Introduction to Cardiovascular Physiology PDF

Introduction to cardiovascular physiology Presented by Dr. Sherif Diaaeldin Assistant Professor of Physiology  Functional anatomy of the heart The heart is a hollow muscular organ surrounded by a connective tissue sac called the pericardium. The pericardium protects the heart...

Introduction to cardiovascular physiology Presented by Dr. Sherif Diaaeldin Assistant Professor of Physiology  Functional anatomy of the heart The heart is a hollow muscular organ surrounded by a connective tissue sac called the pericardium. The pericardium protects the heart and allows its contraction with minimal friction. The wall of the heart is made of cardiac muscle, and it is divided into right and left halves, each of which consists of one atrium and one ventricle. Right atrium and right ventricle  The right atrium is separated from the right ventricle by the tricuspid valve, while the left atrium is separated from the left ventricle by the bicuspid (or mitral) valve. Both valves are called the atrioventricular valves (A-V valves) In the ventricles, there are certain muscle called the papillary muscle the tendons of which (called chordae tendinea) are attached to the A-V valves, to prevent eversion into the atria during the ventricular contraction.  The aorta arises from the left ventricle and the aortic opening is guarded by the aortic valve. The pulmonary artery arises from the right ventricle and the pulmonary artery opening is guarded by the pulmonary valve. What is the function of the heart valves? It allows the blood flow in one direction only Divisions of the circulation The systemic circulation The pulmonary circulation This starts from the left ventricle This starts from the right ventricle Aorta Pulmonary artery Arteries lungs Arterioles Pulmonary capillary Capillaries Pulmonary veins (4 in number) Venules Left atrium Veins Superior and inferior venae cava Right atrium  Functions of the atria and ventricles The atria are the entry way to the ventricles. The ventricles pump the blood to the whole body. The aorta pumps oxygenated blood to the whole body. The pulmonary veins delivers oxygenated blood to the heart from the lungs, while pulmonary artery delivers deoxygenated blood to the lungs. Mechanism of heart beating Heart rate 60-90 beat/min average 72 beats/min in adults The impulse originates at the sino-atrial node (found in the right atrium) causes contraction of the atria. Then the impulse reaches the atrioventricular node then the impulse passes to the ventricle through His-purkinje system causing ventricular contraction Factors affecting the heart rate Factors increasing the heart rate Factors decreasing the heart rate Sympathetic stimulation increases Parasympathetic stimulation the heart rate e.g., in fear and decreases the heart rate. stress. Sleep decreases the heart rate. Exercise increases the heart rate. Decrease in the body temperature Increase body temperature every decreases the heart rate. degree Celsius increases the heart Drugs e.g., beta blockers. rate by 10 beats/min e.g., fever. Thyroxin and adrenalin hormones increase heart rate. Heart Sounds  The cardiac cycle The cardiac cycle consists of one systole-diastole sequence It lasts about 0.8 second During atrial systole the blood passes from the atria to the ventricle, while during ventricular systole the blood passes from the ventricle to the lung on the right side and to the whole body on the left side. During atrial diastole the atria receives blood through the superior and inferior vena cava, while during ventricular diastole the ventricles get filled with blood coming from the atria The cardiac output It is the amount of blood pumped by each ventricle per minute (=5.5 L/min). The stroke volume is the amount of blood pumped by each ventricle per beat (about 80 ml/beat). The cardiac output= heart rate X stroke volume Factors affecting the cardiac output Sympathetic stimulation increases the cardiac output while the parasympathetic stimulation decreases it. Catecholamines and thyroxin increases the cardiac output