Circulatory System Part 2

Human Physiology Lecture: The Circulatory System and Heart: Part 2

• The lecture covers the electrical conduction system of the heart and the sequence of cardiac excitation.
• An echocardiogram is used to display the electrical activity of the heart over time.
• The action potential is a brief change in membrane potential, crucial for nerve and muscle function.
• Depolarization: A change from a negative to a positive charge.
• Repolarization: A change from a positive to a negative charge.
• The electrical conduction system, including the SA node, AV node, and bundle branches.
• The sequence of cardiac excitation, showing atrial excitation followed by ventricular excitation and relaxation.
• The cardiac cycle comprises the systole (contraction) and diastole (relaxation) phases, relating to blood flow in the heart.
• Cardiac output (CO) relates to heart rate (HR) and stroke volume (SV).
• The autonomic nervous system regulates heart rate (HR).
• The autonomic nervous system influences the heart.
• Sympathetic and parasympathetic nerves affect the heart.
• Specific receptors in the heart, like muscarinic and beta1 adrenergic receptors, respond to hormones like norepinephrine/epinephrine.
• Factors like venous return, end-diastolic volume (EDV), and afterload, influence stroke volume (SV), a major component of cardiac output (CO).
• Different types of cardiac action potentials (Sino-Atrial Node AP and Ventricular AP).
• The difference between ventricular AP and skeletal muscle AP.
• The relationship between membrane potential changes in the heart and ventricular contraction.
• The concept of preload, afterload, and contractility.
• Measurement of cardiac activity includes HR, SV, and CO.
• The flow of blood through the heart: diastole, systole, and the different pressures involved.
• The concepts of pressure-volume loops to understand the heart's functions, including end-systolic volume (ESV), and end-diastolic volume (EDV).
• Stroke volume (SV) is calculated as the difference between end-diastolic volume (EDV) and end-systolic volume (ESV).
• Cardiac output (CO) is calculated as the product of heart rate (HR) and stroke volume (SV).
• Factors contributing to systemic pressure, including blood volume, venous tone, and the action of the heart and vessels.
• Arterioles' role in regulating blood flow to different organs in response to the body's need.
• Mechanisms to regulate blood flow through the local intrinsic and extrinsic mechanisms (using nerves, hormones, autoregulation).
• Specific components (like arterioles, capillaries, veins) and their function in controlling blood flow and pressure.

Additional Concepts

• Components of the heart (atria, ventricles, valves etc.)
• The role of pacemaker cells in spontaneous heart beat activity
• Mechanisms of blood flow regulation and pressure maintenance, and implications in disease
• Different cardiovascular pressures and their relation to blood movement
• Heart health and possible disease scenarios.

This lecture explores the electrical conduction system of the heart, detailing the sequence of cardiac excitation. It also covers concepts such as action potentials, the cardiac cycle, and the regulation of heart rate by the autonomic nervous system. Ideal for understanding the complexities of cardiovascular physiology.