Lecture 12 - Introduction to Heart

Introduction to Heart

Overview of the heart as a crucial organ in the body.

Heart: Overview

The heart is an organ of the cardiovascular system. Its primary function is to pump blood throughout the body.

Heart Location - Mediastinum

The heart is located in the mediastinum:

  • Central compartment in the thoracic cavity.

  • Positioned between the lungs.

  • Located behind the sternum and in front of the vertebral column.

Clinical Note: CPR Technique

Cardiopulmonary Resuscitation (CPR) is critical if the heart stops. CPR maintains blood flow until further medical help is available. Proper technique includes applying pressure to the sternum. Hands should be positioned on the sternum between T4 and T9 vertebrae. This technique helps squeeze blood out of the heart and circulate it throughout the body.

Heart: Pericardium

Pericardium is a protective sac within the mediastinum. The term combines "peri" (around), "cardi" (heart), and "ium" (object). Surrounds the heart and consists of three layers and one cavity.

Heart: Serous Pericardium Overview

Serous Pericardium produces and reabsorbs pericardial fluid. It is thin and has two layers:

  • Visceral layer: Lines the outer surface of the heart.

  • Parietal layer.

Heart: Visceral Layer of Serous Pericardium

Visceral Layer directly contacts the heart. Also known as the epicardium. It primarily produces pericardial fluid.

Heart: Parietal Layer of Serous Pericardium

Parietal Layer lines the inner wall of the fibrous pericardium. Mainly responsible for reabsorbing pericardial fluid.

Heart: Pericardial Cavity

The Pericardial Cavity is the space between the visceral and parietal layers of the serous pericardium. It is filled with pericardial fluid which reduces friction and allows the heart to move freely.

Heart: Fibrous Pericardium

Fibrous Pericardium is comprised of thick, sturdy connective tissue. It forms the outer layer of the pericardium that secures the heart's position in the thoracic cavity.

Clinical Note: Pericarditis

Pericarditis is inflammation of the pericardium. It can lead to thickening of the pericardium, making it restrictive and affecting heart pump efficiency. Various causes exist, with viral infections being the most common.

Heart Wall Anatomy

The heart wall consists of three layers:

  • Epicardium: Outer protective layer.

  • Myocardium: Muscular middle layer responsible for pumping blood.

  • Endocardium: Thin inner layer lining the heart.

Heart Wall: Overview

Summary of heart wall layers: Endocardium, Myocardium, Epicardium.

Heart Wall: Endocardium

Endocardium is the deepest layer of the heart wall that covers the interior surface and is characterized by non-smooth ridges. Composed mainly of endothelium tissues.

Heart Wall: Myocardium

Myocardium is the heart's muscular layer and acts as the contractile component, responsible for pumping blood.

Clinical Note: Myocarditis

Myocarditis is inflammation of the myocardium, potentially reducing the heart's pumping capability. Symptoms may include chest pain, shortness of breath, and irregular heartbeats. It is often caused by viral infections, and severe cases can compromise blood supply to the body.

Heart Wall: Epicardium

Epicardium is the most superficial layer of the heart wall. Functionally, it is the visceral layer of the pericardium, primarily made of fat and connective tissue.

Atrial Septum and Heart Valves

Structures include: Atrial septum, left mitral valve, right ventricular septum, left ventricle, and right tricuspid valve.

Chambers of Heart: Overview

The heart comprises two atria and two ventricles:

  • Atria: Smaller and positioned superiorly.

  • Ventricles: Larger and located inferiorly.

Chambers of Heart: Right Atrium

Right Atrium receives deoxygenated blood from the body and pumps blood into the right ventricle.

Chambers of Heart: Auricles

Auricles are located on the anterior surface of each atrium. They are wrinkled pouch-like structures resembling a dog's ear that increase atrial capacity.

Chambers of Heart: Right Ventricle

Right Ventricle accepts deoxygenated blood from the right atrium and pumps blood into the lungs for oxygenation.

Chambers of Heart: Left Atrium

Left Atrium receives oxygenated blood from the lungs and pumps blood into the left ventricle.

Chambers of Heart: Left Ventricle

Left Ventricle receives oxygenated blood from the left atrium and pumps blood out of the heart to supply the rest of the body.

Chambers of Heart: Ventricular Myocardium

The left ventricle has a much thicker wall than the right ventricle. The stronger muscle is necessary for pumping blood further under higher pressure.

Chambers of Heart: Interventricular Septum

Interventricular Septum is a thick myocardial wall separating the right and left ventricles. The interventricular groove (sulcus) is visible externally.

Chambers of Heart: Interatrial Septum

Interatrial Septum is a thin layer of tissue that separates the right and left atria, preventing shunting of blood between the atria in adults.

Clinical Note: Patent Foramen Ovale

Patent Foramen Ovale (PFO) is a persistent hole between the left and right atria post-birth. It can lead to mixing of oxygenated and deoxygenated blood, affecting oxygen delivery to the body.

Questions?

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