Question 1

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.

Accepted Answer

Insulin treatment promotes the shift of potassium into cells, which can lead to hypokalemia if potassium is not supplemented.

Question 2

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

Accepted Answer

Cholecystokinin (CCK) is responsible for stimulating the gallbladder to contract and release bile into the intestine, which helps in the digestion of fats. In a patient with gallstones or cholecystitis, this contraction can cause pain, especially after eating a fatty meal, which triggers increased CCK release.

Question 3

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

Accepted Answer

Increased bone resorption is the most likely reason for an increase in plasma ionized calcium in a patient with primary hyperparathyroidism. This condition leads to an overproduction of parathyroid hormone (PTH), which in turn increases the breakdown of bone tissue, releasing calcium into the bloodstream.

Question 4

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

Accepted Answer

11β-hydroxylase deficiency leads to excess production of adrenal androgens causing virilization (acne, clitoral enlargement) and hypertension due to accumulation of 11-deoxycorticosterone, a potent mineralocorticoid, causing hypernatremia and hypokalemia.

Question 5

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

Accepted Answer

Inadequate LH surge to luteinize the corpus luteum is most likely responsible for luteal insufficiency when ovulation occurs. The LH surge is crucial for the proper formation and function of the corpus luteum, which produces progesterone necessary for the maintenance of the early pregnancy.

Question 6

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

Accepted Answer

EAnaphylactic shock leads to decreased blood volume due to increased vascular permeability, allowing fluid to leak from the blood vessels into the tissues. This process can also trigger the release of atrial natriuretic peptide as the body attempts to reduce blood volume and pressure, counteracting the effects of shock.

Question 7

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

Accepted Answer

Beta-blockers work by blocking the effects of the hormone epinephrine, also known as adrenaline. When epinephrine binds to beta receptors on the heart, it causes the heart to beat more forcefully and more quickly. By blocking these receptors, beta-blockers reduce heart rate and contractility (the force with which the heart muscle contracts), which can be beneficial in treating conditions like myocardial ischemia by reducing the heart's oxygen demand.

Question 8

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

Accepted Answer

The answer of Which of the following causes of brain...

Question 9

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

Accepted Answer

The answer of Your 49-year-old male patient is admitted to...

Question 10

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

Accepted Answer

The most likely diagnosis is Type 1 vitamin D-dependent rickets, which is characterized by the body's inability to convert vitamin D to its active form, 1,25(OH)2-vitamin D3. The improvement with 1,25(OH)2-vitamin D3 treatment confirms this condition.

Question 11

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.

Accepted Answer

The difference in pressures between the aorta and the pulmonary artery is primarily due to the systemic vascular resistance being much greater than the pulmonary vascular resistance. This is because the systemic circulation has to supply blood to the entire body, requiring higher pressure, whereas the pulmonary circulation only supplies the lungs and operates at a lower pressure.

Question 12

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

Accepted Answer

ECalcium channel blockers facilitate coronary vasodilation and are used to lower blood pressure (C) by causing relaxation of the vascular smooth muscle. They also lengthen the plateau phase of the ventricular action potential (E) by slowing the influx of calcium, which is crucial for the action potential in cardiac muscle cells. This effect can lead to a decrease in heart rate and a reduction in the force of cardiac contractions, which is beneficial in conditions like hypertension and angina.

Question 13

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

Accepted Answer

Acute blood loss leads to a decrease in central venous pressure due to reduced blood volume returning to the heart, which in turn decreases cardiac output because there is less blood available for the heart to pump.

Question 14

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

Accepted Answer

The patient has a high blood pH indicating alkalosis, and an elevated HCO3- suggests a metabolic cause. The elevated PCO2 indicates a respiratory compensation attempt, thus it's a partially compensated metabolic alkalosis.

Question 15

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.

Accepted Answer

Vasopressin secretion is stimulated when plasma volume decreases, which would occur due to severe lacerations and blood loss, leading to a compensatory mechanism to conserve water and maintain blood pressure.

Question 16

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)

Accepted Answer

TRH stimulates the release of both TSH and prolactin from the pituitary gland.

Question 17

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.

Accepted Answer

Without insulin, the body starts breaking down proteins for energy, leading to increased nitrogen excretion.

Question 18

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

Accepted Answer

An increase in sympathetic tone to the ventricles during running enhances myocardial contractility, which decreases end-systolic volume and increases stroke volume. This is part of the body's natural response to exercise, allowing more blood to be pumped to meet the increased oxygen demand.

Question 19

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

Accepted Answer

The Golgi tendon organ is responsible for sensing changes in muscle tension. When the weightlifter holds a heavy weight, the tension in the muscles and tendons increases significantly. If the tension becomes too high, the Golgi tendon organs are activated to prevent potential damage to the muscles or tendons by initiating a reflex that causes the muscle to relax. This is why the weightlifter suddenly drops the weight.

Question 20

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

Accepted Answer

Congenital adrenal hyperplasia is the most likely diagnosis in a neonate with ambiguous external genitalia, ovaries, and internal female genitalia. This condition is characterized by enzyme deficiencies in the adrenal gland, leading to excessive androgen production and virilization of female infants.

Quiz 3: The Nervous System

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

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?

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 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?

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?

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

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 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?

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 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?

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 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?

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 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 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?