Practice Test GeeksNBME Practice Test
← All NBME Flashcard Decks

Physiology Flashcards

7 cards from real NBME practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Physiology flashcards as text

  1. During the relative refractory period of a neuronal action potential, what stimulus is required to trigger another action potential?

    Answer: A suprathreshold (stronger-than-normal) stimulus

    During the relative refractory period, some K+ channels remain open, raising the threshold so only a suprathreshold stimulus can trigger another action potential.

  2. Schwann cells in the peripheral nervous system primarily function to:

    Answer: Myelinate peripheral axons to increase conduction velocity

    Schwann cells wrap peripheral axons in myelin sheaths, enabling saltatory conduction and dramatically increasing action potential propagation speed.

  3. A patient presents with hypocalcemia and spontaneous muscle tetany. Deficiency of which hormone is most likely responsible?

    Answer: Parathyroid hormone (PTH)

    PTH deficiency (hypoparathyroidism) reduces calcium reabsorption from bone and kidney, causing hypocalcemia and neuromuscular excitability.

  4. Which of the following is a major metabolic effect of cortisol?

    Answer: Increases gluconeogenesis in the liver

    Cortisol stimulates hepatic gluconeogenesis, promotes muscle protein catabolism, and enhances lipolysis, all serving to raise blood glucose during stress.

  5. Insulin promotes glucose uptake into skeletal muscle primarily by stimulating translocation of:

    Answer: GLUT4

    Insulin activates PI3K/Akt signaling, causing GLUT4 vesicles to translocate to the plasma membrane of muscle and adipose cells.

  6. During the cross-bridge cycle, what event directly produces the power stroke in skeletal muscle?

    Answer: Release of ADP and inorganic phosphate from myosin after actin binding

    After myosin (in the cocked, ADP+Pi-bound state) binds actin, release of ADP and Pi triggers the power stroke, pulling actin toward the M-line.

  7. Ligand binding to a Gs-protein coupled receptor primarily leads to:

    Answer: Activation of adenylyl cyclase and increased intracellular cAMP

    Gs-coupled receptors activate adenylyl cyclase via the Gαs subunit, increasing cAMP and activating protein kinase A.