BIO 241 1nd Edition Lecture 4 Outline of Last Lecture I Hemostasis control of bleeding II Clot retraction syneresis III Fibrinolysis clot dissolution IV Blood types Outline of Current Lecture II Rh system III Introduction to the heart IV Pericardium V Heart wall VI Heart chambers VII Septa of the heart VIII Blood flow through the heart IX Atrioventricular Valves X Semilunar Valves Current Lecture II We know from previous lecture that RBCs have membrane bound agglutinogens that are shaped differently for each of the four blood types There are also Rh agglutinogens in the blood however there are no Rh agglutinins The Rh system of grouping is of main concern when the mother is Rh negative and her first baby is Rh positive The fetal Rh positive blood enters the maternal circulation through the placenta The mom s body will then make anti Rh positive antibodies The second baby will have hemolytic disease of the newborn if the baby is Rh positive since the mother s antibodies will want to destroy the positive Rh This is only an issue if the mom is Rh negative III The heart has a double pump system consisting of the pulmonary the circuit through the lungs where blood is oxygenated and systemic carries oxygenated blood away from the heart circulation systems The diagram below shows the pulmonary circuit and the systemic circuit and if the blood is poor or rich IV Pericardium is broken down so peri equals around and cardium equals heart The pericardium is the membrane that surrounds the heart There is an outer fibrous layer composed mostly of collagen and an inner serous layer Within the serous layer is the parietal layer which is the outer layer of the heart and the visceral layer epicardium you need to know both terms which is the layer on the surface of the heart Another term you need to know is the pericardial cavity which is the space between the parietal and visceral layers This cavity contains pericardial fluid which reduces friction since the heart is constantly contracting relaxing V The heart wall has three general layers listed superficial to deep and shown on the left below epicardium myocardium and endocardium The myocardium layer is controlled by the autonomic nervous system so it is an involuntary muscle Because of the contraction of the H zone in muscles myocardium appears to be striated Myocardium contains intercalated disks which aid in cell to cell communication and is ultimately what causes the heart to contract in functional synctium The two superior atrial chambers are a separate muscle mass from the two inferior ventricular chambers These two masses shown on the right below create the cardiac skeleton which is a figure 8 shape where the masses meet The endocardium is continuous with the endothelium of the heart wall VI The heart is composed of four chambers The top two are known as the right and left atria There are atrial appendages that increase the volume of atria respectively The bottom two chambers are the right and left ventricles The coronary sulcus is the groove around the heart where the big blood vessels are that separates the two muscle masses The posterior interventricular sulcus is where blood vessels separate the right and left ventricles VII There are two septa of the heart The first to name is the interatrial septum When you are a fetus it is a valve called the foramen ovale When you are an adult it forms together and is called the fossa ovalis The next septa is the interventricular septum which is membranous and muscular VIII Now we will go through the steps of blood flow through the heart It is a cycle so we will just jump in with the right atrium Blood flows into the right atrium through the superior and inferior vena cava and the coronary sinus which is where blood drained from the heart collects From the right atria blood goes to the right ventricle where it shoots up the pulmonary trunk to the lungs Blood is oxygenated there and goes from the lungs to the pulmonary veins two on each side It then goes to the left atria then the left ventricle and finally shoots up through the aorta to the body There are vessels known as the great blood vessels and consist of the superior and inferior vena cava pulmonary trunk pulmonary veins and aorta IX Atrioventricular valves begin in the atria and lead to the ventricle The tricuspid valve is on the right and the bicuspid mitral valve is on the left An easy way to remember this is that tri and right are longer words than bi and left The apex is the tip of the heart that leans inferiorly toward the left Chordae tendineae are thread like bands of fibrous tissue which attach on one end to the edges of the tricuspid and mitral valves They help control whether the valve is open or closed with the help of papillary muscles These muscles are located in the ventricles of the heart They attach to the cusps of the atrioventricular valves X There are also semilunar valves This consists of the pulmonary and aortic valve They are arranged as 3 half moon cusps pockets which is the reason they are called semilunar