Cardiovascular System Anatomy Practical [PHL 212]

The Cardiovascular System  A closed system of the heart and blood vessels The heart pumps blood Blood vessels allow blood to circulate to all parts of the body a.Pulmonary circuit—flow of blood through the lungs.  Pulmonary arteries—carry O 2 -poor blood from right ventricle to the lungs.  Pulmonary veins—carry O 2 -rich blood from lungs to the left atrium. b.Systemic circuit—flow of blood through the rest of the body.  Aorta—carries O 2 -rich blood to all body tissues.  Vena cava—returns O 2 -poor blood to the right atrium.  The function of the cardiovascular system is to deliver oxygen and nutrients and to remove carbon dioxide and other waste products

The Heart: Size & Location  The heart is a hollow, cone-shaped, muscular pump  Nine (9) inches long x three (3) inches wide.  Located in the centre of Thorax between the lungs posteriorly by the backbone, and anteriorly by the sternum & resting upon the diaphragm.  Base--attached to several large blood vessels and lies beneath the second rib.  Pointed apex at the fifth intercostal space directed toward left

Location of Heart in thorax

The Heart: Coverings  The heart and the proximal ends of the large blood vessels are enclosed by the pericardium.  Consists of an outer fibrous pericardium which surrounds a more delicate double-layered sac.  Inner layer of this sac--visceral pericardium (epicardium) covers the heart.  At the base of the heart the visceral pericardium turns back on itself to become the parietal pericardium.  Between the parietal and visceral layers is the pericardial cavity which contains serous fluid-- pericardial fluid.

The Heart: Heart Wall  Three layers  Epicardium (Outer layer)  consists of connective tissue covered by epithelium  Functions as an outer protective layer  Myocardium (Middle layer)  Relatively thick  Consists largely of cardiac muscle tissue responsible for forcing blood out of the heart chambers  Pumps 70 ml blood with each contraction  Endocardium (Inner layer)  Relatively thin sheet consists of epithelial and connective tissue that contains many elastic and collagenous fibers.  Lines all of the heart chambers and covers heart valves

Heart Wall

The Heart: Associated Great Vessels  Aorta  Leaves left ventricle  Pulmonary arteries  Leave right ventricle  Vena cava  Enters right atrium  Pulmonary veins  Enter left atrium

External Heart Anatomy

The Heart: Chambers  Four chambers  The Atrium  Upper two chambers  Divided into the Left Atria and the Right Atria  Brings in Blood from the Veins  Receiving chambers  Ventricles  Lower two chambers  Divided into Left Ventricle and Right Ventricle  Pumps in Blood into the arteries  Discharging chambers

The Heart: Valves  Allow blood to flow only in one direction  Four valves  Atrioventricular valves – between atria and ventricles  Bicuspid or Mitral valve (left)  Tricuspid valve (right)  Semilunar valves between ventricle and artery  Pulmonary semilunar valve  Aortic semilunar valve

Right Heart Chambers Right Heart Chambers Right Atrium –Receives O 2 -poor blood from body via Superior and Inferior vena cava Right Ventricle –Receives O 2 -poor blood from right atrium through tricuspid valve –Pumps blood to lungs via Pulmonary Semilunar Valve in pulmonary trunk Left Heart Chambers Left Atrium –Receives O 2 -rich blood from lungs via 4 Pulmonary Veins Left Ventricle (forms apex of heart) –Receives blood from Left Atrium via bicuspid valve (Mitral valve ) –Pumps blood into aorta via Aortic Semilunar Valve to body

Heart Chambers and Valves

Blood Circulation

Two circulatory paths Pulmonary Systemic

Walls of Arteries and Veins Tunica externa –Outermost layer –Connective tissue with varying quantities of elastic fibers and collagen fibers Tunica media –Middle layer –Circular Smooth Muscle –Vaso-constriction/dilation Tunica intima –Innermost layer –Simple squamous epithelium (endothelium). –Minimize friction Lumen

Differences Between Artery & Vein ArteriesVeins Direction of flow Blood Away from HeartBlood to Heart Walls THICKER: Tunica media thicker than tunica externa THINNER: Tunica externa thicker than tunica media Lumen SmallerLarger Pressure HigherLower Valves No valvesValves

1. Blood transported by the pulmonary veins returns to the left atrium. right atrium. right ventricle. left ventricle. 2. The valve between the left ventricle and the blood vessel leaving the left ventricle is the bicuspid valve. tricuspid valve. pulmonary semilunar valve. aortic semilunar valve. 3. The valve located between the right atrium and the right ventricle is the tricuspid valve. bicuspid valve. mitral valve. semilunar valve.