GAF, FPP Wk12, Lect1, Cardio Vascular System Anatomy, 23.pptx

Foundations for Physiotherapy Practice 2023-24 Lecture 1 Structure and function of the CardioVascular System (CVS) UH FPP Wk 12 2023-24 Learning Outcomes By the end of this lecture and the appropriate independent study the successful student should be able to: • Describe the structure of the hear...

Foundations for Physiotherapy Practice 2023-24 Lecture 1 Structure and function of the CardioVascular System (CVS) UH FPP Wk 12 2023-24 Learning Outcomes By the end of this lecture and the appropriate independent study the successful student should be able to: • Describe the structure of the heart • Describe the structure and function of the blood vessels • Describe the mechanism of the heart muscle contraction UH FPP Wk 12 2023-24 Compon ent Heart What What What do do we we do we mean by by the mean mean the CVS? CVS? by the CVS? Blood vessels Blood Function/activity - Size of a fist weighs around 300g - Beats around 100,00 times a day and around 3,000 million (3 billion) times in a lifetime! - Arterial system - Capillary network - Venous system - Different constituents UH FPP Wk 12 2023-24 Location of Locati the heart on of the heart UH FPP Wk 12 2023-24 Task 1 • In groups: • Draw and label the structure of the heart • Draw the path the blood takes through the heart UH FPP Wk 12 2023-24 Structure of Structur the Heart e of the Heart UH FPP Wk 12 2023-24 The Pericardium • The heart is surrounded by a sac of fluid contained within the pericardium UH FPP Wk 12 2023-24 The innermost layer of tissue that lines the chambers of the heart. A very fine layer of squamous epithelium resting on a thin layer of connective tissue Lines the myocardium and valves Continuous with the endothelium of the blood vessels If it becomes damaged there is a risk of thrombus formation The endocardium also provides protection to the valves and heart chambers UH FPP Wk 12 2023-24 The Endocardiu m The Myocardium (Heart Muscle) • Cardiac muscle: striated like skeletal muscle BUT with features of smooth muscle • Muscle fibres are aligned in a way so that when they contract the chambers get smaller • Junctions between the muscle cells allow the muscle to contract as a single unit • Mitochondria much larger so the fibres are far more fatigue resistance (10x the size compared with skeletal muscle) and contain about 5000 mitochondria per cell • Left ventricle much thicker than the right – why? UH FPP Wk 12 2023-24 • Action potential initiated within the heart by autorhythmic cells which are specialised muscle cells that create minimal contraction, but which spontaneously generate action potentials, they act either as: • Pacemaker cells which generate an action potential and so establish the heart rhythm or • Conducting fibres which transmit these action potentials (AV bundle, R+L bundle branches, Purkinje fibres) • Basic rate is 80-100 bpm • No external innervation required but the basic rate is reduced to 60-80 by parasympathetic NS UH FPP Wk 12 2023-24 Specialis ed Function of Heart Muscle Valves • All have three leaflets except the bicuspid which has ………??  two leaflets • Atrioventricular valves • Between the …….. ??  chordae tendinae  papillary muscles • Semilunar valves • Location ……….. ??  Aorta  Pulmonary artery http://www.nlm.nih.gov/medlineplus/ency/imagepages/ 18093.htm UH FPP Wk 12 2023-24 Valves Valv es UH FPP Wk 12 2023-24 Action of the AtrioVentricular Valve Chordae tendinae Papillary muscle (contracted to prevent valve cusps billowing into the atria) Papillary muscle (relaxed) UH FPP Wk 12 2023-24 Action of the Semilunar Valves cusps up, valve open during systole cusps down, valve closed during diastole UH FPP Wk 12 2023-24 Heart muscle contraction mechanisms • 2 Phases • Diastole - the phase of the heartbeat when the heart muscle relaxes and allows the chambers to fill with blood. • Systole - the phase of the heartbeat when the heart muscle contracts and pumps blood from the chambers into the arteries UH FPP Wk 12 2023-24 Mechanical Events • Diastole comprises of 3 phases (4+1)  Isovolumetric ventricular relaxation - all valves are shut  Ventricular filling - atria relaxed with the AV valves open and the Semilunar valves shut  Ventricular filling - atria contract to ‘top them up’ again, with the AV valves open and the Semilunar valves still closed • Systole comprises of 2 phases (2+3)  Isovolumetric ventricular contraction - both the AV and the Semilunar valves are shut UH FPP Wk 12 2023-24 Mechanical Events cont…. UH FPP Wk 12 2023-24 The Coronary Circulation (The Hearts Blood Supply) • Left and right coronary arteries - Arise from the Aortic sinus above aortic semilunar valve - All supply different areas of the heart muscle, valves and conducting system • Coronary sinus - Cardiac veins return blood to coronary sinus to the Right Atrium UH FPP Wk 12 2023-24 Coronary System • Flow mainly in diastole  The intramuscular blood vessels are ‘less compressed’ during myocardial relaxation -diastole UH FPP Wk 12 2023-24 Vasculature • Arteries/arterioles:  carry blood away from heart Blood Vessels • • Veins/venules  carry blood to the heart Capillaries  site of exchange of gases and nutrients etc. with the tissues The CVS is a ‘closed system’ to all intense purposes UH FPP Wk 12 2023-24 Arterial System Arterial System •Arteries • Larger arteries contain large amounts of • Arteries arteries tissue that are able to elastic• Larger and fibrous • contain large amounts of elastic and fibrous withstand high pressure tissue that are able to withstand high pressure As arteries become smaller the amount of elastic • As arteries become smaller theincreases amount tissue decreases and smooth muscle • Arterial system behaves as a pressure reservoir of elastic tissue decreases and smooth • when stretched the elastic forces are stored until diastole, the arterial walls then recoil muscle increases • passively, propelling blood forward and enabling continuous so maintaining • Arterial system behavesflow asand a pressure blood pressure (but at a lesser pressure than during systole) reservoir when stretched the elastic forces are stored until diastole, the arterial walls then recoil passively, propelling blood forward and enabling continuous flow and so maintaining blood pressure (but at a UH FPP Wk 12 2023-24 A single layer of endothelial cell and basement membrane Smallest and thinnest walled - 5 ~10 micromillimetre (10-6 meters) in diameter and to 0.5 micromillimetre wall thickness Primary site for material exchange Sometimes called the microcirculation UH FPP Wk 12 2023-24 Capillari es Venules Venous Venus System System Veins Serve as a volume reservoir for the ventricle s of heart • Walls thinner, than arterioles - very little smooth muscle • Smaller in size than arterioles ~ 20microm diameter • Same size as arteries, but bigger internal diameter ~ 5mm; wall thickness only 0.5microm • Valves present in peripheral veins - but… not in central veins (inside the thoracic cavity) • termed Capacitance vessels • also sensitive to autonomic nervous system input and various electrolytes UH FPP Wk 12 2023-24 Valves in the Veins Valves in the Veins • Serves to prevent blood going • Serve to prevent blood going backwards. backwards. • Assisted by the muscles acting as a pump •surrounding Assisted by the surrounding muscles acting as a pump UH FPP Wk 12 2023-24 Summary of Structural Characteri stics of Blood Vessels UH FPP Wk 12 2023-24 Why do we need vessels? UH FPP Wk 12 2023-24 Composed of: • Plasma Blood : around 5 Litres (70-75 ml/kg +/10ml) • made up of water, proteins, nutrients (glucose, lipids, amino acids), metabolic waste products, gases and electrolytes • Cells • Red blood cells (erythrocytes) containing haemoglobin • White blood cells (leucocytes) involved in the defence mechanisms of the body • Neutrophils, eosinophils, basophils, monocytes and lymphocytes • Platelets • cell fragments from bone marrow that are vital for clotting UH FPP Wk 12 2023-24 Summary • The anatomical structure of the heart • The heart valves • Pericardium, Endocardium and Myocardium • The coronary blood supply • Properties of vessels • Mechanical events of the heart (contraction / relaxation) UH FPP Wk 12 2023-24 Thank you for listening & participating Any Comments or Questions ?? UH FPP Wk 12 2023-24 Bibliography Fox, S. I. (2009). Human physiology. (11th ed.). Boston: McGraw Hill Higher Education. Marieb, E. N. (2004). Human anatomy and physiology. (6th ed.). Pearson Benjamin Cummings. San Francisco: London. Martini, F. H. (2006). Fundamentals of anatomy and physiology. (7th ed.). San Francisco: Pearson Benjamin Cummings. Stanfield, C. L. & Germann, W. J. (2008). Principles of human physiology. (3rd ed.). San Francisco: Pearson Benjamin Cummings. Thibodeau, G. A. & Patton, K. T. (2007). Anatomy and physiology. (6th ed.). St Louis, Missouri: Mosby Elsevier. Widmaier, E. P., Raff, H. & Strang. K.Y. (2006). Vander’s human physiology: The mechanisms of body function. (10th ed.). Boston: McGraw Hill. UH FPP Wk 12 2023-24