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Phase 1A Jono Wells Rizwan Malatagar

CARDIOVASCULAR SYSTEM: Anatomy, physiology, pathology and clinical problems. Phase 1A Jono Wells Rizwan Malatagar. The Peer Teaching Society is not liable for false or misleading information…. introduction. First half – 25mins on anatomy and physiology

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Phase 1A Jono Wells Rizwan Malatagar

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  1. CARDIOVASCULAR SYSTEM:Anatomy, physiology, pathology and clinical problems Phase 1A Jono Wells Rizwan Malatagar The Peer Teaching Society is not liable for false or misleading information…

  2. introduction • First half – 25mins on anatomy and physiology • Second half – 25mins on pathology and clinical applications • Last 5mins – questions and quiz sheets. The Peer Teaching Society is not liable for false or misleading information…

  3. Learning aims: CV system • Know what it is, how it works, how it goes wrong and how to recognise when it does. • Not comprehensive! • Emphasis on understanding principles then applying these to work out signs and symptoms of disease • Know your definitions • Generally doesn’t cover management • Quiz sheet based on the kind of questions in Phase 1A exams. The Peer Teaching Society is not liable for false or misleading information…

  4. Cardiovascular Anatomy Basics: • What is the function of the heart? • Distributing O2 and nutrients to all body tissues • Transportation of CO2 and metabolic waste products (eg. urea) away from the tissues • Distribution of water, electrolytes and hormones • Immune support • Thermoregulation The Peer Teaching Society is not liable for false or misleading information…

  5. Cardiovascular Anatomy The Peer Teaching Society is not liable for false or misleading information…

  6. Location of the Heart • Posterior to the sternum • Medial to the lungs • Anterior to vertebral column • Base lies beneath 2nd rib • Apex at 5th intercostal space • Lies upon diaphragm The Peer Teaching Society is not liable for false or misleading information…

  7. Clinical Relevance The Peer Teaching Society is not liable for false or misleading information…

  8. Heart coverings • Pericardium • Loose fitting double layered sac • Fibrous + Serous • Visceral Pericardium • membrane on the surface of the heart • Parietal Pericardium • secretes pericardial fluid Serous Pericardium The Peer Teaching Society is not liable for false or misleading information…

  9. Coronary Circulation • 2 main arteries R and L • Both arteries originate directly above the aortic valve The Peer Teaching Society is not liable for false or misleading information…

  10. Nervous supply • Sympathetic: • Cervical and upper thoracic portions of sympathetic trunks • +ve chronotropic, +ve inotropic, dilatatory • Norepinephrine/Epinephrine • Parasympathetic: • Branches of the vagus • -ve inotropic, -ve chronotropic, constrictory • Acetylcholine The Peer Teaching Society is not liable for false or misleading information…

  11. Embryology • Not going to cover embryology in this lecture; but worth looking over no matter how boring it may seem!! The Peer Teaching Society is not liable for false or misleading information…

  12. Blood Vessels • Three main types • Arteries • Veins • Capillaries The Peer Teaching Society is not liable for false or misleading information…

  13. Blood Vessels • Function relates to form The Peer Teaching Society is not liable for false or misleading information…

  14. Histology of Blood Vessels The Peer Teaching Society is not liable for false or misleading information…

  15. Cardiac conduction • Controlled by the SA node • Depolarisation spreads through adjacent atria causing atrial systole • AV node limits the depolarisation • Continues through bundle of His • Purkinje fibres distribute impulse to cells in endocardium • Impulse spread through the epicardium The Peer Teaching Society is not liable for false or misleading information…

  16. Cardiac conduction The Peer Teaching Society is not liable for false or misleading information…

  17. Cardiac conduction The Peer Teaching Society is not liable for false or misleading information…

  18. Cardiovascular physiology • Involuntary, striated muscle • Cardiac contraction controlled by calcium concentration • When Ca rises, the cardiac muscle contracts and when it falls the cardiac muscle relaxes The Peer Teaching Society is not liable for false or misleading information…

  19. Cardiovascular physiology Energized cross-bridge binds to actin Cross-bridge moves ATP binds to myosin → cross bridge detaches Hydrolysis of ATP → cross-bridge becomes energized The Peer Teaching Society is not liable for false or misleading information…

  20. Cardiac muscle contraction • Three types of Troponin:- • C: Ca binds to C make a conformational change to Troponin I • T: binds to tropomyosin to form troponin-tropomyosin complex • I: binds to actin to hold the tropomyosin-troponin complexes in place The Peer Teaching Society is not liable for false or misleading information…

  21. Cardiac Cycle • Isovolumic Contraction: • Ventricular pressure>atrial pressure • Causing AV valves close • Approximately 0.9 seconds • Diastole: • Passive filling of the ventricles • AV valves open • Semi lunar valves closed • Isovolumic Relaxation: • Both valves closed • When ventricular pressure<atrial pressure; AV valves open Systole: Ventricular pressure>atrial pressure Semilunar valves open The Peer Teaching Society is not liable for false or misleading information…

  22. Cardiac Cycle The Peer Teaching Society is not liable for false or misleading information…

  23. ECG representation QRS complex = ventricular contraction T wave = ventricular relaxation P wave = atrial contraction The Peer Teaching Society is not liable for false or misleading information…

  24. Regulation of MAP MAP = CO X TPR The Peer Teaching Society is not liable for false or misleading information…

  25. Cardiac output CO = HR X SV mL/min Beats/min mL/beat The Peer Teaching Society is not liable for false or misleading information…

  26. Baroreceptors • What are Baroreceptors? • Located in the carotid sinus and aortic arch • Respond to the stretch of the vessel wall • Impulse carried to medulla • Increases parasympathetic drive: decreases sympathetic drive • Decreases HR and decreases BP The Peer Teaching Society is not liable for false or misleading information…

  27. Chemoreceptors • Located in carotid and aortic bodies • Hypercapnia/hypoxia/acidosis increases excitation • Increased excitation = vasoconstriction + bradycardia The Peer Teaching Society is not liable for false or misleading information…

  28. Stroke volume • “stroke volume of the heart increases in response to the volume of blood filling the heart (end diastolic volume)” – Starling’s law • Preload: force associated with the degree of initial stretch in the ventricle from initial volume load • Contractility: Ability of the heart to contract independently of the afterload and preload The Peer Teaching Society is not liable for false or misleading information…

  29. Total peripheral resistance • Increased TPR = decreased venous return + decreased stroke volume • Control: • Sympathetic nervous system (vasoconstriction) • Hormonal control: The Peer Teaching Society is not liable for false or misleading information…

  30. Cardiovascular pathology • Atherosclerosis • Thromboembolism • Shock • Heart failure • Arrhythmia The Peer Teaching Society is not liable for false or misleading information…

  31. Atherosclerosis - definitions • Arteriosclerosis - thickening and hardening of arteries. • Atherosclerosis – the process leading to arteriosclerosis where atheroma forms. • Arteriolosclerosis – arteriosclerosis of the small vessels. Mainly caused by HTN. The Peer Teaching Society is not liable for false or misleading information…

  32. Atherosclerosis – risk factors • Constitutional • Environmental • Lifestyle The Peer Teaching Society is not liable for false or misleading information…

  33. Atherosclerosis - process The Peer Teaching Society is not liable for false or misleading information…

  34. 1. Endothelial injury The Peer Teaching Society is not liable for false or misleading information…

  35. 2. Fatty streak The Peer Teaching Society is not liable for false or misleading information…

  36. 3. Bulge The Peer Teaching Society is not liable for false or misleading information…

  37. 4. Fibrous cap The Peer Teaching Society is not liable for false or misleading information…

  38. Atherosclerosis - outcomes • Narrowed lumen • Occlusion • Emboli – fragmentation of plaque • Aneurysm – due to loss of elasticity • Learn examples of each. The Peer Teaching Society is not liable for false or misleading information…

  39. Thromboembolism • Virchow’s triad – stasis, hypercoagulability and endothelial injury The Peer Teaching Society is not liable for false or misleading information…

  40. Thromboembolism • Virchow’s triad – stasis, hypercoagulability and endothelial injury • Thrombosis = inappropriate coagulation of blood inside a vessel • In veins it’s fibrin rich due to low pressure, in arteries they’re platelet rich e.g. atheroma. • Main clinical problems are DVT and PE. The Peer Teaching Society is not liable for false or misleading information…

  41. DVT • Where? • Affects deep veins e.g. femoral, popliteal • Presentation? • Pain, swelling, redness and possibly distended superficial veins and distal proximal oedema • Treat with anticoagulation • May also present as pulmonary embolism The Peer Teaching Society is not liable for false or misleading information…

  42. SHOCK! • Definition – an acute failure of the cardiovascular system to perfuse the tissues of the body. • 4 main types: • Hypovolaemic • Distributive • Cardiogenic • Obstructive The Peer Teaching Society is not liable for false or misleading information…

  43. Shock – symptoms and signs Rapid, shallow breathing Faintness, light headedness, dizziness Reduced level of consciousness Skin: Sweating + pallor. Cold Rapid, weak pulse Muscle weakness Oliguria Intravascular compartment potential volume Low end organ perfusion The Peer Teaching Society is not liable for false or misleading information…

  44. Hypovolaemic shock • External fluid loss • Internal fluid loss • What causes these? The Peer Teaching Society is not liable for false or misleading information…

  45. Distributive shock • Total fluid volume is the same, it’s just maldistributed. • Origin: septic or anaphylactic. • Septic – exotoxins released from bacteria or endotoxins released when they die • Anaphylactic • Inflammatory mediators • Peripheral vasodilatation, increased vascular permeability and bronchoconstriction The Peer Teaching Society is not liable for false or misleading information…

  46. Cardiogenic shock • Pump failure – the heart isn’t pumping adequately to maintain the circulation e.g. arrhythmia, MI or myocarditis. • Usually an acute presentation but can occur due to worsening heart failure. The Peer Teaching Society is not liable for false or misleading information…

  47. Obstructive shock • Direct outflow obstruction -> pressure on the heart or vessels leading to inadequate end organ perfusion. • Extrinsic compression – cardiac tamponade or tension pneumothorax • Intrinsic obstruction– Pulmonary embolism The Peer Teaching Society is not liable for false or misleading information…

  48. Heart failure • ‘A Syndrome of heart insufficiency’. It is failure of the heart to deliver oxygenated blood at the rate needed by metabolising tissues. • Commonest cause is myocardial ischaemia. • Other causes include • Pressure overload • Volume overload • Primary myocardial disease The Peer Teaching Society is not liable for false or misleading information…

  49. Changes in circulation • The myocardial failure leads to decreased CO and Starling’s law is impaired. • Laplace’s law means that as heart muscle dilates, the myocytes require more energy to increase tension. • Compensation due to sympathetic and renal system. • Both relate to angiotensin II. The Peer Teaching Society is not liable for false or misleading information…

  50. Heart failure • Commonest symptoms – SOB, fatigue, ankle oedema • Specific signs – raised JVP, displaced apex beat • Heart failure can be right sided, left sided or mixed. • Clinical features of either right or left relate to what’s behind that side in the vascular system. • Also get a functional regurgitation murmur. The Peer Teaching Society is not liable for false or misleading information…

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