THE CARDIOVARSICULAR SYSTEM (CVS) _THE HEART.pptx

Powerpoint

1. THE CARDIOVASCULAR SYSTEM Gladson Monjeza- MPH, BSc HSEd , Clin Med. 15 th May , 2024

2. Introduction Three essential components; The Heart Blood vessels Blood

3. Introduction,,, cont'd The function of the circulatory system is to deliver; Oxygen Nutrients Other substances to all body’s cells Remove waste products of cellular metabolism ,,,,,, achieved by a complex array of tubing (blood vessels) connected to a pump (the heart)

4. Introduction,,, cont'd The heart pumps blood continuously through Blood vessels (with cooperation from other systems) ,,,,,,,,,,,,,nervous and endocrine systems (intrinsic regulators of the heart and blood vessels)

5. Note Nutrients are supplied by the digestive system Oxygen is supplied by the respiratory system Gaseous wastes of cellular metabolism are exhaled by the lungs Other wastes are removed by the kidneys

6. The HEART It is about the size of the fist Lies obliquely (diagonally) in the mediastinum Located on the left of the breast bone an area above the diaphragm between the lungs

7. The HEART

8. Heart structures Described in 3 general categories of function 1. Structural support of heart tissues and circulation of pulmonary and systemic blood through the heart The heart wall and the fibrous skeleton (enclose and support the heart/divide it into 4 chambers) The valves that directs the flow through the chambers The great vessels that conduct blood to and from the heart

9. Heart structures,,,, 2. Maintenance of the heart cells Comprises vessels of the coronary circulation arteries and veins that serve the metabolic needs of the heart cells & lymphatic vessels of the heart)

10. Heart structures,,,,, 3. Stimulation and control of heart action The nerves and specialized muscle cells that; ,,,,,,direct the rhythmic contraction and relaxation of the heart muscles ,,,,,,,propelling blood throughout the pulmonary and systemic circulation systems

11. The Heart Wall (Layers of the Heart) Has 3 main layers 1. Pericardium Contains 2 layers; Parietal (fibrous) and visceral (serous) pericardia The visceral layer is also called the epicardium The layers are separated by a fluid containing space (pericardial cavity) ,,,,,,contains pericardial fluid (10-30mls) ,,,,,,secreted by cells of mesothelium,,,,, lubricates the membranes lining the pericardial cavity

12. The Heart Wall,,,,, Layers of the Heart Functions of the pericardium; Prevents displacement of the heart during gravitational acceleration or deceleration Serves as a physical barrier that protects the heart against infection and inflammation from the lungs and pleural space Contains pain receptors and mechanoreceptors to elicit reflex changes in blood pressure and heart rate

13. The Heart Wall,,,,, Layers of the Heart 2. Myocardium Thickest layer of the heart wall Composed of cardiac muscle Anchored to the heart’s fibrous skeleton Myocardial cells provide the contractile force needed for blood to flow through the heart ,,,,,,and into the pulmonary and systemic circulations

14. The Heart Wall,,,,, Layers of the Heart 3. Endocardium Internal lining of the myocardium Contains connective tissues and squamous cells ,,,,,the lining is continuous with the endothelium that lines all the arteries, veins and capillaries ,,,,,,,,,,,,creating a continuous closed circulatory system

15. Chambers of the Heart Has 4 chambers Left atrium Right atrium Right ventricle Left ventricle Hollow fibrous tissues covered in muscle fibres Right and left heart is separated by the septum membrane

16. Chambers of the Heart Have 4 valves that support the work of the chambers Tricuspid Pulmonary Mitral (bicuspid) Aortic

17. The Atria The atria are smaller than the ventricles and have thinner walls Located above the ventricles The atria are separated by interatrial septum Low pressure chambers Storage units Conduits for blood

18. The Right atrium Kick starts the action of the heart taking deoxygenated blood from all the body parts through superior and inferior venacava Right atrium takes blood into the Right ventricle through Tricuspid valve Right atrial pressure is between 2 to 8mmHg (average of 3mmHg)

19. The Left atrium Receives oxygenated blood from the lungs through pulmonary vein It is a reservoir of blood Passes it to the Left Ventricle through the Mitral valve Left atrial pressure is between 6 to 12mmHg (Average of 8mmHg)

20. The Ventricles The ventricles have a thicker myocardial layer and constitute much of the bulk of the heart Located below the Atria High pressure chambers Mean pulmonary arterial pressure = 12mmHg (10mmHg to 20mmHg) Mean systemic arterial pressure = 95mmHg (70 to 100mmHg)

21. The Right ventricle Right ventricle is shaped like a crescent or triangle like Enables a bellows-like action that efficiently ejects large volumes of blood Receives Deoxygenated blood from the Right artrium Pumps blood through pulmonary valve into pulmonary arteries to the lungs (low pressure pulmonary system) For oxygenation Mean pulmonary arterial pressure is 12mmHg (10mmHg to 20mmHg)

22. The Left ventricle Left ventricle is larger than the right ventricle is bullet shaped ,,,,,helping it to eject blood through a relatively large valve opening into the high pressure systemic circulation; thus to all parts of the body Left ventricle is thicker than the right ventricle Receives blood from the Left atrium through the Mitral valve Pumps blood to all parts of the body through the Aortic valve Mean Systemic Systolic pressure is 95mmHg (70mmHg to 100mmHg)

23. Note: Right and left sides of the heart are separated by the septal membrane; thus the interventricular septum ,,,,prevents blood from crossing over Indentations of the endocardium form valves ,,, that separate the atria from the ventricles ,,,,,ventricles from the ventricles ,,,,, from the aorta and pulmonary arteries

24. Fibrous Skeleton of the Heart Four rings of dense fibrous connective tissue provide a firm anchorage for attachment of; Aortic ring; for Aortic valve The pulmonary ring; for pulmonary valve The left fibrous ring; for bicuspid valve The right fibrus ring for Tricuspid valve The fibrous rings are adjacent and form central fibrous supporting structure ,,,,,termed annuli fibrosi cordis

25. The Valves of the Heart One way blood flow through the heart is ensured by the four heart valves These are; Tricuspid; located between the right atrium and the right ventricle Pulmonary; located between the right ventricle and the pulmonary artery Mitral; located between the left atrium and the left ventricle Aortic; located between the left ventricle and the aorta

26. The Valves of the Heart The right atrioventricular valve is called tricuspid valve The left atrioventricular valve is a bicuspid valve called the mitral valve The tricuspid and the mitral valves work as a unit The atrium, fibrous rings, valvular tissue, chordae tendineae, papillary muscles and ventricular walls are connected Collectively known as tricuspid and mitral complex ,,,,,,,,damage to one of these can alter functioning of the heart significantly

27. Blood Flow through the valves and the chambers One way blood flow through the heart is ensured by the four heart valves During ventricular relaxation Atrioventricular valves (Tricuspid and Mitral valves) When open Blood flows from the atria to the relaxed ventricles ,,,as the ventricles contract (increasing ventricular pressure) causes the valves to close To prevent back flow into the atria

28. Blood Flow through the valves and the chambers Semilunar valves of the heart (Aortic and pulmonary) When intraventricular pressure exceeds aortic and pulmonary pressures ,,,,,,blood flows out of the ventricles into the pulmonary and systemic circulations After ventricular contraction and ejection intraventricular pressure falls ,,,,,,pulmonic and aortic semilunar valves close preventing back flow ,,,,,,,,,,,,,,,,,,into the right and left ventricles

29. Blood Flow through the valves and the chambers The atrioventricular (mitral and tricuspid) valve openings are guarded by Flaps of tissue called leaflets or cusps ,,,,,attached to the papillary muscles by the chordae tendinae cordis The papillary muscles are extension of the myocardium,,,,pull the cups together and downward at the onset of ventricular contraction Preventing their backward expulsion into the atria

30. NOTE: Blood leaves the right ventricle through the pulmonic semilunar valve to the lungs Blood leaves the left ventricle through the aortic semilunar valve to the aorta and the systemic circulation

31. Blood Flow through the valves and the chambers Blood moves in and out of the heart through the several large blood vessels The right heart receives venous blood from systemic circulation through superior and inferior venae cavae ,,,,,,,which enter the right atrium

32. Blood Flow through the valves and the chambers Blood leaves the right ventricle, enters pulmonary circulation through pulmonary artery The artery divides into right and left branches ,,,,transport deoxygenated blood from the right heart to the right and left lungs Pulmonary arteries branch further into pulmonary capillary bed ,,,,where oxygen and carbon dioxide exchange occurs

33. Blood Flow through the valves and the chambers Four pulmonary veins (two from the right and two from the left lung); ,,,,,,carry oxygenated blood from the lungs to the left side of the heart Oxygenated blood moves through the left atrium and ventricle and out into the aorta ,,,,,,,,,, which delivers it to systemic vessels that supply the body

34. Structures that Support Cardiac Metabolism Blood within the heart chambers does not supply oxygen and other nutrients to the cells of the heart ,,,nourished by vessels of the systemic circulation Branch of the systemic circulation that supplies the heart is termed “coronary circulation” ,,,,,,,consists of the coronary arteries ,,,,,receives blood through openings of the aorta

35. Structures that Control Heart Action Continuous rhythmic repetitive cardia cycle (diastolic & systolic); depends on the transmission of electrical impulse,,,,,cardiac action potentials ,,,,,,,, through the myocardium Muscle fibers of the myocardium are uniquely joined ,,,,,,,so that action potentials pass from cell to cell rapidly and efficiently

36. Structures that Control Heart Action Myocardium has its own conduction system ,,,,,,,,specialized cells that enable it to generate and transmit action potential without stimulation from the nervous system ,,,,,,,these cells are concentrated at certain sites in the myocardium called the nodes Cardiac cycle is stimulated by these nodes of specialized cells NOTE: Although the heart is inneverted by the autonomic nervous system, neural impulses are not needed to maintain the cardiac cycle

37. End of presentation