Cardiovascular Physiology: A Cheat Sheet

This cheat sheet covers the fundamental aspects of cardiovascular physiology, including heart structure, electrical conduction, muscle contraction, blood flow dynamics, and common conditions like heart failure.

Core Principles

• The heart is a four-chambered pump with distinct pulmonary and systemic circuits.
• Blood vessels include arteries, capillaries, and veins, forming a closed circulation system.
• Cardiovascular function relies on critical variables: pressure, volume, contractility, and compliance.
• Blood flows down a pressure gradient, highest at the heart and decreasing distally.
• Cardiac muscle cells are autorhythmic, interconnected by intercalated discs (desmosomes and gap junctions), and possess numerous mitochondria.
• Cardiac muscle contraction is initiated by electrical signals, involves calcium influx, and is modulated by the autonomic nervous system.
• Heart failure can be left-sided or right-sided, with distinct causes and symptoms.
• Various medical devices and interventions, such as pacemakers, defibrillators, and heart transplantation, are used to manage cardiovascular conditions.

Action Steps

• Understand the structure and function of the four heart chambers and their associated circuits.
• Differentiate between arteries, capillaries, and veins and their roles in circulation.
• Identify the key variables influencing cardiovascular function: pressure, volume, contractility, and compliance.
• Trace the path of electrical conduction through the heart, from the SA node to the Purkinje fibers.
• Describe the process of cardiac muscle excitation, contraction, and relaxation, including the role of calcium.
• Distinguish between left-sided and right-sided heart failure, including their causes and symptoms.
• Recognize the indications and types of electrical heart devices and interventions.

Formulas

• $Flow~velocity~(v) = \frac{Rate~(Q)}{Cross-sectional~area~(A)}$
• $MAP = \frac{(Diastolic~BP) + 2(Systolic~BP)}{3}$

Key Terms

• Cardiovascular System: The system comprising the heart and blood vessels, responsible for circulating blood throughout the body.
• Systolic Heart Failure: Heart failure characterized by a reduced ejection fraction (EF), where the heart cannot pump blood effectively.
• Diastolic Heart Failure: Heart failure characterized by preserved ejection fraction but impaired ventricular filling due to stiffening of the heart muscle.
• Intercalated Discs: Specialized junctions between cardiac muscle cells that contain desmosomes and gap junctions, facilitating electrical and mechanical coupling.
• SA Node: Sinoatrial node, the primary pacemaker of the heart, initiating the electrical impulse for contraction.
• AV Node: Atrioventricular node, which delays the electrical impulse before it travels to the ventricles, allowing atrial contraction to complete.
• Cardiac Output (CO): The volume of blood pumped by the heart per minute.
• Systemic Vascular Resistance (SVR): The resistance to blood flow in the systemic circulation.
• Vasopressors: Drugs that cause blood vessels to constrict, increasing blood pressure.

Timeline

• 1982-1987: Heart transplantation survival: 7.7-year half-life.
• 1988-1992: Heart transplantation survival: 9.3-year half-life.
• 1993-1997: Heart transplantation survival: 9.1-year half-life.
• 1991: 3.5 million heart failure patients in the US.
• 2000: 4.7 million heart failure patients in the US.
• 2001: 4.8 million heart failure patients in the US.
• 2003-2004: Publication of relevant cardiovascular physiology material.
• 2014: Circulation publication on cardiovascular mortality.
• 2016: JACC publication on artificial heart valves.
• 2037 (estimated): Estimated 10 million heart failure patients in the US.

People

• Dee Unglaub Silverthorn, Ph.D.: Author of 'Human Physiology: An Integrated Approach'
• Dr. Howard D. Booth: Creator of the PowerPoint® Lecture Slide Presentation