Cardiac System.docx

Cardiac System Anatomy 1110 Chapter 8 Objectives Discuss the anatomy of the cardiovascular system Identify the heart chambers and valves Label and Identify the coverings of the heart Identify the major blood vessels associated with the heart Discuss what the Coronary system is Identify the differ...

Cardiac System Anatomy 1110 Chapter 8 Objectives Discuss the anatomy of the cardiovascular system Identify the heart chambers and valves Label and Identify the coverings of the heart Identify the major blood vessels associated with the heart Discuss what the Coronary system is Identify the different types of blood vessels Discuss the auscultation pattern for the heart Anatomy Location Lies within the thoracic cavity within the mediastinum Canine Ovoid shape 3rd and 6th intercostal space Long axis lays at a 45 degree angle to the sternum Base is directed craniodorsally Apex lies to the left of the midline of the diaphragm and sternum Heart is almost completely surrounded by the lungs Feline Extends from the 3rd to 4th and to the 6th and 7th ribs The angle of the heart in the thoracic cavity is more acute Auscultation of the Heart Pulmonic valve Aortic valve Left Atrioventricular valve (mitral/bicuspid) Right Atrioventricular valve (tricuspid) Pericardium Fibrous Sternopericardiac ligament Serous Epicardium The layer between the fibrous and serous layer is called the Pericardial cavity Myocardium Endocardium Chambers and Valves Four chambers Right and left atria foramen ovale Right and left ventricles Pump blood away from the heart Divided in to right and left halves by the interatrial and interventricular septum Vessels Artery Veins Aorta Vessels Associated with Right Ventricle Pulmonary artery Vena cavae Right Atrium Receives deoxygenated blood from the cranial and caudal vena cavae It holds the deoxygenated blood until it is pumped to the right ventricle Right atrioventricular valve (AV) or tricuspid valve During ventricular contraction (systole) the valve closes (AV/triscuspid) The valve consists of: Three leaflets Papillary muscles Right Ventricle Pumps unoxygenated blood into the low pressure pulmonary circulation Pulmonic Valves Semilunar valve Pulmonary artery delivers unoxygenated blood from the right ventricle to the lungs It branches to form left and right pulmonary arteries that go to the respective lung lobes They have corresponding bronchi Ligamentum arteriosum connects the pulmonary artery to the descending aorta Ductus arteriosus Left Atrium Receives and hold oxygenated blood from the pulmonary veins Located on left dorsocaudal aspect of the heart base above the left ventricles Valve- Left AV or mitral During diastole the left AV valve opens Left AV valve has 2 leaflets Malfunction of the AV valve is the most common cause of congested heart failure in a dog Left Ventricle Pumping chamber Largest structure of the heart 2-3 times thicker than the right ventricle Conical in shape Normal Heart Sounds (“lub-dub”) lub”: S1 Closure of the mitral and tricuspid valves at the beginning of ventricular systole Mitral valve is loudest on the left side of the chest; tricuspid valve is best heard on the right “dub”: S2 Closure of the semilunar valves at the beginning of ventricular diastole Easiest to hear on the left side of the chest Aortic Valve Semilunar cusp Second most common congenital heart defect problem is aortic stenosis Aorta Three segments: Ascending Aortic Descending Sinoatrial Node (SA node) Specialized area of cardiac muscle cells located in right atrium Generates electrical impulses that trigger repeated beating of the heart Coronary System Coronary arteries arise from the aorta Arteries that supply oxygenated blood to the myocardium Blood Vessels Arteries-carries blood away from the heart Aorta and pulmonary arteries consist mainly of elastic fibers (aids in propelling) Arterioles Capillaries Smallest blood vessels Veins Constructed like arteries Largest veins have a small amount of smooth muscle Venules http://www.lbah.com/heart/cardiacanatomy.htm Vascular Anatomy and Physiology Blood in the systemic circulation is under higher pressure than blood in the pulmonary or coronary circulation. More pressure is needed to carry blood throughout the body. Blood in systemic circulation encounters more resistance to flow Aorta Largest artery in the body - largest diameter and thickest vessel walls Artery wall layers are similar to the walls of the heart Aorta and pulmonary arteries - middle layer contains more elastic fibers than muscle fibers Allows vessels to stretch slightly as they receive high-pressure blood from the ventricles Vascular Anatomy Subclavian arteries branch off the aorta and travel toward the thoracic limbs Carotid arteries branch off one or both subclavian arteries Vascular Anatomy Main trunk of the aorta arches dorsally then travels caudally Numerous branches emerge in the thoracic and lumbar areas Vascular Anatomy Venous blood is under lower pressure than arterial blood. Veins have thinner walls than arteries. Valves in veins ensure that blood travels only in the direction of the heart. Vessels Smaller arteries continue to split into smaller and smaller vessels and then arterioles Blood flows through arterioles into tiny, thin-walled capillaries. Capillaries have no muscle layer in their walls. Blood travels back to the heart through small venules which merge to form vein Branches of the Aorta Brachiocephalic trunk supplies blood to the head and neck through a pair of common carotids The right subclavian artery t supplies the right forelimb Left subclavian artery supplies blood to the left forelimb Internal iliac artery supplies the pelvic viscera Pair of external iliac arteries supply the hind limb Venous Collection The capillary beds connect the venules which form the larger veins which take the blood back to the heart Cranial vena cava collects blood: Head and neck from the jugular veins Forelimbs from the right and left subclavian veins Caudal vena cava collects blood: from the pelvic viscera, hind limbs and abdominal organs from the various veins that run alongside the arteries and deposits the blood into the right atrium Smooth muscle in walls of most blood vessels Constriction and relaxation allows the vascular system to direct blood to different regions of the body under different circumstances. Venipuncture Cephalic vein: craniomedial aspect of forelimb Femoral vein: medial aspect of hind limb Saphenous: lateral aspect of hind limb Venipuncture Jugular Veins Ventral aspect of each side of the neck in the jugular groove Close to the carotid arteries Care must be taken to avoid accidental injection into the carotid artery Review Identify the heart chambers and valves Identify the coverings of the heart Identify the major blood vessels associated with the heart What is the Pulmonary and the Coronary systems What are the different types of blood vessels Identify major blood vessels