Quiz week 2

Question 1

Which statement about cAMP and the second-messenger mechanism of signal transduction is correct?

A.The chemical messenger stimulus leads to increased amounts of adenylyl cyclase
B.Cyclic AMP binds to the regulatory subunits of specific protein kinases to affect their activities
C.Cyclic AMP interacts with a chemical messenger-receptor complex to dissociate the chemical messenger
D.The chemical messenger-receptor complex enters the cell and affects the activities of target enzymes

Answer 1

Answer Key: B

Feedback: a) is incorrect because stimulation of the receptor by the chemical messenger does not lead to an increase in the number of adnylyl cyclase proteins at the plasma membrane.

b) cyclic AMP binds to regulatory subunit of the Protein Kinase A complex thereby dissociating it from the catalytic subunit, which goes on to phosphorylate and stimulate downstream effectors in the pathway.
c) is incorrect because cyclic AMP is a second messenger, is several steps downstream of the receptor, does not directly interact with the receptor in anyway to cause a conformational change that might dissociate the ligand.
d) is incorrect because cAMP signal transduction involved a plasma membrane receptor (which remains as the membrane), not an intracellular transcription factor receptor (which crosses the plasma membrane and acts in the nucleus).

Question 2

PROBLEM: Scientists have long suspected that there is an association between allergies and gliomas, a common and often fatal type of brain tumor. Studies had been done suggesting that people with allergies were less susceptible to the tumors, but they were all based on patients self-reporting whether or not they had allergies – not on actual blood test evidence of allergy-related immune system variations. And because brain tumors themselves can weaken the immune system, including the immune response to allergens, it’s been difficult to prove which condition came first.

METHODOLOGY: In Norway, blood samples from annual check-ups and voluntary donations are saved and labeled with personal identification numbers. Thanks to this extremely organized and comprehensive system, researchers were able to obtain access to blood samples taken from 594 current glioma patients decades before they were diagnosed. They were also able to match them with samples from people who never developed glioma. In each sample, they measured the levels of two types of IgE, a protein that plays an essential role in allergic reactions. Then, they used statistical analysis to see whether elevated levels of IgE were associated with a reduced risk of developing a glioma. (ref: J Natl Cancer Inst (2012) doi: 10.1093/jnci/djs315)

In a study of the association between prediagnostic IgE levels and risk of glioma, (J Natl Cancer Inst (2012) doi: 10.1093/jnci/djs315), 77 of 594 case subjects (patients with glioma) had elevated IgE in a prediagnostic serum sample. 198 of 1,177 control subjects (patients without glioma) had elevated IgE.

Which of the following study designs best describes this study?

A.Case series
B.Cross-sectional
C.Case-control
D.Cohort
E.Randomized controlled trial

Answer 2

Answer Key: C

Feedback:

a. incorrect: a case series includes only patients with disease, and this study included samples from people who never developed glioma (controls).
b. incorrect: a cross-sectional study measures both exposure (elevated IgE) and disease (glioma) at the same point in time. Here, researchers analyzed blood samples that were obtained before diagnosis of glioma, to identify elevated IgE prior to glioma diagnosis.
c. correct: study participants were identified on the basis of disease status (glioma vs. no glioma) and followed back in time to determine exposure status (elevated IgE) by analyzing previously collected blood samples
d. incorrect: in a cohort study, study participants are identified on the basis of exposure, and observed to see which participants develop disease. Here, participants were identified on the basis of disease (glioma) and followed back in time to determine exposure status (elevated IgE)
e. incorrect: in a randomized controlled trial, the exposure is determined by the investigator. Here, the exposure (IgE level) was observed based on previously collected blood samples.

Question 3

After taking a particularly challenging exam, your friend who has never failed an exam in their life angrily approaches you stating, “it’s not my fault I failed this test, the exam room was noisy, freezing, and our instructor is terrible!” What principle most appropriately explains your friend’s behavior?

A.Cognitive Dissonance
B.Attribution
C.Individuation
D.Social Loafing
E.Attitude Formation

Answer 3

Answer Key: A

Feedback:

A. Cognitive Dissonance (Yes, slide 30. The past belief of never failing conflicts with the reality of failing the exam and the dissonance is resolved by explaining the failure through the environmental conditions and quality of instruction)

B. Attribution (No, slide 34)

C. Individuation (No, slide 26)

D. Social Loafing (No, slide 32)

E. Attitude Formation (No, slide 36)

Question 4

A 65 y.o. man with a long history of high blood pressure presents in the
emergency room complaining of chest pain. An electrocardiogram (ECG)
that assesses the electrical activity of the heart reveals that the
patient is experiencing myocardial ischemia caused by blockage of one of
the major coronary arteries. You resolve the ischemia by removing the
blockage, restoring normal blood flow to the heart. You suspect,
however, that there may be some damage to the heart muscle as a result
of the ischemia. Should you be concerned and why?

A.Satellite cells will rapidly divide and replace the damaged tissue.
B.Even though some cells are lost, hypertrophy of the remaining cells will
fill the space where myocytes were lost.
C.Ischemia will result in long-term disruption of the neuromuscular
junctions that are required for cardiac muscle contraction.
D.Cardiac muscle cannot regenerate and will be replaced by scar tissue
that will cause disruption of contraction and electrical conduction.
E.Ischemia causes long-term changes in the actin filament attachment to
dense bodies causing a decrease in contraction.

Answer 4

Answer Key: D

Feedback: From the scenario, you should be able to ascertain that the patient has
experienced an acute myocardial infarction with effects on cardiac
muscle. Given that heart is composed of cardiac muscle, you know that
choice A and E are incorrect, because there are no satellite cells that
replace damaged cardiac muscle cells (those are in skeletal muscle)and
there are no dense bodies (those are in smooth muscle). Choice C is also
incorrect since there are no neuromuscular junctions required for
cardiac muscle contraction (electrical activity originates within the
heart itself in specialized nodal pacemaking cells). Choice B is
incorrect because hypertrophy does not replace the damaged cells, but
only reflects growth of the remaining cells. The correct answer is C.
Damage to the cardiac muscle tissue is a concern in such situations
because cardiac muscle tissue cannot replicate and/or regenerate and is
rather replaced by fibrotic scar/connective tissue that can cause the
heart wall to become stiffer and disrupt the normal cell-to-cell
conduction of electrical signals heart.

Question 5

A 6 y.o. girl comes to the emergency room with a 2 cm laceration on her right calf. You clean the injury, close the wound with several stitches and apply a dressing. The next week when she returns, the wound site has healed with some residual erythema. Which cells are most likely to be involved in removing the damaged and dying cells at the site of the injury?

A.Macrophages
B.Neutrophils
C.Plasma cells
D.Mast cells
E.Adipocytes
F.Fibroblasts
G.Eosinophils

Answer 5

Answer Key: A

Feedback: Correct ans: A. macrophages are the cells responsible for scavenging necrotic tissue.

Question 6

Which protein domain binds directly to PI 3,4,5-tris-phosphate (PIP3)?

A.SH2 domain
B.Pleckstrin homology domain (PH)
C.kinase domain
D.phosphorylated tyrosine

Answer 6

Answer Key: B

Feedback: a) is incorrect because SH2 domains bind phosphorylated tyrosine residues.

c) is incorrect because PIP3 does not get phosphorylated, thus a kinase domain would not have a reason to bind.
d) is incorrect because SH2 domains bind to phosphorylated tyrosine, and a phosphorylated tyrosine residue is not what binds to PIP3.

Question 7

During a viral infection, which ONE of the following anti-viral soluble mediators is produced first?

A. C3
B.IL-1β
C. IL-4
D. II-12
E. IFN-α/β

Answer 7

Answer Key: E

Feedback:

A: incorrect; C3 is an plasma protein which is part of the Complement cascade

B: Incorrect; IL-1β is a proinflammatory cytokines made by macrophages

C: incorrect; IL-4 is produced by T cells in adaptive immune responses

D: incorrect; Il-12 is produced by macrophages and activates NK cells and T cells

E: correct; *IFN-α/β is produced by multiple cell types and produced rapidly after infection

Question 8

You are a recently arrived MS-1 who has consistently achieved a 4.0 GPA in every year of education since elementary school. In the past, you’ve managed to effortlessly achieve As on exams with virtually no studying. Recently you’ve started noticing more and more of your classmates studying long hours in the library, including on weekends. You suddenly begin to commit long hours of study in the library including weekends as well. The most appropriate principle to describe your change in behavior is:

A.Deindividuation
B.Social Comparison
C.Social Facilitation
D.Affiliation
E.Social Learning

Answer 8

Answer Key: B

Feedback:

Explanation
A. Deindividuation (No, slide 26)
B. Social Comparison (Yes, slide 22. The behavior was inspired by observing peers and initiated without prompt.)
C. Social Facilitation (No, slide 10)
D. Affiliation (No, slide 26)
E. Social Learning (No, slide 28)

Question 9

How would you best describe the enzyme that catalyzes the following reaction?

A.Hydrolase
B.Lyase
C.Oxidoreductase
D.Transferase
E.Ligase

Answer 9

Answer Key: D

Feedback: The reaction involves transfer of a phospate group from ATP to glucose;
therefore the enzyme catalyzing the reaction is a transferase (answer
???d???). The types of reactions catalzyed by the other classes of
enzymes are summarized on pp 130-3 of Marks.

Question 10

A 5-month-old male mouse with bronchopneumonia has developed vascular instability consisting of vasodilation. As part of your investigation protocol you remove all cells from his blood and end up with plasma. When you inject this serum into a second experimental animal you notice that vasodilation is still happening. Which of the following substances is the most likely cause of the vasodilation?

A.Tumor necrosis factor
B.chemokines
C.complement
D.nitric oxide
E.histamine

Answer 10

Feedback: A, B, D, E are incorrect as they are all part of the cell derived pathway
C: correct, it is plasma protein derived

Question 11

Acetylcholine receptors, which mediate sympathetic and parasympathetic nerve signaling, are integral membrane proteins with multiple membrane-spanning -helices. Which one of the following amino acid residues is most likely to be present in membrane spanning regions?

A.Aspartate
B.Glutamine
C.Lysine
D.Histidine
E.Leucine

Answer 11

Answer Key: E

Feedback: Of all the amino acids listed above, Leu has the most hydrophobic side-chain; it is the only side chain with no hydrogen-bonding potential or charged groups. The nonpolar hydrocarbon side chain makes Leu an ideal amino acid to be present inside the hydrophobic interior of a membrane bilayer. Therefore, the correct answer is ???e???

Question 12

Inherited deficiencies in complement components are manifested in variable degrees of immunodeficiency. Deficiency in which ONE of the following complement proteins would most severely affect all three complement pathways?

A.C1
B.C3
C.C9
D.Factor B
E.Mannose-binding lectin

Answer 12

Answer Key: B

Feedback:

A: incorrect; only C3 is an essential intermediate in all 3 complement pathways

B: correct; C3 is an essential intermediate in all 3 complement pathways

C: incorrect; only C3 is an essential intermediate in all 3 complement pathways

D: incorrect; only C3 is an essential intermediate in all 3 complement pathways

E: incorrect; only C3 is an essential intermediate in all 3 complement pathways

Question 13

In the following energy diagram, the activation energy for the
uncatalyzed conversion of S (substrate) to P (product) is indicated by
which arrow?

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

Answer 13

Answer Key: A

Feedback:

The correct answer is A The activation energy for a reaction is the free energy difference between the ground state of the reactant and the transition state. Catalysts lower the activation energy for both forward and reverse reactions, so the curve with the highest activation barrier in the diagram must represent the uncatalyzed reaction.
B = activation energy for uncatalyzed conversion of P to S
C= activation energy for catalyzed conversion of S to P
D= activation energy for catalyzed conversion of P to S
E= change in free energy in S to P conversion

Question 14

A 3 year old patient has multiple recurrent infections. A tissue sample from an infected area is taken and it is noticed that very few neutrophils are present. Analysis of neutrophils in the laboratory shows a defect in rolling. A defect of which of the following would be most consistent with the laboratory findings?

A.Histamine
B.Integrins
C.Selectins
D.TNF
E.VEGF

Answer 14

Answer Key: C

Feedback: Explanation:
Rolling is the loose adherence of neutrophils to the endothelium or vessel wall. This loose adherence is mediated by the selectin???s, this includes the P-selectin and E-selectin. The integrins tightly bind the leukocytes and allow the next process of transmigration across the endothelium. TNF has multiple functions including being an important mediator (cytokine) that up regulates the selectins being expressed on endothelial cells, as well as mediator for fever and pain. VEGF is a growth factor and increases vascular permeability. Histamine is a potent mediator for vasodilation and increased vascular permeability.

Question 15

A 6 y.o. girl has a recently sutured wound and you are concerned about her risk for a bacterial wound infection. The girl’s mother explains that her daughter has had several allergic responses to different antibiotics. Thus you decide to forgo the use of topical antibiotic cream and rely on the girl’s innate host defense to combat any bacterial contamination. The cells most likely to kill bacteria are

A.Macrophages
B.Neutrophils
C.Plasma cells
D.Mast cells
E.Adipocytes
F.Fibroblasts
G.Eosinophils

Answer 15

Answer Key: B

Feedback:

Correct ans: B. neutrophils will secrete antibacterial substances such
as lysozyme and defensins, synthesize super oxide anions and phagocytose
bacteria.

Question 16

When a person gets a thorn in his/her finger, an inflammatory response is the first set of immune reactions to occur under normal conditions. Which are the first leukocytes to emigrate from the circulation to the site of inflammation?

A.B cells
B.Macrophages
C.Neutrophils
D.NK cells
E.T cells

Answer 16

Answer Key: C

Feedback:

A: incorrect; B cells are part of the adaptive immune response which occurs days after the initial inflammatory response

B: incorrect; Macrophages are resident cells in the tissue; circulating immature macrophages are called monocytes

C: correct; neutrophils are made rapidly in the bone marrow and circulate continuously

D: incorrect; NK cells do circulate but in small numbers and are generally associated with killing virus- infected cells and are not a major cell type in the inflammatory response

E: incorrect; T cells do diapedise but usually later in the immune response after being initially activated in the regional lymph node

Question 17

As a research assistant, one of your experiments allows you to evaluate microscopic skin sections from a group of rats on which you produced abdominal skin incisions with a clean scalpel 18 days previously. The incision edges were neatly apposed and sutured. Which of the following statements describes best what you would expect to find?

A.Abundant neutrophils.
B.Edematous and pale skin.
C.Chronic inflammation.
D.Chronic inflammation, marked fibrosis and prominent tissue destruction.
E.You expect to confirm your theory that tissue repair began once inflammation ceased.

Answer 17

Answer Key: C

Feedback: a. Incorrect. Neutrophils are typical of acute inflammation which is rapid in onset (typically within minutes) and is of short duration (hours or few days).

b. Incorrect. Emigration of neutrophils and edema are characteristics of acute inflammation.
c. Correct. Chronic inflammation may follow acute inflammation or be insidious in onset.
d. Incorrect. Chronic inflammation is associated with lymphocytes, macrophages, fibrosis and/or tissue destruction. In this case the clean incision and edge apposition would make marked fibrosis and prominent tissue destruction unlikely.
e. Incorrect. Inflammation is closely intertwined with repair.

Question 18

You are a provider working in a small primary care clinic. Your patient is a 55 year old retired master sergeant whose blood pressure has been elevated each time he has been seen at the clinic. During your clinical interview, the patient reports that when he has his blood pressure taken outside of doctor’s offices, it’s always within normal range. He states that he’s very nervous about visits about physicians monitoring his cardiovascular health since several of his friends have died of cardiovascular disease in their early to mid 50’s. What should you do?

A. Tell him that measurements of blood pressure taken outside of a
physician’s office are inaccurate and not to trust them.
B. Strongly caution him about the dangers associated with high blood
pressure and the risk of an early death.
C. Have his blood pressure retaken by a nurse in a comfortable
environment 5 minutes later.
D. Immediately start an aggressive medication regimen for hypertension.
E. Refer him to behavioral health for treatment of delusions and chronic
lying.

Answer 18

Answer Key: C

Feedback:

This scenario describes a classic case of “white coat hypertension” where the measurement taken in the clinic is a measure of the patient’s physiological response to the stress of being observed by a physician instead of the desired resting blood pressure. Having a non-physician provider in normal clothing retake the blood pressure may yield different results.

Question 19

A male, retired Army E-8, presents for a routine visit. After you introduce yourself and sit down for the interview, which of the following is the optimal manner in which to open the interview?

A.“What brings you in today?”
B.“How old are you?”
C.“Who is your primary care provider?”
D.”Can you give me your name and last four of your SSN?”
E.“When was the last time you saw a doctor?”

Answer 19

Answer Key: A

Feedback:

Answer –a.What brings you in today? is the only open-ended question of the choices. Using open-ended questions at the beginning of the interview is an optimal way to facilitate the acquisition of patient-centered information while also building rapport. All the other choices are closed-ended questions whose answers can be obtained from the medical record typically, and have limited relative clinical value.

Question 20

You have a 6-year-old male patient with a cut that has become infected. The redness surrounding the cut indicates significant inflammation. Which class of molecules is directly required for leukocytes to efficiently enter the inflamed skin from the blood?

A.Antigen receptors
B.Complement molecules
C.Co-stimulatory receptors
D.Immunoglobulin molecules
E.Integrins

Answer 20

Answer Key: E

Feedback:

A: incorrect; adhesion molecules such as integrins are required for transit of leukocytes from blood to peripheral tissues

B: incorrect; adhesion molecules such as integrins are required for transit of leukocytes from blood to peripheral tissues

C. incorrect; adhesion molecules such as integrins are required for transit of leukocytes from blood to peripheral tissues

D: incorrect; adhesion molecules such as integrins are required for transit of leukocytes from blood to peripheral tissues

E: correct; integrins are one type of adhesion molecule required for transit of leukocytes from blood to peripheral tissues

Question 21

A 52-year-old male with bronchopneumonia has developed vascular instability consisting of alternating episodes of vasodilation and vasoconstriction. As part of his overall treatment you decide to add indomethacin to the antibiotics you were already administering. On which of the following mediators is indomethacin not expected to have significant effect?

A. PGI2 (Prostacyclin)
B. TXA2 (Thromboxane)
C. LTB4 (Leukotriene B4)
D. PGE2
E. PGD2

Answer 21

Answer Key: C

Feedback:

A,B, D& E: incorrect. They are all part of the cyclooxygenase pathway that can be inhibited by indomethacin or aspirin,
C: Correct, it is part of the lipoxygenase pathway

Question 22

A 55 year male has a severe cough for 2 months. On chest x-ray he has an infiltrate in the left lung. A tissue sample of the lung is evaluated and a round lesion is identified with lymphocytes, epitheloid histiocytes and giant cells with a small amount of central necrosis. The above description best fits which of the following?

A.Abscess formation
B.Coagulative necrosis
C.Granulation tissue
D.Granulomatous inflammation
E.Serous inflammation
F.Ulceration

Answer 22

Answer Key: D

Feedback: Explanation

a. Incorrect: Abscess formation is a collection of neutrophils (the ???bag of pus???) and is an example of liquefactive necrosis. This can be seen as a consequence of acute inflammation, however a granuloma is described in the question (special type of chronic inflammation).
b. Incorrect: Coagulative Necrosis is a type of necrosis, not chronic inflammation being described.
c. Incorrect: Granulation tissues is seen as a part of healing process, with angiogenesis and inflammation.
d. Correct: this is the description of a granuloma.
e. Incorrect: Serous inflammation is a transudate, this is protein and cell poor fluid.
f. Incorrect: Ulceration is seen on epithelial surfaces as an erosion, often seen in the hospitals or debilitated patients as a result of pressure injury.

Question 23

A 72-year-old diabetic male has a 3-day history of fever and obtundation. Complete blood count reveals leukocytosis; he also shows signs of left foot wet gangrene. Which of the following statements is correct regarding systemic manifestations of this process?

A.Fever is a manifestation of the acute phase response. It is in part mediated by release of cytokines such as IL-6 and TGF-B by leukocytes.
B.Most acute-phase proteins such as C-reactive protein, fibrinogen and serum amyloid A protein are released by the necrotic tissue.
C.Hepcidin binds to and clumps red blood cells causing them to sediment faster than individual red blood cells. This is the basis for the erythrocyte sedimentation rate test.
D.Fibrinogen is another acute phase reactant that reduces the availability of iron. When chronically elevated it is responsible for the anemia associated with chronic inflammation.
E.The leukocytosis is probably associated with a rise of immature neutrophils in blood (shift to the left).

Answer 23

Answer Key: E

Feedback: a. Incorrect. Fever is a manifestation of the acute phase response. It is in part mediated by release of cytokines such as IL-1 and TNF by leukocytes. TGF-B is more involved with repair.

b. Incorrect. Most acute-phase proteins such as C-reactive protein, fibrinogen and serum amyloid A protein are synthesized by the liver.
c. Incorrect. Fibrinogen binds to and clumps red blood cells causing them to sediment faster than individual red blood cells. This is the basis for the erythrocyte sedimentation rate test.
d. Incorrect. Hepcidin is another acute phase reactant that reduces the availability of iron. When chronically elevated it is responsible for the anemia associated with chronic inflammation.
e. Correct. Leukocytosis occurs initially due to accelerated release of marrow postmitotic reserve pool cells; therefore it is associated with a rise of immature neutrophils in blood (shift to the left).

Question 24

The cell whose nucleus is indicated by the arrow is most likely synthesizing (picture 1)

A.Lysozyme B.Collagen C.Triglycerides D.Hemoglobin E.Antibodies

Answer 24

Answer Key: C

Feedback: Correct ans: C. Adipocytes are the cells responsible for the uptake of lipids and conversion to triglycerides for storage.