Anatomy and Function of the Heart

Introduction

• The heart is often associated with emotions but its primary function is as a pump.
• It powers the circulatory system, maintaining pressure to transport blood throughout the body.
• The heart's role is to maintain pressure gradients, facilitating blood flow.

Basic Physiology of the Heart

• Size and Location: About the size of two fists, located in the center of the chest, slightly left.
• Structure: Hollow, cone-shaped, and weighs about 250-350 grams.
• Position: Sits at an angle within the mediastinum cavity.

Heart's Protective Covering

• Pericardium: Double-walled sac encasing the heart.
  • Fibrous Pericardium: Outer layer for protection and structural anchoring.
  • Serous Pericardium: Inner layer with visceral (epicardium) and parietal layers.
  • Lubricated by a film of fluid to reduce friction during heart movement.

Heart Wall Structure

• Epicardium: Outer layer.
• Myocardium: Middle layer, composed of cardiac muscle tissue.
• Endocardium: Innermost thin layer of squamous epithelial tissue.

Heart's Internal Structure

• Chambers: Four chambers - two atria (upper, low pressure) and two ventricles (lower, high pressure).
• Valves: Regulate blood flow direction and prevent backflow.

Blood Flow and Pressure

• Pressure Gradient: High pressure created to pump blood out; low pressure to bring blood back.
• Atria: Receiving chambers for returning blood.
• Ventricles: Discharging chambers, requiring strong walls to pump blood out.

Circulatory Loops

• Pulmonary Circulation: Right ventricle -> Pulmonary arteries -> Lungs -> Pulmonary veins -> Left atrium.
• Systemic Circulation: Left ventricle -> Aorta -> Body -> Vena cava -> Right atrium.

Heart Sounds

• Lub-DUB: Heartbeat sounds caused by valve closures.
  • Lub: Mitral and tricuspid valves closing (ventricular contraction).
  • DUB: Aortic and pulmonary semilunar valves closing (ventricular relaxation).

Blood Pressure

• Systolic Pressure: Pressure during ventricular contraction.
• Diastolic Pressure: Pressure when ventricles relax.
• Measurement: Indicates arterial and ventricular health.

Importance of Blood Pressure

• Essential for maintaining homeostasis and circulation.
• High or low blood pressure can lead to health risks.

Additional Information

• Blood is always red, with varying shades depending on oxygen levels.

Conclusion

• Understanding the heart’s function and structure is crucial to grasping how it supports the body's circulatory needs.
• The episode also highlights the role of blood pressure in heart health.