L16 Cardiovascular System PDF

 LEARNING OUTCOMES 0 Components of the Cardiovascular System, layers of the heart 0 Gross anatomy of the heart, valves, fibrous skeleton of the heart 0 Blood supply or the heart And its significance, 0 Conducting system of the heart 0 Innervation of the heart and blood vessels...

 LEARNING OUTCOMES 0 Components of the Cardiovascular System, layers of the heart 0 Gross anatomy of the heart, valves, fibrous skeleton of the heart 0 Blood supply or the heart And its significance, 0 Conducting system of the heart 0 Innervation of the heart and blood vessels 2 0 Hollow muscular organ 0 Roughly the size of the owner’s fist 3  POSITION 0 Lies in the thoracic cavity in the mediastinum 0 Lies obliquely, more to the left 0 Has base above and the apex below 4  POSITION APEX - 5th intercostal space -9cm to the left of midline BASE -extends to the level of 2nd rib 5 0 ANTERIORLY Sternum ,ribs 0 POSTERIORLY Esophagus, trachea, descending aorta 6 0 INFERIORLY central tendon of diaphragm 0 SUPERIORLY Great blood vessels 7 0 LATERALLY Lungs 8 STRUCTURE Three layers of tissue - PERICARDIUM - MYOCARDIUM - ENDOCARDIUM 9  PERICARDIUM Fibro serous sac Pericardium Fibrous sac Serous sac (open) (closed) 10 Fibrous sac 0 Above continuous with the tunica adventitia of the great vessels 0 Below adherent to the diaphragm 0 Prevents over distention 11 12 SEROUS SAC SEROUS PARIETAL VISCERAL LAYER LAYER 13 14 SEROUS SAC The parietal and the visceral layer are continuous with each other Enclosing a potential space Pericardial cavity 15 0 Serous membrane consists of flattened epithelial cells 0 Secretes serous fluid into the pericardial cavity For smooth movement between them 16 0 An inflammation of the pericardium is known as PERICARDITIS. 0 Associated bleeding into the pericardial cavity compresses the heart (cardiac tamponade) and is potentially lethal. 17 Myocardium 0 Specialized muscle found only in the heart 0 Not under voluntary control( cross stripes seen) 0 Each fiber has nucleus and branches 18 0 These branches are in close contact with one another AT INTERCALATED DISC 0 Therefore act in syncytium 19 Myocardium 0 Thickest at the apex & thins towards the base 0 Thickest in the left ventricle 20 Endocardium 0 Consists of flattened epithelial cells and continuous with the endothelium lining the blood vessel 0 Lines the chambers and valves 0 Permits smooth flow of blood 21  INTERIOR OF THE HEART 0 Divided by a septum into right and left side 0 Each side is divided by an ATRIOVENTRICULAR VALVE into -Upper chamber ATRIA -lower chamber VENTRICLE 22  VALVES OF THE HEART 0 Pumps need a set of valves to keep the fluid flowing in one direction ATRIOVENTRICULAR SEMILUNAR VALVES VALVE 0 The heart has two types of valves that keep the blood flowing in the correct direction. 23 The AV valves are formed by double folds of endocardium strengthened by fibrous tissue 24 0 Flow of blood is one way….. From atria to the ventricles 25 26 Valves are prevented from opening upwards into the atria by tendinous cords CHORDAE TENDINAE 27  Chordae tendinae extend from the inferior surface of the cusps to the Projections of myocardium in the ventricles Papillary muscles 28  VALVE CHORDAE TENDINAE PAPILLARY MUSCLE 29  Circulatory Pathways The blood vessels of the body are functionally divided into two distinctive circuits: 0 Pulmonary circuit 0 Systemic circuit. 30 31 32 33  We see that the atria are assisted by gravity propel blood through the AV valves to the right ventricle Therefore muscle wall of the atria is thinner But ventricles actively pump blood to the lungs and thanthethe ventricles whole body 34 BLOOD SUPPLY OF HEART Right and the left coronary artery 35 Branch from the aorta immediately distal to the aortic valve 5% of the blood pumped from the heart 36 VENOUS DRAINAGE 37 CONDUCTING SYSTEM OF THE HEART 0 Intrinsic system which automatically stimulates the cardiac muscle AUTORHYTHMICITY WITHOUT the need for EXTERNAL STIMULATION 38  Circulating chemicals Nerve impulse in Hormones the brain Conducting system of heart 39  Small groups of SPECIALIZED NEUROMUSCULAR cells in the myocardium initiate and conduct impulses 40 0 SINOATRIAL NODE Small mass of cells in he wall of right atrium near sup. vena cava PACEMAKER Causes atrial contraction 41 0 AV NODE In the wall of atrial septum near AV valves AV nodal delay 0.1 sec So that atria finish contracting before the ventricles start 42 0 NOTE Av node has a SECONDARY PACEMAKER function And it takes over if there is a problem with the SA node But its firing rate is slower 43 0 AV BUNDLE OF HIS Specialized fibers originate from AV node Divides into right and left branch Ramifies in the ventricular myocardium as fine fibers PURKINJE FIBRES 44 PURKINJE FIBERS 45  Nerve supply VAGUS NERVES (PARASYMPATHETIC) 0 Supply mainly SA and AV node and atrial muscle. 0 Parasympathetic stimulation reduces the rate at which impulses are produced ,decreasing the rate and force of heart beat. 46 SYMPATHETIC NERVES: 0 Supply SA and AV nodes and myocardium of atria and ventricles. 0 Sympathetic stimulation increases the rate and force of heartbeat 47