Question 1

A 45-year-old woman is concerned by a history of episodes of confusion and fainting over the past year that occur either on first arising in the morning or after exercising. The episodes are preceded or accompanied by shaking, sweating, and palpitations. The woman's husband has noticed that eating can prevent the onset of symptoms. Which of the following is the most likely cause of this patient's symptoms?

Accepted Answer

A)  Autonomic insufficiency leading to orthostatic hypotension 
B)  Benign insulin-secreting tumor causing periodic hypoglycemia 
C)  Glucagon-secreting tumor causing periodic hypoglycemia 
D)  Meningioma in the region of the frontal cortex 
E)  Norepinephrine-secreting tumor causing periodic hyperglycemia

Question 2

Which one of the following statements is correct regarding salivary secretion?

Accepted Answer

A)  The secretion of saliva is essential for the complete digestion of starch. 
B)  It is primarily under hormonal control. 
C)  It does not prevent decalcification of the teeth. 
D)  It is an acidic solution that begins the digestion of protein in the mouth. 
E)  It is the only hypotonic gastrointestinal secretion.

Question 3

A 32-year-old female undergoes an appendectomy without complications, but has markedly reduced bowel sounds and an absence of flatus or defecation during the immediate postoperative period. Which of the following mechanisms best explains this decrease in bowel sounds?

Accepted Answer

A)  Decreased sympathetic activity to the gut 
B)  Increased activity of the gastrocolic reflex 
C)  Increased parasympathetic activity to the gut 
D)  Increased plasma acetylcholine concentration 
E)  Increased plasma norepinephrine concentration

Question 4

A 45-year-old woman arrives at the clinic and exhibits athetoid movements. She probably has a:

Accepted Answer

A)  Cerebellar lesion 
B)  Lesion in the basal ganglia 
C)  Thalamic lesion 
D)  Frontal eye field lesion 
E)  Lesion in the cerebral cortex

Question 5

A middle-aged woman has had asthma since childhood and has been a heavy smoker since her early teens. During the past few years, she has experienced progressive dyspnea (breathing difficulty) and somnolence (sleepiness). Physical examination reveals a cachectic (general ill health and malnutrition) female with shortness of breath, prolonged expirations, and frequent coughing. Laboratory data are as follows: arterial pH 7.35; arterial HCO3- 32 mEq/L; arterial PCO2 60 mmHg; and arterial PO2, 60 mmHg. Which of the following is a likely diagnosis?

Accepted Answer

A)  Acute metabolic acidosis with renal compensation 
B)  Acute respiratory acidosis without renal compensation 
C)  Chronic metabolic acidosis with considerable renal compensation 
D)  Chronic respiratory acidosis with considerable renal compensation 
E)  Respiratory acidosis with metabolic acidosis

Question 6

Consider a patient with pH = 7.33; [HCO3-] = 36 mEq/L; PCO2 = 70 mmHg. What is the acid-base status of the patient?

Accepted Answer

A)  Compensated metabolic alkalosis 
B)  Compensated metabolic acidosis 
C)  Compensated respiratory alkalosis 
D)  Compensated respiratory acidosis 
E)  Uncompensated respiratory alkalosis

Question 7

A 58-year-old woman has left hemiparesis and right ptosis (droopy eyelids). She cannot adduct, elevate, or depress her right eye. The most likely cause of these findings is a lesion in which of the following sites?

Accepted Answer

A)  Cavernous sinus 
B)  Cerebral cortex 
C)  Left genu of the internal capsule 
D)  Mesencephalon 
E)  Right occipital lobe

Question 8

A medical student complains of severe vomiting and diarrhea for 2 days since eating at the Roadkill Café. His blood pressure is 120/70 mmHg supine and 90/50 mmHg standing. His skin and mucous membranes are dry. Which of the following laboratory finding would you expect to find?

Accepted Answer

A)  Low serum aldosterone concentration 
B)  High atrial natriuretic peptide (ANP) levels 
C)  Low plasma renin activity 
D)  Low urinary sodium concentration 
E)  High urine volume

Question 9

A 56-year-old obese woman suffering from heartburn and regurgitation of acid saliva after large meals is treated with cimetidine. During cimetidine treatment, her serum creatinine concentration increases significantly. The increase in serum creatinine with cimetidine treatment is most likely due to:

Accepted Answer

A)  Being reabsorbed by the nephron in exchange for creatinine 
B)  Blocking synthesis of creatinine by skeletal muscle 
C)  Causing acute renal failure 
D)  Competing with creatinine for renal tubular secretion 
E)  Inhibiting uptake of creatinine ingested with food

Question 10

The primary source of estriol (E3) during pregnancy is the:

Accepted Answer

A)  Maternal ovary 
B)  Fetal ovary 
C)  Fetal adrenal and placenta 
D)  Endometrium 
E)  Corpus luteum

Question 11

A 46-year-old man complains of progressive muscle weakness. Laboratory studies show a serum pH of 7.6, HCO3- of 32 mEq/L, and an elevated plasma aldosterone concentration. The most likely cause of muscle weakness in this patient is:

Accepted Answer

A)  Hyperchloremia 
B)  Hyperkalemia 
C)  Hypocalcemia 
D)  Hypokalemia 
E)  Hyponatremia

Question 12

A middle-aged man is evaluated for polydipsia and polyuria. His 24-hour urine volume is 7.0 L with a low osmolality, and is negative for red blood cells, leukocytes, protein, and glucose. His blood pressure and heart rate are both normal. Which of the following is a likely cause of polyuria in this patient?

Accepted Answer

A)  Acute attack of diabetes mellitus without glucosuria 
B)  Acute renal failure with a severe decrease in glomerular filtration rate (GFR) 
C)  Cerebrovascular accident damaging the anterior pituitary gland 
D)  Renal supersensitivity to the effects of antidiuretic hormone (ADH) 
E)  Suppression of ADH secretion due to polydipsia

Question 13

A newborn presents with somewhat ambiguous external genitalia. The genitalia appear as an enlarged clitoris and a scrotum-like structure that appears to result from labial fusion. An ultrasound reveals normal ovarian development. The karyotype is 46 XX. The findings are most likely due to a deficiency in which one of the following enzymes?

Accepted Answer

A)  11$\beta$-hydroxylase 
B)  16$\alpha$-hydroxylase 
C)  17$\alpha$-hydroxylase 
D)  21$\alpha$-hydroxylase 
E)  3$\beta$-hydroxysteroid dehydrogenase

Question 14

Your patient has been diagnosed with malignant hyperthermia after a surgical procedure. The most common cause of malignant hyperthermia in humans is an
Abnormal response to general anesthetics involving the:

Accepted Answer

A)  Na+-Ca2+ exchanger 
B)  Sarcoplasmic reticulum Ca2+ release channel 
C)  IP3 receptor 
D)  Na+K+-ATPase 
E)  Central nervous system (CNS)

Question 15

A 16-year-old boy has become totally deaf in his left ear after a motor vehicle accident even though hearing in his right ear is normal. A lesion at which of the following sites is the most likely cause of this finding?

Accepted Answer

A)  Left dorsal and ventral cochlear nuclei 
B)  Left inferior colliculus 
C)  Left superior colliculus 
D)  Right medial geniculate nucleus 
E)  Right temporal lobe

Question 16

A 30-year-old female patient with hypercapnia that is not the result of compensation for an acid-base disturbance is seen in the clinic. Thus, this patient is suffering from:

Accepted Answer

A)  Nothing, the patient has normal acid-base balance. 
B)  Respiratory acidosis 
C)  Respiratory alkalosis 
D)  Metabolic acidosis 
E)  Metabolic alkalosis

Question 17

A 30-year-old man complains of progressive muscle weakness and double vision (diplopia) and some difficulty in swallowing solid foods. Neurologic studies show a neuromuscular conduction defect, and diagnostic studies with an intravenous injection of edrophonium are found to rapidly increase his muscle strength. When the patient is treated with neostigmine, his status improves. The most probable target molecule in this treatment is:

Accepted Answer

A)  Acetylcholinesterase 
B)  Choline acetyltransferase 
C)  Monoamine oxidase 
D)  Muscarinic acetylcholine (ACh) receptor 
E)  Nicotinic ACh receptor

Question 18

In a patient recovering from cholera, pH = 7.35; [HCO3-] = 16 mEq/L; PCO2 = 30 mmHg. What is the acid-base status of the patient?

Accepted Answer

A)  Compensated metabolic alkalosis 
B)  Compensated metabolic acidosis 
C)  Compensated respiratory alkalosis 
D)  Compensated respiratory acidosis 
E)  Uncompensated respiratory alkalosis

Question 19

A 60-year-old man develops an acute onset of confusion, ataxia, nystagmus, and hypothermia shortly after the administration of an intravenous solution containing 5% glucose and normal saline. The pathogenesis of this patient's neurologic disorder is most closely related to which of the following conditions?

Accepted Answer

A)  Central pontine myelinolysis 
B)  Purkinje cell atrophy 
C)  Thiamine deficiency 
D)  Viral encephalitis 
E)  Vitamin B12 deficiency

Question 20

A 70-year-old man complains of weakness in his right leg. Physical examination is notable for hyperactive muscle stretch reflexes, a positive Babinski sign, and diffuse areas of weakness in his right leg. Although he can accurately distinguish sharp and dull pain in the right leg he is unable to distinguish these types of pain in his left leg. The most likely cause of these findings is a lesion in the:

Accepted Answer

A)  Cerebellum 
B)  Internal capsule, left anterior limb 
C)  Left lateral funiculus 
D)  Reticular formation 
E)  Right frontal lobe

Exam 2: Physiology of Cells and Molecules

Which one of the following statements is correct regarding salivary secretion?

A 32-year-old female undergoes an appendectomy without complications, but has markedly reduced bowel sounds and an absence of flatus or defecation during the immediate postoperative period. Which of the following mechanisms best explains this decrease in bowel sounds?

A 45-year-old woman arrives at the clinic and exhibits athetoid movements. She probably has a:

Consider a patient with pH = 7.33; [HCO₃^-] = 36 mEq/L; PCO₂ = 70 mmHg. What is the acid-base status of the patient?

A 58-year-old woman has left hemiparesis and right ptosis (droopy eyelids) . She cannot adduct, elevate, or depress her right eye. The most likely cause of these findings is a lesion in which of the following sites?

A medical student complains of severe vomiting and diarrhea for 2 days since eating at the Roadkill Café. His blood pressure is 120/70 mmHg supine and 90/50 mmHg standing. His skin and mucous membranes are dry. Which of the following laboratory finding would you expect to find?

A 56-year-old obese woman suffering from heartburn and regurgitation of acid saliva after large meals is treated with cimetidine. During cimetidine treatment, her serum creatinine concentration increases significantly. The increase in serum creatinine with cimetidine treatment is most likely due to:

The primary source of estriol (E₃) during pregnancy is the:

A 46-year-old man complains of progressive muscle weakness. Laboratory studies show a serum pH of 7.6, HCO₃^- of 32 mEq/L, and an elevated plasma aldosterone concentration. The most likely cause of muscle weakness in this patient is:

Your patient has been diagnosed with malignant hyperthermia after a surgical procedure. The most common cause of malignant hyperthermia in humans is an Abnormal response to general anesthetics involving the:

A 16-year-old boy has become totally deaf in his left ear after a motor vehicle accident even though hearing in his right ear is normal. A lesion at which of the following sites is the most likely cause of this finding?

A 30-year-old female patient with hypercapnia that is not the result of compensation for an acid-base disturbance is seen in the clinic. Thus, this patient is suffering from:

In a patient recovering from cholera, pH = 7.35; [HCO₃^-] = 16 mEq/L; PCO₂ = 30 mmHg. What is the acid-base status of the patient?