Conceptual cardiovascular, respiratory, endocrine, GI, and muscle physiology mechanisms tested on USMLE Step 1, separate from the equations cloze deck.
39 cards · basic cards · AI-written, checked twice. Edit anything.
- What mechanism describes increased venous return leading to increased stroke volume?
- The Frank-Starling mechanism
- What is the physiological basis of the Frank-Starling mechanism?
- Increased sarcomere stretch increases actin-myosin cross-bridge formation
- Where are arterial baroreceptors located?
- Carotid sinus and aortic arch
- How does the baroreceptor reflex respond to a sudden rise in blood pressure?
- Increased parasympathetic and decreased sympathetic output, lowering heart rate and blood pressure
- What effect does vagal (parasympathetic) stimulation have on the SA node?
- It decreases heart rate (negative chronotropy)
- Which part of the cardiac conduction system has the fastest conduction velocity?
- Purkinje fibers
- During which phase of the ventricular cardiac action potential does calcium influx sustain depolarization?
- Phase 2, the plateau phase
- When during the cardiac cycle does most left ventricular coronary perfusion occur?
- During diastole
- What causes the oxygen-hemoglobin dissociation curve to shift right?
- Increased CO2, increased H+ (decreased pH), increased temperature, and increased 2,3-BPG
- What is the Bohr effect?
- Increased CO2 and H+ decrease hemoglobin's affinity for oxygen, promoting oxygen unloading at tissues
- What is the Haldane effect?
- Oxygenation of hemoglobin in the lungs promotes release of CO2
- What is hypoxic pulmonary vasoconstriction?
- Local vasoconstriction in poorly ventilated lung regions that redirects blood flow to better-ventilated areas
- What do central chemoreceptors in the medulla primarily respond to?
- Changes in CSF pH caused by CO2 diffusing across the blood-brain barrier
- Where are peripheral chemoreceptors located?
- Carotid bodies and aortic bodies
- What do peripheral chemoreceptors primarily detect?
- A significant drop in arterial PaO2