Cardiovascular System Overview

Introduction

• Focus on human anatomy and physiology of the cardiovascular system.
• Importance of blood as a vehicle for transporting glucose, gases, etc.

Blood Characteristics

• Human blood is always red, varying from dark red to lighter red based on oxygen levels.
• Educational diagrams use blue and red to indicate oxygen levels for illustration purposes.
• Blood maintains pH, temperature, and osmotic pressure for homeostasis.

Blood Components

• Plasma: Liquid portion containing water, proteins, salts, and lipids.
• Red Blood Cells (RBCs): Transport gases.
• White Blood Cells (WBCs): Fight infections.
• Platelets: Help blood clot.
• Hemoglobin: Iron-rich protein giving blood its red color.

Circulatory Pathways

• Arteries: Carry blood away from the heart. Generally carry oxygen-rich blood.
• Veins: Return blood to the heart. Generally carry oxygen-poor blood.
• Pulmonary Circulation: Pulmonary arteries carry oxygen-poor blood; veins carry oxygen-rich blood.
• Capillaries: Deliver oxygen to tissues and remove carbon dioxide.

Heart Structure

• The heart consists of four chambers: right atrium, right ventricle, left atrium, left ventricle.
• Atria have thinner walls than ventricles.
• Valves act as one-way doors, preventing backflow.

Blood Flow Through the Heart

• Right Atrium -> Tricuspid Valve -> Right Ventricle -> Pulmonary Valve -> Lungs -> Left Atrium -> Mitral Valve -> Left Ventricle -> Aortic Valve -> Aorta.
• Coronary arteries supply heart muscle with oxygenated blood.

Heart's Electrical Conduction System

• SA Node (Sinoatrial): Primary pacemaker, initiates heartbeats.
• Bachman's Bundle: Transmits signals to the left atrium.
• AV Node (Atrioventricular): Delays signal, allowing atria to contract fully.
• Bundle of His: Transmits signals to ventricles.
• Bundle Branches & Purkinje Fibers: Distribute electrical impulses to ventricles.

Heart Defects and Conditions

• Septal Defects: Mixing of oxygen-rich and oxygen-poor blood due to openings in the heart.
• Pacemaker Rates: SA Node (60-100 bpm), AV Node (40-60 bpm), Purkinje Fibers (20-40 bpm).

ECG Basics

• Isoelectric Line: Baseline for electrical activity.
• P-Wave: Atrial depolarization.
• QRS Complex: Ventricular depolarization.
• T-Wave: Ventricular repolarization.
• Atrial repolarization occurs during the QRS complex.

Blood Pressure

• Systolic Pressure: Peak pressure during heart contraction.
• Diastolic Pressure: Pressure when heart is relaxed.
• Normal blood pressure is approximately 120/80.