Cardiovascular System - Blood PDF

Cardiovascular system - Blood Dr. Udeshika Yapa Bandara BSc. (Hons) Human Biology (USJP), PhD (UOC) Learning outcomes ▪ To discuss the components of blood ▪ To discuss the gross anatomy of the heart ▪ To know the microscopic anatomy of Heart Muscle ▪ To discu...

Cardiovascular system - Blood Dr. Udeshika Yapa Bandara BSc. (Hons) Human Biology (USJP), PhD (UOC) Learning outcomes ▪ To discuss the components of blood ▪ To discuss the gross anatomy of the heart ▪ To know the microscopic anatomy of Heart Muscle ▪ To discuss the conduction system of the heart ▪ To know the blood supply and nerve supply of the heart Function of blood Carry nutrients, gases, waste materials, hormones & other components from cell to cell and from one body region to another Composition of blood RBCs / Erythrocytes - Transport O₂ & small amounts of CO₂ - Filled with molecules of Hemoglobin Gives red color - Important features of RBCs are; -No nucleus -Small and flexible -Life span – 120 days Normal count (5 000 000/mm3) Reduction of count Anaemia - Destroy by special cells in the liver and spleen Regulation of RBC production Fate of Hemoglobin molecule Leucocytes / WBCs - Function; protect from harmful bacteria, viruses, parasites and toxic substances - Five main types Platelets/ Thrombocytes - Cell fragments - Manufactured in red bone marrow - Life span 1-2 weeks - Function - promote clotting of blood  Plasma - Clear liquid - 92% water - Plasma proteins – Fibrinogen & Antibodies increase the osmotic pressure - Gases - CO₂ & a lesser extent of O₂ - Nutrients - Wastes - urea and creatine - Electrolytes - Na⁺, K ⁺, Cl⁻ and Ca²⁺ osmotic pressure Plasm a The heart Introduction ‘cardio’ - heart ‘vascular’ - about blood vessels Heart pumps about 70 times/minute Continues from intrauterine life through the entire life span of a human Heart Anatomy 1 3 Heart Anatomy ▪ Approximately the size of your fist ▪ Location ▪ Superior surface of diaphragm ▪ Left of the midline ▪ Anterior to the vertebral column, posterior to the sternum 1 4 Heart Location - Middle of the chest, between the lungs - Apex of the heart is tilted slightly to the left Relations Anteriorly: the body of the sternum, and adjoining costal cartilages; left lung, and pleura (apex) Posteriorly: oesophagus, descending thoracic aorta, azygos, hemiazygos veins, and thoracic duct Superficially : bifurcation of the main pulmonary trunk Inferiorly: diaphragm Laterally: lungs, pleura Structure - Cone-shaped - about the size of your fist - Walls consist of cardiac muscle cells - Four chambers - Enclosed by the pericardium Pericardium Sac surrounding the heart and the roots of great vessels Consists of two components – Fibrous pericardium – Serous pericardium - Is thin and consists of two layers ▪ – Parietal layer ▪ – Visceral layer Pericardium ▪ Pericardium – a double-walled sac around the heart composed of: 1. A superficial fibrous pericardium 2. A deep two-layered serous pericardium a. The parietal layer lines the internal surface of the fibrous pericardium b. The visceral layer or epicardium lines the surface of the heart ▪ They are separated by the fluid-filled pericardial cavity Pericardial Layers of the Heart 20 Pericardium ▪ The Function of the Pericardium: ▪ Protects and anchors the heart ▪ Prevents overfilling of the heart with blood ▪ Allows for the heart to work in a relatively friction- free environment Heart Wall ▪ Epicardium – visceral layer of the serous pericardium ▪ Myocardium – cardiac muscle layer forming the bulk of the heart ▪ Fibrous skeleton of the heart – crisscrossing, interlacing layer of connective tissue ▪ Endocardium – endothelial layer of the inner myocardial surface 22 23  External Heart: Major Vessels of the Heart (Anterior View) ▪ Vessels returning blood to the heart include: 1. Superior and inferior vena cava 2. Right and left pulmonary veins ▪ Vessels conveying blood away from the heart include: 1. Pulmonary trunk, which splits into right and left pulmonary arteries 2. Ascending aorta (three branches) – a. Brachiocephalic b. Left common carotid c. Subclavian arteries External Heart: Anterior View  External Heart: Major Vessels of the Heart (Posterior View) ▪ Vessels returning blood to the heart include: 1. Right and left pulmonary veins 2. Superior and inferior venae cavae ▪ Vessels conveying blood away from the heart include: 1. Aorta 2. Right and left pulmonary arteries External Heart: Posterior View Gross Anatomy of Heart: Frontal Section Chambers of the heart - right atrium - left atrium - right ventricle - left ventricle Valves of the heart – Atrioventricular valves Valves of the heart – Semilunar valves  Atria of the Heart ▪ Atria are the receiving chambers of the heart ▪ Each atrium has a protruding auricle ▪ Pectinate muscles mark atrial walls ▪ Blood enters right atria from superior and inferior venae cavae and coronary sinus ▪ Blood enters left atria from pulmonary veins Ventricles of the Heart ▪ Ventricles are the discharging chambers of the heart ▪ Papillary muscles and trabeculae carneae (muscular ridges) muscles mark ventricular walls ▪ Right ventricle pumps blood into the pulmonary trunk ▪ Left ventricle pumps blood into the aorta Chapter 18, Cardiovascular System 21  Myocardial Thickness and Function Thickness of myocardium varies according to the function of the chamber Atria are thin walled, deliver blood to adjacent ventricles Ventricular walls are much thicker and stronger ▪ right ventricle supplies blood to the lungs (little flow resistance) ▪ left ventricle wall is the thickest to supply systemic circulation Artery Vein Tunica intima Endothelium Subendothelial layer Internal elastic membrane Tunica media (smooth muscle and elastic fibers) External elastic membrane Tunica externa (collagen fibers) Vasa vasorum Valve Capillary network Lumen Lumen Basement membrane Endothelial cells Flow of blood through the heart 1. Systemic circulation 2. Pulmonary circulation Hepatic circulation Pathway of Blood Through the Heart and Lungs ▪ Right atrium - tricuspid valve - right ventricle ▪ Right ventricle - pulmonary semilunar valve - pulmonary arteries - lungs ▪ Lungs - pulmonary veins - left atrium ▪ Left atrium - bicuspid valve - left ventricle ▪ Left ventricle - aortic semilunar valve - aorta ▪ Aorta - systemic circulation  Heart Valves ▪ Heart valves ensure unidirectional blood flow through the heart ▪ Atrioventricular (AV) valves lie between the atria and the ventricles ▪ AV valves prevent backflow into the atria when ventricles contract ▪ Chordae tendineae anchor AV valves to papillary muscles ▪ Semilunar valves prevent backflow of blood into the ventricles ▪ Aortic semilunar valve lies between the left ventricle and the aorta ▪ Pulmonary semilunar valve lies between the right ventricle and pulmonary trunk Heart Valves ▪ Anatomy of the heart https://www.youtube.com/watch?v=uhSBFOTwzDQ  Microscopic Anatomy of Heart Muscle Small with one central nucleus Branching interconnections between cells ▪ Intercalated discs anchor cardiac cells together and allow free passage of ions ▪ Cardiac muscle is striated, short, fat, branched, and interconnected ▪ Intercalated discs: ▪ Interconnect cardiac muscle cells ▪ Secured by desmosomes to convey force of contraction ▪ Linked by gap junctions to propagate action potentials ▪ Heart muscle behaves as a functional syncytium  Conduction system ▪ The specialized heart cells that generate and coordinate the transmission of electrical impulses to myocardial cells. ▪ It consists of Sinoatrial node Atrioventricular node Atrioventricular bundle (bundle of His) Purkinje fibres ▪ The following sequence of electrical events occurs during one full contraction of the heart muscle: ▪ An excitation signal (an action potential) is created by the sinoatrial (SA) node. ▪ The wave of excitation spreads across the atria, causing them to contract. Upon reaching the atrioventricular (AV) node, the signal is delayed. It is then conducted into the bundle of His, down the interventricular septum. The bundle of His and the Purkinje fibres spread the wave impulses along the ventricles, causing them to contract. ▪ Conduction system of the heart https://www.youtube.com/watch?v=TnFoJ7Hhi-M  Blood supply to heart Heart is supplied by coronary arteries Coronary arterial tree has two trunks and many branches. Two trunks are the first branches of the Aorta. Left coronary artery Right coronary artery The right and left coronary arteries are arising from the aortic sinuses. Encircle the heart like a crown. Left coronary artery is usually larger than the right  Blood supply to heart muscles Branches of coronary arteries Right coronary arteryLeft main coronary artery 1. Posterior 1. Left anterior descending descending a. a. - Right ventricle - anterior 2/3 of the inter- - Left ventricle ventricular septum - Inter-ventricular - adjoining part of the left septum ventricular anterior wall Venous drainage 2. Right marginal a. 2. Circumflex coronary a. 1. Coronary sinus - Right ventricle - lateral and posterior 2. Anterior, middle, small portions of the left ventricle. cardiac veins 3. Venae cordis minimae Coronary arteries and Branches  Superior Vena Aorta Cava Pulmonary Artery Right Coronary Left Coronary Artery Artery Left Circumflex Right Atrium Artery Right Posterior Left Anterior Descending artery DescendingArtery Right Ventricle Left marginal Right marginal artery artery Left ventricle Inferior Vena Cava 55 Heart (sternocostal surface) Ascending aorta Right auricle Left coronary artery Right coronary Circumflex artery artery Anterior interventricular artery Right marginal Great cardiac vein artery Pulmonary trunk Heart (base and diaphragmatic surface) Left atrium Right atrium Circumflex artery Right coronary artery Left ventricle Right ventricle  Venous drainage of the heart ❖Venous drainage of the heart occurs through the coronary veins. Functions of coronary veins - Collect CO2 and waste from myocardium  Coronary veins Oblique vein Great cardiac Coronary sinus vein Veins from left Small cardiac vein ventricle Great cardiac Middle cardiac vein vein  Venous drainage from the heart Most of the venous blood is collected into a number of cardiac veins. Cardiac veins join to form the coronary sinus. Coronary sinus - vascular sinus located in the posterior surface of the heart Coronary sinus opens to the right atrium. The remainder passes directly into the heart chambers through little venous channels. Venous drainage of heart: ▪ Coronary sinus and its tributaries ▪ Anterior cardiac veins Coronary sinus: ▪ Largest vein of heart, about 3 cm long ▪ Situated in the posterior part of coronary sulcus between the left atrium and left ventricle ▪ Terminates by opening into the smooth part of right atrium ▪ Opening is guarded by valve of coronary sinus ▪ Receives most of the veins of heart Coronary sinus and its tributaries Left atrium Oblique vein of left atrium Right atrium Great cardiac vein Coronary sinus Small cardiac vein Posterior vein of left ventricle Middle cardiac vein Left ventricle Right ventricle Tributaries of coronary sinus: ▪ Great cardiac vein ▪ Small cardiac vein ▪ Middle cardiac vein ▪ Posterior vein of left ventricle ▪ Oblique vein of left atrium Nerve supply to the heart Autonomic nerve supply 1. Sympathetic supply 2. Parasympathetic supply  Nerve supply of heart: ▪ Supplied by nerves arising from superficial and deep cardiac plexus ▪ Nerves arising from these plexuses run along the coronary arteries and supply the heart ▪ These contain sympathetic and parasympathetic nerves ▪ Sympathetic nerves are cardio-acceleratory, on stimulation increase heart rate and dilate coronary arteries. ▪ Sympathetic nerves are derived from upper 4 or 5 thoracic segments of spinal cord. ▪ Parasympathetic nerves run via vagus. These are cardio-inhibitory, and on stimulation slow down the heart rate. Pathological conditions in cardiovascular system 1.Congestive heart failure - decreased contractility of the myocardium - diminished coronary blood flow - damaged heart valves 2. Ischaemic heart disease - Angina pectoris - Acute myocardial infarction - Cardiac failure - Cardiac arrhythmias Congenital Abnormalities Atrial Septal Defect Atrioventricular Septal Defect Coarctation (narrowing) of the Aorta Double-outlet Right Ventricle Ebstein’s Anomaly Hypoplastic Left Heart Syndrome Interrupted Aortic Arch Questions 1. Outline the conduction system of the heart. 2. Describe the microscopic structure of heart muscle. 3. List 5 congenital abnormalities of the heart and briefly describe their significance compared to normal heart.