Pharm CH 29
Which goal is appropriate for a person attempting to control cholesterol and low-density lipoprotein levels? 1. Limit cholesterol intake to less than 200 mg daily. 2. Limit saturated fat intake to less than 15% of total calories. 3. Limit dietary fat to less than 50% of total calories. 4. Increase plant sterol intake to 1-2 grams daily.
Correct Answer: 1 Global Rationale: Cholesterol intake should be less than 200 mg daily. Saturated fat intake should be reduced to less than 7% of total calories daily. Dietary fat intake should be less than 30% of total calories daily. The recommendation for daily plant sterol intake is 2-3 grams.
Cholesterol, triglycerides, and phospholipids travel between the liver and peripheral tissues through which mechanism? 1. Bound to apoproteins 2. As unbound free molecules 3. Bound to albumin 4. Bound separately in molecule complexes
Correct Answer: 1 Global Rationale: Apoproteins are specific for cholesterol, triglycerides, and phospholipids, and they act as carrier molecules for transporting these lipids through the blood. Lipid molecules are not soluble in plasma and so require protein binding for transport. Albumin is the most common plasma protein, but it is not specific as a carrier for cholesterol, triglycerides, and phospholipids. Lipoprotein molecules that combine lipids with a carrier protein contain different amounts of cholesterol, triglycerides, and phospholipids.
An elevation in low-density lipoprotein (LDL) most likely would be related to which comorbid condition? 1. Diabetes mellitus 2. Renal insufficiency 3. Iron-deficiency anemia 4. Hyperthyroidism
Correct Answer: 1 Global Rationale: Clients with diabetes mellitus require more aggressive therapy to reduce the risk of atherosclerosis. Cholesterol is excreted from the liver through the biliary tract, so diminished renal function has no effect on lipid levels and atherosclerosis risk. There is no association between iron-deficiency anemia and elevated LDL levels, but LDL levels might be decreased if the iron deficiency is severe. Hyperthyroidism increases the rate of lipoprotein metabolism, which would lead to a decrease in LDL levels.
A client is being discharged after a hospital admission for chest pain with a multidrug regimen that includes a new prescription for cholestyramine (Questran). It is most important for the nurse to include which information in discharge teaching about this drug? 1. "You must carefully follow instructions for mixing this drug with liquid." 2. "If you experience bloating or constipation, you should stop taking this drug." 3. "We will monitor your kidney function while you are taking this drug." 4. "Do not take vitamin supplements while taking cholestyramine."
Correct Answer: 1 Global Rationale: Failure to mix the powdered form of this drug adequately can cause gastrointestinal tract obstruction. Gastrointestinal effects such as bloating and constipation are common side effects of cholestyramine. Since this drug binds with many other drugs in the gastrointestinal tract, suddenly stopping the drug could increase absorption of other drugs and lead to drug toxicity. Bile acid sequestrants such as cholestyramine are not systemically absorbed, and do not threaten kidney function. Cholestyramine can reduce absorption of fat-soluble vitamins, so supplementation with vitamins A and D might be necessary.
The nurse is teaching a client with a lipid disorder about dietary modifications to manage the condition. Which statement by the client indicates an appropriate understanding of the rationale underlying a recommendation to increase the intake of plant sterols? 1. "I will eat oatmeal or cold oat cereal for breakfast every morning." 2. "I will try to increase the amount of lettuce I eat." 3. "I will snack on toasted pumpkin seeds." 4. "If I eat enough spinach and other green vegetables, I can stop taking my cholesterol-lowering medicine."
Correct Answer: 1 Global Rationale: Oats are a recommended source of plant sterols. Only dark green, leafy vegetables are a good source of plant sterols. Pumpkin seeds do not contain any significant amount of plant sterols. Increasing plant sterol intake is recommended as an adjunctive strategy for persons taking lipid-lowering drugs.
An adult client is 75 pounds over the ideal weight, eats a diet high in carbohydrates, and drinks 3-4 alcoholic beverages daily. Which pattern of dyslipidemia most likely fits all the findings and behaviors demonstrated by this client? 1. Elevated VLDL, triglycerides, and cholesterol; glucose intolerance 2. Elevated chylomicrons, normal cholesterol, triglycerides more than three times normal 3. Elevated LDL, VLDL, total cholesterol, chylomicrons; triglycerides more than three times normal 4. Elevated LDL and total cholesterol, normal VLDL and triglycerides
Correct Answer: 1 Rationale 1: These alterations represent endogenous dyslipidemia (type IV), which is common in middle-aged adults and associated with obesity and with high alcohol and carbohydrate intake. Rationale 2: These alterations represent exogenous hyperlipidemia (type I), which usually occurs in childhood. Rationale 3: These alterations represent type V hyperlipidemia. Rationale 4: These alterations represent familial hyperlipdemia (type IIa). Global Rationale: These alterations represent endogenous dyslipidemia (type IV), which is common in middle-aged adults and associated with obesity and with high alcohol and carbohydrate intake. The other options are indicative of exogenous hyperlipidemia (type I), which usually occurs in childhood; type V hyperlipidemia; and familial hyperlipdemia (type IIa).
The nurse is planning care for a client who is receiving drug therapy for a lipid disorder. What outcomes depict that the client is experiencing the therapeutic effects of the medication? SELECT ALL THAT APPLY 1. Lowered total cholesterol 2. Lowered LDL 3. Increased HDL 4. Elevated liver enzymes 5. Decreased BUN and creatinine
Correct Answer: 1,2,3 Global Rationale: A lowered total cholesterol level, a lowered LDL, and an increased HDL are expected therapeutic effects to receiving drug therapy for lipid disorders. Elevated liver enzymes is an adverse effect, not an expected therapeutic effect, to receiving drug therapy for lipid disorders. A decreased BUN and creatinine is not an expected therapeutic effect to receiving drug therapy for lipid disorders.
A nursing student is preparing a presentation on the different types of lipids. The student will include which classification of lipids in the presentation? 1. Triglycerides 2. Phospholipids 3. Steroids 4. Lecithins 5. Bile acids
Correct Answer: 1,2,3 Global Rationale: Triglycerides are the most common classifications of lipids. Phospholipids are a class of lipids essential to building plasma membranes. Steriods are a diverse classification of lipids. Lecithins are not a classification of lipids. Lecithin is the best-known phospholipid. Bile acids are not a classification of lipids. Cholesterol is a building block of bile acids.
The nurse educator is teaching a group of students about HMG-CoA Reductase medications. The nurse knows the students understood the lesson when they state which drugs as examples of this classification? SELECT ALL THAT APPLY 1. Lipitor 2. Lescol 3. Questran 4. Mevacor 5. WelChol
Correct Answer: 1,2,4 Global Rationale: Lipitor, lescol, and mevacor are examples of HMG-CoA Reductase medications and would indicate that the student understood the lesson. Question is an example of a Bile Acid Sequestrant and would indicate the need for further teaching. WelChol is an example of a Bile Acid Sequestrant and would indicate the need for further teaching.
A student is discussing lipid transport through the blood with a nursing instructor. The student asks the educator which apoproteins are important to lipid transport. Which responses by the educator are appropriate? SELECT ALL THAT APPLY 1. A-I 2. A-II 3. A-III 4. A-IV 5. B-100
Correct Answer: 1,2,4,5 Global Rationale: A-I, A-II, A-III and B-100 are apoproteins important to lipid transport. A-III is not an apoprotein important to lipid transport.
The nurse is teaching a client regarding therapeutic lifestyle changes that can be implemented to control cholesterol levels in the blood. Which statements made by the client indicate an appropriate understanding of the teaching session? 1. "I will maintain an optimal weight." 2. "I will implement a medically supervised exercise plan." 3. "I will increase intake of dietary saturated fats and cholesterol." 4. " I will decrease soluble fiber in my diet." 5. "I will eliminate tobacco use."
Correct Answer: 1,2,5 Global Rationale: Maintaining an optimal weight is a nonpharmacological therapeutic lifestyle change that can control cholesterol levels in the blood. A medically supervised exercise plan is a nonpharmacological therapeutic lifestyle change that can control cholesterol levels in the blood. Eliminating tobacco use is a nonpharmacological therapeutic lifestyle change that can decrease cholesterol levels in the blood. This statement indicates that the client requires further education, as the client should decrease dietary saturated fats and cholesterol in the diet. It is recommended to increase soluble fiber, not insoluble fiber, in the diet. This statement indicates the need for further education.
Question 25 A seasoned nurse is reviewing the different classifications of medications that are used to decrease blood cholesterol levels with a new nurse on a medical-surgical unit. The seasoned nurse knows the new nurse has comprehended the information when she states which medications as fibric acid agents? SELECT ALL THAT APPLY 1. Atromid-S 2. Zetia 3. Lopid 4. Colestid 5. Zocor
Correct Answer: 1,3 Global Rationale: Atromid-S and lopid are fibric acid agents used to decrease blood cholesterol levels. Zetia is an unclassified agent used to decrease blood cholesterol levels. Colestid is a Bile Acid Sequestrant used to decrease blood cholesterol levels. Zocor is an HMG-CoA Reductase medication used to decrease blood cholesterol levels.
The nurse is reviewing a client's laboratory results. Which finding is of most concern? 1. HDL cholesterol 62 mg/dL 2. Triglycerides 349 mg/dL 3. LDL cholesterol 92 mg/dL 4. Total cholesterol 202 mg/dL
Correct Answer: 2 Global Rationale: A triglyceride level of 349 mg/dL indicates that the client has a very high risk for coronary artery disease. An HDL cholesterol level of 62 mg/dL is within the desirable range for HDL cholesterol. A LDL cholesterol level of 92 mg/dL is within the optimal range for LDL cholesterol. A total cholesterol level of 202 mg/dL indicates a borderline high risk for coronary artery disease for this client.
Which statement indicates that a client understands teaching about avorstatin (Lipitor)? 1. "I should always take this drug on an empty stomach." 2. "I should stop taking this drug if I decide to try to become pregnant." 3. "I might have to increase my dose of digoxin." 4. "I should take this drug with breakfast."
Correct Answer: 2 Global Rationale: Avorstatin is a pregnancy category X drug, and should be avoided by women of childbearing age who might become pregnant. The drug may be taken without regard to meals. Avorstatin (Lipitor) can significantly increase serum digoxin levels. Clients taking avorstatin (Lipitor) might need to decrease their dose of digoxin and should have digoxin levels monitored frequently. Because cholesterol synthesis increases at night, drugs to treat lipid disorders are more effective if taken at bedtime rather than in the morning.
A client who takes avorstatin (Lipitor) daily has been prescribed erythromycin for sinusitis. To prevent consequences of an adverse effect of this combination of drugs, it is most important for the nurse to monitor this client for which clinical manifestation? 1. Lack of expected response to erythromycin. 2. New onset of muscle pain. 3. Abdominal pain and cramping. 4. Bleeding from the oral cavity and bruising.
Correct Answer: 2 Global Rationale: Muscle pain may be a sign of rhabdomyolysis, which is a life-threatening condition. The risk of rhabdomyolysis is increased for clients taking a macrolide drug such as erythromycin, because macrolides significantly increase blood levels of avorstatin. Avorstatin (Lipitor) does not decrease the therapeutic effect of erythromycin. Abdominal pain and cramping are experienced by some clients as a side effect of erythromycin, but this effect is not enhanced by the interaction with avorstatin (Lipitor). Coagulation is not altered as a consequence of the interaction of these two drugs.
The nurse is evaluating a client's response to teaching about managing dyslipidemia. Which statement by this client indicates that additional teaching is needed? 1. "I will read labels carefully so my daily cholesterol intake is no more than 200 mg." 2. "I will include several servings of soybeans in what I eat each week, since they provide lecithin." 3. "I will switch to using olive oil for cooking." 4. "I will decrease my intake of both cholesterol and saturated fat."
Correct Answer: 2 Global Rationale: Once promoted as a natural treatment for high cholesterol levels, controlled studies have not shown lecithin (which is found in soybeans) to be of benefit for high cholesterol. The recommended daily dietary intake of cholesterol is 200 mg or less. Olive oil is a good source of plant sterols, which reduce absorption of dietary cholesterol from the gastrointestinal tract. Cholesterol is essential for synthesis of other steroid compounds in the body, including hormones and bile acids. Additionally, limiting cholesterol intake without limiting saturated fat can lead to excess hepatic synthesis of cholesterol. Limiting both indicates understanding.
The nurse planning care for a client newly diagnosed with elevated serum cholesterol, triglycerides, and LDL initiates a dietary consult for which reason? 1. This particular pattern of dyslipidemia is not amenable to pharmacological agents. 2. Nonpharmacologic approaches to dyslipidemia should be initiated before pharmacologic agents are prescribed. 3. These levels are sufficiently high that pharmacologic intervention alone is unlikely to be successful. 4. Dietary modifications can be useful for lipid disorders, but only as an adjunct intervention after pharmacologic therapy for clients has been initiated.
Correct Answer: 2 Global Rationale: The alterations in laboratory values for this client are in the range of slightly elevated, and pharmacologic agents for lipid disorders carry a risk of adverse effects and potential adverse drug interactions. Therefore, nonpharmacologic approaches should be used before initiating drug therapy. Several available agents are effective in reducing total cholesterol, LDL, and triglycerides. The alterations in laboratory values for this client represent slight rather than extreme elevations. For many clients, dietary modifications might be effective in reducing lipid levels to normal.
The nurse is assigned to care for a client who is prescribed cholestyramine (Questran). To maintain safety for this client relative to potential effects of this drug, the nurse should monitor which laboratory test? 1. Serum glucose 2. Serum transaminases 3. Neutrophil count 4. Serum potassium level
Correct Answer: 2 Global Rationale: Unlike statin drugs, bile acid sequestrants do not carry a risk of hepatic injury. Glucose metabolism is not affected by cholestyramine (Questran). Cholestyramine (Questran) does not affect neutrophil production. Potassium is not affected by cholestyramine (Questran).
The nurse is teaching a community group about the role that cholesterol plays in the development of high blood pressure and atherosclerosis. In order to decrease this risk, the nurse recommends that clients maintain a total cholesterol level less than _____ mg/dL.
Correct Answer: 200 Global Rationale: It is recommended that the total cholesterol level be less than 200 mg/dL
Question 30 Which statement indicates that a client has understood instructions about cholestyramine? 1. "I will take this drug when I wake up in the morning." 2. "I should take this drug at least 1 hour before taking any other drugs." 3. "I will drink plenty of fluids while I am taking this drug." 4. "I should report to my doctor any increase in swelling of my ankles."
Correct Answer: 3 Global Rationale: An adequate fluid intake is necessary to prevent constipation in clients taking cholestyramine. Lipid-lowering drugs should be taken in the evening to take advantage of the diurnal pattern of greater cholesterol synthesis by the liver at night. Cholestyramine should be taken at least 4 hours before or 1 hour after other medications. Cholestyramine does not affect fluid balance by any mechanism.
The nurse is teaching a client about reducing the risk for coronary artery disease. An elevation in which laboratory value is most directly associated with atherosclerosis, leading to coronary artery disease? 1. Total cholesterol 2. Very low-density lipoprotein (VLDL) 3. Low-density lipoprotein (LDL) 4. High-density lipoprotein (HDL)
Correct Answer: 3 Global Rationale: The strength of the association between LDL cholesterol and atherosclerosis is demonstrated by the direct relationship between reduction in LDL cholesterol and acute coronary syndrome risk. LDL cholesterol contains lipoprotein (a), which is highly associated with atherosclerotic plaque. Total cholesterol represents the sum of all types of cholesterol. An elevation in total cholesterol is not the most direct predictor of atherosclerosis risk. Very low-density lipoprotein (VLDL) is a precursor of LDL and thus does not have the most direct relationship with initiation of atherosclerosis. High-density lipoprotein (HDL) carries cholesterol from the peripheral tissues to the liver for metabolism and excretion, so an elevation rather than a decrease in HDL is associated with lowered atherosclerosis risk.
The nurse is teaching a client with elevated LDL cholesterol and decreased HDL cholesterol about strategies to manage this disorder. The client asks the nurse why there is a difference in the direction of change in the goals for altering HDL versus LDL cholesterol. Which response by the nurse is the most appropriate? 1. "It is most important to increase HDL cholesterol, and if we can reduce LDL cholesterol also, that might be of some help." 2. "We want to reduce HDL cholesterol and increase LDL cholesterol because these changes will protect you against atherosclerosis." 3. "We want to increase HDL cholesterol, which helps rid the body of excess cholesterol, and to decrease LDL cholesterol, which carries excess cholesterol to the body tissue to be stored." 4. "I think you have misunderstood what I have told you, since we want both values to be reduced."
Correct Answer: 3 Global Rationale: An elevation in HDL cholesterol and a decrease in LDL cholesterol maintain an optimal balance between storage of cholesterol in tissues and removal of cholesterol by the liver. Both HDL and LDL cholesterol must be within an optimal range to reduce the risk of coronary artery disease. An elevation in LDL cholesterol increases storage of cholesterol in tissues, and a decrease in HDL cholesterol decreases the ability of the liver to metabolize and excrete excess cholesterol. Reduction in LDL cholesterol below 100 mg/dL and an increase in HDL cholesterol above 40 mg/dL are optimal for preventing atherosclerosis.
The nurse is teaching a client who has been prescribed medication to manage HDL cholesterol. Which statement by the client indicates that the teaching has been understood? 1. "Treatment of HDL cholesterol will also decrease my LDL cholesterol level." 2. "Treatment of HDL cholesterol will also raise my LDL cholesterol level." 3. "If I can increase my HDL level, I will be less likely to have a heart attack." 4. "If I can decrease my HDL level, I will be less likely to have a heart attack."
Correct Answer: 3 Global Rationale: An increase of HDL cholesterol has the strongest association with a reduced risk of acute coronary syndromes. Increasing HDL cholesterol and decreasing LDL cholesterol are accomplished by separate pharmacologic mechanisms. Raising HDL cholesterol by drug therapy is not a cause of increased LDL cholesterol. An HDL level that is below the optimal range increases risk for acute coronary syndromes because it represents decreased capacity for carrying cholesterol from peripheral tissues to the liver for metabolism and excretion from the body.
A nurse is evaluating outcomes of teaching for a client with a new prescription for avorstatin (Lipitor). Which response indicates that the client has understood teaching about this drug? 1. "I will avoid taking this drug with meals." 2. "I might need to increase my dose of digoxin while I am taking this drug." 3. "I will stop taking this drug if I am trying to get pregnant." 4. "I should always take this drug right before breakfast."
Correct Answer: 3 Global Rationale: Avorstatin is a pregnancy category X drug, and should be avoided by women of childbearing age who might become pregnant. Absorption of avorstatin (Lipitor) is not inhibited by food in the gastrointestinal tract. Avorstatin (Lipitor) can increase serum digoxin levels significantly. Clients taking avorstatin (Lipitor) might need to decrease their dose of digoxin, and should have digoxin levels monitored frequently. Because cholesterol synthesis increases at night, drugs to treat lipid disorders are more effective if taken at bedtime.
The nurse is caring for a client diagnosed with coronary artery disease. When examining the results of laboratory tests, the nurse notes that which findings are consistent with this diagnosis? 1. Decreased total serum cholesterol and LDL, and elevated HDL 2. Elevated total serum cholesterol, LDL, and HDL 3. Elevated total serum cholesterol and LDL, and decreased HDL 4. Decreased total serum cholesterol, LDL, and HDL
Correct Answer: 3 Global Rationale: Elevated total serum cholesterol is consistent with coronary artery disease. Increased LDL is consistent with coronary artery disease because LDL reflects the amount of cholesterol that is being transported from the liver to peripheral tissue. A decrease in HDL is inconsistent with coronary artery disease because this value reflects how much cholesterol is being carried from the peripheral tissue to the liver for metabolism and excretion.
Niacin and aspirin have been prescribed for a client diagnosed with hyperlipidemia. Which statement regarding why this drug combination is prescribed is the most accurate? 1. "A common side effect of niacin therapy is joint pain." 2. "Taking niacin and aspirin together increases the therapeutic effect of niacin." 3. "Aspirin can decrease discomfort associated with niacin therapy." 4. "Severe headaches are common during the early weeks of niacin therapy."
Correct Answer: 3 Global Rationale: One aspirin tablet administered 30 minutes before a dose of niacin might minimize the frequent side effect of flushing associated with niacin. Joint pain is not associated with nicotinic acid therapy. There is no pharmacodynamic interaction between nicotinic acid and aspirin. Flushing associated with nicotinic acid involves peripheral vasculature, not vasculature in the brain.
Question 26 The nurse is caring for a client taking both gemfibrozil (Lopid) and warfarin (Coumadin). To maintain safety relative to the interaction of these drugs, the nurse should monitor the client closely for which clinical manifestation? 1. Myolysis 2. Clot formation 3. Bleeding 4. Hyperlipidemia
Correct Answer: 3 Global Rationale: The client is at increased risk for bleeding because gemfibrozil competes with warfarin for plasma protein receptors, with the consequence of increasing the anticoagulant effect of an increased amount of free warfarin. There would be an increased risk of myolysis if the drug interaction increased the serum concentration of gemfibrozil. Clot formation would be a risk if the therapeutic anticoagulant effect of warfarin were reduced by its interaction with gemfibrozil. Hyperlipidemia would be a consequence if the serum concentration of gemfibrozil were decreased as a consequence of the drug interaction.
A client taking gemfibrozil (Lopid) and rosuvastatin (Crestor) reports muscle and joint pain. The nurse's response is based on an interpretation that this complaint might indicate which manifestation? 1. Hepatic injury 2. Peripheral neuropathy 3. Myopathy 4. An inflammatory response
Correct Answer: 3 Global Rationale: The risk of myopathy is increased in clients taking both a fibrate and a statin drug for hyperlipidemia. Hepatic injury is a risk associated with these drugs, but the symptom pattern does not indicate damage to the liver. Joint pain is not a manifestation of peripheral nerve damage. The mechanism by which statin and fibrate drugs produce myopathy is unknown.
The nurse is preparing to discharge a client from a medical-surgical unit. The client is going home on niacin therapy to decrease blood cholesterol levels. In educating the client on medication safety, the nurse should instruct the client to report which adverse effects to the health care provider? 1. Nausea 2. Vomiting 3. Stomach pain 4. Joint pain 5. Jaundice
Correct Answer: 3,4,5 Global Rationale: Stomach pain, joint pain, and jaundice are adverse effects that should be reported to the health care provider when a client is taking niacin for the reduction of blood cholesterol levels. Nausea and vomiting are not adverse effects that should be reported to the health care provider when a client is taking niacin for the reduction of blood cholesterol levels.
The nurse is reviewing the adverse effects associated with statins with a client who is prescribed this classification of medication to reduce blood cholesterol levels. The nurse knows the client has understood the teaching when the client states which serious adverse effects associated with statins? SELECT ALL THAT APPLY 1. Headache 2. Abdominal pain 3. Myopathy 4. Muscle or joint pain 5. Rhabdomyolysis
Correct Answer: 3,5 Global Rationale: Severe myopathy is a rare but serious adverse effect associated with statins. Rhabdomyolysis is an example of a rare but serious adverse effect associated with statins. Headache, abdominal pain, and muscle or joint pain are examples of a minor adverse effects associated with statins.
The nurse is providing teaching to a client who has been placed on oral cholestyramine for management of a lipid disorder. Which statement by this client indicates the need for further teaching about this drug? 1. "I should take my warfarin at least 1 hour before I take my cholestyramine." 2. "Before I take this medicine, I should mix it in 2 ounces of water, then add another 2-4 ounces before I swallow it." 3. "I should stop taking a daily multivitamin pill." 4. "I should keep all appointments for monitoring my warfarin therapy, since I might need to decrease the dose of this drug."
Correct Answer: 4 Global Rationale: The interaction between cholestyramine and warfarin produces an increased risk of bleeding by lowering vitamin K levels, so the dose of warfarin the client is taking might need to be lowered. Cholestyramine has a strong potential for delaying absorption of other drugs from the gastrointestinal tract, and so should be taken 1 hour after or 4 hours before other oral medications. Failure to mix cholestyramine powder with an adequate volume of water can lead to gastrointestinal obstruction. Cholestyramine can interfere with vitamin absorption, so vitamin supplementation might be needed.
A nursing instructor explains to a group of students that LDL is often called "bad" cholesterol because this lipoprotein contributes significantly to plaque deposits and coronary artery disease (CAD). The instructor asks the students what percentage of cholesterol is circulating in LDLs. The correct range is 60 to_____%.
Correct Answer: 70 Global Rationale: Of the cholesterol circulating in the blood, 60 to 70% is found in LDLs.
A nurse educator is reviewing the different types of lipids with a group of nursing students. The educator is discussing the importance of triglycerides and states that triglycerides account for___% of the total lipids in the body.
Correct Answer: 90 Global Rationale: Triglycerides account for 90% of the total lipids in the body. Triglycerides are the major storage form of fat in the body and the only type of lipid that serves as an important energy source.
