Deck 8: Comprehensive Examination

Question 1

After extensive testing, a 60-year-old man is found to have a pheochromocytoma that secretes mainly epinephrine.

-Which of the following signs would be expected in this patient?

A) Decreased heart rate
B) Decreased arterial blood pressure
C) Decreased excretion rate of 3-methoxy4-hydroxymandelic acid (VMA)
D) Cold, clammy skin

Answer 1

Cold, clammy skin

Question 2

After extensive testing, a 60-year-old man is found to have a pheochromocytoma that secretes mainly epinephrine.

-Symptomatic treatment would be best achieved in this man with

A) phentolamine
B) isoproterenol
C) a combination of phentolamine and isoproterenol
D) a combination of phentolamine and propranolol
E) a combination of isoproterenol and phenylephrine

Answer 2

a combination of phentolamine and propranolol

Question 3

The principle of positive feedback is illustrated by the effect of

A) $\mathrm{PO}_{2}$ on breathing rate
B) glucose on insulin secretion
C) estrogen on follicle-stimulating hormone (FSH) secretion at midcycle
D) blood $\left[\mathrm{Ca}^{2+}\right]$ on parathyroid hormone (PTH) secretion
E) decreased blood pressure on sympathetic outflow to the heart and blood vessels

Answer 3

estrogen on follicle-stimulating hormone (FSH) secretion at midcycle

Question 4

In the graph at upper right, the response shown by the dotted line illustrates the effect of
Right atrial pressure $(\mathrm{mm} \mathrm{Hg})$ or end-diastolic volume (L)

A) administration of digitalis
B) administration of a negative inotropic agent
C) increased blood volume
D) decreased blood volume
E) decreased total peripheral resistance (TPR)

Question 5

-On the accompanying graph, the shift from curve A to curve B could be caused by

A) fetal hemoglobin (HbF)
B) carbon monoxide (CO) poisoning
C) decreased $\mathrm{pH}$
D) increased temperature
E) increased 2,3-diphosphoglycerate (DPG)

Question 6

-The shift from curve A to curve B is associated with

A) decreased $\mathrm{P}_{50}$
B) decreased affinity of hemoglobin for $\mathrm{O}_{2}$
C) decreased $\mathrm{O}_{2}$ -carrying capacity of hemoglobin
D) increased ability to unload $\mathrm{O}_{2}$ in the tissues

Question 7

A negative free-water clearance $\left(\mathrm{C}_{\mathrm{H}_{2} \mathrm{O}}\right)$ would occur in a person

A) who drinks $2 \mathrm{~L}$ of water in 30 minutes
B) after overnight water restriction
C) who is receiving lithium for the treatment of depression and has polyuria that is unresponsive to antidiuretic hormone $(\mathrm{ADH})$ administration
D) with a urine flow rate of $5 \mathrm{~mL} / \mathrm{min}$ , a urine osmolarity of $295 \mathrm{mOsm} / \mathrm{L}$ , and a serum osmolarity of $295 \mathrm{mOsm} / \mathrm{L}$
E) with a urine osmolarity of $90 \mathrm{mOsm} / \mathrm{L}$ and a serum osmolarity of $310 \mathrm{mOsm} / \mathrm{L}$ after a severe head injury

Question 8

$\mathrm{CO}_{2}$ generated in the tissues is carried in venous blood primarily as

A) $\mathrm{CO}_{2}$ in the plasma
B) $\mathrm{H}_{2} \mathrm{CO}_{3}$ in the plasma
C) $\mathrm{HCO}_{3}{ }^{-}$ in the plasma
D) $\mathrm{CO}_{2}$ in the red blood cells (RBCs)
E) carboxyhemoglobin in the RBCs

Question 9

In a 35-day menstrual cycle, ovulation occurs on day

A) 12
B) 14
C) 17
D) 21
E) 28

Question 10

Which of the following hormones stimulates the conversion of testosterone to $17 \beta$ -estradiol in ovarian granulosa cells?

A) Adrenocorticotropic hormone (ACTH)
B) Estradiol
C) Follicle-stimulating hormone (FSH)
D) Gonadotropin-releasing hormone (GnRH)
E) Human chorionic gonadotropin (HCG)
F) Prolactin
G) Testosterone

Question 11

Which gastrointestinal secretion is hypotonic, has a high $\left[\mathrm{HCO}_{3}^{-}\right]$ , and has its production inhibited by vagotomy?

A) Saliva
B) Gastric secretion
C) Pancreatic secretion
D) Bile

Question 12

A 53-year-old man with multiple myeloma is hospitalized after 2 days of polyuria, polydipsia, and increasing confusion. Laboratory tests show an elevated serum $\left[\mathrm{Ca}^{2+}\right]$ of $15 \mathrm{mg} / \mathrm{dL}$ , and treatment is initiated to decrease it. The patient's serum osmolarity is $310 \mathrm{mOsm} / \mathrm{L}$ .

-The most likely reason for polyuria in this man is

A) increased circulating levels of antidiuretic hormone (ADH)
B) increased circulating levels of aldosterone
C) inhibition of the action of ADH on the renal tubule
D) stimulation of the action of ADH on the renal tubule
E) psychogenic water drinking

Question 13

A 53-year-old man with multiple myeloma is hospitalized after 2 days of polyuria, polydipsia, and increasing confusion. Laboratory tests show an elevated serum $\left[\mathrm{Ca}^{2+}\right]$ of $15 \mathrm{mg} / \mathrm{dL}$ , and treatment is initiated to decrease it. The patient's serum osmolarity is $310 \mathrm{mOsm} / \mathrm{L}$ .

-The treatment drug is administered in error and produces a further increase in the patient's serum $\left[\mathrm{Ca}^{2+}\right]$ . That drug is

A) a thiazide diuretic
B) a loop diuretic
C) calcitonin
D) mithramycin
E) etidronate disodium

Question 14

Which of the following substances acts on its target cells via an inositol 1,4,5-triphosphate ( $\left.\mathrm{IP}_{3}\right)-\mathrm{Ca}^{2+}$ mechanism?

A) Somatomedins acting on chondrocytes
B) Oxytocin acting on myoepithelial cells of the breast
C) Antidiuretic hormone (ADH) acting on the renal collecting duct
D) Adrenocorticotropic hormone (ACTH) acting on the adrenal cortex
E) Thyroid hormone acting on skeletal muscle

Question 15

A key difference in the mechanism of excitation-contraction coupling between the muscle of the pharynx and the muscle of the wall of the small intestine is that

A) slow waves are present in the pharynx, but not in the small intestine
B) adenosine triphosphate (ATP) is used for contraction in the pharynx, but not in the small intestine
C) intracellular $\left[\mathrm{Ca}^{2+}\right]$ is increased after excitation in the pharynx, but not in the small intestine
D) action potentials depolarize the muscle of the small intestine, but not of the pharynx
E) $\mathrm{Ca}^{2+}$ binds to troponin $\mathrm{C}$ in the pharynx, but not in the small intestine, to initiate contraction

Question 16

A 40-year-old woman has an arterial $\mathrm{pH}$ of 7.25, an arterial $\mathrm{PCO}_{2}$ of $30 \mathrm{~mm} \mathrm{Hg}$ , and serum $\left[\mathrm{K}^{+}\right]$ of $2.8 \mathrm{mEq} / \mathrm{L}$ . Her blood pressure is $100 / 80 \mathrm{~mm} \mathrm{Hg}$ when supine and $80 / 50$ $\mathrm{mm} \mathrm{Hg}$ when standing. What is the cause of her abnormal blood values?

A) Vomiting
B) Diarrhea
C) Treatment with a loop diuretic
D) Treatment with a thiazide diuretic

Question 17

Secretion of $\mathrm{HCl}$ by gastric parietal cells is needed for

A) activation of pancreatic lipases
B) activation of salivary lipases
C) activation of intrinsic factor
D) activation of pepsinogen to pepsin
E) the formation of micelles

Question 18

Which of the following would cause an increase in glomerular filtration rate (GFR)?

A) Constriction of the afferent arteriole
B) Constriction of the efferent arteriole
C) Constriction of the ureter
D) Increased plasma protein concentration
E) Infusion of inulin

Question 19

Fat absorption occurs primarily in the

A) stomach
B) jejunum
C) terminal ileum
D) cecum
E) sigmoid colon

Question 20

Which of the following hormones causes constriction of vascular smooth muscle through an inositol 1,4,5-triphosphate (IP ${ }_{3}$ ) second messenger system?

A) Antidiuretic hormone (ADH)
B) Aldosterone
C) Dopamine
D) Oxytocin
E) Parathyroid hormone (PTH)

Question 21

A 30-year-old woman has the anterior lobe of her pituitary gland surgically removed because of a tumor. Without hormone replacement therapy, which of the following would occur after the operation?

A) Absence of menses
B) Inability to concentrate the urine in response to water deprivation
C) Failure to secrete catecholamines in response to stress
D) Failure to secrete insulin in a glucose tolerance test
E) Failure to secrete parathyroid hormone (PTH) in response to hypocalcemia

Question 22

The following graph shows three relationships as a function of plasma [glucose]. At plasma [glucose] less than 200 $\mathrm{mg} / \mathrm{dL}$ , curves $\mathrm{X}$ and $\mathrm{Z}$ are superimposed on each other because

A) the reabsorption and excretion of glucose are equal
B) all of the filtered glucose is reabsorbed
C) glucose reabsorption is saturated
D) the renal threshold for glucose has been exceeded
E) $\mathrm{Na}^{+}$ -glucose cotransport has been inhibited
F) all of the filtered glucose is excreted

Question 23

Which of the following responses occurs as a result of tapping on the patellar tendon?

A) Stimulation of Ib afferent fibers in the muscle spindle
B) Inhibition of Ia afferent fibers in the muscle spindle
C) Relaxation of the quadriceps muscle
D) Contraction of the quadriceps muscle
E) Inhibition of $\alpha$ -motoneurons

Question 24

A 5-year-old boy has a severe sore throat, high fever, and cervical adenopathy.

-It is suspected that the causative agent is Streptococcus pyogenes. Which of the following is involved in producing fever in this patient?

A) Increased production of interleukin-1 (IL-1)
B) Decreased production of prostaglandins
C) Decreased set-point temperature in the hypothalamus
D) Decreased metabolic rate
E) Vasodilation of blood vessels in the skin

Question 25

A 5-year-old boy has a severe sore throat, high fever, and cervical adenopathy.

-Before antibiotic therapy is initiated, the patient is given aspirin to reduce his fever. The mechanism of fever reduction by aspirin is

A) shivering
B) stimulation of cyclooxygenase
C) inhibition of prostaglandin synthesis
D) shunting of blood from the surface of the skin
E) increasing the hypothalamic set-point temperature

Question 26

Arterial $\mathrm{pH}$ of 7.52, arterial $\mathrm{PCO}_{2}$ of $26 \mathrm{~mm} \mathrm{Hg}$ , and tingling and numbness in the feet and hands would be observed in a

A) patient with chronic diabetic ketoacidosis
B) patient with chronic renal failure
C) patient with chronic emphysema and bronchitis
D) patient who hyperventilates on a commuter flight
E) patient who is taking a carbonic anhydrase inhibitor for glaucoma
F) patient with a pyloric obstruction who vomits for 5 days
G) healthy person

Question 27

Albuterol is useful in the treatment of asthma because it acts as an agonist at which of the following receptors?

A) $\alpha_{1}$ Receptor
B) $\beta_{1}$ Receptor
C) $\beta_{2}$ Receptor
D) Muscarinic receptor
E) Nicotinic receptor

Question 28

Which of the following hormones is converted to its active form in target tissues by the action of $5 \alpha$ -reductase?

A) Adrenocorticotropic hormone (ACTH)
B) Aldosterone
C) Estradiol
D) Prolactin
E) Testosterone

Question 29

If an artery is partially occluded by an embolism such that its radius becomes one-half the preocclusion value, which of the following parameters will increase by a factor of 16 ?

A) Blood flow
B) Resistance
C) Pressure gradient
D) Capacitance

Question 30

If heart rate increases, which phase of the cardiac cycle is decreased?

A) Atrial systole
B) Isovolumetric ventricular contraction
C) Rapid ventricular ejection
D) Reduced ventricular ejection
E) Isovolumetric ventricular relaxation
F) Rapid ventricular filling
G) Reduced ventricular filling

Question 31

A 17-year-old boy is brought to the emergency department after being injured in an automobile accident and sustaining significant blood loss. He is given a transfusion of 3 units of blood to stabilize his blood pressure.

-Before the transfusion, which of the following was true about his condition?

A) His total peripheral resistance (TPR) was decreased
B) His heart rate was decreased
C) The firing rate of his carotid sinus nerves was increased
D) Sympathetic outflow to his heart and blood vessels was increased

Question 32

A 17-year-old boy is brought to the emergency department after being injured in an automobile accident and sustaining significant blood loss. He is given a transfusion of 3 units of blood to stabilize his blood pressure.

-Which of the following is a consequence of the decrease in blood volume in this patient?

A) Increased renal perfusion pressure
B) Increased circulating levels of angiotensin II
C) Decreased renal $\mathrm{Na}^{+}$ reabsorption
D) Decreased renal $\mathrm{K}^{+}$ secretion

Question 33

A 37-year-old woman suffers a severe head injury in a skiing accident. Shortly thereafter, she becomes polydipsic and polyuric. Her urine osmolarity is $75 \mathrm{mOsm} / \mathrm{L}$ , and her serum osmolarity is $305 \mathrm{mOsm} / \mathrm{L}$ . Treatment with 1-deamino-8-D-arginine vasopressin (dDAVP) causes an increase in her urine osmolarity to $450 \mathrm{mOsm} / \mathrm{L}$ . Which diagnosis is correct?

A) Primary polydipsia
B) Central diabetes insipidus
C) Nephrogenic diabetes insipidus
D) Water deprivation
E) Syndrome of inappropriate antidiuretic hormone (SIADH)

Question 34

Which diuretic inhibits $\mathrm{Na}^{+}$ reabsorption and $\mathrm{K}^{+}$ secretion in the distal tubule by acting as an aldosterone antagonist?

A) Acetazolamide
B) Chlorothiazide
C) Furosemide
D) Spironolactone

Question 35

Which gastrointestinal secretion has a component that is required for the intestinal absorption of vitamin $\mathrm{B}_{12}$ ?

A) Saliva
B) Gastric secretion
C) Pancreatic secretion
D) Bile

Question 36

Secretion of which of the following hormones is stimulated by extracellular fluid volume expansion?

A) Antidiuretic hormone (ADH)
B) Aldosterone
C) Atrial natriuretic peptide (ANP)
D) 1,25-Dihydroxycholecalciferol
E) Parathyroid hormone (PTH)

Question 37

Which step in the steroid hormone synthetic pathway is stimulated by angiotensin II?

A) Aldosterone synthase
B) Aromatase
C) Cholesterol desmolase
D) 17,20-Lyase
E) $5 \alpha$ -Reductase

Question 38

Use the diagram of an action potential to answer the following questions.


-The action potential shown is from

A) a skeletal muscle cell
B) a smooth muscle cell
C) a sinoatrial (SA) cell
D) an atrial muscle cell
E) a ventricular muscle cell

Question 39

Use the diagram of an action potential to answer the following questions.


-Phase 0 of the action potential shown is produced by an

A) inward $\mathrm{K}^{+}$ current
B) inward $\mathrm{Na}^{+}$ current
C) inward $\mathrm{Ca}^{2+}$ current
D) outward $\mathrm{Na}^{+}$ current
E) outward $\mathrm{Ca}^{2+}$ current

Question 40

Use the diagram of an action potential to answer the following questions.


-Phase 2, the plateau phase, of the action potential shown

A) is the result of $\mathrm{Ca}^{2+}$ flux out of the cell
B) increases in duration as heart rate increases
C) corresponds to the effective refractory period
D) is the result of approximately equal inward and outward currents
E) is the portion of the action potential when another action potential can most easily be elicited

Question 41

Use the diagram of an action potential to answer the following questions.


-The action potential shown corresponds to which portion of an electrocardiogram (ECG)?

A) $\mathrm{P}$ wave
B) PR interval
C) QRS complex
D) ST segment
E) QT interval

Question 42

Which of the following is the first step in the biosynthetic pathway for thyroid hormones that is inhibited by propylthiouracil?

A) Iodide (I-) pump
B) $\mathrm{I}^{-} \rightarrow \mathrm{I}_{2}$
C) $\mathrm{I}_{2}+$ tyrosine
D) Diiodotyrosine (DIT) + DIT
E) Thyroxine $\left(\mathrm{T}_{4}\right) \rightarrow$ triiodothyronine $\left(\mathrm{T}_{3}\right)$

Question 43

Arterial $\mathrm{pH}$ of 7.29 , arterial $\left[\mathrm{HCO}_{3}^{-}\right]$ of $14 \mathrm{mEq} / \mathrm{L}$ , increased urinary excretion of $\mathrm{NH}_{4}^{+}$ , and hyperventilation would be observed in a

A) patient with chronic diabetic ketoacidosis
B) patient with chronic renal failure
C) patient with chronic emphysema and bronchitis
D) patient who hyperventilates on a commuter flight
E) patient who is taking a carbonic anhydrase inhibitor for glaucoma
F) patient with a pyloric obstruction who vomits for 5 days
G) healthy person

Question 44

Activation of which of the following receptors increases total peripheral resistance (TPR)?

A) $\alpha_{1}$ Receptor
B) $\beta_{1}$ Receptor
C) $\beta_{2}$ Receptor
D) Muscarinic receptor
E) Nicotinic receptor

Question 45

The receptor for this hormone has tyrosine kinase activity.

A) Adrenocorticotropic hormone (ACTH)
B) Antidiuretic hormone (ADH)
C) Aldosterone
D) Insulin
E) Parathyroid hormone (PTH)
F) Somatostatin

Question 46

If an artery is partially occluded by an embolism such that its radius becomes one-half the preocclusion value, which of the following parameters will decrease by a factor of 16 ?

A) Blood flow
B) Resistance
C) Pressure gradient
D) Capacitance

Question 47

Which phase of the cardiac cycle is absent if there is no $\mathrm{P}$ wave on the electrocardiogram (ECG)?

A) Atrial systole
B) Isovolumetric ventricular contraction
C) Rapid ventricular ejection
D) Reduced ventricular ejection
E) Isovolumetric ventricular relaxation
F) Rapid ventricular filling
G) Reduced ventricular filling

Question 48

A receptor potential in the pacinian corpuscle

A) is all-or-none
B) has a stereotypical size and shape
C) is the action potential of this sensory receptor
D) if hyperpolarizing, increases the likelihood of action potential occurrence
E) if depolarizing, brings the membrane potential closer to threshold

Question 49

Compared with the base of the lung, in a person who is standing, the apex of the lung has

A) a higher ventilation rate
B) a higher perfusion rate
C) a higher ventilation/perfusion (V/Q) ratio
D) the sameV/Q ratio
E) a lower pulmonary capillary $\mathrm{PO}_{2}$

Question 50

A 54-year-old man with a lung tumor has high circulating levels of antidiuretic hormone (ADH), a serum osmolarity of $260 \mathrm{mOsm} / \mathrm{L}$ , and a negative free-water clearance $\left(\mathrm{C}_{\mathrm{H}_{2} \mathrm{O}}\right)$ . Which diagnosis is correct?

A) Primary polydipsia
B) Central diabetes insipidus
C) Nephrogenic diabetes insipidus
D) Water deprivation
E) Syndrome of inappropriate antidiuretic hormone (SIADH)

Question 51

End-organ resistance to which of the following hormones results in polyuria and elevated serum osmolarity?

A) Antidiuretic hormone (ADH)
B) Aldosterone
C) 1,25-Dihydroxycholecalciferol
D) Parathyroid hormone (PTH)
E) Somatostatin

Question 52

Which diuretic causes increased urinary excretion of $\mathrm{Na}^{+}$ and $\mathrm{K}^{+}$ and decreased urinary excretion of $\mathrm{Ca}^{2+}$ ?

A) Acetazolamide
B) Chlorothiazide
C) Furosemide
D) Spironolactone

Question 53

Arterial $\mathrm{PCO}_{2}$ of $72 \mathrm{~mm} \mathrm{Hg}$ , arterial $\left[\mathrm{HCO}_{3}^{-}\right]$ of $38 \mathrm{mEq} / \mathrm{L}$ , and increased $\mathrm{H}^{+}$ excretion would be observed in a

A) patient with chronic diabetic ketoacidosis
B) patient with chronic renal failure
C) patient with chronic emphysema and bronchitis
D) patient who hyperventilates on a commuter flight
E) patient who is taking a carbonic anhydrase inhibitor for glaucoma
F) patient with a pyloric obstruction who vomits for 5 days
G) healthy person

Question 54

In a skeletal muscle capillary, the capillary hydrostatic pressure $\left(\mathrm{P}_{\mathrm{c}}\right)$ is $32 \mathrm{~mm} \mathrm{Hg}$ , the capillary oncotic pressure $\left(\pi_{\mathrm{c}}\right)$ is $27 \mathrm{~mm} \mathrm{Hg}$ , and the interstitial hydrostatic pressure $\left(\mathrm{P}_{\mathrm{i}}\right)$ is $2 \mathrm{~mm} \mathrm{Hg}$ . Interstitial oncotic pressure $\left(\pi_{\mathrm{i}}\right)$ is negligible. What is the driving force across the capillary wall, and will it favor filtration or absorption?

A) $3 \mathrm{~mm} \mathrm{Hg}$ , favoring absorption
B) $3 \mathrm{~mm} \mathrm{Hg}$ , favoring filtration
C) $7 \mathrm{~mm} \mathrm{Hg}$ , favoring absorption
D) $7 \mathrm{~mm} \mathrm{Hg}$ , favoring filtration
E) $9 \mathrm{~mm} \mathrm{Hg}$ , favoring filtration

Question 55

Which of the following substances has the lowest renal clearance?

A) Creatinine
B) Glucose
C) $\mathrm{K}^{+}$
D) $\mathrm{Na}^{+}$
E) Para-aminohippuric acid (PAH)

Question 56

Atropine causes dry mouth by inhibiting which of the following receptors?

A) $\alpha_{1}$ Receptor
B) $\beta_{1}$ Receptor
C) $\beta_{2}$ Receptor
D) Muscarinic receptor
E) Nicotinic receptor

Question 57

Which of the following transport mechanisms is inhibited by furosemide in the thick ascending limb?

A) $\mathrm{Na}^{+}$ diffusion via $\mathrm{Na}^{+}$ channels
B) $\mathrm{Na}^{+}$ -glucose cotransport (symport)
C) $\mathrm{Na}^{+}-\mathrm{K}^{+}-2 \mathrm{Cl}^{-}$ cotransport (symport)
D) $\mathrm{Na}^{+}-\mathrm{H}^{+}$ exchange (antiport)
E) $\mathrm{Na}^{+}, \mathrm{K}^{+}$ -adenosine triphosphatase (ATPase)

Question 58

Which of the following conditions decreases the likelihood of edema formation?

A) Arteriolar constriction
B) Venous constriction
C) Standing
D) Nephrotic syndrome
E) Inflammation

Question 59

Which of the following conditions causes hypoventilation?

A) Strenuous exercise
B) Ascent to high altitude
C) Anemia
D) Diabetic ketoacidosis
E) Chronic obstructive pulmonary disease (COPD)

Question 60

A 28-year-old man who is receiving lithium treatment for bipolar disorder becomes polyuric. His urine osmolarity is $90 \mathrm{mOsm} / \mathrm{L}$ ; it remains at that level when he is given a nasal spray of dDAVP. Which diagnosis is correct?

A) Primary polydipsia
B) Central diabetes insipidus
C) Nephrogenic diabetes insipidus
D) Water deprivation
E) Syndrome of inappropriate antidiuretic hormone (SIADH)

Question 61

Inhibition of which step in the steroid hormone synthetic pathway blocks the production of all androgenic compounds in the adrenal cortex, but not the production of glucocorticoids or mineralocorticoids?

A) Aldosterone synthase
B) Aromatase
C) Cholesterol desmolase
D) 17,20-Lyase
E) $5 \alpha$ -Reductase

Question 62

Arterial $\mathrm{pH}$ of 7.54, arterial $\left[\mathrm{HCO}_{3}\right]$ of $48 \mathrm{mEq} / \mathrm{L}$ , hypokalemia, and hypoventilation would be observed in a

A) patient with chronic diabetic ketoacidosis
B) patient with chronic renal failure
C) patient with chronic emphysema and bronchitis
D) patient who hyperventilates on a commuter flight
E) patient who is taking a carbonic anhydrase inhibitor for glaucoma
F) patient with a pyloric obstruction who vomits for 5 days
G) healthy person

Question 63

Somatostatin inhibits the secretion of which of the following hormones?

A) Antidiuretic hormone (ADH)
B) Insulin
C) Oxytocin
D) Prolactin
E) Thyroid hormone

Question 64

Which of the following substances is converted to a more active form after its secretion?

A) Testosterone
B) Triiodothyronine $\left(\mathrm{T}_{3}\right)$
C) Reverse triiodothyronine $\left(\mathrm{rT}_{3}\right)$
D) Angiotensin II
E) Aldosterone

Question 65

Levels of which of the following hormones are high during the first trimester of pregnancy and decline during the second and third trimesters?

A) Adrenocorticotropic hormone (ACTH)
B) Estradiol
C) Follicle-stimulating hormone (FSH)
D) Gonadotropin-releasing hormone (GnRH)
E) Human chorionic gonadotropin (HCG)
F) Oxytocin
G) Prolactin
H) Testosterone

Question 66

THE FOLLOWING DIAGRAM APPLIES TO THE FOLLOWING QUESTIONS


-During which labeled wave or segment of the electrocardiogram (ECG) are both the atria and the ventricles completely repolarized?

A) $\mathrm{A}$
B) $\mathrm{B}$
C) $\mathrm{C}$
D) $\mathrm{D}$
E) $\mathrm{E}$

Question 67

THE FOLLOWING DIAGRAM APPLIES TO THE FOLLOWING QUESTIONS


-During which labeled wave or segment of the electrocardiogram (ECG) is aortic pressure at its lowest value?

A) A
B) $\mathrm{B}$
C) $\mathrm{C}$
D) $\mathrm{D}$
E) $\mathrm{E}$

Question 68

-At which site is the amount of paraaminohippuric acid (PAH) in tubular fluid lowest?

A) Site A
B) Site B
C) Site C
D) Site D
E) Site E

Question 69

-At which site is the creatinine concentration highest in a person who is deprived of water?

A) Site A
B) Site B
C) Site C
D) Site D
E) Site E

Question 70

-At which site is the tubular fluid $\left[\mathrm{HCO}_{3}{ }^{-}\right]$ highest?

A) Site A
B) Site B
C) Site C
D) Site D
E) Site E

Question 71

-At which site is the amount of $\mathrm{K}^{+}$ in tubular fluid lowest in a person who is on a very low- $\mathrm{K}^{+}$ diet?

A) Site A
B) Site B
C) Site C
D) Site D
E) Site E

Question 72

-At which site is the composition of tubular fluid closest to that of plasma?

A) Site A
B) Site B
C) Site C
D) Site D
E) Site $\mathrm{E}$

Question 73

-At which site is about one-third of the filtered water remaining in the tubular fluid?

A) Site A
B) Site B
C) Site C
D) Site D
E) Site $\mathrm{E}$

Question 74

-At which site is the tubular fluid osmolarity lower than the plasma osmolarity in a person who is deprived of water?

A) Site A
B) Site B
C) Site C
D) Site D
E) Site E

Question 75

A patient's electrocardiogram (ECG) shows periodic QRS complexes that are not preceded by $\mathrm{P}$ waves and that have a bizarre shape. These QRS complexes originated in the

A) sinoatrial (SA) node
B) atrioventricular (AV) node
C) His-Purkinje system
D) ventricular muscle

Question 76

Which of the following substances would be expected to cause an increase in arterial blood pressure?

A) Saralasin
B) $\mathrm{V}_{1}$ agonist
C) Acetylcholine (ACh)
D) Spironolactone
E) Phenoxybenzamine

Question 77

A decrease in which of the following parameters in an artery will produce an increase in pulse pressure?

A) Blood flow
B) Resistance
C) Pressure gradient
D) Capacitance

Question 78

Which of the following changes occurs during moderate exercise?

A) Increased total peripheral resistance (TPR)
B) Increased stroke volume
C) Decreased pulse pressure
D) Decreased venous return
E) Decreased arterial $\mathrm{PO}_{2}$

Question 79

Plasma renin activity is lower than normal in patients with

A) hemorrhagic shock
B) essential hypertension
C) congestive heart failure
D) hypertension caused by aortic constriction above the renal arteries

Question 80

Inhibition of which enzyme in the steroid hormone synthetic pathway reduces the size of the prostate?

A) Aldosterone synthase
B) Aromatase
C) Cholesterol desmolase
D) 17,20-Lyase
E) $5 \alpha$ -Reductase