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CARDIO-VASCULAR SYSTEM [CVS] FUNCTIONAL ANATOMY OF HEART

CARDIO-VASCULAR SYSTEM [CVS] FUNCTIONAL ANATOMY OF HEART. Lecture – 1 Dr. Zahoor Ali Shaikh. FUNCTIONAL ANATOMY OF HEART. Heart beat starts in the fourth week after conception during intra-uterine life, when embryo is only few millimeters.

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CARDIO-VASCULAR SYSTEM [CVS] FUNCTIONAL ANATOMY OF HEART

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  1. CARDIO-VASCULAR SYSTEM [CVS]FUNCTIONAL ANATOMY OF HEART Lecture – 1 Dr. Zahoor Ali Shaikh

  2. FUNCTIONAL ANATOMY OF HEART • Heart beat starts in the fourth week after conception during intra-uterine life, when embryo is only few millimeters. • Throughout life, heart keeps on beating and it contracts about 3 billion times during an average life span. • Adult heart is about 14cm long and 9cm wide.

  3. CIRCULATORY SYSTEM • Circulatory System has 3 basic components: 1. Heart – works as pump 2. Blood vessels – work as path, through which blood travels to body tissues and then returned to the heart. 3. Blood – it is transport medium for O2, CO2, nutrients, waste products, electrolytes and hormones.

  4. CIRCULATORY SYSTEM • We have two types of circulation: i). Pulmonary Circulation ii). Systemic Circulation • Pulmonary Circulation Blood is carried from the right ventricle of the heart to lungs and back to left atrium of the heart. • Systemic Circulation Blood is carried from left ventricle to the body and back to the right atrium.

  5. FUNCTIONAL ANATOMY OF HEART • Heart is muscular organ. It is involuntary, present in the middle of the thoracic cavity, about the size of fist [14cm long, 9cm wide]. • Sternum lies anteriorly and vertebral column [backbone] lies posteriorly and lungs laterally. • Heart has base and apex. - Base is at the top, behind the 2nd intercostal space. - Apex is lower down in the 5th left intercostal space.

  6. FUNCTIONAL ANATOMY OF HEART • Applied • As the heart lies between the sternum and vertebral column, it is possible to compress the sternum and drive blood out of the heart when heart is not pumping effectively. • This external compression of heart is done in CPR [Cardio-Pulmonary Resuscitation], which is life saving, till proper therapy can be given.

  7. HEART AS A PUMP • Heart is a single organ but right and left side of the heart work as two separate pumps. • Heart has four chambers: - Two Atria [single – atrium] - Two Ventricles • Atria receive blood and send to ventricles and ventricles pump the blood.

  8. HEART AS A PUMP • Right and left atrium are separated from each other by interatrial septum. • Right and Left ventricle are separated by interventricular septum. [Septum is muscular wall which does not allow the blood to mix between two sides.]

  9. HEART AS A PUMP • In between atria and ventricle, there is fibrous ring, in which valves are embedded. • Right atrium gets the blood from superior venaceva [SVC] and inferior venaceva [IVC].It is deoxygenated blood. • Blood from right atrium goes to right ventricle through right AV valve or Tricuspid valve.

  10. HEART AS A PUMP • From right ventricle, blood goes to pulmonary artery through pulmonary valve, to the lungs. • In the lungs, blood gets oxygenated and is returned to left atrium by 4 pulmonary veins. • IMPORTANT • Remember  Pulmonary Artery is the only artery which carries deoxygenated blood and Pulmonary veins are only veins in the body which carry oxygenated blood.

  11. HEART AS A PUMP • From left atrium, blood goes to left ventricle through left AV valve or mitral valve [bicuspid valve]. • From left ventricle, blood goes to aorta through aortic valve to the body.

  12. COMPARISON OF RIGHT & LEFT PUMPS RIGHT PUMP LEFT PUMP Both sides pump equal amount of blood. Right side has deoxygenated blood [goes to lungs and gets O2 in the lungs] . Pulmonary Circulation is low pressure circulation. Pulmonary Circulation is low resistance circulation. Right ventricle wall is thin [2-3mm]. Both sides pump equal amount of blood. Left side has oxygenated blood. Systemic Circulation is high pressure circulation. Systemic Circulation is high resistance circulation. Left ventricle wall is thick [8-10mm].

  13. HEART VALVES • There are four valves. • They are one way valve. • Valves open and close passively because of pressure difference. • Function of the valve is to prevent back flow of the blood.

  14. HEART VALVES • Four Valves are: Two AV [Atrioventricular] Valves i). Right AV Valve – Tricuspid Valve ii). Left AV Valve – Mitral or Bicuspid Valve Semi lunar Valves iii). Aortic Valve iv). Pulmonary Valve

  15. AV VALVES • AV Valves [Tricuspid & Mitral] are attached to the papillary muscle and chordae tendineae. • Chordae tendineae are tendon like tissue and their function is prevent the eversion or bulging of valves into atria. • Chordae tendineae are attached to papillary muscle which protrude from inner surface of ventricular valve. • Important -- Papillary muscle and chordae tendineae are attached to AV valves only.

  16. AV VALVES • When ventricle contract, papillary muscle also contract and pull down the chordae tendineae, which keeps the valve tightly closed. • There are three papillary muscles attached to the right AV valve [tricuspid valve]. • There are two papillary muscle attach to the left AV valve [bicuspid or mitral valve].

  17. SEMI-LUNAR VALVES • Aortic Valve and Pulmonary Valve • Aortic Valve is present at the beginning of aorta and has three cusps. • Pulmonary Valve is present at the beginning of pulmonary artery and has three cusps. • Aortic and Pulmonary Valve open when pressure increases in left and right ventricle during ventricular contraction. • They close when ventricular pressure decreases than aortic and pulmonary artery pressure. • They prevent back flow of the blood.

  18. FIBROUS SKELETON OF THE HEART • In between atria and ventricles, there is fibrous ring [it is dense connective tissue]. • It provides base for attachment of four heart valves. • Atrial Muscle is attached to upper part and ventricular muscle is attached to the bottom of the ring. • Fibrous ring is non-conductive, therefore, special conductive tissue is required to conduct impulse from atria to ventricle.

  19. LAYERS OF THE HEART • Heart has 3 Layers: 1. Endothelium – inner lining of the heart 2. Myocardium – cardiac muscle tissue 3. Pericardium – external layer • Pericardium has two layers inner visceral [called epicardium] and outer parietal layer. • There is pericardial fluid about 5 – 30 ml present between two layers. It prevents friction between the layers as they move over each other with every beat of the heart.

  20. APPLIED - PERICARDITIS • Pericarditis is the inflammation of pericardium. • It results in painful friction rub between the two layers of pericardium. • It can be caused by viral or bacterial infection.

  21. BLOOD SUPPLY TO THE HEART • Heart is supplied by coronary arteries [branches of aorta]. • Cardiac muscle fibers have rich blood supply, about 1 capillary for each myocardial fiber. • Cardiac muscle has abundance of energy generating mitochondria.

  22. AUTONOMIC NERVE SUPPLY • Heart is supplied by sympathetic and parasympathetic nerves. • Sympathetic Stimulation causes increased force of contraction [positive INOTROPIC effect] and increase heart rate [positive CHRONOTROPIC effect]. • Parasympathetic Stimulation decreased force of contraction [negative INOTROPIC effect] and decrease in heart rate [negative CHRONOTROPIC effect].

  23. CARDIAC MUSCLE MICROSCOPIC STRUCTURE • Cardiac Muscle fibers are connected by membrane called ‘INTERCALATED DISC’. • Intercalated Disc have gap junction. • Gap Junction allow relatively free diffusion of ions, therefore, action potential travels from one cell to another easily. • Therefore, cardiac muscle works as SYNCYTIUM [one unit], therefore, heart can be depolarized all at one time, it obeys all or none law.

  24. CARDIAC MUSCLE MICROSCOPIC STRUCTURE • We have Atrial Syncytium and Ventricular Syncytium. They contract as separate units as they are separated by non-conducting fibrous ring. • The impulse travels from the atria to the ventricle by specialized conductive tissue.

  25. APPLIED • Pericarditis • Pericardial Effusion • Valvular Lesions - Stenosis [Narrowing] - Incompetence • Mitral Valve Prolapse • ASD [Atrial Septal Defect] • VSD [Ventricular Septal Defect]

  26. WHAT YOU SHOULD KNOW FROM THIS LECTURE • Functional Anatomy of the Heart • Pulmonary and Systemic Circulation • Valves of the Heart • Layers of the Heart • Autonomic Nerve Supply- Inotropic and Chronotropic effect • Intercalated Disc, Gap Junctions – their function • Function of papillary muscle and chordae tendineae • Mitral valve Prolapse • Pericarditis, ASD, VSD

  27. Thank you

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