277777777777777777777777777777777. CVS.pptx

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1. Introduction to Cardiovascular System Israr Hussain Yousafzai BS (Anesthesia) CRT PGDRT MSPH Senior Respiratory Therapist, HMC Peshawar

2. Cardiovascular System CVS includes heart and blood vessels Heart pumps blood into the blood vessels Blood vessels circulate the blood throughout the body Blood transports nutrients and oxygen to the tissues Also, removes carbon dioxide and waste products from the tissues

3. Heart Heart is a muscular organ, situated in the mediastinum It is made up of four chambers , two atria and two ventricles Atria receive blood while ventricles distribute the blood The right side have deoxygenated blood while left have oxygenated blood The musculature of ventricles is thicker than that of atria Force of contraction of heart depends upon the muscles

4. Right Side of Heart Right atrium is a thin walled and low pressure chamber It has sinoatrial (SA) and atrioventricular (AV ) node It receives venous blood via two large veins i.e. Superior and inferior vena cava It communicate with right ventricle through tricuspid valve Walls of right ventricle is thick and receives blood from right atrium From the right ventricle, pulmonary trunk carries the venous blood to lungs In the lungs, the deoxygenated blood become oxygenated

5. Left Side of Heart Left atrium is a thin walled and low pressure chamber It receives oxygenated blood from the lungs through four pulmonary veins Blood from left atrium enters the left ventricle through mitral valve Wall of the left ventricle is very thick Left ventricle pumps blood to different parts of the body through systemic aorta

6. Septa of Heart Right and left atria are separated by a fibrous septum called interatrial septum Right and left ventricles are separated from one another by interventricular septum The upper part of this septum is a membranous, whereas the lower part is muscular in nature

7. Layers of Heart Heart is made up of three layers: Outer pericardium Middle myocardium Inner endocardium Pericardium is made up of two layers Outer parietal pericardium Inner visceral pericardium/ epicardium The space between the two layers is called pericardial cavity or space and contains a thin film of fluid

8. Myocardium It is formed by cardiac muscle fibers or cardiac myocytes Myocardium forms the bulk of the heart and it is responsible for pumping Myocardium has three types of muscle fibers Muscle fibers which form contractile unit of heart Muscle fibers which form pacemaker Muscle fibers which form conductive system

9. Myocardium These are striated and resemble the skeletal muscle in structure But, it is branched It is bound by sarcolemma having central nucleus Sarcomere have all the contractile proteins Neighboring fibers are fused by a tough double membranous structure, that form junction called intercalated disk At the sides, the membranes of the adjacent muscle fibers fuse together to form gap junctions

10. Myocardium It is permeable to ions and it facilitates the rapid conduction of action potential from one fiber to another Because of this, all the cardiac muscle fibers act like a single unit, called syncytium i.e. atrial and ventricular Some of the muscle fibers are modified into a specialized structure known as pacemaker having less striation Pacemaker generates the impulses for heart beat It is formed by pacemaker cells called P cells ( Sinoatrial (SA) node)

11. Valves o f Heart Valves permit the flow of blood in only one direction Two atrioventricular valves Bicuspid valve Tricuspid valve Cusps of the valves are attached to papillary muscles by means of chordae tendineae Two semilunar valves Aortic valve Pulmonary valve Semilunar valves are made up of three flaps

12. Actions Of Heart Bathmotropism - excitability of cardiac muscle Dromotropism - conduction of impulse Inotropism - Force of contraction Chronotropism - frequency of heartbeat All the actions are regulated by stimulation of nerves supplying or some hormones

13. Blood Vessels Vessels are: Aorta Arteries Arterioles Capillaries Venules Veins Venae cavae

14. Arterial System Walls of the arterial system are formed by three layers: Outer tunica adventitia- connective tissue layer Middle tunica media- smooth muscles Inner tunica intima- endothelium It have two laminae of elastic tissues: External elastic lamina- adventitia and media Internal elastic lamina- media and intima Aorta and arteries have more elastic tissues and the arterioles have more smooth muscles

15. Arterial System Arterial branches become narrower and walls become thinner while reaching the periphery as: Aortic diameter = 25 mm Diameter of end arteries = 4 mm Diameter of ends arterioles = 10 µ Resistance is offered to blood flow in the arterioles and are called resistant vessels Arterioles are continued as capillaries, which are small, thin walled having a diameter of about 5 to 8 µ The exchange of materials between the blood and the tissues occurs through capillaries

16. Venous System From the capillaries, venous system starts as it end on venules Venules are smaller and thinner than the arterioles At a time, a large quantity of blood is held in venules and are called capacitance vessels Venules are continued as veins, that form venae cavae The elastic tissue is less but the smooth muscle fibers are more

17. Circulations Systemic circulation/ greater circulation Oxygenated blood pumped from left ventricle passes through arterial system and reaches the tissues Exchange of various substances between blood and the tissues occurs at the capillaries After that blood enters the venous system and returns to right atrium of the heart Pulmonary circulation/ called lesser circulation Blood is pumped from right ventricle to lungs through pulmonary artery Exchange of gases occurs between blood and alveoli at pulmonary capillaries Oxygenated blood returns to left atrium through the pulmonary veins