The Heart - Anatomy
Serous pericardium
A parietal layer which adheres to the outermost layer A visceral layer ? outer surface of the heart wall
AV valves
Between the atria and the ventricles Composed of flaps (cusps) of endocardium reinforced by connective tissue Between contractions valves 'flap' open Valves attached by chordae tendineae which are anchored by the papillary muscles Chordae Tendineae prevent inversion of the valves
Pulmonary circulation
Carries deoxygenated blood from the R ventricle via the pulmonary trunk to the lungs and returns oxygenated blood through the pulmonary veins in the L atrium
Systemic Circulation
Carries oxygenated blood from the L ventricle via the aroma to the body and returns the deoxygenated blood to the RA
Left Coronary Artery
Circumflex branch supplies the left atrium and posterior wall of the left ventricle Left anterior descending (LAD) or Anterior Inter-ventricular which supplies anterior walls of both ventricles
Obstruction of coronary arteries
Complete blockage leads to tissue death ANGINA is the severe pain that accompanies temporary deficiency in oxygen in the myocardium MYOCARDIAL INFARCTION results from a prolonged blockage and death of myocardial cells Damage to the left ventricle is the most serious —> it pumps blood to the systemic circulation
Coronary Sinus
Empties into the right atrium where the deoxygenates coronary blood joins with oxygen-depleted blood from the rest of the body
3x layers of the heart
Endocardium Myocardium Pericardium
Coronary arteries
Have many connecting branches to provide detours if one is obstructed Arteries and branches lie in the visceral pericardium and penetrate the myocardium The left ventricle receives most of the blood
Location
In the thoracic cavity mediastinum Medial to the lungs Anterior to the vertebrae Posteriorly to the sternum with 2/3 of its bulk to the L). The base of the heart is tipped medially and posteriorly, while the apex is inferiorly and laterally
Myocardium
Layer of cardiac muscle Thicker in the left ventricle, as it pumps around the body Thinner in the right (—> to the lungs) Thinest in the atria
Semilunar valves
Pulmonary semilunar valves concept of 3 cusps which surround the entrance to the artery from the ventricle Half moon shape with curved surface against the wall of the pulmonary trunk When the ventricle contracts and blood is forced from the ventricle to the artery, the cusps are flattened against the wall of the artery As the ventricle relaxes and pressure inside them falls, the cusps act like pockets and fill with blood, bulge out meeting in the centre, blocking the opening completely, preventing the back flow of blood into the ventricle.
Major veins
Superior / Inferior vena cava 4x pulmonary veins Coronary sinus
Coronary Circulation
Supplies the myocardium with oxygen and nutrients and removes waste. Blood in the chambers doesn't supply the myocardium —> too thick for diffusion Right and left coronary arteries branch from the ascending aorta These are squeezed shut when the heart contracts Blood enters when the heart relaxes
Right Coronary Artery
Supplies the right atrium and nearly all of the right ventricle
Pericardium
Surrounds the heart and covers the roots of the great vessels. Composed of 2 layers: Fibrous pericardium Serous pericardium
Endocardium
Thin smooth lining of the heart. Simple squamous epithelial layer which covers the heart valves and is continuous with the blood vessels Thin layer of connective tissue underneath FUNCTION = minimise surface friction as blood flows through the heart
Heart Valve Fn
is to prevent the back flow of blood. Blood flows through the heart from areas of high pressure to areas of low pressure in a one-way system, valves operate in pairs
Fibrous Pericardium
tough connective tissues that Protects the heart Anchors it to the surrounding structures Prevents over filling