Cardiovascular System Basics

Cardiovascular System

• The cardiovascular system consists of the heart, blood vessels, and blood.
• It performs three main functions: transport, protection, and regulation.

Heart Anatomy

• The heart is located in the mediastinum, a median cavity in the thorax.
• The mediastinum is divided into superior and inferior parts at the level of the sternal angle.
• The inferior mediastinum is further subdivided into anterior, middle, and posterior parts.
• The heart is enclosed within the middle mediastinum, which contains the pericardium, root of great vessels, and heart and lungs.
• The heart extends obliquely from the 3rd rib to the 5th intercostal space, anterior to the thoracic vertebrae, and posterior to the sternum.
• It is bordered by the 2 lungs and rests on the diaphragm.
• Two-thirds of its mass lies to the left of the midsternal line.

The Pericardium

• The pericardium is a fibroserous membrane that covers the heart and the root of great vessels.
• It is a double-walled closed sac that contains a film of lubricating serous fluid.
• The pericardium consists of two parts: fibrous pericardium and serous pericardium.
• The fibrous pericardium is a tough, outer dense connective tissue that protects the heart, anchors it to surrounding structures, and prevents overfilling.
• The serous pericardium is a one continuous sheet with two layers: parietal layer (lines the internal surface of the fibrous pericardium) and visceral layer (epicardium, covers the external heart surface).

Gross Features of Heart

• The heart has two atrias (superior) that are thin-walled receiving chambers.
• Each atrium has a small, protruding appendage called auricles, which increase atrial volume.
• The interatrial septum divides the left and right atria.
• The right atrium has muscle bundles called pectinate muscles in its wall, and receives blood from the superior vena cava, inferior vena cava, and coronary sinus.
• The left atrium has a smooth internal anterior and posterior wall, and receives blood from four pulmonary veins (oxygenated blood).