CELLULAR INJURY AND ADAPTATION MCQs | MCQ Quiz | OmpathStudy Kenya

Question 1

A 17-year-old boy infected with hepatitis A experiences mild nausea for about 1 week and develops very mild scleral icterus. On physical examination, he has minimal right upper quadrant tenderness. Laboratory findings include a serum AST of 68 U/L, ALT of 75 U/L, and total bilirubin of 5.1 mg/dL. The increase in this patient's serum enzyme levels most likely results from which of the following changes in the hepatocytes?

Accepted Answer

Defects in the cell membrane — Irreversible cell injury is associated with loss of membrane integrity. This allows intracellular enzymes to leak into the serum. All other morphologic changes listed are associated with reversible cell injury, in which the cell membrane remains intact.

Question 2

A 16-year-old boy sustained blunt trauma to the abdomen when the vehicle he was driving struck a bridge abutment at high speed. Peritoneal lavage shows a hemoperitoneum, and at laparotomy, a small portion of the left lobe of the liver is removed because of the injury. Several weeks later, a CT scan of the abdomen shows that the liver has nearly regained its size before the injury. Which of the following processes best explains this CT scan finding?

Accepted Answer

HyperplasiaF. HypertrophyG. Metaplasia ANSWER: E — The liver is one of the few organs in the human body that can partially regenerate. This is a form of compensatory hyperplasia. The stimuli to hepatocyte mitotic activity cease when the liver has attained its normal size.

Question 3

On a routine visit to the physician, an otherwise healthy 51-year-old man has a blood pressure of 150/95 mm Hg. If his hypertension remains untreated for years, which of the following cellular alterations would most likely be seen in his myocardium?

Accepted Answer

Hypertrophy ANSWER: E — The pressure load on the left ventricle results in an increase in myofilaments in the existing myofibers. The result of continued stress from hypertension is eventual heart failure with decreased contractility, but the cells do not decrease in size.

Question 4

A 72-year-old man died suddenly from congestive heart failure. At autopsy, the heart weighed 580 g and showed marked left ventricular hypertrophy and minimal coronary arterial atherosclerosis. A serum chemistry panel ordered before death showed no abnormalities. Which of the following pathologic processes best accounts for the appearance of the stenotic aortic valve with nodular calcium deposits?

Accepted Answer

Dystrophic calcification — The valve is stenotic because of nodular deposits of calcium. The process is "dystrophic" because calcium deposition occurs in damaged tissues. The damage in this patient is a result of the wear and tear of aging.

Question 5

A 69-year-old woman has had transient ischemic attacks for the past 3 months. On physical examination, she has an audible bruit on auscultation of the neck. A right carotid endarterectomy is performed. The curetted atheromatous plaque has a grossly yellow-tan, firm appearance. Microscopically, which of the following materials can be found in abundance in the form of crystals that produce long, cleft-like spaces?

Accepted Answer

Cholesterol ANSWER: E — Cholesterol is a form of lipid commonly deposited within atheromas in arterial walls, imparting a yellow color to these plaques. Glycogen is a storage form of carbohydrate seen mainly in liver and muscle.

Question 6

A 38-year-old woman experienced severe abdominal pain with hypotension and shock that led to her death within 36 hours after the onset of the pain. The mesentery shows focal, chalky white deposits. Which of the following events has most likely occurred?

Accepted Answer

Acute pancreatitis ANSWER: E — The focal, chalky white deposits are areas of fat necrosis resulting from the release of pancreatic lipases in a patient with acute pancreatitis.

Question 7

In an experiment, cells are subjected to radiant energy in the form of x-rays. This results in cell injury caused by hydrolysis of water. Which of the following cellular enzymes protects the cells from this type of injury?

Accepted Answer

Glutathione peroxidase — Intracellular mechanisms exist that deal with free radical generation, as can occur with radiant injury from irradiation. Glutathione peroxidase reduces such injury by catalyzing the breakdown of hydrogen peroxide.

Question 8

A 47-year-old woman has had worsening dyspnea for the past 5 years. A chest CT scan shows panlobular emphysema. Laboratory studies show the PiZZ genotype of α1-antitrypsin (AAT) deficiency. A liver biopsy specimen examined microscopically shows abundant PAS-positive globules within periportal hepatocytes. Which of the following molecular mechanisms is most likely responsible for this finding in the hepatocytes?

Accepted Answer

Retention of poorly folded AAT in the endoplasmic reticulum — Mutations in the AAT gene give rise to AAT molecules that cannot fold properly. In the PiZZ genotype, both alleles have the mutation. The partially folded molecules accumulate in the endoplasmic reticulum and cannot be secreted.

Question 9

A 68-year-old woman suddenly lost consciousness; on awakening 1 hour later, she could not speak or move her right arm and leg. Two months later, a head CT scan showed a large cystic area in the left parietal lobe. Which of the following pathologic processes has most likely occurred in the brain?

Accepted Answer

Liquefactive necrosis — The high lipid content of central nervous system tissues results in liquefactive necrosis as a consequence of ischemic injury, as in this case of a "stroke."

Question 10

A 30-year-old man sustains a left femoral fracture in a skiing accident, and his leg is placed in a plaster cast. After the leg has been immobilized for several weeks, the diameter of the left calf has decreased. This change is most likely to result from which of the following alterations in the calf muscles?

Accepted Answer

Atrophy — Reduced workload causes shrinkage of cell size because of loss of cell substance, a process called atrophy. Aplasia refers to lack of embryonic development; hypoplasia describes poor or subnormal development.

Question 11

An experiment analyzes cells for enzyme activity associated with sustained cellular proliferation. Which of the following cells is most likely to have the highest telomerase activity?

Accepted Answer

Germ cells — Germ cells have the highest telomerase activity, and the telomere length can be stabilized in these cells. This allows testicular germ cells to retain the ability to divide throughout life.

Question 12

A 32-year-old man experiences "heartburn" and gastric reflux after eating a large meal. After many months of symptoms, he undergoes upper gastrointestinal endoscopy, and a biopsy specimen shows replacement of normal esophageal epithelium with intestinal-type columnar epithelium with goblet cells. Which of the following pathologic changes has most likely occurred?

Accepted Answer

Columnar epithelial metaplasia — Inflammation from reflux of gastric acid has resulted in replacement of normal esophageal squamous epithelium by intestinal-type columnar epithelium with goblet cells. Such conversion of one adult cell type to another cell type is called metaplasia.

Question 13

On day 28 of her menstrual cycle, a 23-year-old woman experiences onset of menstrual bleeding that lasts for 6 days. She has had regular cycles for many years. Which of the following processes is most likely occurring in the endometrium just before the onset of bleeding?

Accepted Answer

Apoptosis — The onset of menstruation is an example of orderly, programmed cell death (apoptosis) through hormonal stimuli. The endometrium breaks down, sloughs off, and then regenerates.

Question 14

In a clinical trial, a chemotherapeutic agent is given to patients with breast cancer metastases. Samples of the cancer cells are obtained and assessed for the presence of death of tumor cells by apoptosis. Mutational inactivation of which of the following products is most likely to render tumor cells resistant to the effects of such an agent?

Accepted Answer

p53 — When DNA damage is induced by chemotherapeutic drugs (or other agents), normal p53 genes trigger the cells to undergo apoptosis. When p53 is inactivated, this pathway of cell death can be blocked, rendering the chemotherapy less effective.

Question 15

After the birth of her first child, a 19-year-old woman breastfed the infant for about 1 year. Which of the following processes that occurred in the breast during pregnancy allowed her to breastfeed the infant?

Accepted Answer

Lobular hyperplasia — Lobules increase under hormonal influence (mainly progesterone) to provide for normal lactation. The breast stroma plays no role in lactation and may increase with pathologic processes.

Question 16

A 22-year-old woman has a congenital anemia that has required multiple transfusions of RBCs for many years. On physical examination, she now has no significant findings; however, liver function tests show reduced serum albumin. Which of the following findings would most likely appear in a liver biopsy specimen?

Accepted Answer

Hemosiderin in hepatocytes ANSWER: E — Each unit of blood contains about 250 mg of iron. The body has no mechanism for getting rid of excess iron. Over time, hemosiderosis involves more and more tissues of the body, particularly the liver.

Question 17

A 50-year-old man experienced an episode of chest pain 6 hours before his death. A histologic section of left ventricular myocardium taken at autopsy showed a deeply eosinophilic-staining area with loss of nuclei and cross-striations in myocardial fibers. There was no hemorrhage or inflammation. Which of the following conditions most likely produced these myocardial changes?

Accepted Answer

Coronary artery thrombosis — The deep eosinophilic staining, loss of nuclei, and loss of cell structure suggest an early ischemic injury, resulting in coagulative necrosis. This finding is typically caused by loss of blood flow.

Question 18

A 69-year-old man has had difficulty with urination, including hesitancy and frequency, for the past 5 years. A digital rectal examination reveals that the prostate gland is palpably enlarged to about twice normal size. A transurethral resection of the prostate is performed, and the microscopic appearance shows nodules of glands with intervening stroma. Which of the following pathologic processes has most likely occurred in the prostate?

Accepted Answer

Hyperplasia — Nodular prostatic hyperplasia (also known as benign prostatic hyperplasia [BPH]) is a common condition in older men that results from proliferation of prostatic glands and stroma. This is an example of pathologic hyperplasia.

Question 19

A 54-year-old man experienced onset of severe substernal chest pain over 3 hours. An ECG showed changes consistent with an acute myocardial infarction. After thrombolytic therapy with tissue plasminogen activator (t-PA), his serum creatine kinase (CK) level increased. Which of the following events most likely occurred after t-PA therapy?

Accepted Answer

Reperfusion injury — If the existing cell damage is not great after myocardial infarction, the restoration of blood flow can help prevent further damage. The reperfusion of damaged cells results in generation of oxygen-derived free radicals, however, causing a reperfusion injury.

Question 20

A 33-year-old woman has had increasing lethargy and decreased urine output for the past week. Laboratory studies show serum creatinine level of 4.3 mg/dL and urea nitrogen level of 40 mg/dL. A renal biopsy is performed, and the specimen is examined using electron microscopy. Which of the following morphologic changes most likely suggests a diagnosis of acute tubular necrosis?

Accepted Answer

Nuclear fragmentation — Loss of the nucleus results in cell death. All other cellular morphologic changes listed represent reversible cellular injury. The plasma membrane and intracellular organelles remain functional unless severe damage causes loss of membrane integrity.

Question 21

A 40-year-old man had undifferentiated carcinoma of the lung. Despite chemotherapy, the man died of widespread metastases. At autopsy, tumors were found in many organs. Histologic examination showed many foci in which individual tumor cells appeared shrunken and deeply eosinophilic. Their nuclei exhibited condensed aggregates of chromatin under the nuclear membrane. The process affecting these shrunken tumor cells was most likely triggered by the release of which of the following substances into the cytosol?

Accepted Answer

Cytochrome c — This histologic picture is typical of apoptosis produced by chemotherapeutic agents. The release of cytochrome c from the mitochondria is a key step in many forms of apoptosis, and it leads to the activation of caspases.

Question 22

A 70-year-old man died suddenly. At autopsy, multiple tissue sites were sampled for microscopic analysis. Examination of the tissues showed noncrystalline amorphous deposits of calcium salts in gastric mucosa, renal interstitium, and alveolar walls of lungs. Which of the following conditions would most likely explain these findings?

Accepted Answer

Chronic glomerulonephritis — The microscopic findings suggest metastatic calcification, with deposition of calcium salts in tissues that have physiologic mechanisms for losing acid. Chronic renal disease reduces phosphate excretion by the kidney, resulting in an increase in serum phosphate, triggering increased parathyroid hormone output to increase the calcium level, which promotes calcium deposition.

Question 23

A 63-year-old man has a 2-year history of worsening congestive heart failure. An echocardiogram shows mitral stenosis with left atrial dilation. A thrombus is present in the left atrium. One month later, he experiences left flank pain and notes hematuria. Laboratory testing shows elevated serum AST. Which of the following patterns of tissue injury is most likely to be present?

Accepted Answer

Coagulative necrosis — Embolization of the thrombus led to blockage of a renal arterial branch, causing an acute renal infarction in this patient. An ischemic injury to most internal organs produces a pattern of cell death called coagulative necrosis.

Question 24

At autopsy, a 40-year-old man has an enlarged (2200 g) liver with a yellow cut surface. The microscopic appearance shows lipid vacuoles in many hepatocytes. Before death, the man's total serum cholesterol and triglyceride levels were normal, but he had a decreased serum albumin concentration and increased prothrombin time. Which of the following activities most likely led to these findings?

Accepted Answer

Drinking beer — The appearance of lipid vacuoles in many of the hepatocytes is characteristic of fatty change (steatosis) of the liver. Alcohol is a hepatotoxin that produces hepatic steatosis. Decreased serum albumin levels and increased prothrombin time suggest alcohol-induced hepatocyte damage.

Question 25

A 22-year-old woman with leukemia undergoes bone marrow transplantation and receives partially mismatched donor marrow. One month later, she has a scaling skin rash. Examination of a skin biopsy specimen reveals shrunken cells with dense eosinophilic cytoplasm and pyknotic nuclei. This change most likely results from which of the following biochemical reactions?

Accepted Answer

Activation of caspases — This cell is shrunken and has been converted into a dense eosinophilic mass. This pattern is typical of apoptosis. Caspase activation is a universal feature of apoptosis, regardless of the initiating cause. Apoptosis induced in recipient cells from donor lymphocytes occurs with graft-versus-host disease.

Question 26

At autopsy, the heart of a 63-year-old man weighs only 250 g and has small right and left ventricles. The myocardium is firm, with a dark chocolate-brown color throughout. The coronary arteries show minimal atherosclerotic changes. An excessive amount of which of the following substances would most likely be found in the myocardial fibers of this heart?

Accepted Answer

Lipofuscin — Lipofuscin is a "wear-and-tear" pigment that increases with aging, particularly in liver and myocardium. The pigment has minimal effect on cellular function in most cases. Rarely, there is marked lipofuscin deposition in a small heart, a so-called brown atrophy.

Question 27

A 69-year-old woman has had a chronic cough for the past year. A chest radiograph shows a 6-cm mass in the left lung, and a needle biopsy specimen of the mass shows carcinoma. A pneumonectomy is performed, and examination of the hilar lymph nodes reveals a uniform, dark black cut surface. Which of the following factors most likely accounts for the appearance of the lymph nodes?

Accepted Answer

Smoking — Anthracotic pigmentation is common in lung and hilar lymph nodes and occurs when carbon pigment is inhaled from polluted air. The tar in cigarette smoke is a major source of such carbonaceous pigment.

Question 28

A 44-year-old man has a history of poorly controlled diabetes mellitus leading to coronary artery disease. He now has decreasing cardiac output. An increase in which of the following substances in his blood is most indicative of reversible cell injury from decreased perfusion of multiple organs and tissues?

Accepted Answer

Lactic acid — Decreased tissue perfusion leads to hypoxemia and depletion of ATP when cell metabolism shifts from aerobic to anaerobic glycolysis, resulting in depletion of glycogen stores and increased production and accumulation of lactic acid, reducing intracellular pH.

Question 29

An experiment introduces a "knockout" gene mutation into a cell line. The frequency of shrunken cells with chromatin clumping and cytoplasmic blebbing is increased compared with a cell line without the mutation. Overall survival of the mutant cell line is reduced. Which of the following genes is most likely to be affected by this mutation?

Accepted Answer

BCL-2 — These histologic findings are typical of apoptosis. The BCL-2 gene product inhibits cellular apoptosis by binding to Apaf-1. When BCL-2 is knocked out, cells undergo increased apoptosis with reduced survival.

Question 30

A tissue preparation is experimentally subjected to a hypoxic environment. The cells in this tissue begin to swell, and chromatin begins to clump in the nucleus. ATPases are activated, and ATP production decreases. Which of the following ions released from mitochondria leads to these findings and to eventual cell death?

Accepted Answer

Ca2+ — Irreversible cellular injury is likely to occur when calcium increases within cells. This calcium can influx into cells and be released from mitochondria and endoplasmic reticulum. The calcium activates ATPases, phospholipases, proteases, and endonucleases, which injure cell components.

Question 31

A chest radiograph of an asymptomatic 37-year-old man showed a 3-cm nodule in the middle lobe of the right lung. The nodule was excised with a pulmonary wedge resection, and sectioning showed the nodule to be sharply circumscribed with a soft, white center. Culture of tissue from the nodule grew Mycobacterium tuberculosis. Which of the following pathologic processes has most likely occurred in this nodule?

Accepted Answer

Caseous necrosis — The cheese-like appearance gives this form of necrosis its name—caseous necrosis. In the lung, tuberculosis and fungal infections are most likely to produce this pattern of tissue injury.

Question 32

The nonpregnant uterus of a 20-year-old woman measures 7 × 4 × 3 cm. The woman becomes pregnant and just before delivery of a term infant, the uterus measures 34 × 18 × 12 cm. Which of the following cellular processes has contributed most to the increase in uterine size?

Accepted Answer

Myometrial smooth muscle hypertrophy — The increase in uterine size is primarily the result of an increase in myometrial smooth muscle cell size. The endometrium also increases in size, but it remains as a lining to the muscular wall and does not contribute as much to the change in size.

Question 33

A 40-year-old woman has had chronic congestive heart failure for the past 3 years. In the past 2 months, she developed a cough productive of rust-colored sputum. A sputum cytology specimen shows numerous hemosiderin-laden macrophages. Which of the following subcellular structures in macrophages is most important for the accumulation of this pigment?

Accepted Answer

Lysosome — Heterophagocytosis by macrophages requires that endocytosed vacuoles fuse with lysosomes to degrade the engulfed material. With congestive failure, extravasation of RBCs into alveoli occurs, and pulmonary macrophages must phagocytose the RBCs, breaking down the hemoglobin and recycling the iron by hemosiderin formation.

Question 34

In an experiment, a large amount of a drug is administered to subjects and is converted by cytochrome P-450 to a toxic metabolite. The accumulation of this metabolite leads to increased lipid peroxidation within cells, causing damage to cell membranes and cell swelling. Depletion of which of the following substances by this mechanism within the cytosol exacerbates the cellular injury?

Accepted Answer

Glutathione — Glutathione in the cytosol helps to reduce cellular injury from many toxic metabolites and free radicals. Depletion of glutathione leaves cells vulnerable to oxidative injury.

Question 35

An experiment is conducted in which cells in tissue culture are subjected to high levels of ultraviolet radiant energy. Electron microscopy shows cellular damage in the form of increased cytosolic aggregates of denatured proteins. In situ hybridization reveals that protein components in these aggregates also are found in proteasomes. Which of the following substances is most likely to bind to the denatured proteins, targeting them for catabolism by cytosolic proteasomes?

Accepted Answer

Adenosine monophosphate — Heat-shock proteins provide for a variety of cellular "housekeeping" activities, including recycling and restoration of damaged proteins and removal of denatured proteins. Ubiquitin targets denatured proteins and facilitates their binding to proteasomes, which then break down the proteins to peptides.

Question 36

A 71-year-old man diagnosed with pancreatic cancer is noted to have decreasing body mass index. His normal cells comprising skeletal muscle undergo atrophy by sequestering organelles and cytosol in a vacuole followed by fusion with a lysosome. However, the cancer continues to increase in size. Which of the following processes is most likely occurring in the normal cells but inhibited in the cancer cells of this man?

Accepted Answer

Autophagy — Autophagy is a form of cellular downsizing in response to stress, as the cell consumes itself, by upregulating Atgs genes. Cancer cells acquire the ability to avoid autophagy and maintain a survival advantage even as the patient is dying.

Question 37

A 5-year-old child ingests 50 iron tablets, each with 27 mg of iron. Within 6 hours the child develops abdominal pain and lethargy. On physical examination he is hypotensive. Laboratory studies show metabolic acidosis. Through formation of which of the following compounds is the cell injury in this child most likely mediated?

Accepted Answer

Hydroxyl radical — Excessive iron ingestion, particularly in a child, can overwhelm the body's ability to bind the absorbed free iron with the transport protein transferrin. The free iron contributes to generation of free radicals via the Fenton reaction.

Question 38

A proponent of Malbec, Syrah, and Merlot wines (all reds) touts their contribution to longevity, but this wine aficionado also controls the caloric content of his diet such that his body mass index is <22. This lifestyle promotes increased insulin sensitivity and glucose utilization. In this man, which of the following proteins will most likely mediate the effect of calorie restriction upon increased longevity?

Accepted Answer

Sirtuin — The histone deacetylase activity of sirtuins may promote transcription of genes encoding for proteins that increase metabolic activity and inhibit effects of free radicals. Red wines have been shown to increase sirtuins.

Question 39

A 45-year-old woman with systemic lupus erythematosus develops progressive renal failure over several years. Laboratory studies show proteinuria of 4.5 g/24 hours and serum creatinine of 3.8 mg/dL. A renal biopsy specimen stained with Congo red shows apple-green birefringence under polarized light in the glomeruli and vessel walls. Which of the following proteins is most likely abnormally deposited in this patient's kidneys?

Accepted Answer

Immunoglobulin light chains — The Congo red positivity with apple-green birefringence indicates amyloid deposition. In chronic inflammatory diseases like SLE, AA amyloid can occur, but the most common renal amyloid is AL type, derived from immunoglobulin light chains produced by plasma cell dyscrasias or chronic immune stimulation.

Question 40

A 28-year-old man with cystic fibrosis undergoes genetic testing that reveals a ΔF508 mutation in the CFTR gene. This mutation results in production of a misfolded protein that is retained in which of the following cellular locations?

Accepted Answer

Endoplasmic reticulum — The ΔF508 mutation produces a misfolded CFTR protein that is retained in the endoplasmic reticulum and degraded rather than being transported to the cell membrane. This is analogous to α1-antitrypsin deficiency where misfolded proteins accumulate in the ER

Question 41

A 55-year-old chronic alcoholic presents with progressive weakness and ataxia. Physical examination reveals loss of position and vibration sense in the lower extremities. A peripheral blood smear shows macrocytic RBCs with hypersegmented neutrophils. Deficiency of which of the following vitamins would most likely produce these findings through impaired DNA synthesis?

Accepted Answer

Vitamin B12 — Vitamin B12 deficiency impairs DNA synthesis, leading to macrocytic anemia with hypersegmented neutrophils. Chronic alcoholism can lead to malabsorption and poor nutrition. The neurologic findings (subacute combined degeneration) are characteristic of B12 deficiency.

Question 42

A 62-year-old man with chronic obstructive pulmonary disease develops cor pulmonale with right ventricular hypertrophy. Which of the following mechanisms best explains the adaptive change in the right ventricle?

Accepted Answer

Increased size of existing myocardial cells — Cardiac myocytes are permanent cells that cannot divide. Hypertrophy results from increased workload (pressure overload from pulmonary hypertension) causing increased synthesis of myofilaments and enlargement of existing cells, not an increase in cell number.

Question 43

A 35-year-old woman undergoes a thyroidectomy for Graves disease. Histologic examination of the thyroid gland shows follicular epithelial cells that are tall and columnar instead of the normal cuboidal shape. This finding is best explained by which of the following processes?

Accepted Answer

Hyperplasia with hypertrophy — In Graves disease, excessive TSH receptor stimulation leads to both increased number (hyperplasia) and increased size (hypertrophy) of follicular cells, causing them to become tall and columnar. This is a physiologic adaptation to hormonal stimulation, not a neoplastic or metaplastic change.

CELLULAR INJURY AND ADAPTATION MCQs | MCQ Quiz | OmpathStudy Kenya

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