

Cerebral edema and coning[ Hyponaremia may cause cerebral edema.]

b.

Hypertension and cardiac failure [ Volume depletion is often present in patients with

a history of excessive sweating, diarrhea, or an osmotic diuresis. History and

physical examination will often provide clues as to the underlying cause of

hypernatremia. Important points to note are the absence or presence of thirst,

diaphoresis, diarrhea, polyuria and current drugs. Look for features of ECF volume

contraction. Evaluate neurologic and mental status.]

c.

Altered mental statusT [ Hypernatremia causes hypertonicity of ECF. Therefore,

water shifts out of cells, leading to a contracted ICF volume. Brain cell volume is

decreased. Hence, the major symptoms of hypernatremia are neurologic and


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include altered mental status, weakness, neuromuscular irritability, focal neurologic

deficits, and occasionally coma or seizures.]

d.

Craving for ice-cold water [ Patients with polydipsia from central diabetes insipidus

tend to prefer ice-cold water.

12)

What is the feature of hypernatremia due to primary Na+ excess?

a.

ECF volume expansion and urine Na+ concentration < 40 mEq/L

b.

ECF volume expansion and urine Na+ concentration >100 mmol/LT [ Measure urinevolume and osmolality in the evaluation of hyperosmolality. ECF volume expansion

and natriuresis (urine Na+ concentration >100 mEq/L) confirms a primary Na+

excess.]

c.

ECF volume contraction and urine Na+ concentration >100 mmol/L

d.

ECF volume contraction and urine Na+ concentration < 20 mEq/L

13)

What does a low volume of maximally concentrated urine indicate?

a.

Extrarenal water loss

b.

Remote renal water loss

c.

Administration of hypertonic Na+ salt solutions

d.

Any of the aboveT [ A urine specific gravity of 1.010 units or less is a dilute urine

and suggests that ADH levels are low. A urine specific gravity greater than 1.030


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units suggests that the urine being produced is close to maximum osmolality. The

correct renal response to hypernatremia is the excretion of the minimum volume

(500 mL/d) of maximally concentrated urine (urine osmolality > 800 mosmol/kg).

These findings suggest extrarenal or remote renal water loss or administration of

hypertonic Na+ salt solutions.]

14)

What is the solute excretion rate?

a.

Urine volume osmolality

b.

Urine volume X osmolalityT [ The solute excretion rate is the product of the urine

volume and osmolality.]c.Urine sodium + potassium + chloride

d.

{ Urine sodium + potassium + chloride + glucose } urine osmolalitye.{ Urine

sodium + potassium + chloride + glucose } urine volume

15)

Treatment of hypernatremiaa.Loop diureticb.Desmopressin

c.

Correct the water deficit [ The most common cause of hypernatremia is loss of

water. Treatment of patients with hypernatremia secondary to dehydration is IV or

oral administration of water. The amount of water required to correct the deficit can

be calculated from the equation given below. Hypernatremic patients typically have

reduced blood volumes. Treat these patients first with the IV infusion of isotonic

saline solutions until the contracted ECF has been restored. Then give sufficient

electrolyte-free water to enable their renal function to produce concentrated urine

and correct the hypernatremia. In patients with prolonged hyperosmolality,

aggressive treatment with hypotonic fluids may cause cerebral edema, which can

lead to coma, convulsions, and death. Lower Na+ only at a rate < 8 mEq/day. Seefigure below.]d.Dialysis

e.

Tetracycline


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Water deficit = plasma sodium concentration 140

X Total body water140

Total body water is approximately 50 of lean body weight in men and and 40% oflean body weight in women

Within minutes after the development of hypertonicity, loss of water from brain cells

causes shrinkage of the brain and an increase in osmolality. Partial restitution of

brain volume occurs within a few hours as electrolytes enter the brain cells (rapid

adaptation). The normalization of brain volume is completed within several days as

a result of the intracellular accumulation of organic osmolytes (slow adaptation).

Slow correction of the hypertonic state reestablishes normal brain osmolality

without inducing cerebral edema, as the dissipation of accumulated electrolytes and

organic osmolytes keeps pace with water repletion. In contrast, rapid correction

may result in cerebral edema as water uptake by brain cells outpaces the

dissipation of accumulated electrolytes and organic osmolytes. Such overly

aggressive therapy carriesthe risk of serious neurologic impairment due to cerebral

edema.

16)

How much is the free water deficit in a 50-kg woman with a plasma Na+

concentration of 160 mEq/L?

a.

1.9 L

b.

2.9 LT [ (20 140) X (0.4 50). Rapid correction of hypernatremia can be

dangerous. A sudden decrease in osmolality may cause a rapid shift of water into

brain cells. Therefore, correct the water deficit slowly over at least 48. The safest

route of administration of water is by mouth. 5% dextrose in water or half-isotonic

saline can be given intravenously safely.]

c.

3.9 L

d.

4.9 L

17)


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34T [ 0.5 X 68]

c.

31[ The estimated volume of total body water in an elderly men and woman

weighing 68 kg would be 68 X 0.45 = 30.6 L.]

d.

25

20)

If 1 liter of 5 percent dextrose is given to the patient described above, what will be

the fall in serum sodium concentration?

a.

2.4 mEq per liter

b.

4.8 mEq per literT [ Change in serum Na

+

= (infusate Na

+

- serum Na

+

) (total body water + 1). According to this formula, the retention of 1 liter of 5

percent dextrose will reduce the serum sodium concentration by 4.8 mEq per liter

[ (0 168) (34+1) = - 4.8.]

c.

9.6 mEq per liter

d.

19.2 mEq per liter

21)

A 58-year-old woman with postoperative ileus is undergoing nasogastric suction.

She is obtunded with diminished skin turgor and mild orthostatic hypotension. The


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serum sodium concentration is 158 mEq per liter, the potassium concentration is

4.0 mEq per liter, and the body weight is 63 kg. What is the treatment?

a.

0.45% sodium chloride IVT [ Hypernatremia caused by hypotonic fluid loss is the

correct diagnosis. The estimated volume of total body water is 31.5 liters (0.5 X 63).

The infusion of 1 liter of 0.45 percent sodium chloride will reduce the serum sodium

concentration by 2.5 mEq per liter (77 158) ( 31.5 + 1) = - 2.5. If the goal is to

reduce the serum sodium concentration by 5 mEq per liter over the next 12 hours, 2

liters of the solution is required (52.5). If 1 liter is added to compensate for

ongoing losses of gastric and other fluids, a total of 3 liters will be administered for

the next 12 hours, or 250 ml per hour.]

b.

0.9% sodium chloride IV[ Although there is evidence of a depletion in the volume of

extracellular fluid, the patients hemodynamic status is not sufficiently

compromised to warrant the initial use of 0.9 percent sodium chloride.]

c.

Furosemide IV

d.

Furosemide oral

e.

Hemodialysis

22)

A 62-year-old man with advanced alcoholic cirrhosis is on lactulose for hepatic

encephalopathy. Examination shows confusion, ascites, and asterixis. The blood

pressure is 105/58 mm Hg in the supine position, and the pulse is 110 beats per

minute. The serum sodium concentration is 160 mEq per liter, the potassium

concentration is 2.6 mEq per liter, and the body weight is 64 kg. What is the

treatment?

a.

Increase the dose of lactulose and give IV normal saline

b.

Withdraw lactulose and give IV 0.2 percent sodium chlorideT [ The hypernatremia is

due to hypotonic sodium and potassium losses induced by lactulose therapy.


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Treatment is withdrawal of lactulose and IV 0.2 percent sodium chloride containing

20 mEq of potassium chloride per liter. With the presence of ascites, the estimated

volume of total body water is about 38 liters (0.6 X 64).

c.

Furosemide IVd.Liver transplantation

e.

Potassium chloride IV

23)

A 60-year-old man has received 10 ampoules of sodium bicarbonate over six hours

during resuscitation after recurrent cardiac arrest. He is stuporous and is

undergoing mechanical ventilation. His blood pressure is 138/86 mm Hg, and

peripheral edema is present. The serum

sodium concentration is 156 mEq per liter, the body weight is 85 kg, and the urinary

output is 30 ml per hour. What is the treatment?

a.

Furosemide[ The hypernatremia is caused by hypertonic sodium gain. For its

correction, the excess sodium and water be excreted. Furosemide alone is not

enough, because furosemide- induced diuresis is equivalent to one-half isotonic

saline solution. Thus, the hypernatremia will be aggravated.]

b.

Furosemide and electrolyte-free waterT [ The correct treatment is administration of

both furosemide and electrolyte-free water. The estimated volume of total body

water is 51 liters (0.6 X85). If 1 liter of 5 percent dextrose is given, it will decrease

the serum sodium concentration by 3.0 mEq per liter (0 156) (51+1) = - 3.0.

Since the patients extracellular-fluid volume is expanded, fluids can be

administered only with great caution. Adjust fluid administration based on close

monitoring of the patients clinical status and serum sodium concentration.]

c.

Hemodialysis [ Hypernatremia with concurrent renal failure and volume overload is

a special problem. Diuretics cannot be relied on to reduce the expanded

extracellular-fluid volume. Therefore, hemodialysis, hemofiltration, or peritoneal

dialysis may be necessary.]

d.

Peritoneal dialysis


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e.

Dopamine

24)

Not suited for correcting hypernatremia in a 50-year-old man with a serum sodiumconcentration of 162 mEq per liter and a body weight of 70 kg is

a.

Isotonic salineT [ Isotonic saline is unsuitable for correcting hypernatremia.

Estimated volume of total body water is 42 liters (0.6 X 70). The retention of 1 liter

of 0.9 percent sodium chloride will decrease the serum sodium concentration by

only 0.2 mEq per liter ( 154 162) (42 + 1) = - 0.2). Although the sodium

concentration of the infusate is lower than the patients serum sodium

concentration, it is not sufficiently low to alter the hypernatremia substantially. The

only indication for administering isotonic saline to a patient with hypernatremia is adepletion of extracellular-fluid volume that is sufficient to cause substantial

hemodynamic compromise. Even in this case, after a limited amount of isotonic

saline has been administered to stabilize the patients circulatory status, give a

hypotonic fluid (i.e., 0.2 percent or 0.45 percent sodium chloride). If a hypotonic

fluid is not substituted for isotonic saline, the extracellular-fluid volume may

become seriously overloaded.]b.0.2 percent sodium chloride

c.

0.45 percent sodium chloride d.All of the above

HYPONATREMIA

1)

How do disorders in sodium balance present?

a.

Altered ECF volume T [ Disorders in sodium balance present chiefly as altered ECF

volume rather than altered sodium concentration.]b.Hyponatremia

c.Hypernatremia

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