Weekly 6-8 Quizzes

Question 1

A 5 year-old girl develops a sudden onset of fever, sore throat, and headache. She is taken to her pediatrician’s office where, on examination, he notes enlargement of her cervical lymph nodes and inflammation of her pharynx and tonsils. The physician swabs the child’s pharynx and does a commercially available rapid antigen detection assay to look for the presence of:

A. protein A of Staphylococcus aureus

B. streptolysin O

C. streptococcal pyrogenic exotoxin A

D. the group A streptococcal antigen

E. the M protein of group A streptococci

Answer 1

D. the group A streptococcal antigen

This is a presumptive case of “strep throat”. The antigen detection kit for group A streptococci detects the Lancefield group A antigen in the cell wall of all serotypes of the organism.

Answer A is wrong because it is an antigen on S. aureus, not group A streptococci.

Answer B is wrong because it is not the antigen in the kit, likely because it is not a cell-surface antigen and thus not readily detectable on the organism.

Answer C is wrong because not all isolates of group A streptococci make that toxin, so the antigen is not part of the kit.

Answer E is wrong because the M protein varies (is antigenically different) among group A streptococci.

Question 2

Multiplication of bacilli in post primary (reactivation) tuberculosis is triggered by:

A. a diminished immune response

B. elevated oxygen tension in the lungs

C. elevated progesterone levels

D. germination of Mycobacterium tuberculosis spores

E. induction of a lysogenic mycobacteriophage

Answer 2

A. a diminished immune response

A diminished immune response allows the bacilli that are still viable within granulomas to grow and spread. Oxygen tension and progesterone levels are not relevant to triggering reactivation. Mycobacteria make no spores and bacteriophage play no role in pathogenesis.

Question 3

A 7-year-old boy attending summer camp complains of sore throat, headache, cough, red eyes, and tiredness and is sent to the infirmary. His temperature is 40°C. Within hours, other campers and counselors visit the infirmary with similar symptoms. Symptoms last for 5 to 7 days. All the patients have gone swimming in the camp pond. More than 50% of the people in the camp complain of symptoms similar to those in the initial case. What is the most likely cause of disease?

A. Respiratory Syncytial virus

B. Rhinovirus

C. Adenovirus

D. Epstein Barr Virus

Answer 3

C. Adenovirus

The patient has disease signs consistent with pharyngoconjunctival fever. An outbreak as large as this indicates a common source of infection. The most likely source of this outbreak is the unchlorinated water in the camp pond. The virus is very hardy and can endure relatively harsh conditions. The capsid of the adenovirus protects the virus from harsh conditions of drying and even the acid and bile of the GI tract to allow the virus to be transmitted by fecal-oral and respiratory routes, through contact, and on fomites. Contamination of the pond would be difficult to eliminate. However, greater care with sewage may prevent further contamination of the pond. Also, campers should not share towels or other items that may come into contact with virus. An eye swab, a fecal sample, and a nasal wipe could be tested for the virus in the infected child. Pond water could be concentrated to allow detection of virus as a common source of the infection. The presence of adenovirus and its type would be analyzed by PCR.

Question 4

A 17-year-old high school student has had low-grade fever and malaise for several days, followed by sore throat, swollen cervical lymph nodes, and increasing fatigue. The patient also notes some discomfort in the left upper quadrant of the abdomen. The sore throat, lymphadenopathy, and fever gradually resolve over the next 2 weeks, but the patient’s full energy level does not return for another 6 weeks. The most likely cause for this disease is?

A. Paramyxovirus

B. Rhinovirus

C. Adenovirus

D. Epstein Barr Virus

Answer 4

D. Epstein Barr Virus

Swollen glands (lymphadenopathy) and fatigue are caused by the large scale activation of the immune response as indicated by the expansion of the numbers of T cells, and is most commonly associated with EBV infections. The age group also suggests that this individual got infected through the saliva and was exposed to the virus for the first time. The most simple test would be a heterophile antibody test, which is specific for EBV and not CMV. Serology for EBV antigens could confirm the diagnosis. These tests will also distinguish between a current and previous course of EBV disease. Immunocompromised individuals are at risk for EBV-induced leukemia and lymphoma-like diseases because EBV-stimulated B cells will grow out of control in the absence of functional T cells. Boys with Duncan’s disease (X-linked immunodeficiency) die of leukemia-like immunoproliferation caused by the inability of their T cells to control the outgrowth of B cells (this function is normally used to limit the outgrowth of B cells in response to antigen).

Question 5

Which of the following would increase the rate of oxygen diffusion from lung alveoli into pulmonary capillaries?

A. a decrease in blood temperature

B. a decrease in alveoli membrane surface area

C. a decrease in peripheral tissue PO2

D. an increase in the thickness of the respiratory membrane

E. a decrease in the alveolar PO2

Answer 5

C. a decrease in peripheral tissue PO2

A decrease in peripheral tissue PO2 would increase the difference of oxygen partial pressure between the compartments from which oxygen would diffuse from and to. All the remaining scenarios are factors that would decrease oxygen diffusion rates.

Question 6

Which statement about carbon dioxide transport is correct?

A. More CO2 is transported as dissolved in plasma than is carried in red blood cells.

B. CO2 concentration in the blood is increased by hyperventilation.

C. Increased PCO2 in the blood is associated with a decrease in pH.

D. Arterial PCO2 is greater than venous PCO2.

Answer 6

C. Increased PCO2 in the blood is associated with a decrease in pH.

Increasing PCO2 in the blood would result in the formation of more carbonic acid, which dissociates into hydrogen ions and bicarbonate. The hydrogen ion production would lead to a decrease in pH (acidity). The remaining answers are incorrect.

(A) More carbon dioxide is transported as bicarbonate and carbamino groups that in the dissolved state.

(B) carbon dioxide concentration in the blood is decreased by hyperventilation as you are decreasing the alveoli partial pressure of carbon dioxide and thus increasing the difference in partial pressures between alveolar air and pulmonary capillaries.

(D) arterial PCO2 is closer to 40 mm Hg and venous is closer to 45 mm Hg.

Question 7

Which form of hypoxemia is NOT associated with a low alveolar-arterial (A-a) oxygen gradient?

A. Low atmospheric oxygen such as a fire in an enclosed space.

B. High altitude

C. Shunt caused by pneumonia

D.Increased carbon dioxide in blood

Answer 7

C. Shunt caused by pneumonia

The other choices are hypoxemia associated with intact oxygen exchange, but with low alveolar oxygen partial pressure.

Question 8

Which one is LEAST likely to improve oxygen delivery significantly?

A. Increasing cardiac output two-fold.

B. Normalizing red blood cell mass in a severely anemic patient.

C. Improving oxygen saturation from 60 percent to 95 percent.

D. Using more supplemental oxygen in a patient who has an oxygen saturation of 95 percent.

Answer 8

D. Using more supplemental oxygen in a patient who has an oxygen saturation of 95 percent.

The main determinants of oxygen delivery are cardiac output/hemoglobin level/oxygen saturation of hemoglobin. Dissolved oxygen in plasma is quite a low percentage of oxygen content.

Question 9

In the image shown above, the structure indicated by the arrow is a:

A. Ganglion
B. Mass of dense, irregular connective tissue
C. Mass of loose connective tissue
D. Mucous gland
E. Nerve
F. Serous gland
G. Skeletal muscle bundle
H. Smooth muscle bundle

Answer 9

E. Nerve

This is a nerve originating in the olfactory epithelium.

Question 10

This is a composite image. The inset image is a magnification of the tissue surrounding the tip of the arrow. This region:

A. has the only skeletal muscle found in the respiratory system.
B. is mainly dense connective tissue.
C. has its functional response controlled by conscious thought.
D.is part of the false vocal fold.
E. usually collapses sleep in a patient suffering from sleep apnea.

Answer 10

C. has its functional response controlled by conscious thought.

This is the true vocal fold.

Question 11

The tissue surrounding the tip of the arrow is principally:

A. Ganglion
B. Mass of dense, irregular connective tissue
C. Mass of loose connective tissue
D. mucous gland
E. nerve
F. serous gland
G. skeletal muscle bundle
H .smooth muscle bundle

Answer 11

H .smooth muscle bundle

This is the trachealis muscle which is a smooth muscle structure.

Question 12

An Army sergeant injured in a roadside explosion presents with altered forced expirations during rest and exercise most likely is suffering from cerebrovascular damage to the:

A. apneustic center
B. pneumotaxic center
C. phrenic nerve center
D. dorsal respiratory center
E. ventral respiratory center

Answer 12

E. ventral respiratory center

VRG controls forced expiration and is involved with coordination of labored inspiration and expiration. Apneustic center limits lung expansion and pneumotaxic center causes rapid shallow breathing. DRG regulate inspiration. Phrenic nerve controls the diaphragm which is mainly inspiratory.

Question 13

Your patient is a 12 year old girl. Recently her family adopted a kitten and now she has been suffering from shortness of breath. Thinking that she may be suffering from allergy-induced asthma, you send her to the Pulmonary Function Laboratory for testing. Which pulmonary parameter is MOST LIKELY to be decreased?

A. Tidal volume
B. Expiratory reserve volume
C. Forced vital capacity
D. Inspiratory reserve volume
E. FEV1

Answer 13

E. FEV1

Narrowing of the airways impairs exhalation. Forced vital capacity is not time dependent so it is not as likely to be effected. Static lung capacities do not change acutely with obstructive lung disease although over time, air trapping can increase residual volume (barrel chest).

Question 14

Which of the conditions below is NOT a cause of hypoxemia?

A. shunt
B. low inspired oxygen content
C. anemia
D. diffusion abnormality
E. hypoventilation

Answer 14

C. anemia

Anemia effects oxygen carrying capacity and oxygen delivery, but not oxygen levels. Even a pulse oximeter will be normal in someone with anemia. The fifth, or missing cause of hypoxia from the list, is VQ mismatch.

Question 15

You evaluate a 2 day old cyanotic baby. A blood gas obtained from the patient while breathing room air reveals a pH of 7.40, a pCO2 of 40, and a pO2 of 50. When placed on 100% oxygen, the patient’s blood gas reveals a pH of 7.40, a pCO2 of 40, and a pO2 of 60. The primary reason for this patient’s condition relates to:

A. hypoventilation
B. diffusion abnormaliy
C. shunt
D. low inspired oxygen content

Answer 15

C. shunt
By definition! If you can’t increase the oxygen levels in the blood after inhaling more oxygen, then the blood must not be in contact with the oxygen you are inhaling (=the blood is bypassing the lung somehow). This could be a cardiac septum defect or an arteriovenous malformation (AVM) among others.

Question 16

A 45 year old man from Indianapolis presents with a chief complaint of shortness of breath. He was well until 4 months ago, when he developed fatigue, headaches, and low grade fevers. Two weeks ago he began feeling short of breath during exercise and over the past week he has begun to feel shortness of breath at rest. He is a floor nurse at a busy hospital and notes that his yearly PPD test, done as recently as two months ago, has always been negative. He reports no travel outside of the continental U.S. A CT scan of the chest is negative for a pulmonary infiltrate, but does reveal mediastinal lymphadenopathy and a large pericardial effusion. He has no evidence of disease elsewhere in his body.
Which of the following tests is most likely to be positive in this patient:

A. repeat PPD test
B. serum histoplasmosis antigen testing
C. sputum evaluation by microscopy
D. urine histoplasmosis antigen testing
E. histoplasmosis serology

Answer 16

E. histoplasmosis serology

This patient most likely has mediastinal histoplasmosis. A is incorrect because his lack of travel, negative PPD test, and geographic location in Indianapolis make histoplasmosis more likely than tuberculosis. Of the 4 testing options provided for histoplasmosis, serology has the greatest sensitivity. Serum and urine histoplasmosis antigen tests have fairly good sensitivity in disseminated disease (60-80%), but low sensitivity in localized disease such as mediastinal histoplasmosis. Since the CT scan of the chest shows no pulmonary infiltrates, it is very unlikely that sputum exam would be positive.

Question 17

A multi-valent polysaccharide-protein conjugate vaccine against Streptococcus pneumoniae is recommended for use in infants to generate a protective response. The older version, a multi-valent polysaccharide- only vaccine, is not recommended for this age group. The reason for these recommendations is that the conjugate vaccine compared to the old vaccine:

A. also includes inactivated pneumolysin.
B. elicits primarily an anti- IgM response against the polysaccharides
C. elicits primarily an anti- IgM response against the polysaccharides
D. is less toxic
E. presents polysaccharides as T-dependent antigens

Answer 17

E. presents polysaccharides as T-dependent antigens

Infants cannot make antibody responses to polylysaccharides because they are T-independent antigens. The conjugate vaccine allows the infant to make an antibody response (and evoke memory cells) because the protein part of the conjugate engages T cells and allows the polysaccharides to be presented as T-dependent antigens.

Answer A is wrong because pneumolysin is not in either vaccine.

Answer B is wrong because T-dependent antibody responses to polysaccharides (as for the conjugate vaccine) are primarily IgG responses.

Answer C is wrong because the conjugate vaccine actually has fewer serotypes than the polysaccharide only vaccine (13 versus 22, respectively).

Answer D is wrong because neither vaccine is toxic.

Question 18

Which ONE of the following correctly describes the mode of action of oseltamivir (Tamiflu), the antiviral drug for influenza virus infection?

A. It is a protease inhibitor
B. It blocks the thymidine kinase
C. It inhibits the M2 ion channel
D. It is effective against influenza virus type A only
E. It prevents virus release

Answer 18

E. It prevents virus release

For envelope viruses to be released from the surface of infected cells, down-regulation of cell surface receptors or removal of cell surface receptors is essential. For influenza virus, neuraminidase (NA) hydrolyzes the glycosidic linkage of the sialic acid moiety, thereby allowing influenza viral particles to detach from the infected cell surface. Inhibition of NA by oseltamivir causes viral particles to remain bound to the surface of infected cells and thus unable to spread and initiate new infection.

Question 19

A 38 year old woman from southern California presents with 3 months of chest pain, fever, and cough. Her cough has become progressively worse and her sputum, which used to be whitish yellow, now has flecks of blood in it. Chest x-ray shows a thin-walled cavity (5cm in diameter) in the right lower lobe. Upon delivering a lung biopsy sample to the microbiology lab, you notify the technicians of the fungus you suspect because of risk of aerosolization of which of the following?

A. Histoplasma capsulatum yeast forms
B. Coccidioides immitis arthroconidia
C. Blastomyces dermatiditis spores
D. Candida albicans yeast forms
E. Mycobacterium tuberculosis bacteria

Answer 19

B. Coccidioides immitis arthroconidia

The patient’s habitation in southern California in combination with the presence of a thin-walled cavity in the lung raise suspicion for Coccidioides immitis. It is very important to notify lab personnel who are conducting cultures of all cases of suspected Coccidiodes because when it grows in culture it is highly infectious to lab personnel. In culture (as in the environment) it grows as a mold. Segmentation of hyphae results in arthroconidia, which can then be breathed in and cause infection if lab personnel are not taking appropriate precautions.

Question 20

Which ONE of the following bacteria is a possible agent of pneumonia that is insidious in onset and where constitutional symptoms often predominate over respiratory symptoms?

A. Haemophilus influenzae
B. Mycobacterium bovis
C. Mycobacterium tuberculosis
D. Mycoplasma hominis
E. Mycoplasma pneumoniae

Answer 20

E. Mycoplasma pneumoniae

Mycoplasma pneumoniae is a human respiratory pathogen while Mycoplasma hominis is a suspected pathogen of the genital tract. The other bacteria are respiratory pathogens that cause different symptoms than those described.

Question 21

The asterisk is in the lumen of a:

A. PCT
B. DCT
C. Cortical collecting tubule
D. Thin segment of loop of Henle
E. Branch of intralobular artery

Answer 21

Answer Key: E

Feedback: The correct answer is E. This is a branch of a small artery. The walls of the vessels have flattened endothelial cells lining the lumen and several complete layers of smooth muscles. Note that there is the arteriole going into the glomerulus in this image.

Question 22

The area directly above the asterisks is the:

A. macula densa
B. loop of Henle
C. podocyte pedicel
D. arcuate artery
E. minor calyx

Answer 22

Answer Key: A

Feedback: The correct answer is A. This is the macula densa. This is a specialized portion of the DCT that senses Na and Cl concentrations. Note the closely apposed nuclei.

Question 23

The infectious form of Chlamydia trachomatis is characterized by which ONE of the following features?

A. Extensive disulfide cross-linking of outer membrane proteins
B. Polar flagella
C. Polysaccharide capsule
D. Thick coat of peptidoglycan
E. Thin, sterol-rich outer membrane

Answer 23

Answer Key: A

Feedback: The correct answer is A. EBs, the infectious form of Chlamydia, have disulfide cross-linked outer membrane proteins. The non-infectious forms (RBs) do not. Chlamydia do not make capsules, do not have flagella and do not have sterols in their outer membrane.

Question 24

Which of the following inhaled asthma medication can be used to control inflammation?

A. albuterol
B. theophylline
C. omalizumab
D. fluticasone
E. tiotropium

Answer 24

Answer Key: D

Feedback: The correct answer is D, fluticasone. As a synthetic corticosteroid, fluticasone has broad anti-inflammatory actions. Their most important action is inhibition of the infiltration of asthmatic airways by lymphocytes, eosinophils and mast cells. They act to reduce bronchial reactivity and reduce the frequency of asthma exacerbations if taken regularly.

Question 25

A 18-year-old male has asthma that has been difficult to manage. His physician has decided to prescribe a fast-acting medication to use for exacerbations. Which of the following would BEST provide fast relief from an acute asthma exacerbation?

A. an oral corticosteroid
B. an inhaled corticosteroid
C. a nebulized anticholinergic agent
D. a leukotriene receptor antagonist
E. a mast cell stabilizer

Answer 25

Answer Key: C

Feedback: The correct answer is C. Muscarinic antagonists block the contraction of airway smooth muscle and the increase in secretion of mucus that occurs in response to vagal activity. As a result, antimuscarinic agents are effective bronchodilators. A nebulized, or inhaled, route of administration allows for rapid onset of action in the lung while limiting systemic side effects.

Question 26

Which of the lettered structures is a proximal convoluted tubule? Note that there are several examples of each choice.

A. A
B. B
C. C
D. D

Answer 26

Answer Key: B

Feedback: The correct answer is B. There are no distinct cell divisions, the nuclei are rounded and set towards the basal side of the cell and there is a fuzzy brush border.

Question 27

A possible function of the cells indicated by the arrows is:

A. Formation of the outer layer of the glomerular basement membrane (GBM)
B. Secretion of renin
C. Secretion of rennin
D. Phagocytosis of excess material at the GBM
E. Regulation of arteriolar blood pressure
F. Monitoring urine sodium levels

Answer 27

Answer Key: D

Feedback: The correct answer is D, these are intraglomerular mesangial cells.

Question 28

The parietal layer of Bowman’s capsule is derived from the:

A. ectoderm
B. endoderm
C. metanephric mesoderm
D. neural crest
E. somites
F. splanchnic mesoderm
G. ureteric bud

Answer 28

Answer Key: C

Feedback: The correct answer is C. The kidney develops from two sources. The excretory units (the nephrons) are derived from the metanephric mesoderm. Bowman’s capsule is part of a nephron. See page 236 of your embryology text.

Question 29

In autosomal recessive polycystic kidney disease, cysts form from the:

A. allantois
B. collecting ducts
C. distal convoluted tubules
D. proximal convoluted tubules
E. vasa recta

Answer 29

Answer Key: B

Feedback: The correct answer is B. See page 237 of your text for more details and clinical correlates.

Question 30

Your patient is a sailor who was rescued from a raft at sea after three days. Unfortunately, the sailor who was without either food or water on his raft has been drinking sea water for the last two days. Immediately after rescue you would expect this patient to manifest:

A. increased intracellular fluid volume
B. decreased extracellular fluid volume
C. decreased extracellular fluid osmolarity
D. increased intracellular fluid osmolarity

Answer 30

Answer Key: D

Feedback: The correct answer is D. Drinking hypertonic sea water is an example of hypertonic expansion. The sodium chloride in the sea water would distribute evenly between the plasma and the interstitial spaces, elevating the interstitial fluid osmolarity. Since the cell walls are essentially impermeable to sodium chloride, sodium chloride cannot enter the intracellular fluid to establish osmotic equilibrium so water osmotically exits the cell until the osmolarity of the extracellular and intracellular fluids are equal. Thus both the extracellular and intracellular fluid osmolarity would be increased, extracellular fluid volume would be increased and intracellular fluid volume would be decreased.

Question 31

Fluid leaving the proximal tubule is:

A. always hypotonic because water is reabsorbed at a rate greater than solute reabsorption
B. always hypotonic because solute is reabsorbed at a rate greater than water reabsorption
C. always hypertonic because solute is reabsorbed at a rate less than water
reabsorption
D. hypertonic when a concentrated (hypertonic) urine is to be excreted
E. always isotonic

Answer 31

Answer Key: E

Feedback: The correct answer is E., always isotonic. Because of the high water permeability of the proximal tubular epithelium, water is reabsorbed as fast as sodium so the osmolar concentration of the fluid is unchanged during its passage along the proximal tubule.

Question 32

You order a full blood work-up of your patient and receive a relevant estimate of glomerular filtration rate from the lab. This estimate was based on:

A. the tubular maximum for inulin secretion
B. creatinine clearance
C. the tubular maximum for PAH reabsorption
D. the tubular maximum for glucose secretion
E. PAH clearance

Answer 32

Answer Key: B

Feedback: The correct answer is B., creatinine clearance. It gives a useable estimate of GFR until the GFR gets down to about 20 ml/min where the errors from the elevated plasma creatinine concentration, and hence marked increased in creatinine secretion, make the estimate unreliable.

Question 33

Which of the following is an example of primary active transport?

A. Potassium transport across the apical (luminal) membrane in the thick ascending limb of the loop of Henle
B. Chloride transport across the apical (luminal) membrane in the distal tubule
C. Sodium transport across the apical (luminal) membrane of the cortical collecting duct
D. Glucose transport across the basolateral membrane of the proximal tubule
E. Hydrogen transport across the apical (luminal) membrane of the alpha intercalated cells of the cortical collecting duct

Answer 33

Answer Key: E

Feedback: The correct answer is E., hydrogen ion transport across the alpha intercalated cells. A is secondary active transport, B is facilitated diffusion, C is facilitated diffusion, D is secondary active transport.

Question 34

The propensity of pyelonephritis due to Proteus mirabilis to lead to kidney stones is due to the production of which one of the following by this organism?

A. Endotoxin
B. Hemolysin
C. Lateral flagella
D. Pyelonephritis-associated (Pap or P) pili
E. Urease

Answer 34

Answer Key: E

Feedback: The correct answer is E. Proteus spp. are common causes of UTI and these infections tend to be more severe than those caused by E. Coli. A higher proportion of these infections represent pyelonephritis. Urease catalyzes the hydrolyzation of urea to CO2 and ammonia, which alkalinizes the urine. This leads to the precipitation of struvite, formation of calculi (stones) and obstruction of indwelling urinary catheters. Kidney stones can serve as foreign bodies in which bacteria are embedded and from which they can emerge and cause recurrent infections.

Question 35

Fluid reabsorption from the interstitial space into the peritubular capillaries will increase if:

A. plasma protein concentration increases
B. interstitial fluid pressure decreases
C. the capillary hydrostatic pressure increases
D. the efferent arterioles dilate
E. arterial pressure increases

Answer 35

Answer Key: A

Feedback: The correct answer is A, plasma protein concentration determines the capillary colloid osmotic pressure which is the main force for reabsorption of fluid into the capillaries from the interstitial space.

Question 36

A 55 year old female is admitted to an outpatient clinic with a 39° C fever and flank pain. She was recently discharged from a 3 day hospital visit during which she was catheterized. Many leukocytes and several white blood cell casts are seen in a microscopic examination of her urine. A Gram-negative organism that ferments lactose was isolated in pure culture from her urine. The woman is aggressively treated with antibiotics. Which one of the following is the most likely diagnosis?

A. Uncomplicated urinary tract infection
B. gallstones
C. pyelonephritis
D. urethritis
E. pelvic inflammatory disease

Answer 36

Answer Key: C

Feedback: The correct answer is C. Pyelonephritis is the clinical syndrome characterized by flank pain, tenderness, or both and fever. It is often associated with dysuria, urgency, frequency and occasionally, suprapubic tenderness. It is accompanied by significant bacteruria and acute infection in the kidney. The risk factors present in this patient are her gender and recent urinary tract catheterization. The presence of leukocytes in her urine suggests acute inflammation, in this case due to acute infection. The white blood cell casts, in this setting, are highly suggestive of pyelonephritis. The lactose fermenting gram negative organism recovered from a culture of her urine is most likely E. Coli. This is the most common causative organism for UTI.

Question 37

Your patient has a significantly decreased extracellular fluid volume due to hemorrhage. You would expect this to result in:

A. decreased release of aldosterone
B. increased renin release
C. increased afferent arteriolar resistance
D. decreased efferent arteriolar resistance
E. decreased circulating levels of angiotensin II

Answer 37

Answer Key: B

Feedback: The correct answer is B. Decreased extracellular fluid volume activates the renin-angiotensin-aldosterone system so you would expect increased levels of angiotensin, increased aldosterone, increased efferent arteriolar resistance and decreased afferent arteriolar resistance.

Question 38

You have a patient that displays high plasma levels of atrial natriuretic peptide (ANP) as a result of significantly increased extracellular fluid volume. This increases sodium excretion from the kidney by:

A. increasing the secretion of aldosterone.
B. increasing plasma angiotensin II.
C. increasing medullary blood flow.
D. decreasing glomerular filtration rate.
E. increasing the release of renin.

Answer 38

Answer Key: C

Feedback: The correct answer is C. ANP increases medullary blood flow, causing washout of sodium from the medullary interstitium. This increases plasma sodium concentrations and hence increases the filtered load of sodium. ANP inhibits rennin release and thus would decrease aldosterone and angiotensin II. It also increases the glomerular filtration rate.

Question 39

You need to accurately measure the glomerular filtration rate (GFR) in you patient with borderline 3rd stage renal disease. To do this, you perform an inulin clearance study.

Inulin is your substance of choice because it:

A. is freely filtered and vigorously secreted into the tubular fluid, being essentially cleared from the blood in a single pass through the kidney.
B. is avidly reabsorbed in the proximal tubule.
C. is freely filtered, not secreted and not reabsorbed.
D. is stored in the principal cells of the late distal tubule and cortical collecting ducts.
E. is metabolized by the intercalated cells in the thin ascending limb of the loop of Henle.

Answer 39

Answer Key: C

Feedback: The correct answer is C. To measure GFR you need a substance that is freely filtered, not reabsorbed, secreted, stored or metabolized in the tubules. Thus the amount filtered = the amount excreted.

Question 40

The transitional epithelium lining the ureter is derived from the:

A. ectoderm
B. endoderm
C. metanephric mesoderm
D. neural crest
E. somites
F. splanchnic mesoderm
G. ureteric bud

Answer 40

Answer Key: G

Feedback: The kidney develops from two sources. The collecting system is derived from the ureteric bud. See page 236 of your embryology text.

Question 41

What are the two physiological reasons for anti-diuretic hormone to be released from the pituitary gland and engage the tubule to reabsorb water?

A. Low serum osmolality and intravascular high volume state clinically
B. High serum osmolality and intravascular low volume state clinically
C. Low serum osmolality and intravascular low volume state clinically
D. High serum osmolality and intravascular high volume state clinically

Answer 41

Answer Key: B

Feedback: The correct answer is B. Increased plasma osmolarity is the most important physiologic stimulus for increasing ADH secretion. Hypovolemia (or volume contraction) is also a potent stimulus for ADH secretion. A decrease of 10% or more in ECF volume may cause a decrease in BP that is sensed by the mechanoreceptors in the atria, carotid artery and aortic arch. This is transmitted to the hypothalamus which directs an increase in ADH secretion. ADH will then stimulate water reabsorption in the collecting ducts in an attempt to restore ECF volume. Hypovolemia can stimulate ADH secretion even in the setting of a plasma osmolarity that is lower than normal. Pain, nausea, hypoglycemia and certain drugs (opioids, nicotine and some antineoplastic agents) can also stimulate ADH release.

Question 42

Which diuretic causes a proximal tubule wasting of bicarbonate?

A. furosemide
B. thiazides
C. acetazolamide
D. spironolactone
E. mannitol

Answer 42

Answer Key: C

Feedback: The correct answer is C. A diuretic is any agent that increases urine volume. Carbonic anhydrase is present in nephron sites but principally is located on the epithelial cells of the proximal convoluted tubule. Carbonic anhydrase catalyzes the dehydration of carbonic acid to carbon dioxide at the luminal membrane and the rehydration of carbon dioxide to carbonic acid in the cytoplasm. Agents that block carbonic anhydrase will blunt sodium bicarbonate reabsorption in the tubule and cause diuresis. Acetazolamide is the prototypical carbonic anhydrase inhibitor. The overall effect of maximal acetazolamide dosage is about 45% inhibition of whole kidney bicarbonate reabsorption.

Question 43

You have a patient that manifests abnormally elevated plasma levels of antidiuretic hormone (ADH) subsequent to traumatic brain injury. This condition would result in:

A. aquaporin 1 channels being trafficked to the basolateral membrane of the proximal convoluted tubule
B. aquaporin 3 channels being trafficked to the apical (luminal) membrane of the intercalated cells
C. aquaporin 2 channels being trafficked to the apical (luminal) membrane of the principal cells
D. aquaporin 4 channels being trafficked to endosomes in the cytoplasm of the proximal tubule
E. the late distal tubule being impermeable to water

Answer 43

Answer Key: C

Feedback: The correct answer is C., aquaporin 2 channels are trafficked to the apical membrane of the principal cells in the collecting duct, making the tubular epithelial cells permeable to water. Aquaporin 1 channels are present in both the apical and basolateral membranes of the proximal tubule at all times and are not dependent on the presence of ADH.

Question 44

You prescribe bumetanide (loop diuretic) for your hypertensive patient. This drug effectively lowers the patient’s blood pressure through its actions on the:

A. amiloride sensitive sodium channels
B. phosphase/sodium cotransporter
C. sodium-potassium-2 chloride cotransporter (NKCC2)
D. epithelial cell sodium channel (ENaC)
E. sodium chloride cotransporter (NCC)

Answer 44

Answer Key: C

Feedback: The correct answer is C. Bumetanide is a loop diuretic and as such decreases the apical transport of sodium by inhibiting the sodium, potassium, two chloride cotransporter (NKCC2).

Question 45

You correctly diagnose your patient as having simple metabolic acidosis. You would expect to see:

A. an increase in plasma bicarbonate concentration
B. a compensatory increase in arterial pC02
C. an increase in arterial pH
D. a compensatory decrease in arterial pC02
E. a decrease in ventilatory rate

Answer 45

Answer Key: D

Feedback: The correct answer is D., a compensatory decrease in arterial pCO2 following partial respiratory compensation as a result in increased ventilatory rate. The cause of the acidosis is a decrease in plasma bicarbonate concentration.

Question 46

You order a full blood work-up of your patient and receive a relevant estimate of glomerular filtration rate from the lab. This estimate was based on:

A. the tubular maximum for inulin secretion
B. creatinine clearance
C. the tubular maximum for PAH reabsorption
D. the tubular maximum for glucose secretion
E. PAH clearance

Answer 46

Answer Key: B

Feedback: The correct answer is B., creatinine clearance. It gives a useable estimate of GFR until the GFR gets down to about 20 ml/min where the errors from the elevated plasma creatinine concentration, and hence marked increased in creatinine secretion, make the estimate unreliable.

Question 47

You have a patient that has a genetic mutation that results in significant decreases in the production of Na+, K+ ATPase. You would expect this patient to manifest:

A. increased sodium reabsorption in the proximal tubule
B. decreased glucose reabsorption in the proximal tubule
C. decreased urinary sodium concentrations
D. increased magnesium reabsorption in the collecting duct
E. increased potassium secretion in the distal tubule

Answer 47

Answer Key: B

Feedback: The correct answer is B., decreased glucose reabsorption in the proximal tubule. Glucose is reabsorbed by secondary active transport and is tied to sodium reabsorption.
Decreases in the Na+ K+-ATPase would decrease the lumen to intracellular gradient, decrease apical (luminal) sodium transport and hence decrease glucose transport.

Question 48

Your patient has adrenal insufficiency that results in a loss of aldosterone production. As such, this patient would be expected to have:

A. increased sodium reabsorption in the proximal tubule
B. decreased sodium reabsorption in the collecting duct
C. decreased potassium reabsorption in the thick ascending loop of Henle
D. increased sodium reabsorption in the distal tubule
E. increased amino acid reabsorption in the proximal tubule

Answer 48

Answer Key: B

Feedback: The correct answer is B., decreased sodium reabsorption in the collecting duct. Aldosterone regulates the sodium permeability of the distal tubule and the collecting duct and its absence would decrease the sodium reabsorption in these two segments of the tubular system. It does not affect the proximal tubule or the loop of Henle.

Question 49

Fluid leaving the proximal tubule is:

A. always hypotonic because water is reabsorbed at a rate greater than solute reabsorption
B. always hypotonic because solute is reabsorbed at a rate greater than water reabsorption
C. always hypertonic because solute is reabsorbed at a rate less than water
reabsorption
D. hypertonic when a concentrated (hypertonic) urine is to be excreted
E. always isotonic

Answer 49

Answer Key: E

Feedback: The correct answer is E., always isotonic. Because of the high water permeability of the proximal tubular epithelium, water is reabsorbed as fast as sodium so the osmolar concentration of the fluid is unchanged during its passage along the proximal tubule.

Question 50

The countercurrent multiplication mechanism that established the renal interstitial hyperosmolarity is dependent upon:

A. the active pumping of sodium across a membrane that is impermeable to water
B. the variable permeability of water in the collecting duct depending on the plasma concentration of antidiuretic hormone (ADH)
C. secretion of potassium ions across the cortical collecting ducts
D. aldosterone-mediated reabsorption of sodium across the proximal tubule
E. The paracellular reabsorption of Mg++ in the proximal tubule

Answer 50

Answer Key: A

Feedback: The correct answer is A., the active pumping of sodium out of the tubular epithelium into the renal interstitial fluid without the concomitant movement of water.

Question 51

What is the fractional excretion of sodium (FENa) in the urine that is considered pre-renal?

A. FENa <5%
B. FENa <7%
C. FENa <2%
D .FENa <1%

Answer 51

Answer Key: D

Feedback: The correct answer is D. Fractional excretion of sodium is the percentage of sodium filtered by the kidney which is excreted in the urine. To calculate FENa=100 x (Na in urine)x(creatinine in plasma)/(sodium in plasma)x(creatinine in urine). A FeNa <1% typical supports a pre-renal etiology for acute renal failure. This is based on the fact that the physiologic response to a decrease in renal perfusion is an increase in sodium reabsorption from the urine to control hypovolemia.

Question 52

In the evaluation of renal causes of acute renal failure, which urine microscopic sediment in most commonly seen in acute tubular necrosis (ATN)?

A.granular casts
B .RBC casts
C. WBC casts
D. hyaline casts

Answer 52

Answer Key: A

Feedback: The correct answer is A. Centrifugation or “spinning of the urine” is a commonly performed test to evaluate acute renal failure. Urinary casts are cylindrical structures that are formed in the distal convoluted tubule and collecting ducts of the nephron. They form via precipitation of uromodulin (also known as Tamm-Horsfall mucoprotein), which forms the matrix of the cast. This mucoprotein is secreted by the renal tubule cells. Cast formation is pronounced in environments favoring protein denaturation and precipation. They generally maintain their shape and composition as they pass through the urinary system. Various elements may be adhered to or included within the mucoprotein base. Some casts (hyaline) are benign. Hyaline casts are composed of pure Tamm-Horsfall mucoprotein. In other instances casts represent a disease state such as RBC casts (glomerulonephritis, nephritic syndrome), WBC casts (indicative of inflammation of infection) and granular casts. Pigmented, muddy brown, granular casts are often seen in cases of acute tubular necrosis or ATN.

Question 53

The MAJOR mechanism of action of thiazide diuretics on the distal tubule of kidney is to

A. act as competitive antagonists of the mineralocorticoid receptor.
B. alter the Na+ channels.
C. inhibit the Na-K-2Cl co-transporter.
D. inhibit the Na-Cl co-transporter.
E. inhibit the Na+/K+ ATPase.

Answer 53

Answer Key: D

Feedback: The correct Answer is D. The site of action of thiazide diuretics is the distal tubule of the kidney.

Question 54

A 38-year-old African American male presents with symptoms consistent with a kidney stone. During the work-up, it is determined that it is composed of calcium oxalate. In addition, the patient is noted to have mild hypertension. A diuretic is chosen to treat both conditions. After he returns in 1 month his blood pressure is normalized and his serum calcium is increased to 11.5 mg/dl from 9 mg/dl. The diuretic most likely to be responsible for these effects is

A. triamterene.
B. acetazolamide.
C. chlorthalidone.
D. furosemide.
E. eplerenone.

Answer 54

Answer Key: C

Feedback: The correct answer is C, chlorthalidone. It is a thazide diuretic that increases calcium reabsorption in the distal tubule which can cause mild hypercalcemia.

Question 55

Which of these structures is most responsible for establishing the high gradient in the renal medulla:

A. proximal tube
B. descending loop
C. ascending loop
D. collecting system tubule

Answer 55

Answer Key: C

Question 56

A seven year old child recently developed bloody diarrhea. He furthermore developed oliguria with minimal urine output and estimated GFR less than 10 ml/min/1.73m2. He has RBCs in urine, mild proteinuria, and elevated blood pressure. He has no increased metabolic rate or fever, but he refuses to drink or eat and feels too sick to do so. The nurse questions you as the Doctor to the appropriate fluid. You indicate:

A. Hypotonic solution of Dextrose 5% and Water and replace urine output each hour
B. Hypertonic solution of normal saline
C. Isotonic solution of Dextrose and saline with urine replacement each hour
D. No fluid at all

Answer 56

Answer Key: A

Question 57

What is normal eGFR and what eGFR is considered kidney failure?

A. 80-90 ml/min/1.73m2 and 60 ml/min/1.73m2
B. 50-60 ml/min/1.73m2 and 30 ml/min/1.73m2
C. 100-120 ml/min/1.73m2 and 60 ml/min/1.73m2
D. 100-120 ml/min/1.73m2 and 30 ml/min/1.73m2

Answer 57

Answer Key: C

Question 58

Which is not an indication for dialysis or renal replacement therapy?

A. Uremia
B. Swelling in the hands, abdomen, and feet
C. Severe Acidosis
D. Hyperkalemia

Answer 58

Answer Key: B

Question 59

Urea is transported:

A. by secondary active transport into the distal convoluted tubule
B. by primary active transport into the cortical collecting duct.
C. by UT-1 transporters in the walls of the vasa recta.
D. by UT-2 transporters in the loop of Henle.
E. by a urea/chloride exchanger in the distal convoluted tubule.

Answer 59

Answer Key: D

Feedback: The correct answer is D., by UT-2 transporters in the loop of Henle. Urea transport is passive, down its concentration gradient.

Question 60

A 65 year old man underwent surgery for the repair of an abdominal aneurysm. In the postoperative period, he was noted to have decreased urine output. His BUN was 29 mg/ dL (Normal 7-20) and creatinine was 1.9 mg/ dL (Normal 0.8-1.4). His fractional excretion of Na+ was 4.2 %. Muddy brown granular casts were observed on urinalysis indicating tubular necrosis. His increased fractional excretion of Na+ is likely due to:

A. Increased filtration of Na+
B. Increased filtration of glucose
C. Decreased reabsorption of Na+
D. Increased secretion of Cl-
E. Increased secretion of Na+

Answer 60

Answer Key: C

Feedback: The correct answer is c. This is an example of post-ischemic acute tubular necrosis. In this case, the patient, who suffered from an apparent leaking abdominal aneurysm, was likely developing hypotension prior to going into the OR. The was likely further blood and fluid loss during surgery leading to a variable period of hypotension and reduced renal blood flow. This leads to ATN. This is characterized by the increased plasma creatinine, reduced urine volume and changes in his urinalysis (granular casts, increase FeNa (>1%)). You can also see an increased fractional excretion of urea (Fe urea) >35%. A number of processes contribute to the pathogenesis of ATN including epithelial and endothelial cell injury, intratubular obstruction, changes in local microvascular blood flow and immunological and inflammatory processes. Poorly functioning renal tubules will not increase secretion. The renal tubules are not involved in filtration (glomeruli). Therefore the answer must be “c”, decreased reabsorption of sodium. The combination of glomerular filtration and impaired proximal and loop resorptive function leads to increase NaCl delivery to the macula densa. This activates the tubuloglomerular feedback mechanism causing afferent arteriolar constriction. This leads to a decreased GFR in an attempt to decrease tubule flow rate.