Chapter 15 Cardiovascular System

Organs Heart - begins beating in the 4 th week of development. –Pumps 7,000 liters of blood each day. –Contracts 2.5 million times in a lifetime. Closed Vessel System –Arteries - carry blood away from the heart. –Veins - carry blood toward the heart. –Capillaries - attach arteries and veins.

Function Circulates blood to every cell in the body and removes waste.

The Heart Location and Size –Size of a man’s fist (14 cm long and 9 cm wide) –Lies within the mediastinum - behind sternum (rests on diaphragm). –2/3 of the heart is on the left side of the body. –Apex is the lower, left “point” of the heart. Stethoscope is placed here to count the beats.

The Heart Coverings –Pericardium - sac around the heart - loose-fitting Fibrous - tough white outer covering, Serous parietal - smooth lining of the fibrous sac. –Epicardium - covers surface of the heart - smooth Also called serous visceral pericardium –Pericardial space - area between pericardium and epicardium Contains fluid - pericardial fluid Lubricates beating heart Pericarditis - inflammation of pericardium due to infection - linings stick together, very painful.

The Structure of the Heart The wall of the heart: –Epicardium – reduces friction. –Myocardium – thick contractile middle layer, high in mitochondria. –Endocardium – delicate inner layer.

The Structure of the Heart Continued Cavities –Upper – atria –Lower – ventricles Larger and thicker walled Carry heavier pumping burden Left is thickest – has to pump blood to all parts of the body

The Structure of the Heart Continued Valves and Openings Blood flows in one direction. –Cuspid valves – between cavities (atria and ventricles) Bicuspid (mitral) valve - left cavities. Valve has 2 cusps or leaflets. Also called the left atrioventricular valve. Tricuspid valve - right cavities. Valve has 3 cusps or leaflets. Also called the right atrioventricular valve.

The semi-lunar valve moves blood out of the heart to the aorta and pulmonary artery. i.Cusps of valve are half moon shaped (‘lunar’) Found at the base of the pulmonary arteries (called the pulmonary valve) and at the base of the aorta (called the aortic valve) Attached by fibrous strings called chordae tendineae to the papillary muscles.

Tricuspid valve repair

A murmer is an abnormal sound that identifies the leakage of blood though valves in the wrong direction

Apex – left coronary artery (auricle)

Left auricle Right auricle Auricle = A small, earlike projection that extends anteriorly from the atrium.

18 1. Aortic arch 2. Superior Vena cava 3.Right Pulmonary Artery 4. Pulmonary trunk 5. Right Pulmonary Veins 6. Pulmonary Valve 7. Right Atrium 8. Tricuspid valve 9. Right ventricle 10. Inferior Vena cava 11. Aorta 12. Interventricular Septum 13. Left ventricle 14. Bicuspid valve (Mitral valve) 15. Aortic valve 16. Left atrium 17. Left pulmonary Veins 18. Left pulmonary artery

The Structure of the Heart Continued Blood Supply –Ventricles get blood from the right and left coronary arteries. –Atria get blood from the small branch coronary artery. –Anastomosis is branching of the main arteries (“detours”) –Myocardial infarction - death of the heart muscles due to a clot (heart attack).

Blood Vessels Structure –Outer – fibrous tissue, keeps firm –Middle – muscle, constriction, and dilation. –Inner – endothelium - capillaries

Blood Vessels Continued Function –Transportation of nutrients to cells Capillaries perform this function Arteries = distributors arterioles capillaries venules veins Veins = carry and pool blood

Blood Vessels Continued Main Blood Vessels –ascending aorta –aortic arch –subclavian –common carotid –common iliac Ascending Aorta

Blood Vessels Continued

Portal Circulation –Organs that do not pour blood into inferior vena cava. –Blood sent to the liver by the portal vein.

Blood Vessels Continued Fetal Circulation –Gets oxygen and food from mother, not own lungs and digestive tract. –Additional vessels Umbilical arteries (2) – carry fetal blood to placenta Placenta – exchanges oxygen and other substances between mother and fetus Umbilical vein – returns oxygenated blood to liver of fetus Foramen ovale – opening between right and left atria bypass lungs, closes with first breath. Shed at birth