the action potential of cells


Question 1

Which of the following statements describes phase 4 of the action potential of cells in the sinoatrial (SA) node?


A. Potassium permeability is allowing the cell membrane to remain depolarized, and Ca2+ channel opens moving Ca2+ back into the cell.

B. The cells are capable of responding to a greater than normal stimulus before the resting membrane potential is reached.

C. A slow depolarization occurs when Na+ is transported out of the cell and K+ moves back in, resulting in resting membrane potential.

D. The fast sodium channels in the cellular membranes close, causing an abrupt decrease in intracellular positivity.

Question 2

A 31-year-old woman with a congenital heart defect reports episodes of light-headedness and syncope, with occasional palpitations. A resting electrocardiogram reveals sinus bradycardia, and she is suspected to have sick sinus syndrome. Which of the following diagnostic methods is the best choice to investigate the suspicion?


A. Signal-averaged ECG

B. Holter monitoring

C. Electrophysiologic study

D. Exercise stress testing

Question 3

A patient has been diagnosed with anemia. The physician suspects an immune hemolytic anemia and orders a Coombs test. The patient asks the nurse what this test will tell the doctor. The nurse replies,


A. “They are looking for the presence of antibody or complement on the surface of the RBC.”

B. “They will wash your RBCs and then mix the cells with a reagent to see if they clump together.”

C. “They will look at your RBCs under a microscope to see if they have an irregular shape (poikilocytosis).”

D. “They will be looking to see if you have enough ferritin in your blood.”

Question 4

Of the following list of patients, who would likely benefit the most from hyperbaric oxygen therapy?


A. A football player who has torn a meniscus in his knee for the third time this year

B. A patient who developed a fistula between her bowel and vagina following cervical cancer surgery

C. A school-aged child who fell on gravel and has terrible road rash

D. A trauma patient who developed Clostridium spp., an anaerobic bacterial infection in his femur

Question 5

A 71-year-old male patient with a history of myocardial infarction (MI) and peripheral vascular disease (PVD) has been advised by his family physician to begin taking 81 mg aspirin once daily. Which of the following statements best captures an aspect of the underlying rationale for the physician’s suggestion?


A. Aspirin inhibits the conversion of fibrinogen into fibrin and consequent platelet plug formation.

B. Platelet aggregation can be precluded through inhibition of prostaglandin production by aspirin.

C. Aspirin can reduce unwanted platelet adhesion by inhibiting TXA2 synthesis.

D. Aspirin helps to inhibit ADP action and minimizes platelet plug formation.

Question 6

Which of the following assessments and laboratory findings would be most closely associated with acute leukemia?


A. Increased serum potassium and sodium levels

B. Increased blood urea nitrogen and bone pain

C. High blast cell counts and fever

D. Decreased oxygen partial pressure and weight loss

Question 7

A 55-year-old male who is beginning to take a statin drug for his hypercholesterolemia is discussing cholesterol and its role in health and illness with his physician. Which of the following aspects of hyperlipidemia would the physician most likely take into account when teaching the patient?