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?

Accepted Answer

[Chapter 2, I C; Table 2.2]. Increased circulating levels of epinephrine from the adrenal medullary tumor stimulate both $\alpha$-adrenergic and $\beta$-adrenergic receptors. Thus, heart rate and contractility are increased and, as a result, cardiac output is increased. Total peripheral resistance (TPR) is increased because of arteriolar vasoconstriction, which leads to decreased blood flow to the cutaneous circulation and causes cold, clammy skin. Together, the increases in cardiac output and TPR increase arterial blood pressure. 3-Methoxy-4-hydroxymandelic acid (VMA) is a metabolite of both norepinephrine and epinephrine; increased VMA excretion occurs in pheochromocytomas.

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

Accepted Answer

[Chapter 2, I; Table 2.3]. Treatment is directed at blocking both the $\alpha$-stimulatory and $\beta$-stimulatory effects of catecholamines. Phentolamine is an $\alpha$-blocking agent; propranolol is a $\beta$-blocking agent. Isoproterenol is a $\beta_{1}$ and $\beta_{2}$ agonist. Phenylephrine is an $\alpha_{1}$ agonist.

Question 3

The principle of positive feedback is illustrated by the effect of

Accepted Answer

[Chapter 7, I D; X E 2]. The effect of estrogen on the secretion of folliclestimulating hormone (FSH) and luteinizing hormone (LH) by the anterior lobe of the pituitary gland at midcycle is one of the few examples of positive feedback in physiologic systems-increasing estrogen levels at midcycle cause increased secretion of FSH and LH. The other options illustrate negative feedback. Decreased arterial $\mathrm{PO}_{2}$ causes an increase in breathing rate (via peripheral chemoreceptors). Increased blood glucose stimulates insulin secretion. Decreased blood $\left[\mathrm{Ca}^{2+}\right]$ causes an increase in parathyroid hormone (PTH) secretion. Decreased blood pressure decreases the firing rate of carotid sinus nerves (via the baroreceptors) and ultimately increases sympathetic outflow to the heart and blood vessels to return blood pressure to normal.

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)

Accepted Answer

[Chapter 3, IV F 3 a; Figures 3.8 and 3.12]. A downward shift of the cardiac output curve is consistent with decreased myocardial contractility (negative inotropism); for any right atrial pressure or end-diastolic volume, the force of contraction is decreased. Digitalis, a positive inotropic agent, would produce an upward shift of the cardiac output curve. Changes in blood volume alter the venous return curve rather than the cardiac output curve. Changes in total peripheral resistance (TPR) alter both the cardiac output and venous return curves.

Question 5

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

Accepted Answer

[Chapter 4, IV A 2, C; Figure 4.7]. Because fetal hemoglobin (HbF) has a greater affinity for $\mathrm{O}_{2}$ than does adult hemoglobin, the $\mathrm{O}_{2}$-hemoglobin dissociation curve would shift to the left. Carbon monoxide poisoning would cause a shift to the left, but would also cause a decrease in total $\mathrm{O}_{2}$-carrying capacity (decreased percent saturation) because $\mathrm{CO}$ occupies $\mathrm{O}_{2}$-binding sites. Decreased pH, increased temperature, and increased 2,3-diphosphoglycerate (DPG) all would shift the curve to the right.

Question 6

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

Accepted Answer

[Chapter 4, IV C 2]. A shift to the left of the $\mathrm{O}_{2}$-hemoglobin dissociation curve represents an increased affinity of hemoglobin for $\mathrm{O}_{2}$. Accordingly, at any given level of $\mathrm{PO}_{2}$, the percent saturation is increased, the $\mathrm{P}_{50}$ is decreased (read the $\mathrm{PO}_{2}$ at $50 \%$ saturation), and the ability to unload $\mathrm{O}_{2}$ to the tissues is impaired (because of the higher affinity of hemoglobin for $\mathrm{O}_{2}$ ). The $\mathrm{O}_{2}$-carrying capacity is determined by hemoglobin concentration and is unaffected by the shift from curve A to curve B.

Question 7

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

Accepted Answer

[Chapter 5, VII D; Table 5.6]. A person with a negative free-water clearance $\left(\mathrm{C}_{\mathrm{H}_{2} \mathrm{O}}\right)$ would, by definition, be producing urine that is hyperosmotic to blood $\left(\mathrm{C}_{\mathrm{H}_{2} \mathrm{O}}=\mathrm{V}-\mathrm{C}_{\mathrm{osm}}\right)$. After overnight water restriction, serum osmolarity increases. This increase, via hypothalamic osmoreceptors, stimulates the release of antidiuretic hormone
$(\mathrm{ADH})$ from the posterior lobe of the pituitary. This ADH circulates to the collecting ducts of the kidney and causes reabsorption of water, which results in the production of hyperosmotic urine. Drinking large amounts of water inhibits the secretion of ADH and causes excretion of dilute urine and a positive $\mathrm{C}_{\mathrm{H}_{2} \mathrm{O}}$. Lithium causes nephrogenic diabetes insipidus by blocking the response of $\mathrm{ADH}$ on the collecting duct cells, resulting in dilute urine and a positive $\mathrm{C}_{\mathrm{H}_{2} \mathrm{O}}$. In option $\mathrm{D}$, the calculated value of $\mathrm{C}_{\mathrm{H}_{2} \mathrm{O}}$ is zero. In option $\mathrm{E}$, the calculated value of $\mathrm{C}_{\mathrm{H}_{2} \mathrm{O}}$ is positive.

Question 8

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

Accepted Answer

[Chapter 4, V B; Figure 4.9]. $\mathrm{CO}_{2}$ generated in the tissues enters venous blood and, in the red blood cells (RBCs), combines with $\mathrm{H}_{2} \mathrm{O}$ in the presence of carbonic anhydrase to form $\mathrm{H}_{2} \mathrm{CO}_{3} . \mathrm{H}_{2} \mathrm{CO}_{3}$ dissociates into $\mathrm{H}^{+}$and $\mathrm{HCO}_{3}^{-}$. The $\mathrm{H}^{+}$remains in the RBCs to be buffered by deoxyhemoglobin, and the $\mathrm{HCO}_{3}{ }^{-}$moves into plasma in exchange for $\mathrm{Cl}^{-}$. Thus, $\mathrm{CO}_{2}$ is carried in venous blood to the lungs as $\mathrm{HCO}_{3}^{-}$. In the lungs, the reactions occur in reverse: $\mathrm{CO}_{2}$ is regenerated and expired.

Question 9

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

Accepted Answer

[Chapter 7, X E 2]. Menses occurs 14 days after ovulation, regardless of cycle length. Therefore, in a 35-day menstrual cycle, ovulation occurs on day 21. Ovulation occurs at the midpoint of the menstrual cycle only if the cycle length is 28 days.

Question 10

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

Accepted Answer

[Chapter 7, X A]. Testosterone is synthesized from cholesterol in ovarian theca cells and diffuses to ovarian granulosa cells, where it is converted to estradiol by the action of aromatase. Follicle-stimulating hormone (FSH) stimulates the aromatase enzyme and increases the production of estradiol.

Question 11

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

Accepted Answer

[Chapter 6, IVA $2-4$ a]. Saliva has a high $\left[\mathrm{HCO}_{3}^{-}\right]$because the cells lining the salivary ducts secrete $\mathrm{HCO}_{3}^{-}$. Because the ductal cells are relatively impermeable to water and because they reabsorb more solute $\left(\mathrm{Na}^{+}\right.$and $\left.\mathrm{Cl}^{-}\right)$than they secrete $\left(\mathrm{K}^{+}\right.$and $\mathrm{HCO}_{3}^{-}$), the saliva is rendered hypotonic. Vagal stimulation increases saliva production, so vagotomy (or atropine) inhibits it and produces dry mouth.

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

Accepted Answer

[Chapter 5, VII D 3; Table 5.6]. The most likely explanation for this patient's polyuria is hypercalcemia. With severe hypercalcemia, $\mathrm{Ca}^{2+}$ accumulates in the inner medulla and papilla of the kidney and inhibits adenylate cyclase, blocking the effect of $\mathrm{ADH}$ on water permeability. Because ADH is ineffective, the urine cannot be concentrated and the patient excretes large volumes of dilute urine. His polydipsia is secondary to his polyuria and is caused by the increased serum osmolarity. Psychogenic water drinking would also cause polyuria, but the serum osmolarity would be lower than normal, not higher than normal.

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

Accepted Answer

[Chapter 5 , VI C]. Thiazide diuretics would be contraindicated in a patient with severe hypercalcemia because these drugs cause increased $\mathrm{Ca}^{2+}$ reabsorption in the renal distal tubule. On the other hand, loop diuretics inhibit $\mathrm{Ca}^{2+}$ and $\mathrm{Na}^{+}$reabsorption and produce calciuresis. When given with fluid replacement, loop diuretics can effectively and rapidly lower the serum $\left[\mathrm{Ca}^{2+}\right]$. Calcitonin, mithramycin, and etidronate disodium inhibit bone resorption and, as a result, decrease serum $\left[\mathrm{Ca}^{2+}\right]$.

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?

Accepted Answer

[Chapter 7; Table 7.2]. Oxytocin causes contraction of the myoepithelial cells of the breast by an inositol 1,4,5-triphosphate ( $\left.\mathrm{IP}_{3}\right)-\mathrm{Ca}^{2+}$ mechanism. Somatomedins (insulin-like growth factor [IGF]), like insulin, act on target cells by activating tyrosine kinase. Antidiuretic hormone (ADH) acts on the $\mathrm{V}_{2}$ receptors of the renal collecting duct by a cyclic adenosine monophosphate (cAMP) mechanism (although in vascular smooth muscle it acts on $\mathrm{V}_{1}$ receptors by an $\mathrm{IP}_{3}$ mechanism).
Adrenocorticotropic hormone (ACTH) also acts via a cAMP mechanism. Thyroid hormone induces the synthesis of new protein (e.g., $\mathrm{Na}^{+}, \mathrm{K}^{+}$-adenosine triphosphatase [ATPase]) by a steroid hormone mechanism.

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

Accepted Answer

[Chapter 1, VI B; VII B; Table 1.3]. The pharynx is skeletal muscle, and the small intestine is unitary smooth muscle. The difference between smooth and skeletal muscle is the mechanism by which $\mathrm{Ca}^{2+}$ initiates contraction. In smooth muscle, $\mathrm{Ca}^{2+}$
binds to calmodulin, and in skeletal muscle, $\mathrm{Ca}^{2+}$ binds to troponin C. Both types of muscle are excited to contract by action potentials. Slow waves are present in smooth muscle but not skeletal muscle. Both smooth and skeletal muscle require an increase in intracellular $\left[\mathrm{Ca}^{2+}\right]$ as the important linkage between excitation (the action potential) and contraction, and both consume adenosine triphosphate (ATP) during 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?

Accepted Answer

[Chapter 5 , IX D; Table 5.9]. The arterial blood values and physical findings are consistent with metabolic acidosis, hypokalemia, and orthostatic hypotension. Diarrhea is associated with the loss of $\mathrm{HCO}_{3}{ }^{-}$and $\mathrm{K}^{+}$from the gastrointestinal (GI) tract, consistent with the laboratory values. Hypotension is consistent with extracellular fluid (ECF) volume contraction. Vomiting would cause metabolic alkalosis and hypokalemia. Treatment with loop or thiazide diuretics could cause volume contraction and hypokalemia, but would cause metabolic alkalosis rather than metabolic acidosis.

Question 17

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

Accepted Answer

[Chapter 6, V B $1 \mathrm{c}$ ]. Pepsinogen is secreted by the gastric chief cells and is activated to pepsin by the low $\mathrm{pH}$ of the stomach (created by secretion of $\mathrm{HCl}$ by the gastric parietal cells). Lipases are inactivated by low $\mathrm{pH}$.

Question 18

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

Accepted Answer

[Chapter 5, II C 6; Table 5.3]. Glomerular filtration rate (GFR) is determined by the balance of Starling forces across the glomerular capillary wall. Constriction of the efferent arteriole increases the glomerular capillary hydrostatic pressure (because blood is restricted in leaving the glomerular capillary), thus favoring filtration. Constriction of the afferent arteriole would have the opposite effect and would reduce the glomerular capillary hydrostatic pressure. Constriction of the ureter would increase the hydrostatic pressure in the tubule and, therefore, oppose filtration. Increased plasma protein concentration would increase the glomerular capillary oncotic pressure and oppose filtration. Infusion of inulin is used to measure the GFR and does not alter the Starling forces.

Question 19

Fat absorption occurs primarily in the

Accepted Answer

[Chapter $6, \mathrm{VC}$ 1, 2]. First, fat absorption requires the breakdown of dietary lipids to fatty acids, monoglycerides, and cholesterol in the duodenum by pancreatic lipases. Second, fat absorption requires the presence of bile acids, which are secreted into the small intestine by the gallbladder. These bile acids form micelles around the products of lipid digestion and deliver them to the absorbing surface of the small intestinal cells. Because the bile acids are recirculated to the liver from the ileum, fat absorption must be complete before the chyme reaches the terminal ileum.

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?

Accepted Answer

[Chapter 7, III C 1 b]. Antidiuretic hormone (ADH) causes constriction of vascular smooth muscle by activating a $V_{1}$ receptor that uses the inositol 1,4,5-triphosphate $\left(\mathrm{IP}_{3}\right)$ and $\mathrm{Ca}^{2+}$ second messenger system. When hemorrhage or extracellular fluid (ECF) volume contraction occurs, $\mathrm{ADH}$ secretion by the posterior pituitary is stimulated via volume receptors. The resulting increase in ADH levels causes increased water reabsorption by the collecting ducts ( $\mathrm{V}_{2}$ receptors) and vasoconstriction ( $\mathrm{V}_{1}$ receptors) to help restore blood pressure.

Quiz 8: Comprehensive Examination

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?

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

The principle of positive feedback is illustrated by the effect of

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

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

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

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

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

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 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

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

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

Fat absorption occurs primarily in the

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

Quiz 8: Comprehensive Examination

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?

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

The principle of positive feedback is illustrated by the effect of

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

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

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

A negative free-water clearance (CH2O) \left(\mathrm{C}_{\mathrm{H}_{2} \mathrm{O}}\right) (CH2​O​) would occur in a person

CO2\mathrm{CO}_{2}CO2​ generated in the tissues is carried in venous blood primarily as

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

Which of the following hormones stimulates the conversion of testosterone to 17β17 \beta17β -estradiol in ovarian granulosa cells?

Which gastrointestinal secretion is hypotonic, has a high [HCO3−]\left[\mathrm{HCO}_{3}^{-}\right][HCO3−​] , and has its production inhibited by vagotomy?

Which of the following substances acts on its target cells via an inositol 1,4,5-triphosphate ( IP3) −Ca2+\left.\mathrm{IP}_{3}\right) -\mathrm{Ca}^{2+}IP3​) −Ca2+ mechanism?

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

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

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

Fat absorption occurs primarily in the

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

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

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

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

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

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?

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

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