Deck 3: The Nervous System

Question 1

The fundamental benefit of applying positive end-expiratory pressure (PEEP) to an 80-year-old patient with a large closing volume would be that PEEP:

A) Increases the area available for gas exchange by opening closed alveoli
B) Increases compliance, making it easier to breathe
C) Promotes an increase in pulmonary blood flow
D) Significantly increases the PaO₂ when the patient is breathing air
E) Stimulates breathing by tonically activating pulmonary stretch receptors

Answer 1

Increases the area available for gas exchange by opening closed alveoli

Question 2

A 44-year-old woman complains of increased 'hairiness' that has developed over her face and body over the past 2 years. Physical exam reveals increased hair growth over the upper lip, chin, chest, and abdomen, but no truncal obesity or purple striae. Laboratory values of which hormones would provide the most pertinent diagnostic information?

A) Cortisol and thyroxine (T₄)
B) Estrogen and progesterone
C) Follicle stimulating hormone (FSH) and luteinizing hormone (LH)
D) 17-alpha-hydroxyprogesterone
E) Testosterone and dehydroepiandrosterone (DHEA) sulphate

Answer 2

Testosterone and dehydroepiandrosterone (DHEA) sulphate

Question 3

An 8-year-old girl developed 'rosy cheeks' while playing outside on a chilly day. What is thought to be the cause of this vasodilation?

A) Paralysis of vascular smooth muscle
B) A decreased thermoregulatory 'set point'
C) Increased prostaglandin E₂ (PGE₂) production
D) Increased parasympathetic activity
E) Secretion of progesterone

Answer 3

Paralysis of vascular smooth muscle

Question 4

A 15-year-old girl is brought to her doctor because of increased irritability, restlessness, weight loss and learning problems over the past 2 months. Physical examination reveals no abnormalities. Laboratory studies reveal increased triiodothyronine (T₃) and thyroxine (T₄) levels. Which of the following is the most likely diagnosis?

A) Hypoglycemia
B) Diabetes mellitus
C) Hyperthyroidism
D) Pituitary adenoma
E) Thyroid cancer

Question 5

A 60-year-old woman complains of persistent breathing difficulties. Her laboratory studies show: pH 7.36; [H⁺] 44 nmol/L; PaCO₂ 55 mmHg; [HCO₃^-] 30 mmol/L. Which of the following is the most likely diagnosis?

A) Combined metabolic acidosis and respiratory acidosis
B) Primary respiratory acidosis, secondary metabolic alkalosis, full pH compensation
C) Primary respiratory acidosis, secondary metabolic alkalosis, partial pH compensation
D) Pure metabolic acidosis without pH compensation
E) Pure respiratory acidosis

Question 6

A 23-year-old girl complains of a 3-month history of malaise and generalized muscle cramps. Laboratory results reveal: serum sodium 144 mmol/L; serum potassium 2.0 mmol/L; serum bicarbonate 40 mmol/L; arterial pH 7.5. Which of the following is the most likely cause of this patient's hypokalemic alkalemia?

A) Hyperaldosteronism
B) Hyperventilation
C) Persistent diarrhea
D) Renal failure
E) Diabetes mellitus

Question 7

While on a rotation in India, you encounter a 10-year-old patient who is suffering cholera and is severely dehydrated. You are asked to prepare an oral rehydration solution. What, in addition to water, would the most important components of the solution be?

A) Bicarbonate and potassium
B) Chloride and potassium
C) Lactate and potassium
D) Sodium and bicarbonate
E) Sodium and glucose

Question 8

A 47-year-old male arrives in the emergency department with acute anterior chest pain, which radiates to the left arm and back and has lasted for 1 h. He is 80 in tall and weighs 190 lbs. His blood pressure is 115/70 mmHg, pulse 116/min, and respiratory rate 20/min. The lungs are clear and an electrocardiogram (ECG) shows no abnormalities. Which of the following is the most likely diagnosis?

A) Angina pectoris
B) Myocardial infarction (MI)
C) Aortic dissection
D) Cervical disc disease
E) Pericardial tamponade

Question 9

A 67-year-old man suffering from metastatic prostate cancer arrives at your emergency department 2 h after the sudden onset of anterior chest pain and shortness of breath. The pain is enhanced by deep breathing movements. He is hypotensive and exhibits a rapid pulse and respiration rate. His blood pressure is 100/56 mmHg, pulse 136/min and respiration rate 28/min. Although the lungs are clear, an electrocardiogram (ECG) shows a right axis deviation not observed before. Which of the following is the most likely diagnosis?

A) Pneumonia
B) Pulmonary embolism
C) Pneumothorax
D) Lung cancer
E) Esophageal spasm

Question 10

A 6-week-old boy is brought to his pediatrician by his mother because of progressively worsening projectile vomiting over the past 2 weeks. Physical examination reveals a wasted, dehydrated infant who is avidly sucking on a nipple. Which of the following laboratory values is most consistent with this child's problem ?

A)
B) $\begin{array} { l l l l } 140 \text { Normal } & 3.8 \text { Normal } & 110 \uparrow & 23 \text { Normal }\end{array}$
C)
D)
E)

Question 11

A 58-year-old man complains of tinnitus that is loudest in his right ear and a decreased sense of taste in the anterior portion of his tongue. His symptoms have become progressively worse during the past 6 months. His physical examination is within normal limits. Which of the following is the most likely diagnosis?

A) Acoustic neuroma
B) Lacunar stroke in the internal capsule
C) Lesion in the caudal medulla
D) Lesion in the mesencephalic tegmentum
E) Lesion in the tectum

Question 12

A 69-year-old man is diagnosed with benign prostatic hypertrophy (BPH). Which of the following hormones is primarily responsible for prostatic enlargement in BPH?

A) Testosterone
B) Androstenedione
C) Dihydrotestosterone (DHT)
D) Estrone
E) Estradiol

Question 13

An 18-year-old patient with trisomy 21 has an unrepaired complete atrioventricular (AV) canal defect and pulmonary hypertension. She is complaining of headache and dizziness. Which of the following tests would be most likely to reveal the etiology of these complaints?

A) Electrocardiography (ECG)
B) Electroencephalography (EEG)
C) Hematocrit
D) Sinus radiography
E) Urinalysis

Question 14

Upon awakening one morning, a 62-year-old man, is unable to use his right hand. In addition, he recently experienced conjugate deviation of the eyes to the left and paralysis of voluntary gaze to the right; 5 days later, however, his eye movements returned to normal. This patient probably has had a stroke involving the:

A) Left frontal cortex
B) Left mesencephalic tegmentum
C) Left occipital cortex
D) Right lateral geniculate nucleus
E) Right occipital cortex

Question 15

A 56-year-old female complains of generalized weakness and a 20 lb weight loss over the past 6 months. Blood pressure is 136/80 mmHg and pulse is 88/min. Laboratory values reveal a hematocrit of 31% (normal 40-45%), hemoglobin level of 10 g/dL (normal 14 g/dL), and a blood smear shows hypochromic microcytic cells. A stool test for occult blood is positive. Which of the following would be the most likely cause of the findings?

A) Acute blood loss
B) Folic acid deficiency
C) Hemochromatosis
D) Iron deficiency
E) ( $\beta$ )-Thalassemia trait

Question 16

A previously healthy 2-year-old girl who developed a sudden onset of persistent coughing is brought to the pediatric clinic. She has no fever and now is coughing up bright red, frothy blood. What is the most likely cause of this child's problem?

A) Arteriovenous malformation of the lung
B) Cystic fibrosis
C) Foreign body in the bronchus
D) Pneumonia
E) Tuberculosis

Question 17

An 8-year-old girl has headache, vomiting, and hypertension. She appears adequately hydrated. Laboratory values are: serum sodium concentration 110 mEq/L (normal 135-145 mEq/L); blood urea nitrogen 10 mg/dL (normal 7-22 mg/dL); serum creatinine, 0.4 mg/dL (normal 0.3-0.7 mg/dL). The sodium concentration of a random sample of urine is 100 mEq/L (normal 130-260 mEq/24 h). An increase in which of the following hormones is the most likely cause of these findings?

A) Antidiuretic hormone (ADH)
B) Atrial natriuretic peptide (ANP)
C) Estrogen
D) Glucocorticoid
E) Mineralocorticoid

Question 18

A 60-year-old hypertensive man is diagnosed with stenosis of a major renal artery. To compensate for decreased blood perfusion of the affected kidney, he produces an excess of the compound labeled X in the figure below. Which of the following best characterizes compound X?

A) It causes arteriolar vasoconstriction.
B) It is produced by juxtaglomerular cells of the kidney.
C) It is secreted in response to infusions rich in Na⁺.
D) It is under tight control of adrenocorticotropic hormone (ACTH).
E) It promotes sodium retention and potassium excretion in the distal tubules of nephrons.

Question 19

A 14-year-old boy complains of a 3-week history of weight loss, excessive thirst, and urination. Type 1 diabetes mellitus is suspected. Laboratory testing of blood samples will most likely show:

A) Increased erythrocyte sedimentation rate
B) Increased serum creatinine level
C) Presence of anti-pancreatic amyloid antibodies
D) Presence of anti-pancreatic islet cell antibodies
E) Presence of anti-streptolysin O antibodies

Question 20

A 15-year-old boy complains of vomiting, anorexia, and weight loss. Laboratory studies reveal: serum calcium 13 mg/dL (normal 8.7-10.6 mg/dL); blood urea nitrogen 36 mg/dL (normal 7-22 mg/dL); serum creatinine, 1.8 mg/dL (normal 0.3-0.7 mg/dL). He has been taking several high-potency vitamin supplements daily for the past year as part of a 'body-building' program. An excess of which of the following vitamins is the most likely cause of these findings?

A) Vitamin A
B) Vitamin B
C) Vitamin C
D) Vitamin D
E) Vitamin E

Question 21

In addition to treating a diabetic patient (type 1) for ketoacidosis with insulin, why is a potassium salt often administered?

A) Insulin directly increases the excretion of potassium by the kidney.
B) Return of plasma pH and glucose to normal will lower the total body potassium content.
C) Return of plasma pH and glucose to normal is accompanied by a shift of potassium into cells.
D) Plasma potassium is usually low in diabetic ketoacidotic patients.
E) Return of plasma glucose to normal will cause a decrease in the plasma volume.

Question 22

A 42-year-old obese woman experiences episodic upper right quadrant abdominal pain. She notes that the pain increases after the ingestion of a fatty meal. The action of which of the following hormones is responsible for the postprandial intensification of her symptoms?

A) Cholecystokinin (CCK)
B) Gastrin
C) Pepsin
D) Secretin
E) Somatostatin

Question 23

You determine that a 45-year-old female patient with kidney stones is suffering from primary hyperparathyroidism. What is the most likely reason for an increase in her plasma ionized calcium?

A) Increased bone resorption
B) Enhanced 24,25(OH)₂-vitamin D₃ production
C) Increased kidney tubule reabsorption of phosphate
D) Decreased osteoclast formation
E) Decreased urinary phosphate

Question 24

Your 21-year-old female patient presents with a history of secondary amenorrhea, acne, hyperpigmentation, clitoral enlargement, and physical and mental fatigue. Her blood pressure is 160/105 mmHg and laboratory values indicate hypokalemia, low fasting blood glucose, and hypernatremia. What, in the light of these findings, is the most likely cause of her symptoms?

A) An adrenocorticotropic hormone (ACTH)-secreting tumor
B) 11β-hydroxylase deficiency
C) Absence of androgen receptors
D) 21-hydroxylase deficiency
E) Primary hypercortisolism

Question 25

A 31-year-old woman attempting to become pregnant after several months sees her gynecologist who diagnoses her with luteal insufficiency, even though ovulation does occur. Which of the following is most likely responsible?

A) High serum levels of periovulatory luteinizing hormone (LH)
B) Elevated levels of periovulatory gonadotropin releasing hormone (GnRH)
C) Insufficient priming of the corpus luteum by follicle stimulating hormone (FSH)
D) Inadequate LH surge to luteinize the corpus luteum
E) High levels of follicular phase estrogen

Question 26

A 10-year-old boy is admitted through the emergency department where he was brought after receiving a wasp sting while on a family outing. During a previous wasp sting, he experienced respiratory problems, itching, and urticaria, and he fainted. Upon admission he was obviously suffering from a generalized systemic inflammatory condition (anaphylaxis). What will anaphylactic shock cause?

A) Increased renal fluid output
B) Hypertension
C) Decreased blood volume
D) Decreased interstitial fluid pressure
E) Increased level of atrial natriuretic peptide

Question 27

Your 54-year-old female patient is suffering from myocardial ischemia. One drug that you suggest to improve her cardiac function is a b-Blocker. What would be the myocardial effect of a b-Blocker?

A) Dilation of peripheral blood vessels, particularly the veins
B) Prevention of pulmonary conversion of angiotensin I to angiotensin II
C) Increased L-type calcium channel activity in ventricular muscle
D) Increase in the dP/dt during ventricular isovolumetric contraction
E) Decreased heart rate and contractility of the myocardium

Question 28

Which of the following causes of brain hypoxia would most strongly stimulate the aortic and carotid chemoreceptors?

A) Carbon monoxide poisoning
B) Severe anemia
C) Formation of methemoglobin
D) A marked decrease in pulmonary diffusing capacity
E) Acute respiratory alkalosis

Question 29

Your 49-year-old male patient is admitted to the heart hospital suffering the classic symptoms of myocardial ischemia. His electrocardiogram (ECG) at admission shows an elevated S-T segment with an inverted T wave. What is the most likely cause of the inverted T wave?

A) Ventricular repolarization occurring from endocardium to epicardium
B) Ventricular repolarization occurring from epicardium to endocardium
C) Ventricular depolarization occurring from epicardium to endocardium
D) Ventricular depolarization occurring from endocardium to epicardium
E) An abnormal delay in atrioventricular (AV) nodal conduction

Question 30

A 10-year-old boy has a low plasma ionized Ca2+ and an increased parathyroid hormone level. He has a high plasma alkaline phosphatase, exhibits muscle weakness, and has skeletal areas that are poorly calcified. You prescribe vitamin D3, but see no improvement. However, treatment with 1,25(OH)2-vitamin D3 causes the patient's ionized Ca2+ level to increase. What would the most likely diagnosis be?

A) Type 1 vitamin D-dependent rickets
B) Rickets due to vitamin D deficiency
C) Inability to form 24(OH)-vitamin D₃
D) Receptors for dehydrocholesterol are absent
E) Inability to form vitamin D₃ in the skin

Question 31

A 33-year-old man complained about chest pain on exertion. He was referred to a cardiologist, who carried out a number of studies, including right- and left-sided catheterization. Among the data obtained during these studies were the findings that at the time of his initial examination the patient's mean aortic pressure was 93 mm Hg and his mean pulmonary artery pressure was 20 mm Hg. These findings can be explained as follows:

A) The patient's systemic vascular resistance was much greater than his pulmonary vascular resistance.
B) The patient's aortic compliance was much greater than his pulmonary artery compliance.
C) The patient's left ventricular stroke volume was much greater than his right ventricular stroke volume.
D) The total cross-sectional area of the patient's pulmonary artery was much greater than the total cross-sectional area of the aorta.
E) The duration of rapid ejection phase of the patient's left ventricle exceeded the duration of the rapid ejection phase of the right ventricle.

Question 32

A 49-year-old woman with coronary artery disease is prescribed a calcium channel blocker to facilitate coronary vasodilatation. Because of their myocardial side-effects, drugs that block L-type calcium channels would be expected to do which of the following?

A) Increase heart rate by enhancing the firing rate of the sinoatrial (SA) node
B) Trigger vasoconstriction
C) Lower blood pressure
D) Increase the force of contraction of the heart
E) Lengthen the plateau phase of the ventricular action potential

Question 33

A 44-year-old woman with severe cardiac failure caused by coronary artery disease was treated by cardiac transplantation. Three months after surgery, she developed a bleeding duodenal ulcer and lost approximately 600 ml of blood in one hour. She was treated with dietary changes and antibiotics and the ulcer was healed in about two weeks. The acute blood loss from the patient's duodenal ulcer would be expected to:

A) Decrease central venous pressure and increase cardiac output
B) Increase central venous pressure and decrease mean arterial pressure
C) Decrease central venous pressure and decrease cardiac output
D) Increase mean arterial pressure and decrease cardiac output
E) Decrease central venous pressure and increase aortic pulse pressure

Question 34

Your 20-year-old female patient has the following laboratory values: arterial blood pH 7.50; HCO3- 40 mEq/L; PCO2 51 mmHg. What is the acid-base status of this patient?

A) Partially compensated metabolic alkalosis
B) Partially compensated metabolic acidosis
C) Partially compensated respiratory alkalosis
D) Partially compensated respiratory acidosis
E) Uncompensated respiratory alkalosis

Question 35

A 9-year-old child has suffered severe lacerations and blood loss in an automobile accident. What is the most likely cause of increased vasopressin secretion in this child?

A) Secretion is stimulated when the plasma volume decreases.
B) Vasopressin decreases fluid loss by inhibiting aquaporin-2 (AQP2) water channel activity.
C) Secretion increases as plasma osmolality decreases.
D) Decreased K⁺ transport by increasing protein kinase A (PKA) activity in kidney cells.
E) Secretion is increased when blood pressure increases.

Question 36

You wish to determine the ability of thyrotropin-releasing hormone (TRH) to stimulate the release of pituitary hormones in a group of volunteer subjects. In addition to measuring thyroid stimulating hormone (TSH), which of the following hormones could you also measure?

A) Growth hormone (GH)
B) Prolactin
C) Luteinizing hormone (LH)
D) Adrenocorticotropic hormone (ACTH)
E) Antidiuretic hormone (ADH)

Question 37

A 58-year-old female patient with type II diabetes mellitus decides to discontinue insulin treatment because she believes she can control the disease with diet alone. What would you expect to happen to this patient shortly after insulin is discontinued?

A) Blood glucose concentration decreases.
B) Excretion of nitrogen increases.
C) Glycogen content in the liver increases.
D) Extracellular concentration of potassium decreases.
E) Rate of conversion of alanine to glucose decreases.

Question 38

In a healthy subject, running is usually associated with a decrease in the end-systolic volume of the right and left ventricles and with an increase in their stroke volume. What is the probable mechanism for this response?

A) A decrease in catecholamine release
B) An increase in sympathetic tone to the ventricles
C) An increase in parasympathetic tone to the ventricles
D) A decrease in venous return of blood to the heart
E) An increase in pulmonary and systemic resistance

Question 39

A 23-year-old weightlifter lifts 325 lbs. over his head and holds it there for 5 s, after which he suddenly drops it to the floor. Which of the following receptors is responsible for this sudden muscle relaxation?

A) Free nerve ending
B) Golgi tendon organ
C) Muscle spindle
D) Merkel's disk
E) Pacinian corpuscle

Question 40

A neonate is brought to the endocrinologist with ambiguous external genitalia. It is determined that the infant has ovaries and internal female genitalia, but external virilization (ambiguous genitalia). Which of the following diagnoses is the most likely?

A) Turner's syndrome (45, XO)
B) Klinefelter's syndrome (47, XXY)
C) Congenital adrenal hyperplasia
D) Deficient estrogens during fetal life
E) 5 $\alpha$ -reductase mutation

Question 41

A 73-year-old patient in the cardiology clinic suffers from an arrhythmia, which prevents the electrical impulse from slowing down at the atrioventricular (AV) node. Which of the following would be a direct result of this type of arrhythmia?

A) Insufficient time for ventricular filling
B) Augmentation of ventricular contraction
C) Increase in venous return
D) Insufficient time for atrial filling
E) Increased aortic pressure

Question 42

A patient is given a drug that prolongs the P-R interval of the electrocardiogram (ECG). What is the most likely action of the drug?

A) Reduced conduction velocity of the atrial fibers
B) Delayed repolarization of the ventricular fibers
C) Reduced conduction velocity of atrioventricular (AV) nodal fibers
D) Increased conduction velocity of the atrial fibers
E) Increased force of contraction of the right ventricle

Question 43

If the venous return to the right atrium should increase from a normal value of about 5 L/min (in the adult) to about 10 L/min, what would a normal heart most likely develop?

A) An increase in atrial and end-diastolic ventricular pressure with decreased stroke volume
B) A decrease in atrial and end-diastolic ventricular pressure with decreased contractility
C) An increase in atrial and end-diastolic ventricular pressure with increased stroke volume
D) Bradycardia and cardiac shock
E) Bradycardia and very low end-diastolic pressure of the right ventricle

Question 44

A 30-year-old man develops adult respiratory distress syndrome (ARDS) after near-drowning due to a boating accident. Conventional mechanical ventilation and inhaled nitric oxide (NO) do not provide sufficient oxygenation. The partial pressure of arterial carbon dioxide (PaCO2) and fraction of inspired oxygen (FIO2) ratio as well as shunt fraction (Qs/Qt) improve greatly after bronchial instillation of surfactant. The improvements in respiratory function occurred because surfactant decreased which of the following?

A) Bronchiolar smooth muscle tone
B) Arterial bicarbonate concentration
C) Lung compliance
D) The work of breathing
E) Functional residual capacity (FRC)

Question 45

A 69-year-old man complains of episodes of "squeezing" substernal chest pains that occur when he physically exerts himself. He sometimes feels the pain in his jaw, and it often radiates down his left arm. After thorough evaluation, he is diagnosed with chronic stable angina (exertional angina) and instructed to take nitroglycerin. The mechanism by which nitroglycerin exerts its beneficial effects in angina is by:

A)Blocking ( $\alpha$ ₁)-adrenergic receptors and reducing myocardial oxygen consumption by decreasing cardiac pre-load and afterload.
B)Blocking ( $\beta$ ₁)-adrenergic receptors and reducing myocardial oxygen consumption by preventing an increase in heart rate and contractility.
C)Blocking slow (Ca²⁺) channels and reducing myocardial oxygen consumption by decreasing cardiac contractility, heart rate, and arterial pressure.
D)Causing smooth muscle relaxation by stimulating the formation of nitric oxide, thereby causing an increase in the level of cyclic guanosine monophosphate ( cGMP ).
E)Preventing platelet aggregation by inhibiting platelet cyclooxygenase activity.

Question 46

In a patient with a fractured pelvis, requiring a 3-week period of bed rest which of the following physiologic changes would be expected to occur?

A) Decreased blood volume
B) Increased plasma concentration of aldosterone
C) Increased plasma volume
D) Increased activity of the sympathetic nervous system
E) Decreased plasma concentration of sodium

Question 47

Your 15-year-old dizzy patient arrives at the emergency department after winning a breath holding contest. Her laboratory values are as follows: pH 7.10; HCO_3- 4 mEq/L; PCO₂ 17 mmHg. What is the acid-base status of this patient?

A) Partially compensated metabolic alkalosis
B) Partially compensated metabolic acidosis
C) Partially compensated respiratory alkalosis
D) Partially compensated respiratory acidosis
E) Uncompensated respiratory alkalosis

Question 48

A 12-year-old girl is seen in your practice for weight loss and diarrhea, with bowel movements described as large, soft, greasy and foul smelling, occurring about ten times a day. After serologic testing and mucosal biopsy of the duodenum, you confirm your diagnosis and the patient's condition improves on a gluten-free diet. What is the most likely diagnosis of this patient's condition?

A) Cystic fibrosis
B) Diverticulosis
C) Gastrinoma
D) Celiac sprue
E) Chagas disease

Question 49

A 70-year-old male with edema and congestive heart failure has diastolic dysfunction characterized by decreased ventricular filling due to reduced ventricular muscle compliance. Which one of the following proteins determines the normal stiffness of ventricular muscle?

A) Calmodulin
B) Troponin
C) Tropomyosin
D) Titin
E) Myosin light chain kinase