Cardiovascular System 2 - Anatomy of the Heart, Fetal Circulation, Pulmonary and Systemic Circulation

Cardiovascular System Overview

  • Focus on the anatomy of the heart, fetal blood circulation, pulmonary and systemic circuits.

Anatomy of the Heart

Key Structures

  • Brachiocephalic trunk

  • Left common carotid artery

  • Left subclavian artery

  • Ligamentum arteriosum

  • Pulmonary trunk

  • Right pulmonary arteries

  • Ascending aorta

  • Right atrium features:

    • Pectinate muscles

    • Conus arteriosus

    • Tricuspid valve

    • Chordae tendineae

  • Right ventricle features:

    • Pulmonary valve

    • Inferior vena cava

  • Left atrium features:

    • Aortic valve

    • Mitral valve

    • Pulmonary veins

  • Left ventricle features:

    • Thick wall for high pressure blood pumping

Heart Location

  • Near anterior chest wall, posterior to sternum.

  • Base lies at the 3rd costal cartilage, apex reaches the 5th intercostal space.

Structural Characteristics

  • Surrounded by pericardial sac, measures about 12.5 cm from base to apex, weighs 250-350 grams.

Heart Wall Structure

  • Epicardium: covers the heart, consists of mesothelium and connective tissue.

  • Myocardium: cardiac muscle layer with blood vessels and nerves.

  • Endocardium: lines heart chambers and valves, consists of simple squamous epithelium.

Circuits of Blood Flow

Pulmonary Circuit

  • Carries deoxygenated blood from the right side of the heart to the lungs for oxygenation.

Systemic Circuit

  • Conducts oxygenated blood from the left side of the heart to the rest of the body.

Fetal Circulation

  • Foramen Ovale: allows blood to bypass the lungs.

  • Ductus Arteriosus: connects pulmonary trunk to descending aorta, closes at birth to form ligamentum arteriosum.

Major Blood Vessels

Great Vessels

  • Aorta: carries blood from the left ventricle.

  • Superior and Inferior Vena Cavae: return deoxygenated blood to the right atrium.

  • Pulmonary arteries and veins transport blood to and from the lungs.

Heart Valves

Types of Valves

  • Atrioventricular Valves: prevent backflow from ventricles to atria (Tricuspid and Mitral valves).

  • Semilunar Valves: prevent backflow from great vessels to ventricles (Pulmonary and Aortic valves).

Valve Function

  • Valves open and close in response to pressure changes during heart contractions and relaxations.

Coronary Circulation

  • Supplies blood to heart itself via coronary arteries originating from the aorta.

  • Right Coronary Artery: serves the right atrium and parts of the ventricles.

  • Left Coronary Artery: supplies the left atrium, left ventricle, and interventricular septum.

Cardiac Veins

  • Great Cardiac Vein drains blood from the anterior interventricular region and empties into the coronary sinus.

  • Posterior cardiac vein and Middle cardiac vein drain areas supplied by posterior and middle coronary arteries respectively.

Structure of Blood Vessels

Types of Blood Vessels

  1. Arteries: carry blood away from the heart; thick, muscular walls for pressure.

  2. Veins: carry blood to the heart; thinner walls with valves to prevent backflow.

  3. Capillaries: smallest, where exchange between blood and tissues occurs.

Layers of Vessels

  • Tunica Interna: inner lining, facilitates smooth blood flow.

  • Tunica Media: muscular layer for regulating vessel diameter.

  • Tunica Externa: outer protective layer.

Portal Circulation

Hepatic Portal System

  • Connects capillary beds of digestive organs to the liver for processing and detoxification.