Human Anatomy - Heart (Cardiovascular System) PDF

Human Anatomy - Heart (includes a bit of physiology + pathophysiology too!) Register code 498185 Lecture 1: Dr Lucy Smyth [email protected] You will be able to describe: Heart location + structure – Gross anatomy – Micro anatomy...

Human Anatomy - Heart (includes a bit of physiology + pathophysiology too!) Register code 498185 Lecture 1: Dr Lucy Smyth [email protected] You will be able to describe: Heart location + structure – Gross anatomy – Micro anatomy Heart function: The cardiac cycle Heart Conduction system  Components of the Cardiovascular system Heart Blood Vessels Blood The Heart is Located in the Thoracic cavity The Heart is Located in the thorax: Mediastinum Heart Location Key Anatomical Features of the Heart  Microscopic Heart anatomy Histology: Myocytes / Cardiocytes  Cardiac muscle cell Properties: (cardiocytes/myocytes) 1. Have a single, centrally located nucleus 2. Have a branching structure 3. Have many mitochondria More on Cardiac muscle cells: cardiocytes/myocytes 4. Have abundant reserves of myoglobin 5. Contain myofibrils which contract 6. Each cell is in contact with several other cells at specialized sites - intercalated discs Cardiac muscle In contrast to skeletal muscle, cardiac muscle cells may be branched instead of linear and longitudinal Intercalated Discs comprise of: A. Adherens Junctions B. Desmosomes C. Gap junctions Collectively uniquely support synchronized contraction of cardiac tissue Adherens Junctions Anchoring sites for actin. Connects sarcomeres together Desmosomes Stop cell separation during contraction: bind intermediate filaments to join the cells together Gap Junctions Allow action potentials to spread between cardiac cells by permitting the passage of ions between cells. A T-tubule is a deep invagination of the cell plasma membrane. What does the heart have to do? Heart Function – The cardiac Cycle  Advantages of a closed circulatory system: Faster transport through vessels. Blood can be directed to specific tissues. Specialized carriers can travel in the vessels and transport hormones or nutrients to specific sites.  Two circulatory blood circuits Pulmonary circuit: from the right heart to the lungs returning to the left heart. Systemic circuit: from the left heart to the rest of the body returning to the right heart. Heart Function: Cardiac cycle Systole (contraction) Diastole (relaxation) Cardiac cycle A closer look at the heart valves A closer look at the valves Heart sounds: Caused by the closing of valves – ensures a 1 way blood flow Beginning of Systole End of Systole  Stages of cardiac cycle Ventricular Diastole Atrial Systole Systole Both atria and Atria ………………….; Atria ………………; ventricles ventricles ventricles ……..………….. ……………..…. ……………………… Atrioventricular AV valves …………….; AV valves (AV) …………..……..; Semilunar valves ………………..; Semilunar valves ………………………. Semilunar valves …………………… …………………. Blood flows Blood flows from Blood flows from through atria into atria into ……………………..into …………………….. ……………………………. pulmonary and systolic circuits Pulmonary and Systemic Circulation Coronary Circulation Atherosclerosis Percutaneous Transluminal Coronary Angioplasty Chapter 18, Cardiovascular System 33 What Causes our hearts to Beat? The Conduction System of the Heart  Cardiac conduction system Composed of “autorhythmic fibres (~ 1% of myocytes) Are of two mycocyte types: – Pacemaker cells – Conduction fibres Heart pacemaker and conduction cells Pacemaker cells Conduction fibre cells Heart pacemaker and conduction cells SA node conduction velocity = 1m/sec AV node = 0.04m/s PF = 5m/sec Pacemaker cells Conduction fibre cells 12 lead ECG ECG trace + heart movements 0.12-0.2 s 0.06-0.1 s 0.08-0.1 s 0.2-0.4 s https://www.youtube.com/watch?v=lIQXzgesdDg  Common Conduction Pathologies detected by ECG http://science-tuition.co.uk/wp- content/uploads/2013/10/ecg_AF_loop_ plain_mp4_hd_video.mp4?_=2  Fetal Circulation Oxygen is supplied from maternal blood (ie mum!) x x x Atrial Septal Defect Chapter 18, Cardiovascular System 46 Ventricular Septal Defect Chapter 18, Cardiovascular System 47 Patent Ductus Arteriosus (PDA) Practise Questions Flash Card: Anatomy of the Heart Tricuspid valve Muscle contraction Systole Purkinge fibers Systemic AV node Myocytes circuit SA node Pericardium Chordae Pulmonary circuit Tendinae Conduction Aorta Bundle of His system Vena Cava Septum ASD Pulmonary Ventricle veins Mitral Valve Pulmonary arteries Atria Semilunar valves Papillary Muscles VSD Diastole  ‘To Boldy Go… Up’ bbc programme – Kevin Fong http://www.bbc.co.uk/programmes/p00n 2r93 ‘To Boldy Go… Down’ http://www.youtube.com/watch?v=zcLd1 uUBp4E