Pulse of Physiology

Discover the difference between minute ventilation (total air movement) and alveolar ventilation (effective gas exchange) . Learn how dead space reduces efficiency and why deep breaths improve oxygenation more than rapid, shallow breathing .

Explore how the lungs regulate airflow and blood flow to optimize gas exchange. Learn how low alveolar O₂ causes vasoconstriction, high CO₂ triggers bronchodilation, and how mismatches (shunts and dead space) impair oxygenation .

Understand how partial pressure gradients drive oxygen and CO₂ exchange between alveoli and blood. Learn how Fick’s Law explains the role of surface area, diffusion distance, and membrane thickness in efficient gas exchange.

Learn how CO₂ is transported in the blood as bicarbonate (HCO₃⁻), bound to hemoglobin, and dissolved in plasma . Explore the carbonic acid-bicarbonate buffer system, the chloride shift, and how CO₂ regulates blood pH .

Explore how oxygen travels bound to hemoglobin or dissolved in plasma , and how the oxygen-hemoglobin dissociation curve reveals oxygen loading and unloading dynamics. Learn how pH, temperature, and CO₂ levels shift the curve to optimize oxygen delivery.

Break down pulmonary volumes (TV, IRV, ERV, RV) and capacities (IC, FRC, VC, TLC), understanding which can be directly measured and how they help assess lung function in both health and disease.

Discover how Boyle’s Law explains air movement and how factors like compliance, airway resistance, and surfactant affect ventilation. Learn how inspiration is active while expiration is usually passive .

Learn about the four key pulmonary pressures —atmospheric, intra-alveolar, intrapleural, and transpulmonary—and how their changes drive inhalation and exhalation . Understand how negative intrapleural pressure prevents lung collapse.

Understand the primary and secondary functions of the respiratory system , including gas exchange, acid-base balance, and vocalization . This episode breaks down ventilation, pulmonary gas exchange, gas transport, and tissue gas exchange .

Explore the three phases of hemostasis —vascular spasm, platelet plug formation, and coagulation. Learn how fibrin stabilizes the clot and how fibrinolysis dissolves the clot once healing is complete , all while understanding the essential roles of calcium and vitamin K .

Understand ABO and Rh blood groups , how antigens and antibodies determine compatibility, and why O-negative is the universal donor while AB-positive is the universal recipient . Learn about hemolytic disease of the newborn and the importance of Rh factor in pregnancy .

Discover how Boyle’s Law explains air movement and how factors like compliance, airway resistance, and surfactant affect ventilation. Learn how inspiration is active while expiration is usually passive .

Learn how the skeletal muscle and respiratory pumps assist venous return . Discover how muscle contractions propel blood toward the heart and how breathing-induced pressure changes enhance circulation, especially during exercise.

Understand how the baroreflex maintains short-term blood pressure stability. This episode explains how baroreceptors in the carotid sinus and aortic arch detect changes in pressure and adjust heart rate and vessel tone via the autonomic nervous system.

Explore the determinants of blood pressure , including cardiac output, total peripheral resistance, and vessel diameter . Learn how arterioles regulate mean arterial pressure (MAP) and how blood velocity changes across the circulatory system to optimize flow.

Dive into pressure-volume loops , which illustrate ventricular function. This episode explains ventricular filling, isovolumic contraction, ejection, and isovolumic relaxation , along with the effects of preload, afterload, and contractility on stroke volume .

Learn how heart rate and stroke volume determine cardiac output (Qc = HR × SV) . This episode explains cardiac reserve, ejection fraction, and the factors that regulate Qc , emphasizing how the heart adjusts to meet metabolic demands.

Understand the mechanical and pressure changes that occur in each heartbeat. This episode covers systolic and diastolic blood pressure, aortic pressure dynamics, and the differences between right and left ventricular pressures , highlighting the left ventricle’s higher workload.

Explore the Wiggers Diagram , a comprehensive visual of the cardiac cycle. This episode connects ventricular pressure, volume changes, ECG activity, and heart sounds , showing how these factors interact during ventricular filling, isovolumic contraction, ejection, and isovolumic relaxation .

Stroke volume—the amount of blood ejected per beat —is influenced by preload, contractility, and afterload . This episode covers the Frank-Starling Law, inotropic effects, and how afterload affects cardiac output .

Cardiac muscle differs from skeletal muscle due to its autorhythmicity, intercalated discs, and plateau phase . This episode explores calcium’s role in contraction, action potential phases, and why the heart cannot undergo tetanus .

The EKG provides a graphical representation of heart activity . This episode breaks down the P-wave, QRS complex, T-wave, and intervals , helping you understand how electrical signals correlate with heart contraction and rhythm.

Trace the electrical pathway of the heart , from the SA node to the Purkinje fibers . Learn how gap junctions coordinate contraction , how AV node delay optimizes filling time , and how backup pacemakers maintain rhythm if the SA node fails .

Heart rate is influenced by sympathetic and parasympathetic control, chronotropic agents, and venous return . This episode examines how heart rate affects cardiac output and filling time , ensuring the heart meets the body's oxygen demands.

Uncover how cardiac pacemaker cells generate the electrical impulses that drive the heartbeat. This episode explains pacemaker potential drift , the role of the SA and AV nodes , and how the autonomic nervous system regulates heart rate .