Academic Success Week 07 - Lipid Metabolism & System-based Practice
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- 1.
Treatment of hypercholesterolemia requires knowledge of the control of HMG-CoA reductase activity and LDL receptor (LDLR) levels. Which of the following statements is correct concerning HMG-CoA reductase and the LDLR?
- A.
Their synthesis in the liver is increased after a meal containing cholesterol and cholesterol esters
- B.
They both contain CoA
- C.
When the LDLR is up-regulated, HMG-CoA reductase is switched on.
- D.
HMG-CoA reductase is activated when the LDLR is down-regulated and the cell requires cholesterol
- E.
Both HMG-CoA reductase and the LDLR are synthesized in response to high levels of intracellular cholesterol
Correct Answer
D. HMG-CoA reductase is activated when the LDLR is down-regulated and the cell requires cholesterolExplanation
HMG-CoA reductase is the enzyme responsible for the synthesis of cholesterol in the liver. When the LDL receptor (LDLR) is down-regulated, it means that there are low levels of cholesterol in the cell. In this situation, the cell requires cholesterol, so HMG-CoA reductase is activated to produce more cholesterol. This statement correctly describes the relationship between HMG-CoA reductase and LDLR in regulating cholesterol levels in the cell.Rate this question:
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- 2.
Inhibiting the rate limiting enzyme of cholesterol biosynthesis would be beneficiary in lowering blood cholesterol levels by one of the following mechanisms:
- A.
Increasing the conversion of cholesterol to bile acids
- B.
Inhibiting the formation of HMG-CoA
- C.
Preventing the reabsorption of bile acids from the intestine
- D.
Inhibiting the formation of mevalonate
- E.
Inhibiting the absorption of cholesterol from the diet
Correct Answer
D. Inhibiting the formation of mevalonateExplanation
Inhibiting the formation of mevalonate would be beneficial in lowering blood cholesterol levels because mevalonate is a precursor molecule in the cholesterol biosynthesis pathway. By inhibiting its formation, the production of cholesterol would be reduced, leading to lower blood cholesterol levels.Rate this question:
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- 3.
Which of the following phospholipids is released by phagocytic cells and leads to superoxide radical production in alveoli macrophages?
- A.
Plasmalogens
- B.
Phosphatidylinositol
- C.
Cardiolipin
- D.
Platelet activating factor
- E.
Phosphatidylcholine
Correct Answer
D. Platelet activating factorExplanation
Platelet activating factor is released by phagocytic cells and leads to superoxide radical production in alveoli macrophages.Rate this question:
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- 4.
A mother takes her one-year-old daughter to the pediatric clinic because she observes that the child keeps walking into objects and does not respond when she talks to her. On examination the pediatrician notes that she has problems with her hearing and cannot see. Other observations included muscle weakness and slow mental and motor development. This patient most likely has which one of the following diseases:
- A.
Tay-Sachs
- B.
Fabry
- C.
Krabbes
- D.
Neimann-Pick
- E.
Faber
Correct Answer
C. KrabbesExplanation
The patient in this scenario presents with symptoms such as walking into objects, lack of response to verbal stimuli, hearing and visual problems, muscle weakness, and slow mental and motor development. These symptoms are characteristic of Krabbe disease, a rare genetic disorder that affects the nervous system. In Krabbe disease, there is a deficiency of the enzyme galactocerebrosidase, leading to the accumulation of toxic substances in the brain and other organs. This results in the destruction of the protective covering of nerve cells, leading to the symptoms described. Tay-Sachs, Fabry, Neimann-Pick, and Faber diseases do not typically present with the combination of symptoms seen in this patient.Rate this question:
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- 5.
Patients with hypothyroidism also present with secondary hypercholesterolemia. One of the reasons for this is:
- A.
HMG-CoA red uctase is activated due to low levels of thyroid hormones
- B.
Low density lipoprotein receptors are upregulated in these patients
- C.
Large amounts of cholic acid are reabsorbed from the intestine which feeds back to 7-a-hydroxylase resulting in inactivation of the enzyme
- D.
High levels of thyroid hormones increase the synthesis of cholesterol
- E.
Thyroid hormones are necessary for the activation of 7a-hydroxylase
Correct Answer
E. Thyroid hormones are necessary for the activation of 7a-hydroxylaseExplanation
Thyroid hormones are necessary for the activation of 7a-hydroxylase. This enzyme is responsible for converting cholesterol into bile acids in the liver. Without sufficient thyroid hormones, 7a-hydroxylase cannot be activated, leading to decreased bile acid synthesis. This results in decreased feedback inhibition on cholesterol synthesis, leading to increased cholesterol levels in the blood. Therefore, patients with hypothyroidism may present with secondary hypercholesterolemia.Rate this question:
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- 6.
A deficiency in the activity of medium chain acyl-CoA dehydrogenase, an enzyme in the pathway for beta-oxidation of fatty acids, is corrected by large doses of its vitamin component in some patients. Which of the following compounds is the vitamin component of this enzyme?
- A.
Carnitine
- B.
Vitamin E
- C.
Riboflavin
- D.
Niacin
- E.
Thiamine
Correct Answer
C. RiboflavinExplanation
Riboflavin is the correct answer because it is the vitamin component of medium chain acyl-CoA dehydrogenase, an enzyme involved in the pathway for beta-oxidation of fatty acids. A deficiency in this enzyme's activity can be corrected by large doses of riboflavin. Carnitine, Vitamin E, Niacin, and Thiamine are not the correct vitamin components for this enzyme.Rate this question:
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- 7.
A patient presents to your clinic complaining of weakness and pain in the muscle and a general lack of energy. A blood test shows that he has high levels of creatine kinase and myoglobin. Urine analysis reveals very low levels of acetoacetate. This patient most likely has which of the following?
- A.
Complete absence of medium chain acyl-CoA dehydrogenase
- B.
Deficiency in one of the enzymes in the ketone body synthetic pathway
- C.
Carnitine deficiency
- D.
A low fat, high carbohydrate diet
- E.
Decreased production of insulin
Correct Answer
C. Carnitine deficiencyExplanation
This patient is most likely experiencing symptoms of carnitine deficiency. Carnitine is responsible for transporting fatty acids into the mitochondria for energy production. Without enough carnitine, the body cannot effectively use fatty acids as an energy source, leading to weakness, muscle pain, and a lack of energy. The high levels of creatine kinase and myoglobin suggest muscle damage, which can occur in carnitine deficiency. The low levels of acetoacetate indicate a disruption in the ketone body synthetic pathway, which is consistent with carnitine deficiency.Rate this question:
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- 8.
During starvation ketone bodies are synthesized in one of the following organs:
- A.
Skeletal muscle
- B.
Spleen
- C.
Liver
- D.
Heart
- E.
Brain
Correct Answer
C. LiverExplanation
During starvation, the body's primary source of energy shifts from glucose to fats. The liver plays a crucial role in this process by synthesizing ketone bodies, which are produced from fatty acids. These ketone bodies can then be used as an alternative fuel source by various organs, including the brain and heart, to meet their energy needs. Therefore, the correct answer is the liver.Rate this question:
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- 9.
A 29-year-old male decides to go on the Atkins diet. After approximately a month on the diet he complains of having what he describes as bad breath. What would be the biochemical findings in this patient?
- A.
Increased synthesis of fatty acids in adipose tissue due to excess free fatty acids released from adipose tissue
- B.
Decreased gluconeogenesis due to lack of activation of pyruvate carboxylase
- C.
Decreased levels of free fatty acids and undetectable ketone bodies in the plasma due to inactivation of LPL
- D.
Increased synthesis and recycling of fatty acids by the liver leading to increased adipose tissue storage of fats
- E.
Increased beta-oxidation due to increased activity of hormone sensitive lipase with subsequent increase in ketone bodies in plasma
Correct Answer
E. Increased beta-oxidation due to increased activity of hormone sensitive lipase with subsequent increase in ketone bodies in plasmaExplanation
The correct answer suggests that the patient on the Atkins diet is experiencing increased beta-oxidation due to increased activity of hormone-sensitive lipase. This leads to an increase in ketone bodies in the plasma, which can cause bad breath. The Atkins diet is a low-carbohydrate, high-fat diet, which promotes the breakdown of fats for energy through beta-oxidation. This results in the production of ketone bodies, which can be detected in the plasma and can contribute to the development of bad breath.Rate this question:
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- 10.
What is the importance of citrate in fatty acid metabolism?
- A.
Activation of fatty acid synthetase
- B.
To act as a precursor for addition of one carbon units
- C.
Activation of acetyl-CoA carboxylase
- D.
To add the activated carbon dioxide in the formation of malonyl-CoA
- E.
Activation of carnitine acyl transferase
Correct Answer
C. Activation of acetyl-CoA carboxylaseExplanation
Citrate plays a crucial role in fatty acid metabolism by activating acetyl-CoA carboxylase. Acetyl-CoA carboxylase is an enzyme that converts acetyl-CoA to malonyl-CoA, which is an important intermediate in fatty acid synthesis. Citrate binds to and activates acetyl-CoA carboxylase, promoting the conversion of acetyl-CoA to malonyl-CoA. This activation step is essential for the initiation of fatty acid synthesis. Therefore, the presence of citrate is necessary for the proper functioning of acetyl-CoA carboxylase and subsequent fatty acid metabolism.Rate this question:
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- 11.
The reducing equivalents necessary for fatty acid synthesis are produced during the conversion of:
- A.
Glyceraldehyde-1, 3-bisphosphate to 3-phosphoglycerate
- B.
Glucose-6-phosphate to ribulose-5-phosphate
- C.
Glucose-6-phosphate to fructose-6-phosphate
- D.
Citrate to malate
- E.
Pyruvate to lactate
Correct Answer
B. Glucose-6-pHospHate to ribulose-5-pHospHateExplanation
During the conversion of glucose-6-phosphate to ribulose-5-phosphate, the enzyme glucose-6-phosphate dehydrogenase catalyzes the reaction, producing NADPH as a byproduct. NADPH is a reducing equivalent that is utilized in fatty acid synthesis. Therefore, this conversion provides the reducing equivalents necessary for fatty acid synthesis.Rate this question:
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- 12.
When excess acetyl-CoA, produced by the liver, cannot be used by the TCA cycle, it accumulates in the body as:
- A.
Glucose
- B.
Triglycerides
- C.
P-hydroxybutarate
- D.
Acetyl-CoA
- E.
Glycogen
Correct Answer
C. P-hydroxybutarateExplanation
When excess acetyl-CoA cannot be used by the TCA cycle, it is converted into p-hydroxybutarate. This is a type of ketone body that accumulates in the body. Ketone bodies are produced during periods of prolonged fasting or low carbohydrate intake, when the body needs an alternative source of energy. p-hydroxybutarate can be used by the brain and other tissues as an energy source.Rate this question:
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- 13.
Which of the following disorders of sphingolipid metabolism can be treated by bone marrow transplant?
- A.
Fabrys
- B.
Tay-Sachs
- C.
Nieman-Pick
- D.
Gauchers
- E.
Krabbes
Correct Answer
D. GauchersExplanation
Gaucher's disease is caused by a deficiency of the enzyme glucocerebrosidase, resulting in the accumulation of glucocerebroside in cells. This leads to the enlargement of the liver and spleen, anemia, and bone abnormalities. Bone marrow transplant can be used as a treatment option for Gaucher's disease because it introduces healthy stem cells that can produce the missing enzyme, thereby correcting the underlying metabolic defect. This can help alleviate the symptoms and improve the quality of life for individuals with Gaucher's disease.Rate this question:
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- 14.
Which of the following organelles, which is defective in Gauchers disease, contains enzymes that degrade complex carbohydrates, proteins and complex lipids?
- A.
Lysosome
- B.
Peroxisome
- C.
Mitochondrion
- D.
Endoplasmic reticulum
- E.
Plasma membrane
Correct Answer
A. LysosomeExplanation
Lysosomes are organelles that contain enzymes capable of breaking down complex carbohydrates, proteins, and complex lipids. In Gaucher's disease, there is a defect in the lysosomal enzyme glucocerebrosidase, which leads to the accumulation of a lipid called glucocerebroside. This buildup affects various organs and tissues in the body, causing symptoms such as hepatosplenomegaly, anemia, and bone abnormalities. Therefore, the correct answer is lysosome.Rate this question:
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- 15.
Some of the apoproteins have very important functions in lipoprotein metabolism. Which of the following apoproteins is an important activator of lecithin cholesterol acyl transferase (LCAT)?
- A.
Apo All
- B.
Apo Al
- C.
Apo CII
- D.
Apo AIV
- E.
Apo E
Correct Answer
B. Apo AlExplanation
Apo Al is an important activator of lecithin cholesterol acyl transferase (LCAT).Rate this question:
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- 16.
Prostaglandins are synthesized from which of the following essential fatty acids?
- A.
Linolenic acid
- B.
Linoleic acid
- C.
Arachidonic acid
- D.
Ecosapentanoic acid
- E.
Palmitic acid
Correct Answer
A. Linolenic acidExplanation
Prostaglandins are synthesized from linolenic acid. Linolenic acid is an essential omega-3 fatty acid that is converted into other omega-3 fatty acids, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are precursors for the synthesis of prostaglandins. Linoleic acid is an essential omega-6 fatty acid, while arachidonic acid is a derivative of linoleic acid. Ecosapentanoic acid is a derivative of linolenic acid. Palmitic acid is a saturated fatty acid and is not involved in the synthesis of prostaglandins.Rate this question:
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- 17.
In patients with systemic lupus erythematosus, autoantibodies are produced to a membrane lipid in platelets, resulting in blood clotting disorders. This membrane lipid is:
- A.
Phosphatidylserine
- B.
Cardiolipin
- C.
Phosphatidyl inositol
- D.
Dipalmitoylphosphatidylcholine
- E.
Platelet activating factor
Correct Answer
B. CardiolipinExplanation
In patients with systemic lupus erythematosus, autoantibodies are produced to a membrane lipid called cardiolipin. This immune response leads to the formation of blood clots and clotting disorders. Cardiolipin is an important component of the inner mitochondrial membrane and is also found in the plasma membrane of various cells. The presence of autoantibodies against cardiolipin is a characteristic feature of lupus and is often used as a diagnostic marker for the disease.Rate this question:
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- 18.
A 5-year old female is presented with hepatosplenomegaly, abnormal bleeding disorders, defects in long bone development and neurological dysfunction. Laboratory analysis of a liver biopsy reveals that the patient has only 30 % activity of the enzyme glucoceribrosidase. This patient most likely is suffering from one of the following diseases:
- A.
Fa brys
- B.
Sandhoff-Jatzkewitz
- C.
Krabbes
- D.
Gauchers
- E.
Neimann-Pick
Correct Answer
D. GauchersExplanation
The patient is most likely suffering from Gaucher's disease. Gaucher's disease is a lysosomal storage disorder caused by a deficiency of the enzyme glucocerebrosidase. This enzyme is responsible for breaking down a fatty substance called glucocerebroside. The symptoms described in the patient, such as hepatosplenomegaly, abnormal bleeding disorders, defects in long bone development, and neurological dysfunction, are characteristic of Gaucher's disease. The laboratory analysis revealing only 30% activity of glucocerebrosidase further supports this diagnosis.Rate this question:
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- 19.
A 22-year-old woman with poorly controlled gestational diabetes delivers a large -forgestational-age infant at 24 weeks. Within six hours of birth the baby develops respiratory difficulties associated with rapid respiration and cyanosis. Which of the following substances is most likely deficient in this newborn?
- A.
Cardiolipin
- B.
Ceramide
- C.
Sphingomyelin
- D.
Dipalmitoyl phosphatidylcholine
- E.
Ganglioside
Correct Answer
D. Dipalmitoyl pHospHatidylcholineExplanation
The correct answer is Dipalmitoyl phosphatidylcholine. Dipalmitoyl phosphatidylcholine is a major component of pulmonary surfactant, which is essential for reducing surface tension in the alveoli and preventing alveolar collapse. In premature infants, surfactant production is limited, leading to respiratory distress syndrome. The large-for-gestational-age infant in this case likely has poorly controlled gestational diabetes, which can lead to accelerated lung maturation and increased surfactant production. However, the premature delivery at 24 weeks may still result in insufficient surfactant production, leading to respiratory difficulties.Rate this question:
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- 20.
The site of action of the nonsteroidal anti-inflammatory drugs is:
- A.
Thromboxane synthase
- B.
Prostaglandin E dehydrogenase
- C.
Lipoxygenase
- D.
Cyclooxygenase
- E.
Prostacyclin synthase
Correct Answer
D. CyclooxygenaseExplanation
Nonsteroidal anti-inflammatory drugs (NSAIDs) work by inhibiting the enzyme cyclooxygenase (COX). COX is responsible for the production of prostaglandins, which are inflammatory mediators that cause pain, fever, and inflammation. By inhibiting COX, NSAIDs reduce the production of prostaglandins, thereby reducing pain and inflammation. Thromboxane synthase, prostaglandin E dehydrogenase, lipoxygenase, and prostacyclin synthase are not the primary targets of NSAIDs and do not play a significant role in the anti-inflammatory effects of these drugs.Rate this question:
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- 21.
Which of the following ph spholipids induces hypersensitivity, triggers thrombotic events and causes alveolar n71acrophages to generate superoxide radicals?
- A.
Cardiolipin
- B.
Phosphatidylinositol
- C.
Plasmalogens
- D.
Dipalmitoylphophatidylcholine
- E.
Platelet activating factor
Correct Answer
E. Platelet activating factorExplanation
Platelet activating factor is the correct answer because it is known to induce hypersensitivity, trigger thrombotic events, and cause alveolar macrophages to generate superoxide radicals. Platelet activating factor is a potent lipid mediator that plays a role in various inflammatory and immune responses in the body. It is involved in platelet aggregation, bronchoconstriction, and the release of inflammatory mediators. Its ability to induce hypersensitivity reactions, promote blood clot formation, and stimulate the production of reactive oxygen species by alveolar macrophages contributes to its role in various pathological conditions.Rate this question:
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- 22.
Cytidine nucleotides are involved in phospholipid synthesis because:
- A.
They are involved in the activation of choline, ethanolamine and diacylglycerol (DAG)
- B.
They provide the energy to convert choline to ethanolamine
- C.
They are involved in the phosphorylation of choline and ethanolamine
- D.
They are recognition molecules for phospholipid transferases
- E.
They are important in signal transduction
Correct Answer
A. They are involved in the activation of choline, ethanolamine and diacylglycerol (DAG)Explanation
Cytidine nucleotides are involved in phospholipid synthesis because they play a crucial role in the activation of choline, ethanolamine, and diacylglycerol (DAG). These molecules need to be activated before they can be incorporated into phospholipids. Cytidine nucleotides provide the necessary chemical energy for this activation process. In other words, they help in the conversion of these molecules into their active forms, allowing them to participate in the synthesis of phospholipids, which are essential components of cell membranes.Rate this question:
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- 23.
Lipoprotein lipase is a very important enzyme in lipid metabolism. Found on many tissues in the body its main function is to facilitate the fatty acid uptake in these tissues. In a patient with severely decreased insulin output after a meal, what would you expect to be the metabolic outcome?
- A.
The patient can go into cardiac arrest because of lack of fatty acids for ATP production.
- B.
A plasma sample taken 45 minutes after a meal would reveal high levels of triglycerides due to lack of function of adipose tissue lipoprotein lipase
- C.
Coma could result because of lack of fatty acids as fuel for the brain
- D.
The patient would present with low levels of plasma ketone bodies due to lack of uptake of fatty acids in liver
- E.
A plasma sample would reveal both low levels of triglycerides and glucose
Correct Answer
B. A plasma sample taken 45 minutes after a meal would reveal high levels of triglycerides due to lack of function of adipose tissue lipoprotein lipase -
- 24.
A patient reports to you that he has had aches and pains in his muscles for the past seven days. A blood test shows increased levels of creatine kinase MM, fatty acids and also myoglobin. A second blood sample, this time taken after an overnight fast, revealed low levels of blood glucose and elevated very low density lipoprotein (VLDL). This patient most likely has which of the following conditions?
- A.
Essential amino acid deficiency
- B.
Type 1 glycogen storage disease
- C.
Acute alcohol toxicity
- D.
Carnitine acyltranferase deficiency
- E.
Elevated insulin levels, which cause the hypoglycemia and increase fatty acid mobilization from adipose tissue
Correct Answer
D. Carnitine acyltranferase deficiencyExplanation
This patient most likely has carnitine acyltransferase deficiency. Carnitine acyltransferase deficiency is a disorder that impairs the transportation of fatty acids into the mitochondria for energy production. This leads to the accumulation of fatty acids in the blood, which can cause muscle pain and weakness. The elevated levels of creatine kinase MM, fatty acids, and myoglobin further support this diagnosis. The low levels of blood glucose and elevated VLDL in the second blood sample are consistent with the metabolic abnormalities seen in carnitine acyltransferase deficiency.Rate this question:
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- 25.
System-based practice Measurement of healthcare systems occurs on many levels. Measurement may be used for research, for judgment, and for improvement of care. Here is a table comparing outcomes of care at a state level with a composite score, acute myocardial infarction (AMI), chronic heart failure (CHF) and pneumonia. Table. Technical Process Quality Measure Scores (0-100; low—hi) State Composite AMI CHF Pneumonia California 86 93 94 72 Connecticut 80 90 84 61 Massachusetts 93 96 95 87 This is an example of what type of measurement?
- A.
Research
- B.
Judgment
- C.
Improvement
- D.
Combination of judgment and improvement
Correct Answer
B. JudgmentExplanation
This table comparing outcomes of care at a state level with quality measure scores is an example of judgment. The scores provide a basis for evaluating and making judgments about the performance of healthcare systems in different states. By comparing the scores for different conditions, such as acute myocardial infarction, chronic heart failure, and pneumonia, judgments can be made about the quality of care provided in each state.Rate this question:
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- 26.
You are working with a team in mental health to improve the access time for new patients in psychiatry clinic. Over the past several months, the clinic has seen an increase in the number of patients, but this has led to long wait times for some patients to get seen in the clinic. The clinic has set a goal of referral to appointment date of 21 days. You examine the number of days from a patient's referral until he or she is seen in the clinic and chart the past 30 patient referrals on the following run chart. You notice a trend with 8 increasing data points from patient 18 through patient 25. What is the appropriate next step for the team?
- A.
Ignore the special cause as it is likely not important .
- B.
Although the trend was upward, it isn’t important since the most recent data (patients 28- 30) show that the process is improving.
- C.
Start a patient access committee for mental health
- D.
Patient access to appointment is not a physician's responsibility This work should be referred to administrative staff.
- E.
Investigate the special cause signal to find why the time from referral to appointment increased.
Correct Answer
E. Investigate the special cause signal to find why the time from referral to appointment increased.Explanation
The appropriate next step for the team is to investigate the special cause signal to find why the time from referral to appointment increased. This is because the trend of increasing data points from patient 18 through patient 25 suggests a potential issue or factor that is causing the increased wait times. It is important to identify and address the specific cause in order to improve the access time for new patients in the psychiatry clinic.Rate this question:
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Mar 21, 2023Quiz Edited by
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Feb 22, 2012Quiz Created by
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