Cardiac Muscle and Conduction
This ECG wave represents ventricular depolarization and corresponds to ventricular systole.
What is the QRS complex?
These are the final fibers in the conduction system that transmit signals to the ventricular myocardium.
What are the Purkinje fibers?
This structure of fetal circulation allows blood to bypass the lungs and normally closes at birth.
What is the foramen ovale?
This measurement is calculated by multiplying heart rate by stroke volume.
What is cardiac output?
This hormone system promotes retention of sodium, chloride, and water, increasing total plasma volume.
What is the renin-angiotensin-aldosterone system (RAAS)?
This phase of the cardiac action potential is characterized by slow calcium influx and reduced potassium efflux, allowing for prolonged contraction.
What is Phase 2 (plateau phase)?
This ECG abnormality, often caused by hyperkalemia.
What is a peaked T wave?
These six structures form the functional unit of the mitral and tricuspid valves, and damage to any of them can result in heart failure.
What are the atria, fibrous rings, valvular tissue, chordae tendineae, papillary muscles, and ventricular walls?
This law explains how increased preload enhances ventricular contraction strength up to a physiological limit.
What is the Frank-Starling Law?
This is the primary hormone responsible for vasodilation and blood volume reduction.
What is atrial natriuretic peptide (ANP)?
This struct enables ion flow between myocardial cells and allows them to contract as functional syncytium.
What are intercalated discs?
This molecule must bind to myosin to release it from actin and restart the contraction cycle.
What is ATP?
This component of the fibrous skeleton anchors heart valves and provides structural support for musculature.
What are the annuli fibrosis cordis?
This formula calculates wall tension in the ventricle and helps explain the impact of ventricular dilation on stress.
What is Laplace’s Law: (Pressure × Radius) / (2 × Wall Thickness)?
A 54-year-old man experiences hemorrhagic shock after a traumatic injury. His blood pressure drops to 75/45 mmHg. Name TWO hormones that act to preserve blood volume in this scenario.
What are antidiuretic hormone (ADH) and aldosterone?
A 24-year-old runner faints after a long-distance race. His ECG shows prolonged Phase 2 of the ventricular action potential. This ion is primarily responsible for that plateau.
What is calcium (Ca²⁺)?
A healthy 30-year-old woman has a P-R interval of 0.24 seconds. Though asymptomatic, this ECG finding indicates a delay in conduction at this location.
What is the AV node?
Following aortic and pulmonary valve closure, this phase of the cardiac cycle begins, allowing passive ventricular filling once pressure in the atria exceeds that in the ventricles.
What is diastole?
An echocardiogram reveals an EDV of 130 mL and stroke volume of 78 mL.
What is an ejection fraction of 60%?
A woman develops tortuous, distended superficial leg veins postpartum. What pathology, often associated with pregnancy, is most likely?
What are varicose veins?
A 58-year-old man with heart failure is given a positive inotropic drug. It enhances calcium-induced calcium release by binding to this receptor in the sarcoplasmic reticulum.
What is the ryanodine receptor?
A patient develops arrhythmia due to disruption in the intercalated disks. These specific structures within the disks allow for electrical synchronization.
What are gap junctions?
You hear a holosystolic murmur at the apex. The abnormal sound is best heard at this auscultation site, downstream from a valve supported by chordae tendineae and papillary muscles.
What is the 5th intercostal space, midclavicular line (mitral valve area)?
A 70-year-old hypertensive patient has preserved ejection fraction at rest but decreased ejection fraction during stress testing.
What is exercise-induced reduced ejection fraction due to impaired contractility and increased afterload?
A patient with aortic stenosis has reduced coronary perfusion pressure. Coronary flow is most compromised during this phase of the cardiac cycle.
What is systole?