Anatomy ? Physiology II Chapter 15, Section 1 The Cardiovascular System
The heart is a remarkable organ It pumps 7000L (1800 gallons) of blood through our body every day
The heart contracts 2.5 billion times in a lifetime
The heart contains two pumps The pulmonary circuit carries blood to the lungs The systemic circuit carries blood to the body
The heart is located within the mediastinum It is about the size of a fist (14cm x 9cm)
2/3 of the heart is left of the midline
The heart is posterior to the sternum Base attachment of major vessels 2nd intercostal space Apex Pointed inferior margin 5th intercostal space
A pericardial membrane surrounds the heart. The fibrous pericardium forms a thick outer layer of connective tissue. The parietal pericardium is a serous membrane attached directly to the fibrous layer. A visceral pericardium is a serous membrane that forms the outer layer of the heart wall. The pericardial cavity contains serous fluid.
The wall of the heart contains 3 layers
The epicardium is also called the visceral pericardium The myocardium contains a thick layer of cardiac muscle, with blood vessels and nerves The endocardium is a smooth layer of squamous epithelium that lines the heart chambers and valves
The heart has 4 chambers The left atrium receives blood from the lungs The right atrium receives blood from the body The left ventricle pumps blood towards the body The right ventricle pumps blood towards the lungs Interventricular septum
Auricles increase the volume of the atria
Great veins carry blood towards the heart The superior vena cava returns blood from the upper body to the heart The inferior vena cava returns blood from the lower body to the heart The coronary sinus returns blood from the myocardium to the heart Four pulmonary veins return blood from the lungs to the heart
Great arteries carry blood away from the heart The aorta conveys oxygenated blood to the systemic circulation The pulmonary trunk* conveys deoxygenated blood to the pulmonary circulation * The pulmonary trunk immediately divides into a left and right pulmonary artery.
AV* valves prevent backflow into the atria. The tricuspid valve guards the right AV orifice The bicuspid (mitral) valve guards the left AV orifice *AV = atrioventricular
Chordae tendineae anchor the cusps papillary muscles
Papillary muscles contract to pull the valves tightly shut
AV valves are anchored to the ventricles Mitral Valve Prolapse – cusp protrudes into atrium. Symptoms include: chest pain, heart palpitations, and fatigue.
An Aortic valve (not shown) is located at the base of the aorta Semilunar valves prevent backflow into the ventricles A pulmonary valve is located at the base of the pulmonary trunk
The valves close shut whenever the ventricles are relaxed. Semilunar valves prevent backflow into the ventricles Each cusp of a semilunar valve is shaped like a crescent moon
Path of blood through the right heart chambers 1. Blood from SVC & IVC enter the right atrium. 2. It passes through the tricuspid valve into the right ventricle 3. Blood is pumped from the right ventricle, through the pulmonary valve, and into the pulmonary trunk. 4. Blood passes into the pulmonary arteries towards the lungs 1 2 3 4 4
Path of blood through the left heart chambers 5. Oxygenated blood is returned to the heart through 4 pulmonary veins. 5 5 9. Blood enters systemic circulation to the tissues throughout the body. 6. Blood enters the left atrium. 6 7. Blood passes through the bicuspid valve into the left ventricle. 8. The left ventricle pumps blood through the aortic valve into the aorta. 8 9 9 9 7
