Cardiovascular

Cardiac System Notes

Main Root Word: Cardio (Greek: kardia = heart), Vascular = vessels

Tissues and Circulatory Systems:

  • Systemic Circuit: The systemic circuit is responsible for delivering oxygenated blood from the heart to the body, ensuring that all tissues receive the necessary nutrients and oxygen for metabolism.

  • Pulmonary Circuit: This circuit transports deoxygenated blood from the heart to the lungs for oxygenation and returns oxygen-rich blood back to the heart.

Delivery Mechanism:

  • The heart pumps blood through an extensive network of blood vessels, ensuring efficient delivery of nutrients, oxygen, and hormones to various body tissues.

  • It also plays a crucial role in the removal of metabolic wastes, including carbon dioxide, heat, and other byproducts from cellular metabolism.

Veins:

  • These blood vessels return blood to the heart. They can carry either oxygen-rich or oxygen-poor blood, depending on their location. For instance, pulmonary veins are oxygen-rich, while systemic veins generally carry deoxygenated blood.

Arteries:

  • Arteries carry blood away from the heart, and similar to veins, they may also transport either oxygen-rich or oxygen-poor blood. The aorta, for example, carries oxygen-rich blood from the left ventricle to the body, while the pulmonary arteries carry deoxygenated blood to the lungs.

Heart Anatomy:

  • Apex: The apex of the heart lies to the left of the midline and is situated in an oblique position. It weighs approximately 300 grams and is positioned in the mediastinum between the lungs.

Chambers of the Heart:

  • The heart comprises four primary chambers:

    • Right Atrium: Receives deoxygenated blood from the body through the superior and inferior vena cavae.

    • Right Ventricle: Pumps deoxygenated blood to the lungs via the pulmonary artery.

    • Left Atrium: Receives oxygenated blood from the lungs through the pulmonary veins.

    • Left Ventricle: Pumps oxygenated blood to the body through the aorta.

  • The base of the heart refers to the top portion, which is the widest part, while the apex represents the pointed bottom.

Layers of the Heart:

  • Epicardium: The outer layer, made up of epithelial tissue and fat, which houses the major coronary blood vessels.

  • Myocardium: The thick muscular middle layer composed of cardiac muscle tissue, responsible for the pumping action of the heart.

  • Endocardium: The innermost layer made of epithelial tissue that lines the heart chambers and covers the heart valves, providing a smooth surface for blood flow.

Protective Structures:

  • Pericardium: A double-walled sac that protects the heart and lungs from friction. It also provides a barrier against infections that may stem from the lungs, including bronchitis, COVID-19, and pneumonia.

  • Pericardial Sac: Contains the heart within a protective shell.

  • Pericardial Cavity: The fluid-filled space that reduces friction as the heart beats.

  • Fibrous Layer: The outer wall of the pericardium, providing additional protection and structure.

  • Serous Layer: The inner layer that produces serous fluid to lubricate the heart.

  • Epicardium: Comes from the serous layer and forms the outer layer of the heart wall.

Potential Complications:

  • Pericardial Effusion: Refers to an accumulation of excess fluid in the pericardial cavity, which can lead to a variety of symptoms, such as:

    • Trouble breathing (dyspnea)

    • Chest pain (angina)

    • A feeling of fullness in the chest

    • Lightheadedness or fainting

    • Swelling in the abdomen and extremities (legs)

Walls and Valves of the Heart:

  • Interatrial Septum: The wall that separates the left and right atriums to prevent mixing of oxygenated and deoxygenated blood.

  • Interventricular Septum: The wall that separates the left and right ventricles, critical for maintaining proper pressure and flow dynamics.

  • Heart Valves: Ensure unidirectional blood flow through the heart:

    • Atrioventricular (AV) Valves:

      • Right Tricuspid Valve: Composed of three flap-like structures that prevent backflow of blood into the right atrium.

      • Left Bicuspid Valve (Mitral Valve): Comprising two flaps that prevent backflow into the left atrium.

    • Tendinous Cords: Connect the valve cusps to papillary muscles, ensuring proper valve closure during ventricular contraction.

    • Pulmonary Valve: The first semilunar valve located between the right ventricle and the pulmonary trunk, preventing backflow into the ventricle.

    • Aortic Valve: The second semilunar valve positioned between the left ventricle and the aorta to prevent backflow into the ventricle.