Cardiovascular System

1. Cardiovascular System

2. The cardiovascular sys is composed of heart and blood vessels • Circulates blood to supply oxygen and remove waste from body cells • Pulmonary circuit – sends oxygen-poor blood to lungs • Systemic circuit – sends oxygen-rich blood and nutrients to all body cells and removes wastes • Structure of Heart • About 14 cm long and 9cm wide • Enclosed in pericardium • Tough layer of dense connective tissue • Epicardium – protects heart by reducing friction, includes capillaries and nerve fibers, often contains fat

4. Myocardium – thickest layer, made of cardiac muscle • Endocardium – epithelium and connective tissue, lines the chambers of heart and valves • Coronary arteries – supply heart with blood • Cardiac veins – drain blood that has passed through capillaries of myocardium • Heart Chambers and Valves • 4 hollow chambers • Upper – right and left atrium • Lower – right and left ventricle • Major valves prevent blood from flowing the wrong direction • Tricuspid valve • Pulmonary valve • Mitral valve • Aortic valve

5. Path of Blood Flow

6. Blood from systemic circuit • Venaecavae and coronary sinus • Right atrium • Tricuspid valve • Right Ventricle • Pulmonary artery • Pulmonary trunk • Pulmonary arteries • Alveolar capillaries (lungs) • Pulmonary Veins • Left atrium • Mitral valve • Left ventricle • Aortic valve • Aorta • Blood to systemic circuit

7. Heart Actions • Systole – contract • Diastole – relax • Cardiac cycle – Atria contract/ventricles relax Ventricles relax/ atria contract • Heart Sounds • Lubb-dubb • Lubb - AV valves closing • Dubb – closing of pulmonary and aortic valves • Electrocardiogram – ECG records electrical changes in the myocardium during cardiac cycle

8. Blood Pressure • The force blood exerts against the inner walls of blood vessels • Arterial blood pressure • The made mainly by heart action; rises and falls with parts of cardiac cycle • Systolic pressure occurs when ventricle contracts; diastolic pressure is when ventricle relaxes • Expanding and recoiling of the arterial wall is what we detect as pulse • Upper number is systolic pressure, lower number is diastolic pressure

9. Blood Vessels • Arteries and arterioles • Adapted to carry blood under high pressure • Arterioles are branches of arteries • Arteries carry blood away from the heart • Arterial System • Branches of aorta • Ascending aorta – right and left coronary artery • Branches of aortic arch – brachiocephalic, left common carotid, left subclavian arteries • Descending aorta – throacic and abdominal groups • Subclavian and common carotid – to brain, head and neck

11. Capillaries • Connect arterioles and venules • Single layer of squamous epithelial cells that form semipermeable membrane • Gases, nutrients and metabolic by-products are exchanged between capillary blood and tissue fluid • Materials move through diffusion

12. Venules and veins • Venules continue from capillaries and merge to form veins • Veins carry blood to the heart • Many veins contain flaplike valves that open to allow blood to flow to the heart but close to prevent back flow • Venous System • Larger veins usually run parallel to major arteries • Veins from head, neck, and face – jugular; unite with subclavian veins to form brachiocephalic veins • Veins from upper limb and shoulder – sets of superficial and deep veins drain the upper limb • Digital veins drain into pairs of radial veins and ulnar veins which merge to form a pair of brachial veins

14. Lifespan Changes • Plaque build-up can begin early • Fibrous connective tissue and adipose tissue enlarge the heart by filling in when the number and size of cardiac muscle cells fall • Heart rate and output decline slightly with age • Blood pressure increases with age and resting heart rate decreases