Physiology Question Set 2

Two medical residents volunteer for a study being held by the physiology department of the affiliated medical school. They are both healthy, with no active medical issues, not taking any medications, similar lifestyles, and nearly identical dietary habits. Both of them have vitals within normal (expected) limits. Resident A weighs 75.0 kg (165 lb) and Resident B 74.5 kg (164 lb). Preliminary lab results show: Resident A: Serum Glucose (fasting): 88 mg/dL Serum Electrolytes: Sodium: 138 mEq/L Potassium: 3.8 mEq/L Chloride: 99 mEq/L Serum Creatinine: 0.8 mg/dl Blood Urea Nitrogen: 10 mg/dl Alanine aminotransferase (ALT): 18 U/L Aspartate aminotransferase (AST): 16 U/L Hemoglobin (Hb %): 13 g/dL Mean Corpuscular Volume (MCV): 84 fl Reticulocyte count: 0.9 % Erythrocyte count: 5.2 million/mm^3 Platelet count: 300,000/mm^3 Urinalysis: Negative Proteins: Negative Glucose: Negative Ketones: Negative Leucocytes: Negative Nitrites: Negative Red Blood Cells (RBC): Negative Casts: Negative. Resident B: Serum Glucose (fasting): 81 mg/dL Serum Electrolytes: Sodium: 142 mEq/L Potassium: 3.9 mEq/L Chloride: 101 mEq/L Serum Creatinine: 0.9 mg/dl Blood Urea Nitrogen: 11 mg/dl Alanine aminotransferase (ALT): 20 U/L Aspartate aminotransferase (AST): 18 U/L Hemoglobin (Hb %): 15 g/dL Mean Corpuscular Volume (MCV): 85 fl Reticulocyte count: 1 % Erythrocyte count: 5.1 million/mm^3 Platelet count: 325,000/mm^3 Urinalysis: Negative Proteins: Negative Glucose: Negative Ketones: Negative Leucocytes: Negative Nitrites: Negative Red Blood Cells (RBC): Negative Casts: Negative. Over the course of a single day, oral potassium is given to both volunteers: 25 mEq to resident A and 250 mEq to resident B. At the end of the day, blood tests show both of them to have an equal blood potassium level of 4.2 mEq/L. Which segment of nephron is responsible for this result?

A 30-year-old male presents to the physician for a follow-up appointment as he had a blood pressure of 140/90 mmHg during his last visit. He was advised to record his blood pressure at home with an automated device twice every day. He recorded a wide range of blood pressure values in the past week ranging from 110/70 mmHg to 135/84 mmHg. His past medical history is unremarkable and he takes no medications. He occasionally drinks after work but denies smoking and illicit drug use. Which of the following factor is responsible for maintaining a near normal renal blood flow over a wide range of systemic blood pressures?

A 20-year-old healthy female volunteer is enrolled in a study on renal perfusion. Her medical history is unremarkable and she takes no medications. She denies smoking, drinking, and drug use. Her family history is unremarkable. Examination reveals no abnormal findings. A drug which is known to very selectively act on a segment of the renal vasculature is administered and her Glomerular Filtration Rate (GFR) and Filtration Fraction (FF) both increase. Which of the following could be the mechanism of action of the administered drug?

A 9-year-old boy is brought to the doctor's office by his mother because of facial swelling for 2 days. The mother says that her boy has always been healthy and active but is becoming increasingly lethargic and now has a puffy face. Upon inquiry, the boy describes a foamy appearance of his urine but denies having blood in urine, urinary frequency at night or pain during urination. He has no history of renal or urinary diseases. Physical examination is unremarkable except for generalized swelling of the face and pitting edema on the lower limbs. Dipstick analysis reveals 4+ proteinuria. An abdominal ultrasound shows normal size and morphology of the kidneys. Renal biopsy yields no findings under light and fluorescence microscopy, however, glomerular podocyte foot effacement is seen on electron microscopy. Which of the following factors is responsible for the expected increase in Glomerular Filtration Rate (GFR) in the patient?

To reduce the hemolysis that occurs with dialysis, researchers have developed an organic filtration membrane for dialysis that is believed to mimic the physiological filtering apparatus of the human glomerulus. The permeability characteristics of this membrane are believed to be identical to those of the glomerular filtering membrane. Which of the following substances should be absent in the filtrate produced by this membrane?

A 75-year-old female is brought to the physician's office by her son with the complaints of diarrhea and vomiting for 1 day. Her stool is loose, watery, and yellow-colored while her vomitus contains partially digested food particles. She denies having blood or mucous in her stools and vomitus. Since the onset of symptoms, she has not had anything to eat and her son adds that she is unable to tolerate fluids either. Her past medical history is unremarkable and she does not take any medication regularly. Vitals show a pulse of 115 bpm, respirations 16/min, blood pressure 100/60 mmHg and temperature of 37.0 °C (98.6 °F). Examination shows dry mucous membranes and slightly sunken eyes. Her abdomen is soft and non-tender. Which of the following physiological changes in glomerular filtration rate (GFR), renal plasma flow (RPF) and filtration fraction (FF) are expected in this patient?

A 70-year-old male presents to the doctor's office with shortness of breath for one month. He gets "easily winded" and is unable to keep up with his grandchildren at the park. Over the last few weeks, he had to increase the number of pillows under his head to sleep comfortably. He denies cough and fever. His medical history includes hypercholesterolemia and hypertension. His current medications are aspirin, carvedilol, and rosuvastatin. VItals include blood pressure: 150/90 mmHg, pulse: 90 /min, respirations: 14/min. Physical examination reveals distended jugular veins, bilateral pitting edema of the lower limbs, and fine crackles at the base of lungs. An echocardiogram reveals an ejection fraction of 40 %. Inhibition of which of the following hormones would be most beneficial for this patient?

In a healthy patient with no renal abnormalities, several mechanisms are responsible for moving various filtered substances into and out of the tubule. Para AminoHippurate (PAH) is frequently used to estimate renal blood flow when maintained at low plasma concentrations. The following table illustrates the effect of changing plasma PAH concentration on PAH excretion: Plasma PAH Concentration (mg/dl) --> Urinary PAH Concentration (mg/dl): 0 --> 0, 10 --> 60, 20 --> 120, 30 --> 150, 40 --> 180. Which of the following mechanisms best explains the decrease in PAH excretion with the increase in its plasma concentration?

A healthy volunteer receives multiple daily doses of a substance X that is not metabolized in the body. Substance X is freely filtered and undergoes secretion in the renal tubules but minimal reabsorption. His renal studies show the following: Inulin clearance: 125 mL/min Plasma concentration of Inulin: 1 mg/mL Tubular Secretion of Substance X: 30 mg/min Tubular Reabsorption of Substance X: 5 mg/min Renal Excretion of Substance X: 400 mg/min. Calculate the plasma concentration of the substance in the volunteer.

A large pharmaceutical company is seeking healthy volunteers to participate in a drug trial. The drug is excreted in the urine and the volunteers must agree to laboratory testing before enrolling in the trial. One of the volunteers' lab results are shown below: Serum Glucose (random): 148 mg/dL Serum Electrolytes: Sodium: 140 mEq/L Potassium: 4 mEq/L Chloride: 100 mEq/L Serum Creatinine: 1 mg/dl Urine: Glucose: absent Sodium: 35 mEq/L Potassium: 10 mEq/L Chloride: 45 mEq/L Creatinine: 100 mg/dl Assuming an urine flow rate of 1 ml/min, which set of values below is the clearance of glucose, sodium and creatinine respectively in this patient?

A 45-year-old male comes to the physician for a follow-up visit for his diabetes mellitus. His complaint during his last visit was postprandial abdominal fullness which he happily reports has resolved with regular exercise and metformin. He also mentions that his urinary frequency has decreased. He remembers seeing a positive value for glucose in his urine lab report and is now concerned that if he urinates less ‘the sugar won't be expelled’. His labs from the last visit and this one are given below. Previous Visit: Serum Glucose (fasting): 288 mg/dL Serum Electrolytes: Sodium: 142 mEq/L Potassium: 4.3 mEq/L Chloride: 99 mEq/L Serum Creatinine: 0.7 mg/dl Blood Urea Nitrogen: 10 mg/dl Urinalysis: Proteins: Negative Glucose: 1+ Ketones: Negative Leucocytes: Negative Nitrites: Negative Red Blood Cells (RBC): Negative Casts: Negative This Visit: Serum Glucose (fasting): 88 mg/dL Serum Electrolytes: Sodium: 139 mEq/L Potassium: 3.9 mEq/L Chloride: 101 mEq/L Serum Creatinine: 1.0 mg/dl Blood Urea Nitrogen: 15 mg/dl Urinalysis: Proteins: Negative Glucose: Negative Ketones: Negative Leucocytes: Negative Nitrites: Negative Red Blood Cells (RBC): Negative Casts: Negative The physician counsels him that his urinary frequency and the positive urinary glucose result were both pathological complications of his diabetes mellitus and that the body does not need to ‘expel excess sugars’. Which of the following best explains the initial urinary findings in this patient?

A 22-year-old male college student volunteers for a research study relating to renal functions. He undergoes several laboratory tests: Urine: Glucose: 0 mg/dl Inulin: 100 mg/dl Para-Aminohippurate (PAH): 150 mg/dl. Serum: Glucose: 93 mg/dl Inulin: 1.0 mg/dl Para-Aminohippurate (PAH): 0.2 mg/dl. Hematocrit: 50 % Urine Flow Rate: 1ml/min What is his estimated renal blood flow?

A 55-year-old woman presents to the physician's clinic for a scheduled follow-up visit for his diabetes. She recently lost some weight and believes her diabetes is 'winding down' because her urinary frequency has abated. She has been poorly compliant with her medications and the physician suspects that she might be heading towards renal failure. Which substance can be used to most accurately assess this patient's Glomerular Filtration Rate (GFR)?

A 35-year-old male is recovered from the wilderness behind a ski resort where he was lost 2 days back. He has not had any water nor food during this time and is rushed to the emergency department for medical care. Which of the following parameters best describes his physiologic state when found? (Dec = Decresed; Inc = Increased)

A 47-year-old female presents to the physician with vomiting and diarrhea for 2 days. Her symptoms started after a company picnic a few days back. Initially she was unable to tolerate any solids or liquids by mouth but has now started taking sips of water. She has had a mild headache which was relieved by acetaminophen. Her past medical history is unremarkable. She does not take any medications. Vitals show blood pressure of 120/60 mmHg and heart rate of 60 /min. On examination, her mucous membranes are dry and her eyes seem slightly sunken. Where is most of the sodium reabsorbed in this patient's kidneys?

Researchers develop a drug X that acts on the loop of Henle but find that it does not reach its intended site of action within the nephron. It is freely filtered but rapidly disappears from the proximal tubule. They modify several of its chemical properties to produce drug Y which cannot be reabsorbed from the proximal tubule. Neither drug is secreted into the tubule. Which of the following natural substances mimic the concentrations of drug X and drug Y in the proximal tubule?

A 9-year-old male is brought to the physician by his mother due to generalized weakness, increased urination, and increased thirst. The mother mentions that her boy is always tired and it's getting worse. He prefers watching television rather than go out and play with other kid. Furthermore, he has had frequent episodes of constipation since birth. Except for frequent cravings for salty foods, the boy eats a regular diet. The patient was delivered healthy and is fully immunized. Medical history is unremarkable and he takes no medications. He has no siblings, his father is a banker and his mother is a librarian. His pulse rate is 90 /min, blood pressure is 110/75 mmHg, and respiratory rate is 15/min. He is in the bottom 10th percentile for height and weight according to his age. The remainder of the physical examination is unremarkable. Lab test show: Serum Electrolytes: Sodium: 135 mEq/L Potassium: 3.2 mEq/L Chloride: 95 mEq/L Plasma renin activity: 10 ng/mL/hr (normal 0.5 - 3.3 ng/mL/hr) Plasma aldosterone concentration: 20 ng/dl (normal 2 - 9 ng/dl). What is the most likely diagnosis?

A 62-year-old woman comes to the doctor’s office for a regular checkup. She is a smoker, has high cholesterol, and both of her parents suffered from high blood pressure. Her father died of heart attack few years ago. Her ECG shows high T wave. High T wave is a result of a high K+ levels in plasma and her biochemical analysis confirms that. What does T wave represent when ECG is observed?

A 38-year-old man comes to the emergency room with shortness of breath and chest pain. He has family history of thrombophilia. His mother is also suffering from it and has had several miscarriages before his birth. He had a car accident several weeks ago when he broke his leg. A pulmonary embolism is also diagnosed. What is expected to happen with ventilation, perfusion and V/Q in the present case?

A 67-year-old woman comes to her GP because of severe vomiting in the last two days. She says she hasn’t been able to eat or drink anything, because she would vomit after ingesting anything. She is pale, hypoventilates and seems dehydrated. She doesn’t take any chronic therapy. She reports that her grandchildren had similar symptoms and were given intravenous rehydration by their pediatrician. Which of the following is expected to be seen in her acid-base status?

A 49-year-old, overweight man comes to the emergency room (ER) with palpitations. On examination, he is tachycardic (heart rate is above 100) and looks scared, but other than that his physical examination is unremarkable. He says he suffers from mild bronchial asthma, but other than that he is healthy. He only uses drugs during an asthma attack and hasn’t used it at since a week. Which of the following group of drugs should be given to treat tachycardia in the present case?