Renin Angiotensin Aldosterone System (RAAS): Pathway, Functions & Terms

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Kidney Disease

When liver disease is detected, it may be monitored on a regular basis over time with the liver panel or with one or more of its components.

A liver panel may also be ordered regularly to monitor the effectiveness of treatment for the liver disorder. Liver panel test results are not diagnostic of a specific condition; they indicate that there may be a problem with the liver. In a person who does not have symptoms or identifiable risk factors, abnormal liver test results may indicate a temporary liver injury or reflect something that is happening elsewhere in the body — such as in the skeletal muscles, pancreas, or heart.

Results of liver panels are usually evaluated together. Several sets of results from tests performed over a few days or weeks are often assessed together to determine if a pattern is present. Each person will have a unique set of test results that will typically change over time.

A healthcare practitioner evaluates the combination of liver test results to gain clues about the underlying condition. This table shows examples of some combinations of results that may be seen in certain types of liver conditions or diseases. If a person is taking drugs that may affect their liver, then abnormal test results may indicate a need to reevaluate the dosage or choice of medication.

When a person with liver disease is being monitored, then the healthcare practitioner will evaluate the results of the liver panel together to determine if liver function or damage is worsening or improving. Moderate increases may be seen with chronic hepatitis. People with blocked bile ducts, cirrhosis, and liver cancer may have ALT concentrations that are only moderately elevated or close to normal.

Alkaline phosphatase ALP ALP may be significantly increased with obstructed bile ducts, cirrhosis, liver cancer, and also with bone disease. AST may be normal to moderately increased with chronic hepatitis. In people with blocked bile ducts, cirrhosis, and liver cancer, AST concentrations may be moderately increased or close to normal.

When liver damage is due to alcohol, AST often increases much more than ALT this is a pattern seen with few other liver diseases. AST is also increased after heart attacks and with muscle injury. Bilirubin Bilirubin is increased in the blood when too much is being produced, less is being removed, due to bile duct obstructions, or to problems with bilirubin processing.

It is not uncommon to see high bilirubin levels in newborns, typically 1 to 3 days old. Albumin Albumin is often normal in liver disease but may be low due to decreased production. Total protein TP Total protein is typically normal with liver disease. Increased GGT levels are also seen with alcohol consumption and with conditions, such as congestive heart failure.

Lactate dehydrogenase LD This is a non-specific marker of tissue damage. It is usually not elevated with most liver diseases, but it may be elevated with very acute liver disease or liver tumors. It is also elevated with a number of other conditions that do not affect the liver.

Prothrombin time PT A prolonged or increased PT can be seen with liver disease, vitamin K deficiency , use of drugs to reduce risk of clotting warfarin , and with coagulation factor deficiencies. Your healthcare provider will want to evaluate everything you are taking as a whole.

Many over-the-counter drugs and herbal or dietary supplements have the potential to affect the liver. For instance, both excessive acetaminophen use and the combination of acetaminophen and alcohol can cause severe liver damage. Yes, early acute liver disease and chronic liver disease often cause no symptoms or mild nonspecific symptoms, such as fatigue and nausea.

Yes, many temporary conditions, such as shock, burns, severe infections, muscle trauma, dehydration , pancreatitis , hemolysis , and pregnancy , can cause one or more of the liver function tests to be abnormal. Some liver conditions, such as hemochromatosis and Wilson disease , may be inherited and can progressively damage the liver.

Early detection of these conditions allows them to be treated and managed appropriately. Depending on the results of the liver panel and other factors such as signs , symptoms and clinical and family history, a healthcare practitioner may suspect a particular cause of liver disorder and order follow-up tests. American Liver Foundation MedlinePlus: Jan 30, Taylor, W, Ziegler, O.

University of Rochester Medical Center. Available online at https: August Yamini Durani, MD. Hepatic Liver Function Panel. Available online at http: Feb 4 Sood G. Pagana K, Pagana T. Mosby's Manual of Diagnostic and Laboratory Tests. Mayo Clinic staff July College of American Pathologists [On-line information]. PDF available for download through http: Hepatic [Liver] Function Panel. KidsHealth from Nemours [On-line information]. Mosby's Diagnostic and Laboratory Test Reference. Pp , , , , , , Tietz Clinical Guide to Laboratory Tests.

Pp , , , , , Harrison's Principles of Internal Medicine. Contemporary Practice in Clinical Chemistry. Updated October MedlinePlus Medical Encyclopedia [On-line information]. American Liver Foundation [On-line information].

Approach to the Patient with Liver Disease: Cleveland Clinic [On-line information]. Available online through http: Merck Manual for Healthcare Professionals [On-line information]. If your question relates to this web site and not to a specific lab test, please submit it via our Contact Us page instead.

Send Us Your Feedback. Choose Topic At a Glance What is being tested? This article was last reviewed on March 10, This article was last modified on March 20, When To Get Tested? Mevalonate is phosphorylated sequentially by ATP by three kinases, and after decarboxylation the active isoprenoid unit, Isopentenyl pyrophosphate C5 , is formed.

Isopentenyl diphosphate is isomerized by a shift of the double bond to form dimethylallyl pyrophosphate, then condensed with another molecule of Isopentenyl diphosphate to form the ten-carbon intermediate Geranyl pyrophosphate C A further condensation of Geranyl pyrophosphate C10 with Isopentenyl pyrophosphate forms Farnesyl pyrophosphate C Cholesterol is the final product of the pathway.

Which of the following compounds is the direct precursor for the heme nitrogen atoms? Heme is synthesized in living cells by a pathway that requires Succinyl-CoA, derived from the citric acid cycle in mitochondria, and the amino acid glycine. Through a number of further steps Heme is synthesized. Glucose does not have nitrogen in its structure to contribute towards heme formation, whereas alanine and methionine do possess amino groups but they do not contribute to Heme nitrogen.

A pregnant woman is able to transfer oxygen to her fetus because fetal hemoglobin has a greater affinity for oxygen than does adult hemoglobin. Why is the affinity of fetal hemoglobin for oxygen higher?

The right answer is -c. It is not due to more prevalence of tense form of fetal hemoglobin in the circulation. It is also not due to less 2, 3 BPG in the fetal circulation, the Bohr Effect is not enhanced in the fetus and the oxygen -binding curve of fetal Hb is also not shifted to the right. In Hb A adult Hb when 2, 3-BPG binds to deoxyhemoglobin, it acts to stabilize the low oxygen affinity state T state of the oxygen carrier, exploiting the molecular symmetry and positive polarity by forming salt bridges with lysine and histidine residues in the four subunits of hemoglobin.

The R state, with oxygen bound to a heme group, has a different conformation and does not allow this interaction. By selectively binding to deoxyhemoglobin, 2, 3-BPG stabilizes the T state conformation, making it harder for oxygen to bind hemoglobin and more likely to be released to adjacent tissues.

Fetal hemoglobin HbF exhibits a low affinity for 2, 3-BPG, resulting in a higher binding affinity for oxygen. A year-old female presents with severe dehydration and decreased urine output. Her blood urea nitrogen level is abnormally elevated because her kidneys are not able to excrete urea in the urine.

In the production of urea, which of the following is an important intermediate? Urea formation requires the participation of 6 amino acids which are aspartic acid, ornithine, citrulline, argino succinic acid, arginine and N-Acetyl glutamate. Out of these N -Acetyl glutamate is the only amino acid that acts as an allosteric activator of Carbamoyl phosphate synthase-1 enzyme, rest all participate in urea formation. Ornithine acts as a catalyst in the process of urea formation.

Ornithine is a non standard amino acid, it is not incorporated in to tissue proteins but it participates in urea formation and polyamine synthesis. Serine does not participate in urea formation. It is glucogenic, incorporated in to tissue proteins, required for synthesis of glycine, cysteine and sphingosine. Also participates in one carbon metabolism, forming O- glycosidic linkages and is present in at the active site of many enzymes.

Glutamate is a precursor of GABA, glutamine, glucogenic, a neurotransmitter and is incorporated in to tissue proteins. It does not participate in urea formation. Proline also does not participate in urea formation; it is incorporated in to tissue proteins and is present at those places where kinks or bends are needed in the folding of the proteins since it is an imino acid.

Collagen is rich in hydroxy proline its hydroxylated form. Leucine is a branched chain amino acid; it is purely ketogenic and has no role in urea formation. Which of the following is a common compound shared by the TCA cycle and the urea cycle? Alpha ketoglutarate is an intermediate of TCA cycle; it has no connection with urea cycle.

Argino succinic acid is an intermediate of urea cycle and is formed by condensation of aspartic acid and Citrulline. It is not connected to TCA cycle, but upon breakdown it produces Arginine and fumarate. Fumarate is channeled towards TCA cycle. Fumarate is converted to malate and then to oxaloacetate through TCA cycle enzymes.

Oxalo acetate is transaminated to form Aspartic acid that can be reutilized to form Argino succinic acid for continuation of urea cycle. Aspartic acid is needed in urea formation but it is not an intermediate of TCA cycle. Which enzyme often mal functions in diseases associated with the symptoms of high blood triglyceride levels and Steatorrhea? Steatorrhea occurs due to impaired digestion and absorption of lipids and other chief nutrients.

It is characterized by passage of bulky stools and is often associated with deficiencies of fat soluble vitamins. Hypertriglyceridemia is a characteristic finding in Pancreatitis and there are several causes of Acute and chronic pancreatitis. In pancreatic disorders, pancreatic lipase deficiency results in impaired digestion of lipids as well as other nutrients causing Steatorrhea.

Phospholipase D enzyme is required for removal of nitrogenous base from phospholipid. It cannot cause the symptoms of high blood triglyceride levels and Steatorrhea. Lipoprotein lipase is an enzyme for the degradation of triglacylglycerols present in chylomicrons and VLDL.

Impaired activity can cause increase in serum triacylglycerol levels but Steatorrhea is unlikely to happen. Thiokinase is the first enzyme of beta oxidation of fatty acids.

It is required for the conversion of free fatty acid to fatty acyl co A activation of fatty acid ; it is also called Acyl Co A synthetase. This enzyme has nothing to do with lipid digestion or absorption and is not involved in the synthesis or degradation of triacylglycerols. Acetyl co A carboxylase is an enzyme of fatty acid synthesis.

It catalyzes the first step of conversion of acetyl co A to malonyl co A. It is the rate limiting step of de no fatty acid synthesis, malfunctioning of this enzyme cannot cause increase in TGs or Steatorrhea.

An infant is born with a high forehead, abnormal eye folds, and deformed ear lobes. He shows little muscle tone and movement. After multiple tests, he is diagnosed with Zellweger syndrome, a disorder caused by malformation of peroxisomes. Which of the following is expected to be high in concentration in brain tissue of the affected individual?

Zellweger syndrome, also called cerebrohepatorenal syndrome is a rare, congenital disorder present at birth , characterized by the reduction or absence of Peroxisomes in the cells of the liver, kidneys, and brain. In Zellweger syndrome the Peroxisomal trimming is impaired, thus VLFA accumulate in brain and blood of affected patients. The option ketone body is ruled out because the above said symptoms are not characteristic of ketosis.

Lactate is also ruled out because excess of lactate lactic acidosis is also not a congenital disorder; lactate accumulates either due to non utilization as in liver disorders or excessive production as in anaerobic conditions.

Cholesterol excess, hypercholesterolemia is also not the right option; the symptoms are suggestive of a congenital disorder that has affected the brain and physical growth. There is no such clinical state associated with hypercholesterolemia and impaired mental development. Hyperglycemia is also not the right choice. Hyperglycemia is never associated with malformation of peroxisomes.

Hence the right option is very long chain fatty acids. For further details of Zellweger syndrome follow the link. Which of the following enzymes is most likely inhibited? The right answer is d — Alpha ketoglutarate dehydrogenase deficiency. The patient is most probably suffering from cardiac beriberi.

The above said patient is a known alcoholic, mal nourished and has heart failure. The probable diagnosis is Thiamine deficiency, which can be confirmed by Erythrocyte Transketolase activity. Thiamine is required as a coenzyme for Pyruvate dehydrogenase complex, alpha ketoglutarate dehydrogenase complex, transketolase and alpha keto acid dehydrogenase complex. Out of all the given options only alpha ketoglutarate dehydrogenase is the only enzyme which is Thiamine dependent and that could possibly be inhibited in beri-beri.

Aconitase is iron dependent enzyme of TCA cycle. All the enzymes enlisted are though enzymes of TCA cycle, but the deficiencies of Aconitase, citrate synthase, isocitrate dehydrogenase and succinate thiokinase are unknown. Alpha ketoglutarate dehydrogenases deficiency is unknown but its impaired activity is observed in thiamine deficiency.

A month-old girl was found to have ingested approximately 30 mL of an acetonitrile-based cosmetic nail remover when she vomited 15 minutes post ingestion. The poison control center was contacted, but no treatment was recommended because it was confused with an acetone-based nail polish remover. The child was put to bed at her normal time, which was 2 hours post ingestion. Respiratory distress developed sometime after the child was put to bed, and she was found dead the next morning.

The right answer is-b — Cytochrome oxidase. Acetonitrile is used mainly as a solvent. Acetonitrile has only a modest toxicity in small doses.

It can be metabolized to produce hydrogen cyanide, which is the source of the observed toxic effects. Generally the onset of toxic effects is delayed, due to the time required for the body to metabolize acetonitrile to cyanide generally about 2—12 hours. It has been used in formulations for nail polish remover, despite its low but significant toxicity. Acetone and ethyl acetate are often preferred as safer for domestic use, and acetonitrile has been banned in cosmetic products in the European Economic Area since March Cyanide released from the metabolism of acetonitrile, is an inhibitor of Cytochrome oxidase.

Cyanide and azide react with the ferric form of heme a 3, whereas carbon monoxide inhibits the ferrous form. Inhibition of the electron-transport chain also inhibits ATP synthesis because the proton-motive force can no longer be generated. The options given above represent the complexes of electron transport chain. There are site specific inhibitors for each of the complexes of electron transport chain.

It is only cytochrome oxidase that is inhibited by Cyanide. For further details- follow the link given below. Which of the following enzymes is not present in adipose tissue? Answer- b The right answer is Glycerol kinase. It is absent in adipose tissue, that is the reason glycerol released by hydrolysis of triglycerides cannot be reutilized there.

It is a waste product. It is transported through blood to liver where it is first phosphorylated to form GlycerolP, by glycerol kinase and then converted to Dihydroxy acetone phosphate by the action of glycerolP dehydrogenase. DHAP can be either used for glucose production or oxidized through glycolysis as per the need. In adipose tissue glycerolp is obtained through glycolysis from dihydroxy acetone phosphate for esterification to form triglyceride.

Hexokinase and Phosphofructokinase are enzymes of glycolytic pathway, they are present in muscle. Hormone sensitive lipase is the enzyme for breakdown of triglycerides; it is present in adipose tissue.

Acetyl co A carboxylase is the rate limiting enzyme of fatty acid synthesis, it catalyzes the first step of conversion of acetyl co A to malonyl co A, and it is present in adipose tissue.

A postpartum woman from a rural community recently gave birth to a baby boy with the aid of a midwife at home. She now brings the baby to the hospital because of continued bleeding and oozing from the umbilical stump. It is likely that this bleeding diathesis is secondary to a deficiency of which vitamin? The right answer is-b Vitamin K. Newborn infants are at risk of developing vitamin K deficiency, and this coagulation abnormality leads to serious bleeding.

Transplacental transfer of vitamin K is very limited during pregnancy, and the storage of vitamin K in neonatal liver is also limited. This makes the newborn infant uniquely vulnerable to hemorrhagic disorders unless exogenous vitamin K is given for prevention of bleeding immediately after birth. Vitamin A has a role in vision, repair, reproduction and maintenance of epithelial structures. Deficiency is known to cause ophthalmological defects leading eventually to blindness.

Vitamin E is primarily an antioxidant and has also a role in reproduction. Vitamin D — Its main function is in the regulation of calcium absorption and homeostasis. It has no role in coagulation of blood. Deficiency causes rickets in children and osteomalacia in adults. Folic acid has a role in nucleotide synthesis and acts as a carrier of one carbon fragments.

Deficiency causes megaloblastic anemia. A year-old male presents with excruciating pain in his left flank. He is diagnosed to have a kidney stone and is prescribed citrate to help prevent future stone formation. Which of the following would be most likely to inhibit Isocitrate dehydrogenase?

Isocitrate dehydrogenase is inhibited by excessive concentration of NADH. Acetyl co A, in excess inhibits PDH complex, but it has no effect on activity of Isocitrate dehydrogenase. A year-old female presents with severe abdominal pain. Her serum amylase and lipase levels are abnormally elevated and she is diagnosed with pancreatitis.

Which linkage between glucose residues is cleaved by amylase? Answer- a alpha — 1, 4 is the right answer. Both starch and glycogen are polymers of glucose. A year-old -girl presents with polyuria, polydipsia and polyphagia. She is diagnosed with Type 1 Diabetes mellitus, a disease characterized by a deficiency of Insulin. Which of the following would occur in this patient? Answer- The right answer is -e Increased conversion of fatty acids to acetyl co A. In diabetes mellitus, Insulin to glucagon ratio is reversed as a result there is a state of catabolism.

Triglycerides stores in adipose tissue are decreased due to adipolysis under the influence of glucagon. In diabetes mellitus, de novo fatty acid synthesis in liver is deceased because in insulin deficiency the catalytic activity of Acetyl co A carboxylase rate limiting — insulin dependent enzyme is decreased, hence the overall pathway is inhibited. Cholesterol synthesis in diabetes mellitus is increased. It is expected that cholesterol synthesis would decrease in insulin deficiency since insulin stimulates the activity of HMG Co A reductase rate limiting enzyme of cholesterol pathway , but on the contrary de novo cholesterol synthesis is increased.

In diabetes mellitus, due to non utilization of glucose, fatty acid oxidation takes place excessively to compensate for energy, as a result there is accumulation of acetyl co A product of fatty acid oxidation. Excess acetyl co A since TCA cycle is in a state of suppression is channeled either towards ketogenic pathway or it is utilized for cholesterol synthesis.

Uncontrolled diabetes mellitus is a commonest cause of hypercholesterolemia. Which of the following is a compound formed from both a hydroxylation with an enzyme requiring vitamin C and subsequent methylation? Neural cells convert tyrosine to epinephrine and norepinephrine. Tyrosine is first converted to DOPA by tyrosine hydroxylase enzyme. Dopa decarboxylase, a pyridoxal phosphate-dependent enzyme, forms dopamine.

In the adrenal medulla, phenyl ethanolamine- N -methyltransferase utilizes S -adenosylmethionine to methylate the primary amine of norepinephrine, forming epinephrine. Gamma Amino butyrate GABA functions in brain tissue as an inhibitory neurotransmitter by altering transmembrane potential differences.

It is formed by decarboxylation of glutamate, a reaction catalyzed by L-glutamate decarboxylase. Glycine, arginine, and methionine all participate in creatine biosynthesis. Synthesis of creatine is completed by methylation of guanidoacetate by S -adenosylmethionine. Creatinine is an anhydrous product of creatine. Serotonin 5-hydroxytryptamine , a potent vasoconstrictor and stimulator of smooth muscle contraction, is formed by hydroxylation of tryptophan to 5-hydroxytryptophan followed by decarboxylation.

A deficiency of biotin in higher animal is likely to be accompanied by which one of the following: Answer- The right answer is c — Defective synthesis of fatty acids. Biotin is mainly required as a coenzyme for carboxylation reactions and the main examples are carboxylation of-i pyruvate to oxaloacetate first step of gluconeogenesis ; ii Acetyl co A to Malonyl co A first step of fatty acid synthesis and iii Propionyl co A to D-Methyl malonyl co A in the conversion of propionyl co A to Succinyl co A to gain entry to TCA cycle.

In biotin deficiency, out of the given options, defective fatty acid synthesis is the most suited option because of the impaired conversion of acetyl co A to malonyl co A.

Biotin is also not needed as a coenzyme during the conversion of pyruvate to Acetyl co A. Formation of lactic acid in muscle takes place from pyruvate in a reaction catalyzed by lactate dehydrogenase which requires NADH as a coenzyme. A 54 -year-old Native- American living on an Indian reservation in southwest Arizona presents to the clinic with impaired memory, diarrhea and a rash on the face, neck, and dorsum of hands.

It is likely that the patient has a deficiency of which of the following vitamins? Pellagra is a common finding in Maize eaters.

Maize lacks tryptophan which is an endogenous source of niacin, besides that niacin is also present in the bound form in maize that is biologically unavailable. Hence maize eaters always carry a predisposition to niacin deficiency. There is no specific disorder associated with Vitamin E deficiency, but generalized neurological symptoms and infertility have been found to be associated with vitamin E deficiency. Deficiency of vitamin B6 is manifested by skin changes pellagra , neurological changes and Sideroblastic anemia.

Vitamin B6 is required as a coenzyme in the pathway of niacin synthesis from tryptophan. Hence B6 deficiency also leads to niacin deficiency. A year-old man presents with severe pain in his legs upon walking. He is diagnosed with atherosclerotic plaques in the arteries of his legs.

High level of cholesterol and LDL contribute to the formation of atherosclerotic plaques. Which of the following is metabolized to form LDL? The primary function of LDL is to provide cholesterol to the peripheral tissues. Cholesterol cannot be the answer, since it is through lipoproteins only that cholesterol is transported to the peripheral tissues. Cholesteryl esters are esterified forms of cholesterol.

A fatty acid is esterified at 3-OH group of cholesterol. Plasma contains both free and esterified cholesterol. Chylomicrons are transporters of dietary lipids. Upon metabolism in the similar way as VLDL, they are converted to chylomicron remnants that are removed from the circulation by liver.

A 5-year-old boy presents with altered mental status, heart failure and muscle weakness. His serum level of glucose and ketone are abnormally low. He is diagnosed with primary carnitine deficiency. Had there been no carnitine deficiency, how many ATP molecules would have been produced form the complete oxidation of a fatty acid with 14 carbon atoms?

Fatty acid with 14 carbon atoms will undergo 6 cycles of beta oxidation and yield 7 Acetyl co A. A year-old female presents with complaints of intestinal bloating, gas, cramps, and diarrhea following a meal including dairy products. A lactose-tolerance test confirms that she has a deficiency of lactase. Which of the following dairy products could you recommend that would be least likely to cause her difficulties in the future?

A 25 year-old female meets with her family physician. She is interested in starting a family soon and is looking for advice on what nutritional supplements would be beneficial during pregnancy. Which of the two supplements should be considered as the most important? A 16 -year-old girl presents with severe menstrual camping, caused by increased prostaglandin production. Prostaglandins are synthesized from which of the following? A 45 -year-old man presents with multiple gunshot wounds to the abdomen.

He undergoes emergent surgery during which a part of his intestine is resected. After surgery he is placed on total parenteral nutrition TPN , an intravenous form of nutrition. TPN supplies essential fatty acids also in the diet. Which of the following is an essential fatty acid? A 35 year-old woman presents with severe upper abdominal pain, nausea and vomiting.

She is diagnosed with pancreatitis an inflammation of pancreas. Triglycerides are primarily synthesized in which of the following tissues? The child has a history of epilepsy and ataxia. Blood biochemistry reveals lactic acidosis. Which of the following products is the fate of pyruvate when the reaction is catalyzed by pyruvate carboxylase?

After digestion of a piece of cake that contains flour, milk and sucrose as its primary ingredients, the major carbohydrate products entering the blood are-. Which of the following enzymes is not present in muscle? A year-old man with a long history of poorly controlled hypertension presents to the emergency with a severe headache. Which of the following products derived from amino acids, might bring down his highly elevated blood pressure?

Lactase breaks down lactose into two simpler forms of sugar called glucose and galactose, which are then absorbed into the bloodstream. Lactose intolerance is caused by a deficiency of the enzyme lactase, which is produced by the cells lining the small intestine. Enzyme levels are highest shortly after birth and decline with aging, despite a continued intake of lactose.

Most people with lactose intolerance can tolerate some amount of lactose in their diet. Gradually introducing small amounts of milk or milk products may help some people adapt to them with fewer symptoms. Lactose-free, lactose-reduced milk , Soy milk and other products may be recommended. Yogurt is also a good source of dietary calcium. Thus yogurt would cause least difficulties and can be safely recommended to the patient. Copper and selenium are the trace elements that are rarely deficient.

Thiamine is present in grain products. Vitamin C and D are sufficiently obtained from the diet. Vitamin A derivative are teratogenic and therefore should be avoided during pregnancy.

Vitamin K deficiency is common in newborns and often the supplementation is required after birth. Arachidonate, which may be obtained from the diet, but is usually derived from the 2nd position of phospholipids in the plasma membrane by the action of phospholipase A2, is the substrate for the synthesis of the prostanoids — prostaglandins PG2 and thromboxane TX2 series by the cyclooxygenase pathway, or the leukotrienes- LT4 and Lipoxins -LX4 series by the lipoxygenase pathway, with the two pathways competing for the arachidonate substrate.

Arachidonic acid is relatively non-essential since it can be synthesized from Linoleic acid in the body. Palmitic acid is a saturated fatty acid with 18 carbon atoms.

Elaidic and oleic are Trans and cis isomers respectively with 18 carbon atoms. Elaidic acid is the major Trans fat found in hydrogenated vegetable oils. Erucic acid has 22 carbon atoms and one double bond. Triglycerides are mainly synthesized in the liver but they can also be synthesized in the adipose tissue and intestinal cells. In the liver they are packaged in VLDL and are secreted in to the blood. The triglycerides synthesized in the intestine are packaged in chylomicrons and are transported to peripheral cells for utilization.

Triglycerides cannot be synthesized in skeletal, heart muscle, spleen and red blood cells. They are stored in adipose tissue and liver. Biotin is required as a cofactor in this energy requiring reaction. Lactate is the product of lactate dehydrogenase catalyzed reaction. Acetyl co A is the product of pyruvate dehydrogenase reaction. Acetaldehyde is the product of pyruvate decarboxylase catalyzed reaction that does not occurs in human beings.

This reaction is common in micro organisms and is commercially used for fermentation of glucose for wine production. No oxygen is used; hence the right answer is zero 0. Glycolysis can provide energy in the absence of oxygen; it is the unique pathway that can operate both aerobically as well as anaerobically.

One mol of glucose yields 2 moles of lactate, with a yield of 2ATP by substrate level phosphorylation. In aerobic respiration via Electron transport chain O2 is used as a final acceptor and is reduced to water. Flour- Starch-Starch is a polymer of glucose.

The digestion of starch would produce glucose. Milk- Lactose milk sugar. Lactose is a disaccharide of galactose and glucose.

Thus the digestion products of milk would be galactose and glucose. Sucrose is a disaccharide, made up of glucose and fructose. Digestion by sucrase in intestine would produce glucose and fructose. At the end, the net products of digestion entering blood would be — Glucose, galactose and fructose. Glucosep produced from gluconeogenesis or from degradation of glycogen is channeled towards glycolytic pathway in muscle.

Lactate dehydrogenase is not absent in muscle. Hexokinase is the first enzyme of glycolytic pathway, glycogen synthase is the rate controlling enzyme of glycogenesis synthesis and phosphorylase is the rate limiting enzyme of glycogen degradation, all these three are present in muscle. This may be accomplished with IV nitroprusside, a short-acting vasodilator with a rapid onset of action that allows for minute-to-minute control of blood pressure.

Nitroprusside acts by releasing Nitric oxide NO. Nitric oxide was previously referred as endothelial derived relaxing factor. It is a smooth muscle relaxant and a potent vasodilator. Melanin is derived from Tyrosine and is the major pigment of skin and hair. GABA gamma amino butyric acid , a decarboxylation product of glutamic acid is an inhibitory neurotransmitter. Dopamine is derived from decarboxylation of DOPA, which is a product of tyrosine.

Dopamine is used for raising the blood pressure in patients of shock. It is a stimulatory neurotransmitter. Serotonin is derived from tryptophan; it is also a vasoconstrictor and a stimulatory neuro transmitter.

Serotonin is involved in mood elevation and depression. His brain has reduced its need for glucose by using which of the following substances as an alternate source of energy? Laboratory examination reveals ketones in her urine.

Which of the followings is the most likely source of ketones? What is the possible cause for these symptoms? Which of the following enzymes would most likely be deficient? Imaging reveals a compression fracture of one of the vertebrae and diffuse osteoporosis, which is a common condition resulting from calcium depletion in bones.

As a treatment she should be prescribed. She is diagnosed with bacterial pneumonia. She is a known case of type 1 Diabetes mellitus. She injects herself subcutaneously every day with exogenous insulin.

As insulin is absorbed into her blood it binds to insulin receptors that activate-. In preparation, the intern has not eaten from the past 15 hours. The liver, to maintain blood glucose levels, is synthesizing glucose via the gluconeogenic pathway. Which of the following enzymes involved in these pathways would be most likely to exhibit Michaelis—Menten kinetics, that is, have a hyperbolic curve when plotting substrate concentration versus velocity of the reaction?

The patient is diagnosed with arsenic poisoning, which inhibits which of the following enzymes? The physician suspects lead poisoning. Lead typically interferes with which of the following enzymes? Ketone bodies serve as alternative fuel for brain during prolonged fasting or starvation.

Fatty acids due to long hydrophobic chain cannot cross blood brain barrier. Glycerol is a substrate of gluconeogenesis. It can be oxidized through glycolysis after phosphorylation. Beta carotene is a provitamin ; it is not a source of energy. Amino acids cannot be directly utilized, the carbon skeleton is oxidized in TCA cycle to provide energy or is used for glucose production.

In Diabetes Mellitus glucose utilization is impaired due to absolute or relative insulin deficiency. Fatty acid breakdown occurs to provide energy and the resultant excessive Acetyl co A enters the pathway of ketogenesis. Protein breakdown provides amino acids, 6 amino acids are ketogenic , while 14 are glucogenic. Hence protein breakdown contributes only a little towards formation of Acetyl co A. The major contribution is through fatty acid breakdown. Glycogenolysis and Gluconeogenesis produce glucose only.

Glucose oxidation produces pyruvate or lactate, but in diabetes mellitus glucose utilization is impaired. The clinical manifestations are typical of classical Galactosemia. In juvenile diabetes mellitus, jaundice and hepatomegaly are not observed. Erythrocytes lack mitochondria so the end product of glycolysis is always lactate.

The mode of glycolysis during intense exercise is anaerobic; hence lactate is formed as a result of glycolysis. Alanine is transported to liver through Glucose Alanine cycle. Glycerol is also similarly transported but not from the erythrocytes or skeletal muscles, rather from the adipose tissues.

Glycerol is a waste product in adipose tissues since without phosphorylation it cannot be utilized and the phosphorylating enzyme glycerol kinase is absent in adipose tissues.

Acetyl co A cannot be produced since pyruvate to acetyl co A conversion takes place in mitochondria, Whereas RBCs lack mitochondria, hence this conversion is not possible. During the process of glycogen synthesis, branching enzyme creates branch points and further elongation is carried out by Glycogen synthase. Alpha Amylase is an enzyme for digestion of starch and glycogen. Debranching enzyme deficiency results in the accumulation of abnormal glycogen, There is inability to remove the branch points, the resultant structure resembles Limit dextrin , thus it is also called Limit dextrinosis.

Glycogen synthase deficiency is rare but even if it is there it affects overall glycogen synthesis, since glycogen synthase is the key regulatory enzyme of pathway of glycogen synthesis. Even chain fatty acids, predominantly present in our body, yield Acetyl co A upon oxidation, which can not contribute towards gluconeogenesis.

It is not observed in Type 2 diabetes. Hyperglycemic Nonketotic hyperosmolar coma is observed in elderly patients of type 2 diabetes mellitus. Glucose is the true substrate for this enzyme. Fructosephosphatethe end product of Hexokinase reaction can enter glycolytic pathway to be utilized further, so it does not accumulate to produce the toxic effects. Aldolase A, present in all the cells of the body cleaves Fructose 1,6 bisphosphate , the product of PFK-1 catalyzed reaction of glycolysis.

Fructose can be converted to glycogen only if it is metabolized through Fructose kinase, Aldolase and subsequent steps. Since there is block at first step, further metabolism and conversion to glycogen does not take place. Debranching enzyme has two components. Both components are present on the same polypeptide chain.

Glucose phosphatase does produce free glucose but it is absent in skeletal muscles. Branching enzyme is involved in creating branch point, there is no free glucose release by this enzyme. Glucocorticoid are important in response to stress. Glucagon is the hormone to increase blood glucose levels during periods of fasting and starvation.

Calcitonin inhibits release of calcium from bone and also decreases blood calcium levels. Calcium, vitamin D and Calcitonin may be prescribed to help treat osteoporosis. Parathyroid hormone promotes calcium and phosphate mobilization from bone, increasing calcium levels. Oxytocin, Prolactin and Estradiol are not significant for calcium level regulation.

Insulin binds to a cell surface receptor that acts as a Tyrosine kinase. Phospholipase C acts on Phosphatidyl Inositol membrane Phospholipid to cleave it to Inositol triphosphate and diacylglycerol. Approximately hours after a meal, the liver maintains normal blood glucose level by glycogenolysis. Within 30 hours liver glycogen stores are depleted, leaving gluconeogenesis as the primary source for maintaining blood glucose levels. In the fed state, insulin is the main hormone while in the fasting state, glucagon level increases.

The activity of regulatory enzymes such as fructose-1, 6-bisphosphatase , hexokinase , phosphofructokinase 1, and pyruvate kinase are frequently controlled by binding allosteric effectors.

These allosteric enzymes usually exhibit sigmoidal kinetics.

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