Cardiovascular Physiology: A Cheat Sheet

This cheat sheet covers the fundamental aspects of cardiovascular physiology, including heart structure, function, electrical activity, blood flow, and common pathologies like heart failure.

Core Principles

• The heart is a four-chambered pump responsible for circulating blood throughout the body via pulmonary and systemic circuits.
• Blood vessels, including arteries, capillaries, and veins, form a closed circulatory system.
• Blood flow is driven by pressure gradients and influenced by resistance, vessel diameter, blood viscosity, and tube length.
• Cardiac muscle cells are autorhythmic, interconnected by intercalated discs (desmosomes and gap junctions), and possess unique contractile properties.
• The electrical activity of the heart, initiated by the SA node, coordinates the cardiac cycle, which can be visualized through ECGs.
• Heart rate and stroke volume are critical determinants of cardiac output, regulated by nervous and hormonal systems.
• Various factors, including preload, afterload, and contractility, influence stroke volume and the pressure-volume relationship of the ventricles.
• Cardiovascular diseases, such as heart failure and myocardial infarction, disrupt normal heart function and can be diagnosed through various clinical tools and markers.

Action Steps

• Understand the structure and function of the heart chambers and valves.
• Trace the path of blood through the pulmonary and systemic circuits.
• Identify the key electrical components of the heart's conduction system.
• Recognize the components of an ECG waveform (P wave, QRS complex, T wave) and their significance.
• Differentiate between left-sided and right-sided heart failure symptoms.
• List common causes and risk factors for heart failure and cardiovascular disease.
• Explain the concept of pressure-volume loops and how they represent the cardiac cycle.
• Describe the factors that regulate heart rate and stroke volume.

Formulas

• Flow velocity (v) = Rate (Q) / Cross-sectional area (A)
• Cardiac Output = Heart Rate × Stroke Volume
• Stroke Volume (SV) = End-Diastolic Volume (EDV) - End-Systolic Volume (ESV)

Key Terms

• Cardiac Output: The volume of blood pumped by the heart per minute.
• Stroke Volume: The volume of blood pumped by the left ventricle per contraction.
• Preload: The stretch of the cardiac muscle fibers at the end of diastole, determined by ventricular filling.
• Afterload: The resistance the heart must overcome to eject blood into the arteries.
• Contractility: The intrinsic ability of the cardiac muscle to contract, independent of preload and afterload.
• ECG: Electrocardiogram; a recording of the electrical activity of the heart.
• Heart Failure: A condition in which the heart cannot pump enough blood to meet the body's needs.
• Myocardial Infarction: Heart attack; occurs when blood flow to a part of the heart muscle is blocked.

Timeline

• 1887: First ECG measurements by Augustus Waller using a capillary electrometer.
• Circa 1900s: Development and refinement of ECG technology and interpretation.
• Mid-20th Century: Advancements in understanding cardiac muscle physiology, electrical conduction, and the cardiac cycle.
• Late 20th Century: Development of artificial heart valves and ventricular assist devices.
• Early 21st Century: Continued research into cardiovascular diseases, treatments, and diagnostic tools like advanced ECG analysis and biomarkers.

People

• Dee Unglaub Silverthorn: Author of 'Human Physiology: An Integrated Approach'
• Augustus Waller: Pioneer in electrocardiography
• Dr. Howard D. Booth: Creator of the PowerPoint® Lecture Slide Presentation