Pulse of Physiology

Explains the stages of labor and the hormonal regulation of childbirth and breastfeeding. Discusses the role of oxytocin and prostaglandins in labor, and prolactin and oxytocin in milk production and ejection.

Follows the journey from sperm-egg fusion through blastocyst formation and implantation. Highlights the role of hCG, the formation of the placenta, and key hormones like progesterone, estrogen, and hCG in sustaining pregnancy.

Covers the menstrual, proliferative, and secretory phases of the uterine cycle. Describes how estrogen and progesterone prepare the endometrium for implantation and how their withdrawal leads to menstruation when pregnancy does not occur.

Explores the development and maturation of ovarian follicles through the follicular and luteal phases. Emphasizes the roles of FSH, LH, estrogen, progesterone, and inhibin, and explains how hormonal feedback regulates ovulation and corpus luteum function.

Details the process of sperm development, distinguishing between spermatogenesis and spermiogenesis. Explains the roles of Sertoli and Leydig cells and describes how FSH, LH, testosterone, and inhibin regulate sperm production through hormonal feedback loops.

Provides an introduction to the male and female reproductive systems, outlines homologous structures, and summarizes the functions of key reproductive hormones, including GnRH, FSH, LH, testosterone, estrogen, progesterone, and inhibin.

Focuses on how the enteric nervous system (ENS), autonomic input, and digestive hormones like gastrin, secretin, and CCK regulate motility and secretion during the cephalic, gastric, and intestinal phases of digestion.

Breaks down the chemical digestion of carbohydrates, proteins, and fats. Introduces digestive enzymes and their sources, the role of hydrochloric acid, and how bile salts aid fat digestion. Wraps up with the role of the gut microbiome in digestion and health.

Explores how food moves through the GI tract using peristalsis, segmentation, mixing waves, and mass movement. Discusses how factors like chyme composition and volume influence gastric emptying, and how neural and hormonal signals regulate motility.

Covers the six major functions of the digestive system—ingestion, propulsion, mechanical digestion, chemical digestion, absorption, and defecation. Differentiates between GI tract structures and accessory organs, and explains how food is broken down and moved through the digestive system.

Apply your knowledge to diagnose and interpret acid-base imbalances using arterial blood gas (ABG) values. Differentiate between respiratory and metabolic acidosis or alkalosis, and determine whether compensation has occurred.

Understand how the respiratory and urinary systems compensate for acid-base disturbances. Learn how the body responds to respiratory or metabolic acidosis and alkalosis, and the time course of each compensatory mechanism.

Learn the basics of pH regulation, including the roles of acids, bases, and buffers. Get introduced to the bicarbonate, phosphate, and protein buffer systems, and why maintaining a stable pH is essential for enzyme and cell function.

Discover how the cardiovascular, endocrine, and urinary systems respond to dehydration or hemorrhage to restore blood volume and pressure. Compare how the body responds to osmolar vs. isotonic disturbances.

Explore how aldosterone regulates potassium levels and how parathyroid hormone (PTH) maintains calcium balance. Learn the causes and effects of hyperkalemia, hypokalemia, hypercalcemia, and hypocalcemia, and why they matter for muscle and nerve function.

Understand how the body regulates osmolarity through osmoreceptors, ADH release, and thirst mechanisms. Explore how water gain and loss affect osmolarity and how the body restores balance during dehydration or fluid overload.

Break down how total body water is distributed between the intracellular fluid (ICF) and extracellular fluid (ECF) compartments. Learn about solute concentrations, fluid movement, and the importance of maintaining fluid balance for homeostasis.

Explore how the sympathetic nervous system, RAAS, ADH, and natriuretic peptides regulate GFR in response to systemic blood pressure and volume changes, ensuring whole-body fluid and pressure homeostasis.

Understand how the kidneys regulate their own filtration rate using the myogenic mechanism and tubuloglomerular feedback, maintaining stable GFR despite changes in blood pressure.

Learn how GFR is calculated using Starling forces, how arteriole diameter affects filtration, and why GFR is a key measure of kidney function and fluid balance.

Discover how different parts of the nephron contribute to urine formation and how osmolarity changes throughout. Learn how countercurrent mechanisms create and preserve the medullary concentration gradient.

Review the major functions of the urinary system, including waste excretion, fluid and electrolyte balance, and blood pressure regulation. Understand the differences between plasma, filtrate, and urine, and the processes of filtration, reabsorption, secretion, and excretion.

Explore how hydrostatic and oncotic pressures regulate capillary exchange. Learn how net filtration pressure (NFP) drives fluid in or out of capillaries and how the lymphatic system prevents edema by returning excess fluid to circulation.

Understand how local control mechanisms adjust blood flow to match tissue demand. Explore metabolic and myogenic responses, precapillary sphincters, and the balance between vasodilation and vasoconstriction in maintaining perfusion.

Learn how central and peripheral chemoreceptors regulate breathing in response to CO₂, O₂, and pH levels. Understand how hyperventilation affects breath-holding time and why neural input anticipates respiratory changes during exercise.

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 intopressure-volume loops, which illustrate ventricular function. This episode explainsventricular filling, isovolumic contraction, ejection, and isovolumic relaxation, along with the effects ofpreload, afterload, and contractility on stroke volume.

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

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

Explore theWiggers Diagram, a comprehensive visual of the cardiac cycle. This episode connectsventricular pressure, volume changes, ECG activity, and heart sounds, showing how these factors interact duringventricular 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.