National Board Of Medical Examiners (NBME) Preparation Series: Trivia Quiz

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MS is approximately threefold more common in women than men. The age of onset is typically between 20 and 40 years (slightly later in men than in women), but the disease can present across the life span.
The onset of MS may be abrupt or insidious. Symptoms may be severe or seem so trivial that a patient may not seek medical attention for months or years. Indeed, at autopsy, approximately 0.1% of individuals who were asymptomatic during life will be found, unexpectedly, to have pathologic evidence of MS. Similarly, in the modern era, an MRI scan obtained for an unrelated reason may show evidence of asymptomatic MS. Symptoms of MS are extremely varied and depend on the location and severity of lesions within the CNS. Examination often reveals evidence of neurologic dysfunction, often in asymptomatic locations. For example, a patient may present with symptoms in one leg but signs in both.
MRI has revolutionized the diagnosis and management of MS; characteristic abnormalities are found in >95% of patients although more than 90% of the lesions visualized by MRI are asymptomatic. An increase in vascular permeability from a breakdown of the BBB is detected by leakage of intravenous gadolinium (Gd) into the parenchyma. Such leakage occurs early in the development of an MS lesion and serves as a useful marker of inflammation. Gd enhancement persists for approximately 1 month, and the residual MS plaque remains visible indefinitely as a focal area of hyperintensity (a lesion)
Relapsing/remitting MS (RRMS) accounts for 85% of MS cases at onset and is characterized by discrete attacks that generally evolve over days to weeks (rarely over hours). There is often complete recovery over the ensuing weeks to months. However, when ambulation is severely impaired during an attack, approximately half will fail to improve. Between attacks, patients are neurologically stable.
Weakness of the limbs may manifest as loss of strength, speed, or dexterity, as fatigue, or a disturbance of gait. Exercise-induced weakness is a characteristic symptom of MS. The weakness is of the upper motor neuron type and is usually accompanied by other pyramidal signs such as spasticity, hyper-reflexia, and Babinski's signs. Occasionally a tendon reflex may be lost (simulating a lower motor neuron lesion) if an MS lesion disrupts the afferent reflex fibers in the spinal cord

Optic neuritis (ON) presents as diminished visual acuity, dimness, or decreased color perception (desaturation) in the central field of vision. These symptoms can be mild or may progress to severe visual loss. Rarely, there is complete loss of light perception. Visual symptoms are generally monocular but may be bilateral. Periorbital pain (aggravated by eye movement) often precedes or accompanies the visual loss. An afferent pupillary defect is usually present. Funduscopic examination may be normal or reveal optic disc swelling (papillitis). Pallor of the optic disc (optic atrophy) commonly follows ON. Uveitis is uncommon and should raise the possibility of alternative diagnoses such as sarcoid or lymphoma.

This is a description of tetanus toxicity, which causes trismus (lockjaw) and opisthotonos (severe hyperextension leading to arching of the body).The mechanism of action of the tetanus toxin (tetanospasmin) is blocking the release of GABA (inhibitory neurotransmitter) and glycine at the neuromuscular junction.

The patient's history of irregular menses, hirsutism, acne, and obesity are consistent with polycystic ovarian syndrome (PCOS). PCOS is a common cause of infertility in women due to hormonal imbalances that affect ovulation. The patient's physical examination findings, including the absence of abnormalities in the exterior genitalia and limited bimanual examination due to obesity, further support the diagnosis of PCOS. Hypothyroidism, Klinefelter syndrome, pituitary adenoma, and primary ovarian failure are less likely causes of infertility in this patient.

Fresh frozen plasma is the most appropriate initial therapy in this case because the 3-year-old boy has ingested warfarin, which is a vitamin K antagonist that inhibits the synthesis of factors II, VII, IX, and X. This leads to an increase in prothrombin time (PT) and international normalized ratio (INR). Fresh frozen plasma contains all the coagulation factors, including factors II, VII, IX, and X, and can rapidly correct the coagulopathy caused by warfarin. Factor IX concentrate is used for the treatment of hemophilia B, fibrinogen concentrate is used for the treatment of hypofibrinogenemia, platelet concentrates are used for thrombocytopenia, and vitamin B12 is not indicated in this case.

The given answer states that 37 is missing from the original. This implies that there is a set or sequence of numbers from which 37 is absent. Therefore, the correct answer is "True" because it affirms the absence of 37 from the original set or sequence.

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The most likely diagnosis for this patient is bladder cancer. The patient's history of smoking for 35 years is a significant risk factor for bladder cancer. The painless, blood-tinged urine is a common symptom of bladder cancer. The normal physical examination and urinalysis findings, except for microscopic blood, further support this diagnosis. Bladder diverticulum, interstitial cystitis, nephrolithiasis, and urinary tract infection are less likely given the patient's presentation and risk factors.

The patient in the scenario presented with pain in her left leg while walking, a decreased pulse in the left lower extremity, and a diastolic heart murmur. Angiography revealed complete obstruction of the distal left femoral artery by a thrombus, which was successfully removed. Microscopic examination of the removed specimen showed scattered mesenchymal cells in an abundant extracellular matrix. Echocardiography confirmed a diagnosis of cardiac tumor. Based on these findings, the most likely type of cardiac tumor in this patient is a myxoma. Myxomas are the most common primary cardiac tumors and can present with symptoms related to embolization, such as peripheral arterial occlusion.

PATHOMA excerpt:

V. PLACENTA ACCRETA
A. Improper implantation of placenta into the myometrium with little or no
intervening decidua
B. Presents with difficult delivery of the placenta and postpartum bleeding
C. Often requires hysterectomy

The most likely cause of the girl's symptoms is enterotoxin ingestion. The symptoms of severe abdominal pain, nausea, and vomiting that began after attending a party where cake and other pastries were served suggest that the girl may have ingested food contaminated with enterotoxins. Enterotoxins are toxins produced by certain bacteria that can cause gastrointestinal symptoms such as abdominal pain, nausea, and vomiting. This is supported by the absence of abnormalities on skin examination and the presence of hyperactive bowel sounds, which are consistent with a gastrointestinal cause.

Acetazolamide is a carbonic anhydrase inhibitor that is commonly used to prevent altitude sickness. It works by inhibiting the enzyme carbonic anhydrase in the proximal tubule of the kidney. By inhibiting this enzyme, acetazolamide reduces the reabsorption of bicarbonate ions, leading to increased excretion of bicarbonate in the urine. This causes a metabolic acidosis, which stimulates the respiratory center in the brain to increase ventilation, helping to compensate for the decrease in oxygen availability at high altitudes. Therefore, acetazolamide acts predominately in the proximal tubule of the kidney in this patient.

The most appropriate initial action by the physician regarding the patient's request for extra pain medication is to reevaluate the patient after his pain has been controlled. This is because the patient is experiencing severe pain due to sickle cell disease, which is a known complication of the condition. It is important to address the patient's pain and provide appropriate pain management. However, it is also important to assess the patient's overall condition and mental state once the pain has been controlled, as the patient's request for extra pain medication may be influenced by factors such as depression or emotional distress.

The most likely explanation for this patient's behavior is separation anxiety disorder. This is indicated by the patient's temper tantrums when her parents leave her, refusal to sleep alone, and calling for her mother when she is in another room. Additionally, her difficulty attending social events and crying when being brought to school are consistent with separation anxiety. The fact that her father recalls behaving the same way at her age suggests a possible genetic predisposition. Conduct disorder and oppositional defiant disorder involve more aggressive and antisocial behaviors. Post-traumatic stress disorder would require a traumatic event as a trigger, which is not mentioned in the scenario. Normal behavior would not explain the chronic and distressing nature of the patient's symptoms.

Micafungin is an antifungal medication that belongs to the echinocandin class. Echinocandins specifically target the cell wall of fungi. They inhibit the synthesis of β-(1,3)-D-glucan, a major component of the fungal cell wall. By disrupting the cell wall, echinocandins weaken the fungal cell and ultimately lead to cell death. Therefore, the most likely cellular structure targeted by micafungin is the cell wall.

The vagus nerve splits into branches that go to different parts of the stomach. Stimulation from these branches causes stomach to produce acid. Too much stomach acid leads to ulcers that may eventually bleed and create an emergency situation. Vagotomy is performed when acid production in the stomach cannot be reduced by other means. Usually used when ulcers in the stomach and duodenum do not respond to medications and changes in diet. Although elective vagotomy has decreased, it is often performed in conjunction with gastrointestinal surgery, such as partial removal of the stomach as in this case. There are several types of vagotomies. Truncal vagotomy severs the trunk of the vagus nerve as it enters the abdomen. Parietal cell or proximal gastric vagotomy leaves the trunk intact, but severs the branches that go to different parts of the stomach.
Holla H.Z.

The hysterosalpingogram shows a uterine anomaly, suggesting a malformation of the paramesonephric (muillerian) ducts. These ducts are responsible for the development of the female reproductive tract, including the fallopian tubes, uterus, cervix, and upper vagina. Malformations of the paramesonephric ducts can lead to infertility and other reproductive issues. The other options, such as germ cells, gonadal ridges, mesonephric (wolffian) ducts, urogenital folds, and urogenital sinus, are not directly involved in the development of the female reproductive tract.

Answer: E) The test is simulating RAS (Renal Artery Stenosis). And the question is addressing your understanding of the RAAS. Juxtaglomerular (JG) cells associated with the afferent arteriole entering the renal glomerulus are the primary site of renin storage and release in the body. A reduction in afferent arteriole pressure (kidney thinks you are hypotensive - less blood going to kidney) causes the release of renin from the JG cells, whereas increased pressure inhibits renin release. So, in this scenario the Renin will be increased leaving the efferent of the Left Kidney as that is the Kidney affected by RAS. A) ADH is released from the posterior pituitary in response to increased renin and increases fluid retention. B) Aldosterone released from the Adrenal Cortex is caused by increase Renin. C) Endothelin (ET-1) is used to control local smooth muscle constriction Endothelial cells upregulate ET-1 in response to hypoxia, oxidized LDL, pro-inflammatory cytokines, and bacterial toxins D) Epinephrine is a sympathetic response and is produced by chromaffin cells in the Adrenal medulla.

Lactulose is the most likely drug to improve this patient's mental status because he has hepatic encephalopathy, which is a complication of cirrhosis. Lactulose works by decreasing the production and absorption of ammonia in the gut, which is thought to be the main cause of hepatic encephalopathy. By reducing ammonia levels, lactulose can improve the patient's mental status and alleviate symptoms such as confusion and lethargy. The other drugs listed are not indicated for the treatment of hepatic encephalopathy.

The patient's family history of renal failure, previous history of renal calculi and hypertension, and physical examination findings of bilateral palpable masses in the upper abdomen suggest a diagnosis of polycystic kidney disease. The presence of crenated erythrocytes and mild proteinuria on urinalysis further supports this diagnosis. A CT scan of the abdomen can confirm the presence of multiple cysts in the kidneys, which is characteristic of polycystic kidney disease. Adrenal adenoma, glomerulonephritis, Henoch-Schonlein purpura, and renal cell adenoma are less likely diagnoses based on the clinical presentation and findings.

The patient's laboratory findings, specifically the low serum sodium level (hyponatremia) and high urine osmolality, suggest the presence of syndrome of inappropriate antidiuretic hormone secretion (SIADH). SIADH is commonly associated with small cell lung carcinoma, which is indicated by the CT scan findings of a mass in the right upper lobe eroding into the right bronchus. ADH (vasopressin) is responsible for the reabsorption of water in the renal tubules, leading to concentrated urine and dilutional hyponatremia. Therefore, an excess of ADH is the most likely cause of the patient's laboratory findings.

The patient's symptoms, including severe headache, slurred speech, confusion, hemianopia, and gaze preference to the right, are consistent with a stroke. The presence of left-sided numbness and paralysis, more severe in the face and upper extremity, suggests involvement of the contralateral motor cortex. The middle cerebral artery supplies blood to the lateral aspect of the cerebral hemisphere, including the motor cortex, and is the most likely artery involved in this patient's condition.

SCHIZOID describes people who are uninterested in social attachment.

SCHIZOTYPAL people have both diminished capacity for relationships and peculiar patterns of thought, including magical thinking, odd beliefs, odd perceptual experiences, and subtle, low grade abnormalities of thought form.
Mistrust, projection, and the attribution of malevolence are all elements of PARANOIA, which may be either psychotic, implying a break from reality, or nonpsychotic, as in personalty disorder.

CARDIOVASCULAR EFFECTS — The major cardiovascular effects of cocaine appear to be caused by the inhibition of norepinephrine reuptake into the synaptic cleft by sympathetic neurons [2]. Since reuptake is the major mechanism by which neurotransmitters are removed from active receptor sites, this inhibition results in potentiation of the response to sympathetic stimulation of innervated organs and to infused catecholamine. Cocaine may also enhance the release of catecholamines from central and peripheral stores [4]. The ensuing sympathomimetic actions (increased myocardial inotropy, heart rate, systemic blood pressure, and coronary artery constriction) are mediated by stimulation of the alpha- and beta adrenergic receptors and result in increased myocardial oxygen demand. (uptodate.com)

Variable expressivity is the best explanation for the findings in the boy and his mother. Variable expressivity refers to the phenomenon where individuals with the same genetic mutation can have different symptoms or severity of symptoms. In this case, both the boy and his mother have tuberous sclerosis complex, but they are manifesting different symptoms. The boy has intracranial neoplasms, mental retardation, and seizures, while the mother only has angiofibromas. This demonstrates the variable expressivity of the disorder, where different individuals can have different manifestations of the same genetic mutation.

Heteroplasmy best explains the findings in this family. Heteroplasmy refers to the presence of both normal and mutated mitochondrial DNA in an individual. In this case, the mother has the mutation in only 50% of her mitochondrial DNA, while her children have the mutation in 100% of their mitochondrial DNA. This explains why the mother's symptoms are not as severe as her children's, as the proportion of mutated DNA affects the severity of symptoms. This pattern of inheritance is consistent with heteroplasmy, making it the best genetic principle to explain the findings.

The presence of alveolar hyaline membrane in the biopsy specimen suggests diffuse alveolar damage rather than bronchiolitis obliterans-organizing pneumonia. Alveolar hyaline membrane is a hallmark feature of diffuse alveolar damage, which is commonly seen in acute respiratory distress syndrome (ARDS). It is composed of fibrin, cellular debris, and necrotic epithelial cells lining the alveoli. In contrast, bronchiolitis obliterans-organizing pneumonia is characterized by fibroblastic plugs within the small airways and alveolar ducts. The other options listed are not specific to either condition.

One minute before the man begins pedaling, his heart rate increases. This suggests that the increase in heart rate is due to the activation of beta-1 (B1) adrenergic receptors by norepinephrine. Norepinephrine is a neurotransmitter released by sympathetic nerves and acts on B1 receptors in the heart, increasing heart rate and contractility. Acetylcholine, on the other hand, acts on muscarinic receptors and would typically decrease heart rate. Therefore, option D, Norepinephrine acting on B1 receptors, best explains the increase in heart rate in this man.

The most likely cause of rejection of the transplant in this patient is direct cytotoxicity. This is suggested by the presence of numerous infiltrating CD8+ T lymphocytes in the biopsy specimen. CD8+ T lymphocytes are known to be cytotoxic and can directly kill cells. In this case, the CD8+ T lymphocytes are likely recognizing the transplanted kidney as foreign and mounting an immune response against it, leading to rejection. Antibody synthesis, complement activation, histamine release, and nitric oxide production are not the most likely causes of rejection in this scenario.

The correct answer is Interferon-y receptor deficiency. This immunodeficiency impairs the body's ability to respond to interferon-y, which is important for the immune response against Mycobacterium tuberculosis. The familial history of atypical mycobacterial infections, including the death of two brothers, suggests a genetic immunodeficiency. Complement deficiency, leukocyte adhesion deficiency, and X-linked agammaglobulinemia are not associated with an increased susceptibility to mycobacterial infections.

Listeria monocytogenes is a gram-positive rod-shaped bacterium that can cause severe infections, especially in pregnant women. The patient in the scenario is a pregnant woman presenting with fever, nausea, vomiting, and muscle aches, which are consistent with a Listeria infection. Listeria can cause flu-like symptoms and can be transmitted through contaminated food, such as unpasteurized dairy products or deli meats. Given the patient's symptoms and the fact that Listeria can cause serious complications in pregnancy, it is the most likely causal organism in this case.

The symptoms described in the question, including frantic sucking, inconsolable crying, overreaction to stimuli, and a marked startle response, are consistent with neonatal abstinence syndrome (NAS). NAS occurs when a newborn is exposed to drugs in utero and experiences withdrawal symptoms after birth. Heroin is a potent opioid that can easily cross the placenta and cause NAS in newborns. Alcohol, LSD, marijuana, and psilocybin are not typically associated with the same withdrawal symptoms seen in NAS.

The lack of blood vessels in the ligament will most likely limit healing of this injury. Blood vessels are essential for delivering oxygen and nutrients to the injured tissues, as well as removing waste products and promoting the inflammatory response necessary for healing. Without an adequate blood supply, the injured ligament may not receive the necessary resources for proper healing, leading to delayed or impaired recovery.

In this patient with a pituitary mass, the most likely diagnosis is Cushing's syndrome, which is characterized by excessive production of cortisol. Cortisol is produced by the adrenal glands, and in Cushing's syndrome, there is bilateral adrenal hyperplasia. This is reflected in the answer choice of "Cortical hyperplasia," which refers to the hyperplasia of the adrenal cortex. Cortical hypertrophy, cortical metaplasia, medullary hyperplasia, medullary hypertrophy, and medullary metaplasia are not typically seen in Cushing's syndrome.

The patient's symptoms of weakness, light-headedness, pallor, and megaloblastic anemia are consistent with a diagnosis of pernicious anemia, which is caused by a failure of intrinsic factor production. Intrinsic factor is necessary for the absorption of vitamin B12 in the small intestine. Without intrinsic factor, vitamin B12 cannot be absorbed, leading to a deficiency of this vitamin. This deficiency results in the accumulation of methylmalonic acid and homocysteine, which can be detected in serum studies. The other options, such as cystathionine B-synthase deficiency, folic acid deficiency, Helicobacter pylori gastritis, and methylmalonyl-CoA mutase deficiency, are not associated with the clinical presentation described in the patient.

The longevity of the herpes simplex virus is best explained by its establishment of a latent infection in sensory nerve cells. The virus can remain dormant in these cells for long periods of time, periodically reactivating and causing recurrent episodes of symptoms. This ability to establish latency allows the virus to persist in the body indefinitely, leading to a lifelong infection.

The bacterium in this patient is likely Escherichia coli, as indicated by its characteristics on the agar plates and indole positivity. Adhesins are molecules on the surface of bacteria that enable them to adhere to host cells or tissues. In this case, the production of adhesins by the bacterium aids in its ability to attach to and infect the urinary tract, leading to symptoms such as urinary frequency, urgency, and pain with urination. This adherence is an important step in the pathogenesis of urinary tract infections caused by E. coli.

UTEROSACRAL LIGAMENT,
a ligament that extends from the cervix to the posterior pelvic wall. It is thought to help stabilize the uterus in the pelvic cavity

The underlying disease is Multiple Myloma: Hypercalcemia in multiple myeloma, where there is bone marrow infiltration by tumor has been ascribed to the release of osteoclast activating factors by the tumor cells. Osteoclast-induced bone resorption may occur in discrete focal areas (lytic lesions) or throughout the skeleton. The high rate of bone resorption is associated with an absence of osteoblast-mediated bone formation, resulting in diffuse bone loss. The uncoupling of bone resorption and formation results from paracrine factors, which enhance osteoclast formation and activity and inhibit the capacity for marrow stromal cells to differentiate into osteoblasts. In multiple myeloma, various studies have implicated interleukin (IL)-6, RANKL (from TNF family), macrophage inflammatory protein 1a, osteoclast activating factor [aka IL-1], osteoprotegerin, and IL-3 as factors contributing to the development of lytic bone disease and hypercalcemia.

The patient's history of a pulmonary embolism and a stillborn delivery at 23 weeks' gestation suggests a history of thrombotic events. The increased partial thromboplastin time indicates a prolongation in the time it takes for blood to clot, which is a characteristic finding in antiphospholipid antibody syndrome. This syndrome is an autoimmune disorder characterized by the presence of antiphospholipid antibodies, which can lead to an increased risk of blood clots. The other options, including Factor V Leiden mutation, increased factor VIII concentration, protein C deficiency, and Prothrombin G20210A mutation, are all associated with an increased risk of thrombosis but do not fully explain the patient's clinical presentation.

The patient's symptoms, including retinitis pigmentosa, ataxia, loss of deep tendon reflexes, chronic diarrhea, and low serum cholesterol, are consistent with a diagnosis of abetalipoproteinemia. Abetalipoproteinemia is an autosomal recessive disorder characterized by a deficiency of apolipoprotein B (Apo B), which is required for the synthesis and secretion of chylomicrons and very low-density lipoproteins (VLDL). This deficiency leads to malabsorption of dietary fat and fat-soluble vitamins, as well as the accumulation of lipid droplets in enterocytes and hepatocytes. Therefore, the most likely deficient apolipoprotein in this patient is Apo B.

The variability in outcome assessment raises the most concern about the validity of the conclusion that vitamin C supplements prevent the common cold. If there is a high degree of variability in how the outcome (common cold) is assessed by the parents, it could introduce bias and affect the accuracy of the results. This variability could lead to inconsistent reporting of colds, making it difficult to determine the true effectiveness of vitamin C in preventing the common cold.

The patient's symptoms of progressive difficulty breathing and left shoulder pain, along with his history of poorly controlled hypertension and angina pectoris, suggest a cardiac cause for his symptoms. The fact that his symptoms began after exertion further supports this. The presence of crackles, rhonchi, and wheezing on lung auscultation indicates fluid accumulation in the lungs, which is consistent with pulmonary edema. The low arterial Po2 level also suggests impaired oxygenation. Therefore, the most likely diagnosis in this case is pulmonary edema.

The loading dose of a drug is calculated based on the volume of distribution and the desired peak serum concentration. In this case, the volume of distribution is given as 0.35 L/kg and the desired peak serum concentration is 8 mg/L. The patient weighs 55 kg, so the volume of distribution would be 0.35 L/kg * 55 kg = 19.25 L. To achieve a peak serum concentration of 8 mg/L, the loading dose would be 8 mg/L * 19.25 L = 154 mg. Since the question asks for the most appropriate loading dose, the closest option to 154 mg is 150 mg.

The most likely cause of this patient's seizure disorder is a vascular malformation. The patient had a well-controlled seizure disorder for 25 years, suggesting a chronic underlying cause. The photograph of the coronal section of the brain obtained at autopsy may show evidence of a vascular malformation, such as an arteriovenous malformation (AVM) or cavernous malformation. These vascular abnormalities can disrupt the normal blood flow in the brain and lead to seizures. Glioblastoma multiforme, herpes simplex encephalitis, mesial temporal sclerosis, and neonatal ischemic stroke are less likely causes in this case.

The antibody to the liver cell surface antigen prevents the formation of tumor nodules in the liver, but tumor nodules still develop in the ovaries and lungs. This suggests that the antibody is affecting the process of homing, which is the ability of cancer cells to migrate and establish themselves in specific organs. The antibody likely inhibits the binding of the B-16 melanoma cells to the liver cells, preventing their homing to the liver and subsequent tumor formation. However, it does not affect the ability of the cells to invade or migrate to the ovaries and lungs, as tumor nodules still develop in these organs.

The correct answer is above the 9th rib in the midscapular line. This is the most appropriate location to insert the catheter because it is above the area of dullness to percussion, indicating the location of the pleural effusion. Inserting the catheter above the 9th rib ensures that it will be positioned correctly to drain the effusion.

The correct answer is F) Decreased peristalsis, decreased lower esophageal sphincter tone. This is the most likely set of findings on esophageal manometry because the patient's symptoms of heartburn and difficulty swallowing solid food and liquid are consistent with a diagnosis of achalasia. Achalasia is characterized by impaired peristalsis and decreased lower esophageal sphincter tone, leading to difficulty in moving food down the esophagus and into the stomach. The patient's history of pain and swelling in her wrists and hands suggests an underlying autoimmune disorder, which can be associated with achalasia. The absence of wrinkles on the face and neck may be a clue to the diagnosis of systemic sclerosis, which can also be associated with achalasia.

The Glasgow Coma Scale (GCS) is a neurological scale used to assess a patient's level of consciousness. It consists of three components: eye opening, verbal response, and motor response. 1 Pupillary response, while an important neurological assessment, is not part of the GCS.  

In this patient, the urine osmolality is significantly lower than the serum osmolality, indicating that the tubular fluid is more dilute compared to the serum. This suggests that water is being reabsorbed in the tubules, leading to a hypotonic tubular fluid. The only option that matches this finding is option F, which states that the tubular osmolality is hypotonic compared to the serum in all three segments of the nephron (proximal tubule, juxtaglomerular apparatus, and medullary collecting duct).